| # ----------------------------------------------------------------------------- |
| # ply: yacc.py |
| # |
| # Copyright (C) 2001-2009, |
| # David M. Beazley (Dabeaz LLC) |
| # All rights reserved. |
| # |
| # Redistribution and use in source and binary forms, with or without |
| # modification, are permitted provided that the following conditions are |
| # met: |
| # |
| # * Redistributions of source code must retain the above copyright notice, |
| # this list of conditions and the following disclaimer. |
| # * Redistributions in binary form must reproduce the above copyright notice, |
| # this list of conditions and the following disclaimer in the documentation |
| # and/or other materials provided with the distribution. |
| # * Neither the name of the David Beazley or Dabeaz LLC may be used to |
| # endorse or promote products derived from this software without |
| # specific prior written permission. |
| # |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| # ----------------------------------------------------------------------------- |
| # |
| # This implements an LR parser that is constructed from grammar rules defined |
| # as Python functions. The grammer is specified by supplying the BNF inside |
| # Python documentation strings. The inspiration for this technique was borrowed |
| # from John Aycock's Spark parsing system. PLY might be viewed as cross between |
| # Spark and the GNU bison utility. |
| # |
| # The current implementation is only somewhat object-oriented. The |
| # LR parser itself is defined in terms of an object (which allows multiple |
| # parsers to co-exist). However, most of the variables used during table |
| # construction are defined in terms of global variables. Users shouldn't |
| # notice unless they are trying to define multiple parsers at the same |
| # time using threads (in which case they should have their head examined). |
| # |
| # This implementation supports both SLR and LALR(1) parsing. LALR(1) |
| # support was originally implemented by Elias Ioup (ezioup@alumni.uchicago.edu), |
| # using the algorithm found in Aho, Sethi, and Ullman "Compilers: Principles, |
| # Techniques, and Tools" (The Dragon Book). LALR(1) has since been replaced |
| # by the more efficient DeRemer and Pennello algorithm. |
| # |
| # :::::::: WARNING ::::::: |
| # |
| # Construction of LR parsing tables is fairly complicated and expensive. |
| # To make this module run fast, a *LOT* of work has been put into |
| # optimization---often at the expensive of readability and what might |
| # consider to be good Python "coding style." Modify the code at your |
| # own risk! |
| # ---------------------------------------------------------------------------- |
| |
| __version__ = "3.3" |
| __tabversion__ = "3.2" # Table version |
| |
| #----------------------------------------------------------------------------- |
| # === User configurable parameters === |
| # |
| # Change these to modify the default behavior of yacc (if you wish) |
| #----------------------------------------------------------------------------- |
| |
| yaccdebug = 0 # Debugging mode. If set, yacc generates a |
| # a 'parser.out' file in the current directory |
| |
| debug_file = 'parser.out' # Default name of the debugging file |
| tab_module = 'parsetab' # Default name of the table module |
| default_lr = 'LALR' # Default LR table generation method |
| |
| error_count = 3 # Number of symbols that must be shifted to leave recovery mode |
| |
| yaccdevel = 0 # Set to True if developing yacc. This turns off optimized |
| # implementations of certain functions. |
| |
| resultlimit = 40 # Size limit of results when running in debug mode. |
| |
| pickle_protocol = 0 # Protocol to use when writing pickle files |
| |
| import re, types, sys, os.path |
| |
| # Compatibility function for python 2.6/3.0 |
| if sys.version_info[0] < 3: |
| def func_code(f): |
| return f.func_code |
| else: |
| def func_code(f): |
| return f.__code__ |
| |
| # Compatibility |
| try: |
| MAXINT = sys.maxint |
| except AttributeError: |
| MAXINT = sys.maxsize |
| |
| # Python 2.x/3.0 compatibility. |
| def load_ply_lex(): |
| if sys.version_info[0] < 3: |
| import lex |
| else: |
| import ply.lex as lex |
| return lex |
| |
| # This object is a stand-in for a logging object created by the |
| # logging module. PLY will use this by default to create things |
| # such as the parser.out file. If a user wants more detailed |
| # information, they can create their own logging object and pass |
| # it into PLY. |
| |
| class PlyLogger(object): |
| def __init__(self,f): |
| self.f = f |
| def debug(self,msg,*args,**kwargs): |
| self.f.write((msg % args) + "\n") |
| info = debug |
| |
| def warning(self,msg,*args,**kwargs): |
| self.f.write("WARNING: "+ (msg % args) + "\n") |
| |
| def error(self,msg,*args,**kwargs): |
| self.f.write("ERROR: " + (msg % args) + "\n") |
| |
| critical = debug |
| |
| # Null logger is used when no output is generated. Does nothing. |
| class NullLogger(object): |
| def __getattribute__(self,name): |
| return self |
| def __call__(self,*args,**kwargs): |
| return self |
| |
| # Exception raised for yacc-related errors |
| class YaccError(Exception): pass |
| |
| # Format the result message that the parser produces when running in debug mode. |
| def format_result(r): |
| repr_str = repr(r) |
| if '\n' in repr_str: repr_str = repr(repr_str) |
| if len(repr_str) > resultlimit: |
| repr_str = repr_str[:resultlimit]+" ..." |
| result = "<%s @ 0x%x> (%s)" % (type(r).__name__,id(r),repr_str) |
| return result |
| |
| |
| # Format stack entries when the parser is running in debug mode |
| def format_stack_entry(r): |
| repr_str = repr(r) |
| if '\n' in repr_str: repr_str = repr(repr_str) |
| if len(repr_str) < 16: |
| return repr_str |
| else: |
| return "<%s @ 0x%x>" % (type(r).__name__,id(r)) |
| |
| #----------------------------------------------------------------------------- |
| # === LR Parsing Engine === |
| # |
| # The following classes are used for the LR parser itself. These are not |
| # used during table construction and are independent of the actual LR |
| # table generation algorithm |
| #----------------------------------------------------------------------------- |
| |
| # This class is used to hold non-terminal grammar symbols during parsing. |
| # It normally has the following attributes set: |
| # .type = Grammar symbol type |
| # .value = Symbol value |
| # .lineno = Starting line number |
| # .endlineno = Ending line number (optional, set automatically) |
| # .lexpos = Starting lex position |
| # .endlexpos = Ending lex position (optional, set automatically) |
| |
| class YaccSymbol: |
| def __str__(self): return self.type |
| def __repr__(self): return str(self) |
| |
| # This class is a wrapper around the objects actually passed to each |
| # grammar rule. Index lookup and assignment actually assign the |
| # .value attribute of the underlying YaccSymbol object. |
| # The lineno() method returns the line number of a given |
| # item (or 0 if not defined). The linespan() method returns |
| # a tuple of (startline,endline) representing the range of lines |
| # for a symbol. The lexspan() method returns a tuple (lexpos,endlexpos) |
| # representing the range of positional information for a symbol. |
| |
| class YaccProduction: |
| def __init__(self,s,stack=None): |
| self.slice = s |
| self.stack = stack |
| self.lexer = None |
| self.parser= None |
| def __getitem__(self,n): |
| if n >= 0: return self.slice[n].value |
| else: return self.stack[n].value |
| |
| def __setitem__(self,n,v): |
| self.slice[n].value = v |
| |
| def __getslice__(self,i,j): |
| return [s.value for s in self.slice[i:j]] |
| |
| def __len__(self): |
| return len(self.slice) |
| |
| def lineno(self,n): |
| return getattr(self.slice[n],"lineno",0) |
| |
| def set_lineno(self,n,lineno): |
| self.slice[n].lineno = lineno |
| |
| def linespan(self,n): |
| startline = getattr(self.slice[n],"lineno",0) |
| endline = getattr(self.slice[n],"endlineno",startline) |
| return startline,endline |
| |
| def lexpos(self,n): |
| return getattr(self.slice[n],"lexpos",0) |
| |
| def lexspan(self,n): |
| startpos = getattr(self.slice[n],"lexpos",0) |
| endpos = getattr(self.slice[n],"endlexpos",startpos) |
| return startpos,endpos |
| |
| def error(self): |
| raise SyntaxError |
| |
| |
| # ----------------------------------------------------------------------------- |
| # == LRParser == |
| # |
| # The LR Parsing engine. |
| # ----------------------------------------------------------------------------- |
| |
| class LRParser: |
| def __init__(self,lrtab,errorf): |
| self.productions = lrtab.lr_productions |
| self.action = lrtab.lr_action |
| self.goto = lrtab.lr_goto |
| self.errorfunc = errorf |
| |
| def errok(self): |
| self.errorok = 1 |
| |
| def restart(self): |
| del self.statestack[:] |
| del self.symstack[:] |
| sym = YaccSymbol() |
| sym.type = '$end' |
| self.symstack.append(sym) |
| self.statestack.append(0) |
| |
| def parse(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None): |
| if debug or yaccdevel: |
| if isinstance(debug,int): |
| debug = PlyLogger(sys.stderr) |
| return self.parsedebug(input,lexer,debug,tracking,tokenfunc) |
| elif tracking: |
| return self.parseopt(input,lexer,debug,tracking,tokenfunc) |
| else: |
| return self.parseopt_notrack(input,lexer,debug,tracking,tokenfunc) |
| |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # parsedebug(). |
| # |
| # This is the debugging enabled version of parse(). All changes made to the |
| # parsing engine should be made here. For the non-debugging version, |
| # copy this code to a method parseopt() and delete all of the sections |
| # enclosed in: |
| # |
| # #--! DEBUG |
| # statements |
| # #--! DEBUG |
| # |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| def parsedebug(self,input=None,lexer=None,debug=None,tracking=0,tokenfunc=None): |
| lookahead = None # Current lookahead symbol |
| lookaheadstack = [ ] # Stack of lookahead symbols |
| actions = self.action # Local reference to action table (to avoid lookup on self.) |
| goto = self.goto # Local reference to goto table (to avoid lookup on self.) |
| prod = self.productions # Local reference to production list (to avoid lookup on self.) |
| pslice = YaccProduction(None) # Production object passed to grammar rules |
| errorcount = 0 # Used during error recovery |
| |
| # --! DEBUG |
| debug.info("PLY: PARSE DEBUG START") |
| # --! DEBUG |
| |
| # If no lexer was given, we will try to use the lex module |
| if not lexer: |
| lex = load_ply_lex() |
| lexer = lex.lexer |
| |
| # Set up the lexer and parser objects on pslice |
| pslice.lexer = lexer |
| pslice.parser = self |
| |
| # If input was supplied, pass to lexer |
| if input is not None: |
| lexer.input(input) |
| |
| if tokenfunc is None: |
| # Tokenize function |
| get_token = lexer.token |
| else: |
| get_token = tokenfunc |
| |
| # Set up the state and symbol stacks |
| |
| statestack = [ ] # Stack of parsing states |
| self.statestack = statestack |
| symstack = [ ] # Stack of grammar symbols |
| self.symstack = symstack |
| |
| pslice.stack = symstack # Put in the production |
| errtoken = None # Err token |
| |
| # The start state is assumed to be (0,$end) |
| |
| statestack.append(0) |
| sym = YaccSymbol() |
| sym.type = "$end" |
| symstack.append(sym) |
| state = 0 |
| while 1: |
| # Get the next symbol on the input. If a lookahead symbol |
| # is already set, we just use that. Otherwise, we'll pull |
| # the next token off of the lookaheadstack or from the lexer |
| |
| # --! DEBUG |
| debug.debug('') |
| debug.debug('State : %s', state) |
| # --! DEBUG |
| |
| if not lookahead: |
| if not lookaheadstack: |
| lookahead = get_token() # Get the next token |
| else: |
| lookahead = lookaheadstack.pop() |
| if not lookahead: |
| lookahead = YaccSymbol() |
| lookahead.type = "$end" |
| |
| # --! DEBUG |
| debug.debug('Stack : %s', |
| ("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip()) |
| # --! DEBUG |
| |
| # Check the action table |
| ltype = lookahead.type |
| t = actions[state].get(ltype) |
| |
| if t is not None: |
| if t > 0: |
| # shift a symbol on the stack |
| statestack.append(t) |
| state = t |
| |
| # --! DEBUG |
| debug.debug("Action : Shift and goto state %s", t) |
| # --! DEBUG |
| |
| symstack.append(lookahead) |
| lookahead = None |
| |
| # Decrease error count on successful shift |
| if errorcount: errorcount -=1 |
| continue |
| |
| if t < 0: |
| # reduce a symbol on the stack, emit a production |
| p = prod[-t] |
| pname = p.name |
| plen = p.len |
| |
| # Get production function |
| sym = YaccSymbol() |
| sym.type = pname # Production name |
| sym.value = None |
| |
| # --! DEBUG |
| if plen: |
| debug.info("Action : Reduce rule [%s] with %s and goto state %d", p.str, "["+",".join([format_stack_entry(_v.value) for _v in symstack[-plen:]])+"]",-t) |
| else: |
| debug.info("Action : Reduce rule [%s] with %s and goto state %d", p.str, [],-t) |
| |
| # --! DEBUG |
| |
| if plen: |
| targ = symstack[-plen-1:] |
| targ[0] = sym |
| |
| # --! TRACKING |
| if tracking: |
| t1 = targ[1] |
| sym.lineno = t1.lineno |
| sym.lexpos = t1.lexpos |
| t1 = targ[-1] |
| sym.endlineno = getattr(t1,"endlineno",t1.lineno) |
| sym.endlexpos = getattr(t1,"endlexpos",t1.lexpos) |
| |
| # --! TRACKING |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # The code enclosed in this section is duplicated |
| # below as a performance optimization. Make sure |
| # changes get made in both locations. |
| |
| pslice.slice = targ |
| |
| try: |
| # Call the grammar rule with our special slice object |
| del symstack[-plen:] |
| del statestack[-plen:] |
| p.callable(pslice) |
| # --! DEBUG |
| debug.info("Result : %s", format_result(pslice[0])) |
| # --! DEBUG |
| symstack.append(sym) |
| state = goto[statestack[-1]][pname] |
| statestack.append(state) |
| except SyntaxError: |
| # If an error was set. Enter error recovery state |
| lookaheadstack.append(lookahead) |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] |
| sym.type = 'error' |
| lookahead = sym |
| errorcount = error_count |
| self.errorok = 0 |
| continue |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| else: |
| |
| # --! TRACKING |
| if tracking: |
| sym.lineno = lexer.lineno |
| sym.lexpos = lexer.lexpos |
| # --! TRACKING |
| |
| targ = [ sym ] |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # The code enclosed in this section is duplicated |
| # above as a performance optimization. Make sure |
| # changes get made in both locations. |
| |
| pslice.slice = targ |
| |
| try: |
| # Call the grammar rule with our special slice object |
| p.callable(pslice) |
| # --! DEBUG |
| debug.info("Result : %s", format_result(pslice[0])) |
| # --! DEBUG |
| symstack.append(sym) |
| state = goto[statestack[-1]][pname] |
| statestack.append(state) |
| except SyntaxError: |
| # If an error was set. Enter error recovery state |
| lookaheadstack.append(lookahead) |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] |
| sym.type = 'error' |
| lookahead = sym |
| errorcount = error_count |
| self.errorok = 0 |
| continue |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| if t == 0: |
| n = symstack[-1] |
| result = getattr(n,"value",None) |
| # --! DEBUG |
| debug.info("Done : Returning %s", format_result(result)) |
| debug.info("PLY: PARSE DEBUG END") |
| # --! DEBUG |
| return result |
| |
| if t == None: |
| |
| # --! DEBUG |
| debug.error('Error : %s', |
| ("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip()) |
| # --! DEBUG |
| |
| # We have some kind of parsing error here. To handle |
| # this, we are going to push the current token onto |
| # the tokenstack and replace it with an 'error' token. |
| # If there are any synchronization rules, they may |
| # catch it. |
| # |
| # In addition to pushing the error token, we call call |
| # the user defined p_error() function if this is the |
| # first syntax error. This function is only called if |
| # errorcount == 0. |
| if errorcount == 0 or self.errorok: |
| errorcount = error_count |
| self.errorok = 0 |
| errtoken = lookahead |
| if errtoken.type == "$end": |
| errtoken = None # End of file! |
| if self.errorfunc: |
| global errok,token,restart |
| errok = self.errok # Set some special functions available in error recovery |
| token = get_token |
| restart = self.restart |
| if errtoken and not hasattr(errtoken,'lexer'): |
| errtoken.lexer = lexer |
| tok = self.errorfunc(errtoken) |
| del errok, token, restart # Delete special functions |
| |
| if self.errorok: |
| # User must have done some kind of panic |
| # mode recovery on their own. The |
| # returned token is the next lookahead |
| lookahead = tok |
| errtoken = None |
| continue |
| else: |
| if errtoken: |
| if hasattr(errtoken,"lineno"): lineno = lookahead.lineno |
| else: lineno = 0 |
| if lineno: |
| sys.stderr.write("yacc: Syntax error at line %d, token=%s\n" % (lineno, errtoken.type)) |
| else: |
| sys.stderr.write("yacc: Syntax error, token=%s" % errtoken.type) |
| else: |
| sys.stderr.write("yacc: Parse error in input. EOF\n") |
| return |
| |
| else: |
| errorcount = error_count |
| |
| # case 1: the statestack only has 1 entry on it. If we're in this state, the |
| # entire parse has been rolled back and we're completely hosed. The token is |
| # discarded and we just keep going. |
| |
| if len(statestack) <= 1 and lookahead.type != "$end": |
| lookahead = None |
| errtoken = None |
| state = 0 |
| # Nuke the pushback stack |
| del lookaheadstack[:] |
| continue |
| |
| # case 2: the statestack has a couple of entries on it, but we're |
| # at the end of the file. nuke the top entry and generate an error token |
| |
| # Start nuking entries on the stack |
| if lookahead.type == "$end": |
| # Whoa. We're really hosed here. Bail out |
| return |
| |
| if lookahead.type != 'error': |
| sym = symstack[-1] |
| if sym.type == 'error': |
| # Hmmm. Error is on top of stack, we'll just nuke input |
| # symbol and continue |
| lookahead = None |
| continue |
| t = YaccSymbol() |
| t.type = 'error' |
| if hasattr(lookahead,"lineno"): |
| t.lineno = lookahead.lineno |
| t.value = lookahead |
| lookaheadstack.append(lookahead) |
| lookahead = t |
| else: |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] # Potential bug fix |
| |
| continue |
| |
| # Call an error function here |
| raise RuntimeError("yacc: internal parser error!!!\n") |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # parseopt(). |
| # |
| # Optimized version of parse() method. DO NOT EDIT THIS CODE DIRECTLY. |
| # Edit the debug version above, then copy any modifications to the method |
| # below while removing #--! DEBUG sections. |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| |
| def parseopt(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None): |
| lookahead = None # Current lookahead symbol |
| lookaheadstack = [ ] # Stack of lookahead symbols |
| actions = self.action # Local reference to action table (to avoid lookup on self.) |
| goto = self.goto # Local reference to goto table (to avoid lookup on self.) |
| prod = self.productions # Local reference to production list (to avoid lookup on self.) |
| pslice = YaccProduction(None) # Production object passed to grammar rules |
| errorcount = 0 # Used during error recovery |
| |
| # If no lexer was given, we will try to use the lex module |
| if not lexer: |
| lex = load_ply_lex() |
| lexer = lex.lexer |
| |
| # Set up the lexer and parser objects on pslice |
| pslice.lexer = lexer |
| pslice.parser = self |
| |
| # If input was supplied, pass to lexer |
| if input is not None: |
| lexer.input(input) |
| |
| if tokenfunc is None: |
| # Tokenize function |
| get_token = lexer.token |
| else: |
| get_token = tokenfunc |
| |
| # Set up the state and symbol stacks |
| |
| statestack = [ ] # Stack of parsing states |
| self.statestack = statestack |
| symstack = [ ] # Stack of grammar symbols |
| self.symstack = symstack |
| |
| pslice.stack = symstack # Put in the production |
| errtoken = None # Err token |
| |
| # The start state is assumed to be (0,$end) |
| |
| statestack.append(0) |
| sym = YaccSymbol() |
| sym.type = '$end' |
| symstack.append(sym) |
| state = 0 |
| while 1: |
| # Get the next symbol on the input. If a lookahead symbol |
| # is already set, we just use that. Otherwise, we'll pull |
| # the next token off of the lookaheadstack or from the lexer |
| |
| if not lookahead: |
| if not lookaheadstack: |
| lookahead = get_token() # Get the next token |
| else: |
| lookahead = lookaheadstack.pop() |
| if not lookahead: |
| lookahead = YaccSymbol() |
| lookahead.type = '$end' |
| |
| # Check the action table |
| ltype = lookahead.type |
| t = actions[state].get(ltype) |
| |
| if t is not None: |
| if t > 0: |
| # shift a symbol on the stack |
| statestack.append(t) |
| state = t |
| |
| symstack.append(lookahead) |
| lookahead = None |
| |
| # Decrease error count on successful shift |
| if errorcount: errorcount -=1 |
| continue |
| |
| if t < 0: |
| # reduce a symbol on the stack, emit a production |
| p = prod[-t] |
| pname = p.name |
| plen = p.len |
| |
| # Get production function |
| sym = YaccSymbol() |
| sym.type = pname # Production name |
| sym.value = None |
| |
| if plen: |
| targ = symstack[-plen-1:] |
| targ[0] = sym |
| |
| # --! TRACKING |
| if tracking: |
| t1 = targ[1] |
| sym.lineno = t1.lineno |
| sym.lexpos = t1.lexpos |
| t1 = targ[-1] |
| sym.endlineno = getattr(t1,"endlineno",t1.lineno) |
| sym.endlexpos = getattr(t1,"endlexpos",t1.lexpos) |
| |
| # --! TRACKING |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # The code enclosed in this section is duplicated |
| # below as a performance optimization. Make sure |
| # changes get made in both locations. |
| |
| pslice.slice = targ |
| |
| try: |
| # Call the grammar rule with our special slice object |
| del symstack[-plen:] |
| del statestack[-plen:] |
| p.callable(pslice) |
| symstack.append(sym) |
| state = goto[statestack[-1]][pname] |
| statestack.append(state) |
| except SyntaxError: |
| # If an error was set. Enter error recovery state |
| lookaheadstack.append(lookahead) |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] |
| sym.type = 'error' |
| lookahead = sym |
| errorcount = error_count |
| self.errorok = 0 |
| continue |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| else: |
| |
| # --! TRACKING |
| if tracking: |
| sym.lineno = lexer.lineno |
| sym.lexpos = lexer.lexpos |
| # --! TRACKING |
| |
| targ = [ sym ] |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # The code enclosed in this section is duplicated |
| # above as a performance optimization. Make sure |
| # changes get made in both locations. |
| |
| pslice.slice = targ |
| |
| try: |
| # Call the grammar rule with our special slice object |
| p.callable(pslice) |
| symstack.append(sym) |
| state = goto[statestack[-1]][pname] |
| statestack.append(state) |
| except SyntaxError: |
| # If an error was set. Enter error recovery state |
| lookaheadstack.append(lookahead) |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] |
| sym.type = 'error' |
| lookahead = sym |
| errorcount = error_count |
| self.errorok = 0 |
| continue |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| if t == 0: |
| n = symstack[-1] |
| return getattr(n,"value",None) |
| |
| if t == None: |
| |
| # We have some kind of parsing error here. To handle |
| # this, we are going to push the current token onto |
| # the tokenstack and replace it with an 'error' token. |
| # If there are any synchronization rules, they may |
| # catch it. |
| # |
| # In addition to pushing the error token, we call call |
| # the user defined p_error() function if this is the |
| # first syntax error. This function is only called if |
| # errorcount == 0. |
| if errorcount == 0 or self.errorok: |
| errorcount = error_count |
| self.errorok = 0 |
| errtoken = lookahead |
| if errtoken.type == '$end': |
| errtoken = None # End of file! |
| if self.errorfunc: |
| global errok,token,restart |
| errok = self.errok # Set some special functions available in error recovery |
| token = get_token |
| restart = self.restart |
| if errtoken and not hasattr(errtoken,'lexer'): |
| errtoken.lexer = lexer |
| tok = self.errorfunc(errtoken) |
| del errok, token, restart # Delete special functions |
| |
| if self.errorok: |
| # User must have done some kind of panic |
| # mode recovery on their own. The |
| # returned token is the next lookahead |
| lookahead = tok |
| errtoken = None |
| continue |
| else: |
| if errtoken: |
| if hasattr(errtoken,"lineno"): lineno = lookahead.lineno |
| else: lineno = 0 |
| if lineno: |
| sys.stderr.write("yacc: Syntax error at line %d, token=%s\n" % (lineno, errtoken.type)) |
| else: |
| sys.stderr.write("yacc: Syntax error, token=%s" % errtoken.type) |
| else: |
| sys.stderr.write("yacc: Parse error in input. EOF\n") |
| return |
| |
| else: |
| errorcount = error_count |
| |
| # case 1: the statestack only has 1 entry on it. If we're in this state, the |
| # entire parse has been rolled back and we're completely hosed. The token is |
| # discarded and we just keep going. |
| |
| if len(statestack) <= 1 and lookahead.type != '$end': |
| lookahead = None |
| errtoken = None |
| state = 0 |
| # Nuke the pushback stack |
| del lookaheadstack[:] |
| continue |
| |
| # case 2: the statestack has a couple of entries on it, but we're |
| # at the end of the file. nuke the top entry and generate an error token |
| |
| # Start nuking entries on the stack |
| if lookahead.type == '$end': |
| # Whoa. We're really hosed here. Bail out |
| return |
| |
| if lookahead.type != 'error': |
| sym = symstack[-1] |
| if sym.type == 'error': |
| # Hmmm. Error is on top of stack, we'll just nuke input |
| # symbol and continue |
| lookahead = None |
| continue |
| t = YaccSymbol() |
| t.type = 'error' |
| if hasattr(lookahead,"lineno"): |
| t.lineno = lookahead.lineno |
| t.value = lookahead |
| lookaheadstack.append(lookahead) |
| lookahead = t |
| else: |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] # Potential bug fix |
| |
| continue |
| |
| # Call an error function here |
| raise RuntimeError("yacc: internal parser error!!!\n") |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # parseopt_notrack(). |
| # |
| # Optimized version of parseopt() with line number tracking removed. |
| # DO NOT EDIT THIS CODE DIRECTLY. Copy the optimized version and remove |
| # code in the #--! TRACKING sections |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| def parseopt_notrack(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None): |
| lookahead = None # Current lookahead symbol |
| lookaheadstack = [ ] # Stack of lookahead symbols |
| actions = self.action # Local reference to action table (to avoid lookup on self.) |
| goto = self.goto # Local reference to goto table (to avoid lookup on self.) |
| prod = self.productions # Local reference to production list (to avoid lookup on self.) |
| pslice = YaccProduction(None) # Production object passed to grammar rules |
| errorcount = 0 # Used during error recovery |
| |
| # If no lexer was given, we will try to use the lex module |
| if not lexer: |
| lex = load_ply_lex() |
| lexer = lex.lexer |
| |
| # Set up the lexer and parser objects on pslice |
| pslice.lexer = lexer |
| pslice.parser = self |
| |
| # If input was supplied, pass to lexer |
| if input is not None: |
| lexer.input(input) |
| |
| if tokenfunc is None: |
| # Tokenize function |
| get_token = lexer.token |
| else: |
| get_token = tokenfunc |
| |
| # Set up the state and symbol stacks |
| |
| statestack = [ ] # Stack of parsing states |
| self.statestack = statestack |
| symstack = [ ] # Stack of grammar symbols |
| self.symstack = symstack |
| |
| pslice.stack = symstack # Put in the production |
| errtoken = None # Err token |
| |
| # The start state is assumed to be (0,$end) |
| |
| statestack.append(0) |
| sym = YaccSymbol() |
| sym.type = '$end' |
| symstack.append(sym) |
| state = 0 |
| while 1: |
| # Get the next symbol on the input. If a lookahead symbol |
| # is already set, we just use that. Otherwise, we'll pull |
| # the next token off of the lookaheadstack or from the lexer |
| |
| if not lookahead: |
| if not lookaheadstack: |
| lookahead = get_token() # Get the next token |
| else: |
| lookahead = lookaheadstack.pop() |
| if not lookahead: |
| lookahead = YaccSymbol() |
| lookahead.type = '$end' |
| |
| # Check the action table |
| ltype = lookahead.type |
| t = actions[state].get(ltype) |
| |
| if t is not None: |
| if t > 0: |
| # shift a symbol on the stack |
| statestack.append(t) |
| state = t |
| |
| symstack.append(lookahead) |
| lookahead = None |
| |
| # Decrease error count on successful shift |
| if errorcount: errorcount -=1 |
| continue |
| |
| if t < 0: |
| # reduce a symbol on the stack, emit a production |
| p = prod[-t] |
| pname = p.name |
| plen = p.len |
| |
| # Get production function |
| sym = YaccSymbol() |
| sym.type = pname # Production name |
| sym.value = None |
| |
| if plen: |
| targ = symstack[-plen-1:] |
| targ[0] = sym |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # The code enclosed in this section is duplicated |
| # below as a performance optimization. Make sure |
| # changes get made in both locations. |
| |
| pslice.slice = targ |
| |
| try: |
| # Call the grammar rule with our special slice object |
| del symstack[-plen:] |
| del statestack[-plen:] |
| p.callable(pslice) |
| symstack.append(sym) |
| state = goto[statestack[-1]][pname] |
| statestack.append(state) |
| except SyntaxError: |
| # If an error was set. Enter error recovery state |
| lookaheadstack.append(lookahead) |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] |
| sym.type = 'error' |
| lookahead = sym |
| errorcount = error_count |
| self.errorok = 0 |
| continue |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| else: |
| |
| targ = [ sym ] |
| |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| # The code enclosed in this section is duplicated |
| # above as a performance optimization. Make sure |
| # changes get made in both locations. |
| |
| pslice.slice = targ |
| |
| try: |
| # Call the grammar rule with our special slice object |
| p.callable(pslice) |
| symstack.append(sym) |
| state = goto[statestack[-1]][pname] |
| statestack.append(state) |
| except SyntaxError: |
| # If an error was set. Enter error recovery state |
| lookaheadstack.append(lookahead) |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] |
| sym.type = 'error' |
| lookahead = sym |
| errorcount = error_count |
| self.errorok = 0 |
| continue |
| # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
| |
| if t == 0: |
| n = symstack[-1] |
| return getattr(n,"value",None) |
| |
| if t == None: |
| |
| # We have some kind of parsing error here. To handle |
| # this, we are going to push the current token onto |
| # the tokenstack and replace it with an 'error' token. |
| # If there are any synchronization rules, they may |
| # catch it. |
| # |
| # In addition to pushing the error token, we call call |
| # the user defined p_error() function if this is the |
| # first syntax error. This function is only called if |
| # errorcount == 0. |
| if errorcount == 0 or self.errorok: |
| errorcount = error_count |
| self.errorok = 0 |
| errtoken = lookahead |
| if errtoken.type == '$end': |
| errtoken = None # End of file! |
| if self.errorfunc: |
| global errok,token,restart |
| errok = self.errok # Set some special functions available in error recovery |
| token = get_token |
| restart = self.restart |
| if errtoken and not hasattr(errtoken,'lexer'): |
| errtoken.lexer = lexer |
| tok = self.errorfunc(errtoken) |
| del errok, token, restart # Delete special functions |
| |
| if self.errorok: |
| # User must have done some kind of panic |
| # mode recovery on their own. The |
| # returned token is the next lookahead |
| lookahead = tok |
| errtoken = None |
| continue |
| else: |
| if errtoken: |
| if hasattr(errtoken,"lineno"): lineno = lookahead.lineno |
| else: lineno = 0 |
| if lineno: |
| sys.stderr.write("yacc: Syntax error at line %d, token=%s\n" % (lineno, errtoken.type)) |
| else: |
| sys.stderr.write("yacc: Syntax error, token=%s" % errtoken.type) |
| else: |
| sys.stderr.write("yacc: Parse error in input. EOF\n") |
| return |
| |
| else: |
| errorcount = error_count |
| |
| # case 1: the statestack only has 1 entry on it. If we're in this state, the |
| # entire parse has been rolled back and we're completely hosed. The token is |
| # discarded and we just keep going. |
| |
| if len(statestack) <= 1 and lookahead.type != '$end': |
| lookahead = None |
| errtoken = None |
| state = 0 |
| # Nuke the pushback stack |
| del lookaheadstack[:] |
| continue |
| |
| # case 2: the statestack has a couple of entries on it, but we're |
| # at the end of the file. nuke the top entry and generate an error token |
| |
| # Start nuking entries on the stack |
| if lookahead.type == '$end': |
| # Whoa. We're really hosed here. Bail out |
| return |
| |
| if lookahead.type != 'error': |
| sym = symstack[-1] |
| if sym.type == 'error': |
| # Hmmm. Error is on top of stack, we'll just nuke input |
| # symbol and continue |
| lookahead = None |
| continue |
| t = YaccSymbol() |
| t.type = 'error' |
| if hasattr(lookahead,"lineno"): |
| t.lineno = lookahead.lineno |
| t.value = lookahead |
| lookaheadstack.append(lookahead) |
| lookahead = t |
| else: |
| symstack.pop() |
| statestack.pop() |
| state = statestack[-1] # Potential bug fix |
| |
| continue |
| |
| # Call an error function here |
| raise RuntimeError("yacc: internal parser error!!!\n") |
| |
| # ----------------------------------------------------------------------------- |
| # === Grammar Representation === |
| # |
| # The following functions, classes, and variables are used to represent and |
| # manipulate the rules that make up a grammar. |
| # ----------------------------------------------------------------------------- |
| |
| import re |
| |
| # regex matching identifiers |
| _is_identifier = re.compile(r'^[a-zA-Z0-9_-]+$') |
| |
| # ----------------------------------------------------------------------------- |
| # class Production: |
| # |
| # This class stores the raw information about a single production or grammar rule. |
| # A grammar rule refers to a specification such as this: |
| # |
| # expr : expr PLUS term |
| # |
| # Here are the basic attributes defined on all productions |
| # |
| # name - Name of the production. For example 'expr' |
| # prod - A list of symbols on the right side ['expr','PLUS','term'] |
| # prec - Production precedence level |
| # number - Production number. |
| # func - Function that executes on reduce |
| # file - File where production function is defined |
| # lineno - Line number where production function is defined |
| # |
| # The following attributes are defined or optional. |
| # |
| # len - Length of the production (number of symbols on right hand side) |
| # usyms - Set of unique symbols found in the production |
| # ----------------------------------------------------------------------------- |
| |
| class Production(object): |
| reduced = 0 |
| def __init__(self,number,name,prod,precedence=('right',0),func=None,file='',line=0): |
| self.name = name |
| self.prod = tuple(prod) |
| self.number = number |
| self.func = func |
| self.callable = None |
| self.file = file |
| self.line = line |
| self.prec = precedence |
| |
| # Internal settings used during table construction |
| |
| self.len = len(self.prod) # Length of the production |
| |
| # Create a list of unique production symbols used in the production |
| self.usyms = [ ] |
| for s in self.prod: |
| if s not in self.usyms: |
| self.usyms.append(s) |
| |
| # List of all LR items for the production |
| self.lr_items = [] |
| self.lr_next = None |
| |
| # Create a string representation |
| if self.prod: |
| self.str = "%s -> %s" % (self.name," ".join(self.prod)) |
| else: |
| self.str = "%s -> <empty>" % self.name |
| |
| def __str__(self): |
| return self.str |
| |
| def __repr__(self): |
| return "Production("+str(self)+")" |
| |
| def __len__(self): |
| return len(self.prod) |
| |
| def __nonzero__(self): |
| return 1 |
| |
| def __getitem__(self,index): |
| return self.prod[index] |
| |
| # Return the nth lr_item from the production (or None if at the end) |
| def lr_item(self,n): |
| if n > len(self.prod): return None |
| p = LRItem(self,n) |
| |
| # Precompute the list of productions immediately following. Hack. Remove later |
| try: |
| p.lr_after = Prodnames[p.prod[n+1]] |
| except (IndexError,KeyError): |
| p.lr_after = [] |
| try: |
| p.lr_before = p.prod[n-1] |
| except IndexError: |
| p.lr_before = None |
| |
| return p |
| |
| # Bind the production function name to a callable |
| def bind(self,pdict): |
| if self.func: |
| self.callable = pdict[self.func] |
| |
| # This class serves as a minimal standin for Production objects when |
| # reading table data from files. It only contains information |
| # actually used by the LR parsing engine, plus some additional |
| # debugging information. |
| class MiniProduction(object): |
| def __init__(self,str,name,len,func,file,line): |
| self.name = name |
| self.len = len |
| self.func = func |
| self.callable = None |
| self.file = file |
| self.line = line |
| self.str = str |
| def __str__(self): |
| return self.str |
| def __repr__(self): |
| return "MiniProduction(%s)" % self.str |
| |
| # Bind the production function name to a callable |
| def bind(self,pdict): |
| if self.func: |
| self.callable = pdict[self.func] |
| |
| |
| # ----------------------------------------------------------------------------- |
| # class LRItem |
| # |
| # This class represents a specific stage of parsing a production rule. For |
| # example: |
| # |
| # expr : expr . PLUS term |
| # |
| # In the above, the "." represents the current location of the parse. Here |
| # basic attributes: |
| # |
| # name - Name of the production. For example 'expr' |
| # prod - A list of symbols on the right side ['expr','.', 'PLUS','term'] |
| # number - Production number. |
| # |
| # lr_next Next LR item. Example, if we are ' expr -> expr . PLUS term' |
| # then lr_next refers to 'expr -> expr PLUS . term' |
| # lr_index - LR item index (location of the ".") in the prod list. |
| # lookaheads - LALR lookahead symbols for this item |
| # len - Length of the production (number of symbols on right hand side) |
| # lr_after - List of all productions that immediately follow |
| # lr_before - Grammar symbol immediately before |
| # ----------------------------------------------------------------------------- |
| |
| class LRItem(object): |
| def __init__(self,p,n): |
| self.name = p.name |
| self.prod = list(p.prod) |
| self.number = p.number |
| self.lr_index = n |
| self.lookaheads = { } |
| self.prod.insert(n,".") |
| self.prod = tuple(self.prod) |
| self.len = len(self.prod) |
| self.usyms = p.usyms |
| |
| def __str__(self): |
| if self.prod: |
| s = "%s -> %s" % (self.name," ".join(self.prod)) |
| else: |
| s = "%s -> <empty>" % self.name |
| return s |
| |
| def __repr__(self): |
| return "LRItem("+str(self)+")" |
| |
| # ----------------------------------------------------------------------------- |
| # rightmost_terminal() |
| # |
| # Return the rightmost terminal from a list of symbols. Used in add_production() |
| # ----------------------------------------------------------------------------- |
| def rightmost_terminal(symbols, terminals): |
| i = len(symbols) - 1 |
| while i >= 0: |
| if symbols[i] in terminals: |
| return symbols[i] |
| i -= 1 |
| return None |
| |
| # ----------------------------------------------------------------------------- |
| # === GRAMMAR CLASS === |
| # |
| # The following class represents the contents of the specified grammar along |
| # with various computed properties such as first sets, follow sets, LR items, etc. |
| # This data is used for critical parts of the table generation process later. |
| # ----------------------------------------------------------------------------- |
| |
| class GrammarError(YaccError): pass |
| |
| class Grammar(object): |
| def __init__(self,terminals): |
| self.Productions = [None] # A list of all of the productions. The first |
| # entry is always reserved for the purpose of |
| # building an augmented grammar |
| |
| self.Prodnames = { } # A dictionary mapping the names of nonterminals to a list of all |
| # productions of that nonterminal. |
| |
| self.Prodmap = { } # A dictionary that is only used to detect duplicate |
| # productions. |
| |
| self.Terminals = { } # A dictionary mapping the names of terminal symbols to a |
| # list of the rules where they are used. |
| |
| for term in terminals: |
| self.Terminals[term] = [] |
| |
| self.Terminals['error'] = [] |
| |
| self.Nonterminals = { } # A dictionary mapping names of nonterminals to a list |
| # of rule numbers where they are used. |
| |
| self.First = { } # A dictionary of precomputed FIRST(x) symbols |
| |
| self.Follow = { } # A dictionary of precomputed FOLLOW(x) symbols |
| |
| self.Precedence = { } # Precedence rules for each terminal. Contains tuples of the |
| # form ('right',level) or ('nonassoc', level) or ('left',level) |
| |
| self.UsedPrecedence = { } # Precedence rules that were actually used by the grammer. |
| # This is only used to provide error checking and to generate |
| # a warning about unused precedence rules. |
| |
| self.Start = None # Starting symbol for the grammar |
| |
| |
| def __len__(self): |
| return len(self.Productions) |
| |
| def __getitem__(self,index): |
| return self.Productions[index] |
| |
| # ----------------------------------------------------------------------------- |
| # set_precedence() |
| # |
| # Sets the precedence for a given terminal. assoc is the associativity such as |
| # 'left','right', or 'nonassoc'. level is a numeric level. |
| # |
| # ----------------------------------------------------------------------------- |
| |
| def set_precedence(self,term,assoc,level): |
| assert self.Productions == [None],"Must call set_precedence() before add_production()" |
| if term in self.Precedence: |
| raise GrammarError("Precedence already specified for terminal '%s'" % term) |
| if assoc not in ['left','right','nonassoc']: |
| raise GrammarError("Associativity must be one of 'left','right', or 'nonassoc'") |
| self.Precedence[term] = (assoc,level) |
| |
| # ----------------------------------------------------------------------------- |
| # add_production() |
| # |
| # Given an action function, this function assembles a production rule and |
| # computes its precedence level. |
| # |
| # The production rule is supplied as a list of symbols. For example, |
| # a rule such as 'expr : expr PLUS term' has a production name of 'expr' and |
| # symbols ['expr','PLUS','term']. |
| # |
| # Precedence is determined by the precedence of the right-most non-terminal |
| # or the precedence of a terminal specified by %prec. |
| # |
| # A variety of error checks are performed to make sure production symbols |
| # are valid and that %prec is used correctly. |
| # ----------------------------------------------------------------------------- |
| |
| def add_production(self,prodname,syms,func=None,file='',line=0): |
| |
| if prodname in self.Terminals: |
| raise GrammarError("%s:%d: Illegal rule name '%s'. Already defined as a token" % (file,line,prodname)) |
| if prodname == 'error': |
| raise GrammarError("%s:%d: Illegal rule name '%s'. error is a reserved word" % (file,line,prodname)) |
| if not _is_identifier.match(prodname): |
| raise GrammarError("%s:%d: Illegal rule name '%s'" % (file,line,prodname)) |
| |
| # Look for literal tokens |
| for n,s in enumerate(syms): |
| if s[0] in "'\"": |
| try: |
| c = eval(s) |
| if (len(c) > 1): |
| raise GrammarError("%s:%d: Literal token %s in rule '%s' may only be a single character" % (file,line,s, prodname)) |
| if not c in self.Terminals: |
| self.Terminals[c] = [] |
| syms[n] = c |
| continue |
| except SyntaxError: |
| pass |
| if not _is_identifier.match(s) and s != '%prec': |
| raise GrammarError("%s:%d: Illegal name '%s' in rule '%s'" % (file,line,s, prodname)) |
| |
| # Determine the precedence level |
| if '%prec' in syms: |
| if syms[-1] == '%prec': |
| raise GrammarError("%s:%d: Syntax error. Nothing follows %%prec" % (file,line)) |
| if syms[-2] != '%prec': |
| raise GrammarError("%s:%d: Syntax error. %%prec can only appear at the end of a grammar rule" % (file,line)) |
| precname = syms[-1] |
| prodprec = self.Precedence.get(precname,None) |
| if not prodprec: |
| raise GrammarError("%s:%d: Nothing known about the precedence of '%s'" % (file,line,precname)) |
| else: |
| self.UsedPrecedence[precname] = 1 |
| del syms[-2:] # Drop %prec from the rule |
| else: |
| # If no %prec, precedence is determined by the rightmost terminal symbol |
| precname = rightmost_terminal(syms,self.Terminals) |
| prodprec = self.Precedence.get(precname,('right',0)) |
| |
| # See if the rule is already in the rulemap |
| map = "%s -> %s" % (prodname,syms) |
| if map in self.Prodmap: |
| m = self.Prodmap[map] |
| raise GrammarError("%s:%d: Duplicate rule %s. " % (file,line, m) + |
| "Previous definition at %s:%d" % (m.file, m.line)) |
| |
| # From this point on, everything is valid. Create a new Production instance |
| pnumber = len(self.Productions) |
| if not prodname in self.Nonterminals: |
| self.Nonterminals[prodname] = [ ] |
| |
| # Add the production number to Terminals and Nonterminals |
| for t in syms: |
| if t in self.Terminals: |
| self.Terminals[t].append(pnumber) |
| else: |
| if not t in self.Nonterminals: |
| self.Nonterminals[t] = [ ] |
| self.Nonterminals[t].append(pnumber) |
| |
| # Create a production and add it to the list of productions |
| p = Production(pnumber,prodname,syms,prodprec,func,file,line) |
| self.Productions.append(p) |
| self.Prodmap[map] = p |
| |
| # Add to the global productions list |
| try: |
| self.Prodnames[prodname].append(p) |
| except KeyError: |
| self.Prodnames[prodname] = [ p ] |
| return 0 |
| |
| # ----------------------------------------------------------------------------- |
| # set_start() |
| # |
| # Sets the starting symbol and creates the augmented grammar. Production |
| # rule 0 is S' -> start where start is the start symbol. |
| # ----------------------------------------------------------------------------- |
| |
| def set_start(self,start=None): |
| if not start: |
| start = self.Productions[1].name |
| if start not in self.Nonterminals: |
| raise GrammarError("start symbol %s undefined" % start) |
| self.Productions[0] = Production(0,"S'",[start]) |
| self.Nonterminals[start].append(0) |
| self.Start = start |
| |
| # ----------------------------------------------------------------------------- |
| # find_unreachable() |
| # |
| # Find all of the nonterminal symbols that can't be reached from the starting |
| # symbol. Returns a list of nonterminals that can't be reached. |
| # ----------------------------------------------------------------------------- |
| |
| def find_unreachable(self): |
| |
| # Mark all symbols that are reachable from a symbol s |
| def mark_reachable_from(s): |
| if reachable[s]: |
| # We've already reached symbol s. |
| return |
| reachable[s] = 1 |
| for p in self.Prodnames.get(s,[]): |
| for r in p.prod: |
| mark_reachable_from(r) |
| |
| reachable = { } |
| for s in list(self.Terminals) + list(self.Nonterminals): |
| reachable[s] = 0 |
| |
| mark_reachable_from( self.Productions[0].prod[0] ) |
| |
| return [s for s in list(self.Nonterminals) |
| if not reachable[s]] |
| |
| # ----------------------------------------------------------------------------- |
| # infinite_cycles() |
| # |
| # This function looks at the various parsing rules and tries to detect |
| # infinite recursion cycles (grammar rules where there is no possible way |
| # to derive a string of only terminals). |
| # ----------------------------------------------------------------------------- |
| |
| def infinite_cycles(self): |
| terminates = {} |
| |
| # Terminals: |
| for t in self.Terminals: |
| terminates[t] = 1 |
| |
| terminates['$end'] = 1 |
| |
| # Nonterminals: |
| |
| # Initialize to false: |
| for n in self.Nonterminals: |
| terminates[n] = 0 |
| |
| # Then propagate termination until no change: |
| while 1: |
| some_change = 0 |
| for (n,pl) in self.Prodnames.items(): |
| # Nonterminal n terminates iff any of its productions terminates. |
| for p in pl: |
| # Production p terminates iff all of its rhs symbols terminate. |
| for s in p.prod: |
| if not terminates[s]: |
| # The symbol s does not terminate, |
| # so production p does not terminate. |
| p_terminates = 0 |
| break |
| else: |
| # didn't break from the loop, |
| # so every symbol s terminates |
| # so production p terminates. |
| p_terminates = 1 |
| |
| if p_terminates: |
| # symbol n terminates! |
| if not terminates[n]: |
| terminates[n] = 1 |
| some_change = 1 |
| # Don't need to consider any more productions for this n. |
| break |
| |
| if not some_change: |
| break |
| |
| infinite = [] |
| for (s,term) in terminates.items(): |
| if not term: |
| if not s in self.Prodnames and not s in self.Terminals and s != 'error': |
| # s is used-but-not-defined, and we've already warned of that, |
| # so it would be overkill to say that it's also non-terminating. |
| pass |
| else: |
| infinite.append(s) |
| |
| return infinite |
| |
| |
| # ----------------------------------------------------------------------------- |
| # undefined_symbols() |
| # |
| # Find all symbols that were used the grammar, but not defined as tokens or |
| # grammar rules. Returns a list of tuples (sym, prod) where sym in the symbol |
| # and prod is the production where the symbol was used. |
| # ----------------------------------------------------------------------------- |
| def undefined_symbols(self): |
| result = [] |
| for p in self.Productions: |
| if not p: continue |
| |
| for s in p.prod: |
| if not s in self.Prodnames and not s in self.Terminals and s != 'error': |
| result.append((s,p)) |
| return result |
| |
| # ----------------------------------------------------------------------------- |
| # unused_terminals() |
| # |
| # Find all terminals that were defined, but not used by the grammar. Returns |
| # a list of all symbols. |
| # ----------------------------------------------------------------------------- |
| def unused_terminals(self): |
| unused_tok = [] |
| for s,v in self.Terminals.items(): |
| if s != 'error' and not v: |
| unused_tok.append(s) |
| |
| return unused_tok |
| |
| # ------------------------------------------------------------------------------ |
| # unused_rules() |
| # |
| # Find all grammar rules that were defined, but not used (maybe not reachable) |
| # Returns a list of productions. |
| # ------------------------------------------------------------------------------ |
| |
| def unused_rules(self): |
| unused_prod = [] |
| for s,v in self.Nonterminals.items(): |
| if not v: |
| p = self.Prodnames[s][0] |
| unused_prod.append(p) |
| return unused_prod |
| |
| # ----------------------------------------------------------------------------- |
| # unused_precedence() |
| # |
| # Returns a list of tuples (term,precedence) corresponding to precedence |
| # rules that were never used by the grammar. term is the name of the terminal |
| # on which precedence was applied and precedence is a string such as 'left' or |
| # 'right' corresponding to the type of precedence. |
| # ----------------------------------------------------------------------------- |
| |
| def unused_precedence(self): |
| unused = [] |
| for termname in self.Precedence: |
| if not (termname in self.Terminals or termname in self.UsedPrecedence): |
| unused.append((termname,self.Precedence[termname][0])) |
| |
| return unused |
| |
| # ------------------------------------------------------------------------- |
| # _first() |
| # |
| # Compute the value of FIRST1(beta) where beta is a tuple of symbols. |
| # |
| # During execution of compute_first1, the result may be incomplete. |
| # Afterward (e.g., when called from compute_follow()), it will be complete. |
| # ------------------------------------------------------------------------- |
| def _first(self,beta): |
| |
| # We are computing First(x1,x2,x3,...,xn) |
| result = [ ] |
| for x in beta: |
| x_produces_empty = 0 |
| |
| # Add all the non-<empty> symbols of First[x] to the result. |
| for f in self.First[x]: |
| if f == '<empty>': |
| x_produces_empty = 1 |
| else: |
| if f not in result: result.append(f) |
| |
| if x_produces_empty: |
| # We have to consider the next x in beta, |
| # i.e. stay in the loop. |
| pass |
| else: |
| # We don't have to consider any further symbols in beta. |
| break |
| else: |
| # There was no 'break' from the loop, |
| # so x_produces_empty was true for all x in beta, |
| # so beta produces empty as well. |
| result.append('<empty>') |
| |
| return result |
| |
| # ------------------------------------------------------------------------- |
| # compute_first() |
| # |
| # Compute the value of FIRST1(X) for all symbols |
| # ------------------------------------------------------------------------- |
| def compute_first(self): |
| if self.First: |
| return self.First |
| |
| # Terminals: |
| for t in self.Terminals: |
| self.First[t] = [t] |
| |
| self.First['$end'] = ['$end'] |
| |
| # Nonterminals: |
| |
| # Initialize to the empty set: |
| for n in self.Nonterminals: |
| self.First[n] = [] |
| |
| # Then propagate symbols until no change: |
| while 1: |
| some_change = 0 |
| for n in self.Nonterminals: |
| for p in self.Prodnames[n]: |
| for f in self._first(p.prod): |
| if f not in self.First[n]: |
| self.First[n].append( f ) |
| some_change = 1 |
| if not some_change: |
| break |
| |
| return self.First |
| |
| # --------------------------------------------------------------------- |
| # compute_follow() |
| # |
| # Computes all of the follow sets for every non-terminal symbol. The |
| # follow set is the set of all symbols that might follow a given |
| # non-terminal. See the Dragon book, 2nd Ed. p. 189. |
| # --------------------------------------------------------------------- |
| def compute_follow(self,start=None): |
| # If already computed, return the result |
| if self.Follow: |
| return self.Follow |
| |
| # If first sets not computed yet, do that first. |
| if not self.First: |
| self.compute_first() |
| |
| # Add '$end' to the follow list of the start symbol |
| for k in self.Nonterminals: |
| self.Follow[k] = [ ] |
| |
| if not start: |
| start = self.Productions[1].name |
| |
| self.Follow[start] = [ '$end' ] |
| |
| while 1: |
| didadd = 0 |
| for p in self.Productions[1:]: |
| # Here is the production set |
| for i in range(len(p.prod)): |
| B = p.prod[i] |
| if B in self.Nonterminals: |
| # Okay. We got a non-terminal in a production |
| fst = self._first(p.prod[i+1:]) |
| hasempty = 0 |
| for f in fst: |
| if f != '<empty>' and f not in self.Follow[B]: |
| self.Follow[B].append(f) |
| didadd = 1 |
| if f == '<empty>': |
| hasempty = 1 |
| if hasempty or i == (len(p.prod)-1): |
| # Add elements of follow(a) to follow(b) |
| for f in self.Follow[p.name]: |
| if f not in self.Follow[B]: |
| self.Follow[B].append(f) |
| didadd = 1 |
| if not didadd: break |
| return self.Follow |
| |
| |
| # ----------------------------------------------------------------------------- |
| # build_lritems() |
| # |
| # This function walks the list of productions and builds a complete set of the |
| # LR items. The LR items are stored in two ways: First, they are uniquely |
| # numbered and placed in the list _lritems. Second, a linked list of LR items |
| # is built for each production. For example: |
| # |
| # E -> E PLUS E |
| # |
| # Creates the list |
| # |
| # [E -> . E PLUS E, E -> E . PLUS E, E -> E PLUS . E, E -> E PLUS E . ] |
| # ----------------------------------------------------------------------------- |
| |
| def build_lritems(self): |
| for p in self.Productions: |
| lastlri = p |
| i = 0 |
| lr_items = [] |
| while 1: |
| if i > len(p): |
| lri = None |
| else: |
| lri = LRItem(p,i) |
| # Precompute the list of productions immediately following |
| try: |
| lri.lr_after = self.Prodnames[lri.prod[i+1]] |
| except (IndexError,KeyError): |
| lri.lr_after = [] |
| try: |
| lri.lr_before = lri.prod[i-1] |
| except IndexError: |
| lri.lr_before = None |
| |
| lastlri.lr_next = lri |
| if not lri: break |
| lr_items.append(lri) |
| lastlri = lri |
| i += 1 |
| p.lr_items = lr_items |
| |
| # ----------------------------------------------------------------------------- |
| # == Class LRTable == |
| # |
| # This basic class represents a basic table of LR parsing information. |
| # Methods for generating the tables are not defined here. They are defined |
| # in the derived class LRGeneratedTable. |
| # ----------------------------------------------------------------------------- |
| |
| class VersionError(YaccError): pass |
| |
| class LRTable(object): |
| def __init__(self): |
| self.lr_action = None |
| self.lr_goto = None |
| self.lr_productions = None |
| self.lr_method = None |
| |
| def read_table(self,module): |
| if isinstance(module,types.ModuleType): |
| parsetab = module |
| else: |
| if sys.version_info[0] < 3: |
| exec("import %s as parsetab" % module) |
| else: |
| env = { } |
| exec("import %s as parsetab" % module, env, env) |
| parsetab = env['parsetab'] |
| |
| if parsetab._tabversion != __tabversion__: |
| raise VersionError("yacc table file version is out of date") |
| |
| self.lr_action = parsetab._lr_action |
| self.lr_goto = parsetab._lr_goto |
| |
| self.lr_productions = [] |
| for p in parsetab._lr_productions: |
| self.lr_productions.append(MiniProduction(*p)) |
| |
| self.lr_method = parsetab._lr_method |
| return parsetab._lr_signature |
| |
| def read_pickle(self,filename): |
| try: |
| import cPickle as pickle |
| except ImportError: |
| import pickle |
| |
| in_f = open(filename,"rb") |
| |
| tabversion = pickle.load(in_f) |
| if tabversion != __tabversion__: |
| raise VersionError("yacc table file version is out of date") |
| self.lr_method = pickle.load(in_f) |
| signature = pickle.load(in_f) |
| self.lr_action = pickle.load(in_f) |
| self.lr_goto = pickle.load(in_f) |
| productions = pickle.load(in_f) |
| |
| self.lr_productions = [] |
| for p in productions: |
| self.lr_productions.append(MiniProduction(*p)) |
| |
| in_f.close() |
| return signature |
| |
| # Bind all production function names to callable objects in pdict |
| def bind_callables(self,pdict): |
| for p in self.lr_productions: |
| p.bind(pdict) |
| |
| # ----------------------------------------------------------------------------- |
| # === LR Generator === |
| # |
| # The following classes and functions are used to generate LR parsing tables on |
| # a grammar. |
| # ----------------------------------------------------------------------------- |
| |
| # ----------------------------------------------------------------------------- |
| # digraph() |
| # traverse() |
| # |
| # The following two functions are used to compute set valued functions |
| # of the form: |
| # |
| # F(x) = F'(x) U U{F(y) | x R y} |
| # |
| # This is used to compute the values of Read() sets as well as FOLLOW sets |
| # in LALR(1) generation. |
| # |
| # Inputs: X - An input set |
| # R - A relation |
| # FP - Set-valued function |
| # ------------------------------------------------------------------------------ |
| |
| def digraph(X,R,FP): |
| N = { } |
| for x in X: |
| N[x] = 0 |
| stack = [] |
| F = { } |
| for x in X: |
| if N[x] == 0: traverse(x,N,stack,F,X,R,FP) |
| return F |
| |
| def traverse(x,N,stack,F,X,R,FP): |
| stack.append(x) |
| d = len(stack) |
| N[x] = d |
| F[x] = FP(x) # F(X) <- F'(x) |
| |
| rel = R(x) # Get y's related to x |
| for y in rel: |
| if N[y] == 0: |
| traverse(y,N,stack,F,X,R,FP) |
| N[x] = min(N[x],N[y]) |
| for a in F.get(y,[]): |
| if a not in F[x]: F[x].append(a) |
| if N[x] == d: |
| N[stack[-1]] = MAXINT |
| F[stack[-1]] = F[x] |
| element = stack.pop() |
| while element != x: |
| N[stack[-1]] = MAXINT |
| F[stack[-1]] = F[x] |
| element = stack.pop() |
| |
| class LALRError(YaccError): pass |
| |
| # ----------------------------------------------------------------------------- |
| # == LRGeneratedTable == |
| # |
| # This class implements the LR table generation algorithm. There are no |
| # public methods except for write() |
| # ----------------------------------------------------------------------------- |
| |
| class LRGeneratedTable(LRTable): |
| def __init__(self,grammar,method='LALR',log=None): |
| if method not in ['SLR','LALR']: |
| raise LALRError("Unsupported method %s" % method) |
| |
| self.grammar = grammar |
| self.lr_method = method |
| |
| # Set up the logger |
| if not log: |
| log = NullLogger() |
| self.log = log |
| |
| # Internal attributes |
| self.lr_action = {} # Action table |
| self.lr_goto = {} # Goto table |
| self.lr_productions = grammar.Productions # Copy of grammar Production array |
| self.lr_goto_cache = {} # Cache of computed gotos |
| self.lr0_cidhash = {} # Cache of closures |
| |
| self._add_count = 0 # Internal counter used to detect cycles |
| |
| # Diagonistic information filled in by the table generator |
| self.sr_conflict = 0 |
| self.rr_conflict = 0 |
| self.conflicts = [] # List of conflicts |
| |
| self.sr_conflicts = [] |
| self.rr_conflicts = [] |
| |
| # Build the tables |
| self.grammar.build_lritems() |
| self.grammar.compute_first() |
| self.grammar.compute_follow() |
| self.lr_parse_table() |
| |
| # Compute the LR(0) closure operation on I, where I is a set of LR(0) items. |
| |
| def lr0_closure(self,I): |
| self._add_count += 1 |
| |
| # Add everything in I to J |
| J = I[:] |
| didadd = 1 |
| while didadd: |
| didadd = 0 |
| for j in J: |
| for x in j.lr_after: |
| if getattr(x,"lr0_added",0) == self._add_count: continue |
| # Add B --> .G to J |
| J.append(x.lr_next) |
| x.lr0_added = self._add_count |
| didadd = 1 |
| |
| return J |
| |
| # Compute the LR(0) goto function goto(I,X) where I is a set |
| # of LR(0) items and X is a grammar symbol. This function is written |
| # in a way that guarantees uniqueness of the generated goto sets |
| # (i.e. the same goto set will never be returned as two different Python |
| # objects). With uniqueness, we can later do fast set comparisons using |
| # id(obj) instead of element-wise comparison. |
| |
| def lr0_goto(self,I,x): |
| # First we look for a previously cached entry |
| g = self.lr_goto_cache.get((id(I),x),None) |
| if g: return g |
| |
| # Now we generate the goto set in a way that guarantees uniqueness |
| # of the result |
| |
| s = self.lr_goto_cache.get(x,None) |
| if not s: |
| s = { } |
| self.lr_goto_cache[x] = s |
| |
| gs = [ ] |
| for p in I: |
| n = p.lr_next |
| if n and n.lr_before == x: |
| s1 = s.get(id(n),None) |
| if not s1: |
| s1 = { } |
| s[id(n)] = s1 |
| gs.append(n) |
| s = s1 |
| g = s.get('$end',None) |
| if not g: |
| if gs: |
| g = self.lr0_closure(gs) |
| s['$end'] = g |
| else: |
| s['$end'] = gs |
| self.lr_goto_cache[(id(I),x)] = g |
| return g |
| |
| # Compute the LR(0) sets of item function |
| def lr0_items(self): |
| |
| C = [ self.lr0_closure([self.grammar.Productions[0].lr_next]) ] |
| i = 0 |
| for I in C: |
| self.lr0_cidhash[id(I)] = i |
| i += 1 |
| |
| # Loop over the items in C and each grammar symbols |
| i = 0 |
| while i < len(C): |
| I = C[i] |
| i += 1 |
| |
| # Collect all of the symbols that could possibly be in the goto(I,X) sets |
| asyms = { } |
| for ii in I: |
| for s in ii.usyms: |
| asyms[s] = None |
| |
| for x in asyms: |
| g = self.lr0_goto(I,x) |
| if not g: continue |
| if id(g) in self.lr0_cidhash: continue |
| self.lr0_cidhash[id(g)] = len(C) |
| C.append(g) |
| |
| return C |
| |
| # ----------------------------------------------------------------------------- |
| # ==== LALR(1) Parsing ==== |
| # |
| # LALR(1) parsing is almost exactly the same as SLR except that instead of |
| # relying upon Follow() sets when performing reductions, a more selective |
| # lookahead set that incorporates the state of the LR(0) machine is utilized. |
| # Thus, we mainly just have to focus on calculating the lookahead sets. |
| # |
| # The method used here is due to DeRemer and Pennelo (1982). |
| # |
| # DeRemer, F. L., and T. J. Pennelo: "Efficient Computation of LALR(1) |
| # Lookahead Sets", ACM Transactions on Programming Languages and Systems, |
| # Vol. 4, No. 4, Oct. 1982, pp. 615-649 |
| # |
| # Further details can also be found in: |
| # |
| # J. Tremblay and P. Sorenson, "The Theory and Practice of Compiler Writing", |
| # McGraw-Hill Book Company, (1985). |
| # |
| # ----------------------------------------------------------------------------- |
| |
| # ----------------------------------------------------------------------------- |
| # compute_nullable_nonterminals() |
| # |
| # Creates a dictionary containing all of the non-terminals that might produce |
| # an empty production. |
| # ----------------------------------------------------------------------------- |
| |
| def compute_nullable_nonterminals(self): |
| nullable = {} |
| num_nullable = 0 |
| while 1: |
| for p in self.grammar.Productions[1:]: |
| if p.len == 0: |
| nullable[p.name] = 1 |
| continue |
| for t in p.prod: |
| if not t in nullable: break |
| else: |
| nullable[p.name] = 1 |
| if len(nullable) == num_nullable: break |
| num_nullable = len(nullable) |
| return nullable |
| |
| # ----------------------------------------------------------------------------- |
| # find_nonterminal_trans(C) |
| # |
| # Given a set of LR(0) items, this functions finds all of the non-terminal |
| # transitions. These are transitions in which a dot appears immediately before |
| # a non-terminal. Returns a list of tuples of the form (state,N) where state |
| # is the state number and N is the nonterminal symbol. |
| # |
| # The input C is the set of LR(0) items. |
| # ----------------------------------------------------------------------------- |
| |
| def find_nonterminal_transitions(self,C): |
| trans = [] |
| for state in range(len(C)): |
| for p in C[state]: |
| if p.lr_index < p.len - 1: |
| t = (state,p.prod[p.lr_index+1]) |
| if t[1] in self.grammar.Nonterminals: |
| if t not in trans: trans.append(t) |
| state = state + 1 |
| return trans |
| |
| # ----------------------------------------------------------------------------- |
| # dr_relation() |
| # |
| # Computes the DR(p,A) relationships for non-terminal transitions. The input |
| # is a tuple (state,N) where state is a number and N is a nonterminal symbol. |
| # |
| # Returns a list of terminals. |
| # ----------------------------------------------------------------------------- |
| |
| def dr_relation(self,C,trans,nullable): |
| dr_set = { } |
| state,N = trans |
| terms = [] |
| |
| g = self.lr0_goto(C[state],N) |
| for p in g: |
| if p.lr_index < p.len - 1: |
| a = p.prod[p.lr_index+1] |
| if a in self.grammar.Terminals: |
| if a not in terms: terms.append(a) |
| |
| # This extra bit is to handle the start state |
| if state == 0 and N == self.grammar.Productions[0].prod[0]: |
| terms.append('$end') |
| |
| return terms |
| |
| # ----------------------------------------------------------------------------- |
| # reads_relation() |
| # |
| # Computes the READS() relation (p,A) READS (t,C). |
| # ----------------------------------------------------------------------------- |
| |
| def reads_relation(self,C, trans, empty): |
| # Look for empty transitions |
| rel = [] |
| state, N = trans |
| |
| g = self.lr0_goto(C[state],N) |
| j = self.lr0_cidhash.get(id(g),-1) |
| for p in g: |
| if p.lr_index < p.len - 1: |
| a = p.prod[p.lr_index + 1] |
| if a in empty: |
| rel.append((j,a)) |
| |
| return rel |
| |
| # ----------------------------------------------------------------------------- |
| # compute_lookback_includes() |
| # |
| # Determines the lookback and includes relations |
| # |
| # LOOKBACK: |
| # |
| # This relation is determined by running the LR(0) state machine forward. |
| # For example, starting with a production "N : . A B C", we run it forward |
| # to obtain "N : A B C ." We then build a relationship between this final |
| # state and the starting state. These relationships are stored in a dictionary |
| # lookdict. |
| # |
| # INCLUDES: |
| # |
| # Computes the INCLUDE() relation (p,A) INCLUDES (p',B). |
| # |
| # This relation is used to determine non-terminal transitions that occur |
| # inside of other non-terminal transition states. (p,A) INCLUDES (p', B) |
| # if the following holds: |
| # |
| # B -> LAT, where T -> epsilon and p' -L-> p |
| # |
| # L is essentially a prefix (which may be empty), T is a suffix that must be |
| # able to derive an empty string. State p' must lead to state p with the string L. |
| # |
| # ----------------------------------------------------------------------------- |
| |
| def compute_lookback_includes(self,C,trans,nullable): |
| |
| lookdict = {} # Dictionary of lookback relations |
| includedict = {} # Dictionary of include relations |
| |
| # Make a dictionary of non-terminal transitions |
| dtrans = {} |
| for t in trans: |
| dtrans[t] = 1 |
| |
| # Loop over all transitions and compute lookbacks and includes |
| for state,N in trans: |
| lookb = [] |
| includes = [] |
| for p in C[state]: |
| if p.name != N: continue |
| |
| # Okay, we have a name match. We now follow the production all the way |
| # through the state machine until we get the . on the right hand side |
| |
| lr_index = p.lr_index |
| j = state |
| while lr_index < p.len - 1: |
| lr_index = lr_index + 1 |
| t = p.prod[lr_index] |
| |
| # Check to see if this symbol and state are a non-terminal transition |
| if (j,t) in dtrans: |
| # Yes. Okay, there is some chance that this is an includes relation |
| # the only way to know for certain is whether the rest of the |
| # production derives empty |
| |
| li = lr_index + 1 |
| while li < p.len: |
| if p.prod[li] in self.grammar.Terminals: break # No forget it |
| if not p.prod[li] in nullable: break |
| li = li + 1 |
| else: |
| # Appears to be a relation between (j,t) and (state,N) |
| includes.append((j,t)) |
| |
| g = self.lr0_goto(C[j],t) # Go to next set |
| j = self.lr0_cidhash.get(id(g),-1) # Go to next state |
| |
| # When we get here, j is the final state, now we have to locate the production |
| for r in C[j]: |
| if r.name != p.name: continue |
| if r.len != p.len: continue |
| i = 0 |
| # This look is comparing a production ". A B C" with "A B C ." |
| while i < r.lr_index: |
| if r.prod[i] != p.prod[i+1]: break |
| i = i + 1 |
| else: |
| lookb.append((j,r)) |
| for i in includes: |
| if not i in includedict: includedict[i] = [] |
| includedict[i].append((state,N)) |
| lookdict[(state,N)] = lookb |
| |
| return lookdict,includedict |
| |
| # ----------------------------------------------------------------------------- |
| # compute_read_sets() |
| # |
| # Given a set of LR(0) items, this function computes the read sets. |
| # |
| # Inputs: C = Set of LR(0) items |
| # ntrans = Set of nonterminal transitions |
| # nullable = Set of empty transitions |
| # |
| # Returns a set containing the read sets |
| # ----------------------------------------------------------------------------- |
| |
| def compute_read_sets(self,C, ntrans, nullable): |
| FP = lambda x: self.dr_relation(C,x,nullable) |
| R = lambda x: self.reads_relation(C,x,nullable) |
| F = digraph(ntrans,R,FP) |
| return F |
| |
| # ----------------------------------------------------------------------------- |
| # compute_follow_sets() |
| # |
| # Given a set of LR(0) items, a set of non-terminal transitions, a readset, |
| # and an include set, this function computes the follow sets |
| # |
| # Follow(p,A) = Read(p,A) U U {Follow(p',B) | (p,A) INCLUDES (p',B)} |
| # |
| # Inputs: |
| # ntrans = Set of nonterminal transitions |
| # readsets = Readset (previously computed) |
| # inclsets = Include sets (previously computed) |
| # |
| # Returns a set containing the follow sets |
| # ----------------------------------------------------------------------------- |
| |
| def compute_follow_sets(self,ntrans,readsets,inclsets): |
| FP = lambda x: readsets[x] |
| R = lambda x: inclsets.get(x,[]) |
| F = digraph(ntrans,R,FP) |
| return F |
| |
| # ----------------------------------------------------------------------------- |
| # add_lookaheads() |
| # |
| # Attaches the lookahead symbols to grammar rules. |
| # |
| # Inputs: lookbacks - Set of lookback relations |
| # followset - Computed follow set |
| # |
| # This function directly attaches the lookaheads to productions contained |
| # in the lookbacks set |
| # ----------------------------------------------------------------------------- |
| |
| def add_lookaheads(self,lookbacks,followset): |
| for trans,lb in lookbacks.items(): |
| # Loop over productions in lookback |
| for state,p in lb: |
| if not state in p.lookaheads: |
| p.lookaheads[state] = [] |
| f = followset.get(trans,[]) |
| for a in f: |
| if a not in p.lookaheads[state]: p.lookaheads[state].append(a) |
| |
| # ----------------------------------------------------------------------------- |
| # add_lalr_lookaheads() |
| # |
| # This function does all of the work of adding lookahead information for use |
| # with LALR parsing |
| # ----------------------------------------------------------------------------- |
| |
| def add_lalr_lookaheads(self,C): |
| # Determine all of the nullable nonterminals |
| nullable = self.compute_nullable_nonterminals() |
| |
| # Find all non-terminal transitions |
| trans = self.find_nonterminal_transitions(C) |
| |
| # Compute read sets |
| readsets = self.compute_read_sets(C,trans,nullable) |
| |
| # Compute lookback/includes relations |
| lookd, included = self.compute_lookback_includes(C,trans,nullable) |
| |
| # Compute LALR FOLLOW sets |
| followsets = self.compute_follow_sets(trans,readsets,included) |
| |
| # Add all of the lookaheads |
| self.add_lookaheads(lookd,followsets) |
| |
| # ----------------------------------------------------------------------------- |
| # lr_parse_table() |
| # |
| # This function constructs the parse tables for SLR or LALR |
| # ----------------------------------------------------------------------------- |
| def lr_parse_table(self): |
| Productions = self.grammar.Productions |
| Precedence = self.grammar.Precedence |
| goto = self.lr_goto # Goto array |
| action = self.lr_action # Action array |
| log = self.log # Logger for output |
| |
| actionp = { } # Action production array (temporary) |
| |
| log.info("Parsing method: %s", self.lr_method) |
| |
| # Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items |
| # This determines the number of states |
| |
| C = self.lr0_items() |
| |
| if self.lr_method == 'LALR': |
| self.add_lalr_lookaheads(C) |
| |
| # Build the parser table, state by state |
| st = 0 |
| for I in C: |
| # Loop over each production in I |
| actlist = [ ] # List of actions |
| st_action = { } |
| st_actionp = { } |
| st_goto = { } |
| log.info("") |
| log.info("state %d", st) |
| log.info("") |
| for p in I: |
| log.info(" (%d) %s", p.number, str(p)) |
| log.info("") |
| |
| for p in I: |
| if p.len == p.lr_index + 1: |
| if p.name == "S'": |
| # Start symbol. Accept! |
| st_action["$end"] = 0 |
| st_actionp["$end"] = p |
| else: |
| # We are at the end of a production. Reduce! |
| if self.lr_method == 'LALR': |
| laheads = p.lookaheads[st] |
| else: |
| laheads = self.grammar.Follow[p.name] |
| for a in laheads: |
| actlist.append((a,p,"reduce using rule %d (%s)" % (p.number,p))) |
| r = st_action.get(a,None) |
| if r is not None: |
| # Whoa. Have a shift/reduce or reduce/reduce conflict |
| if r > 0: |
| # Need to decide on shift or reduce here |
| # By default we favor shifting. Need to add |
| # some precedence rules here. |
| sprec,slevel = Productions[st_actionp[a].number].prec |
| rprec,rlevel = Precedence.get(a,('right',0)) |
| if (slevel < rlevel) or ((slevel == rlevel) and (rprec == 'left')): |
| # We really need to reduce here. |
| st_action[a] = -p.number |
| st_actionp[a] = p |
| if not slevel and not rlevel: |
| log.info(" ! shift/reduce conflict for %s resolved as reduce",a) |
| self.sr_conflicts.append((st,a,'reduce')) |
| Productions[p.number].reduced += 1 |
| elif (slevel == rlevel) and (rprec == 'nonassoc'): |
| st_action[a] = None |
| else: |
| # Hmmm. Guess we'll keep the shift |
| if not rlevel: |
| log.info(" ! shift/reduce conflict for %s resolved as shift",a) |
| self.sr_conflicts.append((st,a,'shift')) |
| elif r < 0: |
| # Reduce/reduce conflict. In this case, we favor the rule |
| # that was defined first in the grammar file |
| oldp = Productions[-r] |
| pp = Productions[p.number] |
| if oldp.line > pp.line: |
| st_action[a] = -p.number |
| st_actionp[a] = p |
| chosenp,rejectp = pp,oldp |
| Productions[p.number].reduced += 1 |
| Productions[oldp.number].reduced -= 1 |
| else: |
| chosenp,rejectp = oldp,pp |
| self.rr_conflicts.append((st,chosenp,rejectp)) |
| log.info(" ! reduce/reduce conflict for %s resolved using rule %d (%s)", a,st_actionp[a].number, st_actionp[a]) |
| else: |
| raise LALRError("Unknown conflict in state %d" % st) |
| else: |
| st_action[a] = -p.number |
| st_actionp[a] = p |
| Productions[p.number].reduced += 1 |
| else: |
| i = p.lr_index |
| a = p.prod[i+1] # Get symbol right after the "." |
| if a in self.grammar.Terminals: |
| g = self.lr0_goto(I,a) |
| j = self.lr0_cidhash.get(id(g),-1) |
| if j >= 0: |
| # We are in a shift state |
| actlist.append((a,p,"shift and go to state %d" % j)) |
| r = st_action.get(a,None) |
| if r is not None: |
| # Whoa have a shift/reduce or shift/shift conflict |
| if r > 0: |
| if r != j: |
| raise LALRError("Shift/shift conflict in state %d" % st) |
| elif r < 0: |
| # Do a precedence check. |
| # - if precedence of reduce rule is higher, we reduce. |
| # - if precedence of reduce is same and left assoc, we reduce. |
| # - otherwise we shift |
| rprec,rlevel = Productions[st_actionp[a].number].prec |
| sprec,slevel = Precedence.get(a,('right',0)) |
| if (slevel > rlevel) or ((slevel == rlevel) and (rprec == 'right')): |
| # We decide to shift here... highest precedence to shift |
| Productions[st_actionp[a].number].reduced -= 1 |
| st_action[a] = j |
| st_actionp[a] = p |
| if not rlevel: |
| log.info(" ! shift/reduce conflict for %s resolved as shift",a) |
| self.sr_conflicts.append((st,a,'shift')) |
| elif (slevel == rlevel) and (rprec == 'nonassoc'): |
| st_action[a] = None |
| else: |
| # Hmmm. Guess we'll keep the reduce |
| if not slevel and not rlevel: |
| log.info(" ! shift/reduce conflict for %s resolved as reduce",a) |
| self.sr_conflicts.append((st,a,'reduce')) |
| |
| else: |
| raise LALRError("Unknown conflict in state %d" % st) |
| else: |
| st_action[a] = j |
| st_actionp[a] = p |
| |
| # Print the actions associated with each terminal |
| _actprint = { } |
| for a,p,m in actlist: |
| if a in st_action: |
| if p is st_actionp[a]: |
| log.info(" %-15s %s",a,m) |
| _actprint[(a,m)] = 1 |
| log.info("") |
| # Print the actions that were not used. (debugging) |
| not_used = 0 |
| for a,p,m in actlist: |
| if a in st_action: |
| if p is not st_actionp[a]: |
| if not (a,m) in _actprint: |
| log.debug(" ! %-15s [ %s ]",a,m) |
| not_used = 1 |
| _actprint[(a,m)] = 1 |
| if not_used: |
| log.debug("") |
| |
| # Construct the goto table for this state |
| |
| nkeys = { } |
| for ii in I: |
| for s in ii.usyms: |
| if s in self.grammar.Nonterminals: |
| nkeys[s] = None |
| for n in nkeys: |
| g = self.lr0_goto(I,n) |
| j = self.lr0_cidhash.get(id(g),-1) |
| if j >= 0: |
| st_goto[n] = j |
| log.info(" %-30s shift and go to state %d",n,j) |
| |
| action[st] = st_action |
| actionp[st] = st_actionp |
| goto[st] = st_goto |
| st += 1 |
| |
| |
| # ----------------------------------------------------------------------------- |
| # write() |
| # |
| # This function writes the LR parsing tables to a file |
| # ----------------------------------------------------------------------------- |
| |
| def write_table(self,modulename,outputdir='',signature=""): |
| basemodulename = modulename.split(".")[-1] |
| filename = os.path.join(outputdir,basemodulename) + ".py" |
| try: |
| f = open(filename,"w") |
| |
| f.write(""" |
| # %s |
| # This file is automatically generated. Do not edit. |
| _tabversion = %r |
| |
| _lr_method = %r |
| |
| _lr_signature = %r |
| """ % (filename, __tabversion__, self.lr_method, signature)) |
| |
| # Change smaller to 0 to go back to original tables |
| smaller = 1 |
| |
| # Factor out names to try and make smaller |
| if smaller: |
| items = { } |
| |
| for s,nd in self.lr_action.items(): |
| for name,v in nd.items(): |
| i = items.get(name) |
| if not i: |
| i = ([],[]) |
| items[name] = i |
| i[0].append(s) |
| i[1].append(v) |
| |
| f.write("\n_lr_action_items = {") |
| for k,v in items.items(): |
| f.write("%r:([" % k) |
| for i in v[0]: |
| f.write("%r," % i) |
| f.write("],[") |
| for i in v[1]: |
| f.write("%r," % i) |
| |
| f.write("]),") |
| f.write("}\n") |
| |
| f.write(""" |
| _lr_action = { } |
| for _k, _v in _lr_action_items.items(): |
| for _x,_y in zip(_v[0],_v[1]): |
| if not _x in _lr_action: _lr_action[_x] = { } |
| _lr_action[_x][_k] = _y |
| del _lr_action_items |
| """) |
| |
| else: |
| f.write("\n_lr_action = { "); |
| for k,v in self.lr_action.items(): |
| f.write("(%r,%r):%r," % (k[0],k[1],v)) |
| f.write("}\n"); |
| |
| if smaller: |
| # Factor out names to try and make smaller |
| items = { } |
| |
| for s,nd in self.lr_goto.items(): |
| for name,v in nd.items(): |
| i = items.get(name) |
| if not i: |
| i = ([],[]) |
| items[name] = i |
| i[0].append(s) |
| i[1].append(v) |
| |
| f.write("\n_lr_goto_items = {") |
| for k,v in items.items(): |
| f.write("%r:([" % k) |
| for i in v[0]: |
| f.write("%r," % i) |
| f.write("],[") |
| for i in v[1]: |
| f.write("%r," % i) |
| |
| f.write("]),") |
| f.write("}\n") |
| |
| f.write(""" |
| _lr_goto = { } |
| for _k, _v in _lr_goto_items.items(): |
| for _x,_y in zip(_v[0],_v[1]): |
| if not _x in _lr_goto: _lr_goto[_x] = { } |
| _lr_goto[_x][_k] = _y |
| del _lr_goto_items |
| """) |
| else: |
| f.write("\n_lr_goto = { "); |
| for k,v in self.lr_goto.items(): |
| f.write("(%r,%r):%r," % (k[0],k[1],v)) |
| f.write("}\n"); |
| |
| # Write production table |
| f.write("_lr_productions = [\n") |
| for p in self.lr_productions: |
| if p.func: |
| f.write(" (%r,%r,%d,%r,%r,%d),\n" % (p.str,p.name, p.len, p.func,p.file,p.line)) |
| else: |
| f.write(" (%r,%r,%d,None,None,None),\n" % (str(p),p.name, p.len)) |
| f.write("]\n") |
| f.close() |
| |
| except IOError: |
| e = sys.exc_info()[1] |
| sys.stderr.write("Unable to create '%s'\n" % filename) |
| sys.stderr.write(str(e)+"\n") |
| return |
| |
| |
| # ----------------------------------------------------------------------------- |
| # pickle_table() |
| # |
| # This function pickles the LR parsing tables to a supplied file object |
| # ----------------------------------------------------------------------------- |
| |
| def pickle_table(self,filename,signature=""): |
| try: |
| import cPickle as pickle |
| except ImportError: |
| import pickle |
| outf = open(filename,"wb") |
| pickle.dump(__tabversion__,outf,pickle_protocol) |
| pickle.dump(self.lr_method,outf,pickle_protocol) |
| pickle.dump(signature,outf,pickle_protocol) |
| pickle.dump(self.lr_action,outf,pickle_protocol) |
| pickle.dump(self.lr_goto,outf,pickle_protocol) |
| |
| outp = [] |
| for p in self.lr_productions: |
| if p.func: |
| outp.append((p.str,p.name, p.len, p.func,p.file,p.line)) |
| else: |
| outp.append((str(p),p.name,p.len,None,None,None)) |
| pickle.dump(outp,outf,pickle_protocol) |
| outf.close() |
| |
| # ----------------------------------------------------------------------------- |
| # === INTROSPECTION === |
| # |
| # The following functions and classes are used to implement the PLY |
| # introspection features followed by the yacc() function itself. |
| # ----------------------------------------------------------------------------- |
| |
| # ----------------------------------------------------------------------------- |
| # get_caller_module_dict() |
| # |
| # This function returns a dictionary containing all of the symbols defined within |
| # a caller further down the call stack. This is used to get the environment |
| # associated with the yacc() call if none was provided. |
| # ----------------------------------------------------------------------------- |
| |
| def get_caller_module_dict(levels): |
| try: |
| raise RuntimeError |
| except RuntimeError: |
| e,b,t = sys.exc_info() |
| f = t.tb_frame |
| while levels > 0: |
| f = f.f_back |
| levels -= 1 |
| ldict = f.f_globals.copy() |
| if f.f_globals != f.f_locals: |
| ldict.update(f.f_locals) |
| |
| return ldict |
| |
| # ----------------------------------------------------------------------------- |
| # parse_grammar() |
| # |
| # This takes a raw grammar rule string and parses it into production data |
| # ----------------------------------------------------------------------------- |
| def parse_grammar(doc,file,line): |
| grammar = [] |
| # Split the doc string into lines |
| pstrings = doc.splitlines() |
| lastp = None |
| dline = line |
| for ps in pstrings: |
| dline += 1 |
| p = ps.split() |
| if not p: continue |
| try: |
| if p[0] == '|': |
| # This is a continuation of a previous rule |
| if not lastp: |
| raise SyntaxError("%s:%d: Misplaced '|'" % (file,dline)) |
| prodname = lastp |
| syms = p[1:] |
| else: |
| prodname = p[0] |
| lastp = prodname |
| syms = p[2:] |
| assign = p[1] |
| if assign != ':' and assign != '::=': |
| raise SyntaxError("%s:%d: Syntax error. Expected ':'" % (file,dline)) |
| |
| grammar.append((file,dline,prodname,syms)) |
| except SyntaxError: |
| raise |
| except Exception: |
| raise SyntaxError("%s:%d: Syntax error in rule '%s'" % (file,dline,ps.strip())) |
| |
| return grammar |
| |
| # ----------------------------------------------------------------------------- |
| # ParserReflect() |
| # |
| # This class represents information extracted for building a parser including |
| # start symbol, error function, tokens, precedence list, action functions, |
| # etc. |
| # ----------------------------------------------------------------------------- |
| class ParserReflect(object): |
| def __init__(self,pdict,log=None): |
| self.pdict = pdict |
| self.start = None |
| self.error_func = None |
| self.tokens = None |
| self.files = {} |
| self.grammar = [] |
| self.error = 0 |
| |
| if log is None: |
| self.log = PlyLogger(sys.stderr) |
| else: |
| self.log = log |
| |
| # Get all of the basic information |
| def get_all(self): |
| self.get_start() |
| self.get_error_func() |
| self.get_tokens() |
| self.get_precedence() |
| self.get_pfunctions() |
| |
| # Validate all of the information |
| def validate_all(self): |
| self.validate_start() |
| self.validate_error_func() |
| self.validate_tokens() |
| self.validate_precedence() |
| self.validate_pfunctions() |
| self.validate_files() |
| return self.error |
| |
| # Compute a signature over the grammar |
| def signature(self): |
| try: |
| from hashlib import md5 |
| except ImportError: |
| from md5 import md5 |
| try: |
| sig = md5() |
| if self.start: |
| sig.update(self.start.encode('latin-1')) |
| if self.prec: |
| sig.update("".join(["".join(p) for p in self.prec]).encode('latin-1')) |
| if self.tokens: |
| sig.update(" ".join(self.tokens).encode('latin-1')) |
| for f in self.pfuncs: |
| if f[3]: |
| sig.update(f[3].encode('latin-1')) |
| except (TypeError,ValueError): |
| pass |
| return sig.digest() |
| |
| # ----------------------------------------------------------------------------- |
| # validate_file() |
| # |
| # This method checks to see if there are duplicated p_rulename() functions |
| # in the parser module file. Without this function, it is really easy for |
| # users to make mistakes by cutting and pasting code fragments (and it's a real |
| # bugger to try and figure out why the resulting parser doesn't work). Therefore, |
| # we just do a little regular expression pattern matching of def statements |
| # to try and detect duplicates. |
| # ----------------------------------------------------------------------------- |
| |
| def validate_files(self): |
| # Match def p_funcname( |
| fre = re.compile(r'\s*def\s+(p_[a-zA-Z_0-9]*)\(') |
| |
| for filename in self.files.keys(): |
| base,ext = os.path.splitext(filename) |
| if ext != '.py': return 1 # No idea. Assume it's okay. |
| |
| try: |
| f = open(filename) |
| lines = f.readlines() |
| f.close() |
| except IOError: |
| continue |
| |
| counthash = { } |
| for linen,l in enumerate(lines): |
| linen += 1 |
| m = fre.match(l) |
| if m: |
| name = m.group(1) |
| prev = counthash.get(name) |
| if not prev: |
| counthash[name] = linen |
| else: |
| self.log.warning("%s:%d: Function %s redefined. Previously defined on line %d", filename,linen,name,prev) |
| |
| # Get the start symbol |
| def get_start(self): |
| self.start = self.pdict.get('start') |
| |
| # Validate the start symbol |
| def validate_start(self): |
| if self.start is not None: |
| if not isinstance(self.start,str): |
| self.log.error("'start' must be a string") |
| |
| # Look for error handler |
| def get_error_func(self): |
| self.error_func = self.pdict.get('p_error') |
| |
| # Validate the error function |
| def validate_error_func(self): |
| if self.error_func: |
| if isinstance(self.error_func,types.FunctionType): |
| ismethod = 0 |
| elif isinstance(self.error_func, types.MethodType): |
| ismethod = 1 |
| else: |
| self.log.error("'p_error' defined, but is not a function or method") |
| self.error = 1 |
| return |
| |
| eline = func_code(self.error_func).co_firstlineno |
| efile = func_code(self.error_func).co_filename |
| self.files[efile] = 1 |
| |
| if (func_code(self.error_func).co_argcount != 1+ismethod): |
| self.log.error("%s:%d: p_error() requires 1 argument",efile,eline) |
| self.error = 1 |
| |
| # Get the tokens map |
| def get_tokens(self): |
| tokens = self.pdict.get("tokens",None) |
| if not tokens: |
| self.log.error("No token list is defined") |
| self.error = 1 |
| return |
| |
| if not isinstance(tokens,(list, tuple)): |
| self.log.error("tokens must be a list or tuple") |
| self.error = 1 |
| return |
| |
| if not tokens: |
| self.log.error("tokens is empty") |
| self.error = 1 |
| return |
| |
| self.tokens = tokens |
| |
| # Validate the tokens |
| def validate_tokens(self): |
| # Validate the tokens. |
| if 'error' in self.tokens: |
| self.log.error("Illegal token name 'error'. Is a reserved word") |
| self.error = 1 |
| return |
| |
| terminals = {} |
| for n in self.tokens: |
| if n in terminals: |
| self.log.warning("Token '%s' multiply defined", n) |
| terminals[n] = 1 |
| |
| # Get the precedence map (if any) |
| def get_precedence(self): |
| self.prec = self.pdict.get("precedence",None) |
| |
| # Validate and parse the precedence map |
| def validate_precedence(self): |
| preclist = [] |
| if self.prec: |
| if not isinstance(self.prec,(list,tuple)): |
| self.log.error("precedence must be a list or tuple") |
| self.error = 1 |
| return |
| for level,p in enumerate(self.prec): |
| if not isinstance(p,(list,tuple)): |
| self.log.error("Bad precedence table") |
| self.error = 1 |
| return |
| |
| if len(p) < 2: |
| self.log.error("Malformed precedence entry %s. Must be (assoc, term, ..., term)",p) |
| self.error = 1 |
| return |
| assoc = p[0] |
| if not isinstance(assoc,str): |
| self.log.error("precedence associativity must be a string") |
| self.error = 1 |
| return |
| for term in p[1:]: |
| if not isinstance(term,str): |
| self.log.error("precedence items must be strings") |
| self.error = 1 |
| return |
| preclist.append((term,assoc,level+1)) |
| self.preclist = preclist |
| |
| # Get all p_functions from the grammar |
| def get_pfunctions(self): |
| p_functions = [] |
| for name, item in self.pdict.items(): |
| if name[:2] != 'p_': continue |
| if name == 'p_error': continue |
| if isinstance(item,(types.FunctionType,types.MethodType)): |
| line = func_code(item).co_firstlineno |
| file = func_code(item).co_filename |
| p_functions.append((line,file,name,item.__doc__)) |
| |
| # Sort all of the actions by line number |
| p_functions.sort() |
| self.pfuncs = p_functions |
| |
| |
| # Validate all of the p_functions |
| def validate_pfunctions(self): |
| grammar = [] |
| # Check for non-empty symbols |
| if len(self.pfuncs) == 0: |
| self.log.error("no rules of the form p_rulename are defined") |
| self.error = 1 |
| return |
| |
| for line, file, name, doc in self.pfuncs: |
| func = self.pdict[name] |
| if isinstance(func, types.MethodType): |
| reqargs = 2 |
| else: |
| reqargs = 1 |
| if func_code(func).co_argcount > reqargs: |
| self.log.error("%s:%d: Rule '%s' has too many arguments",file,line,func.__name__) |
| self.error = 1 |
| elif func_code(func).co_argcount < reqargs: |
| self.log.error("%s:%d: Rule '%s' requires an argument",file,line,func.__name__) |
| self.error = 1 |
| elif not func.__doc__: |
| self.log.warning("%s:%d: No documentation string specified in function '%s' (ignored)",file,line,func.__name__) |
| else: |
| try: |
| parsed_g = parse_grammar(doc,file,line) |
| for g in parsed_g: |
| grammar.append((name, g)) |
| except SyntaxError: |
| e = sys.exc_info()[1] |
| self.log.error(str(e)) |
| self.error = 1 |
| |
| # Looks like a valid grammar rule |
| # Mark the file in which defined. |
| self.files[file] = 1 |
| |
| # Secondary validation step that looks for p_ definitions that are not functions |
| # or functions that look like they might be grammar rules. |
| |
| for n,v in self.pdict.items(): |
| if n[0:2] == 'p_' and isinstance(v, (types.FunctionType, types.MethodType)): continue |
| if n[0:2] == 't_': continue |
| if n[0:2] == 'p_' and n != 'p_error': |
| self.log.warning("'%s' not defined as a function", n) |
| if ((isinstance(v,types.FunctionType) and func_code(v).co_argcount == 1) or |
| (isinstance(v,types.MethodType) and func_code(v).co_argcount == 2)): |
| try: |
| doc = v.__doc__.split(" ") |
| if doc[1] == ':': |
| self.log.warning("%s:%d: Possible grammar rule '%s' defined without p_ prefix", |
| func_code(v).co_filename, func_code(v).co_firstlineno,n) |
| except Exception: |
| pass |
| |
| self.grammar = grammar |
| |
| # ----------------------------------------------------------------------------- |
| # yacc(module) |
| # |
| # Build a parser |
| # ----------------------------------------------------------------------------- |
| |
| def yacc(method='LALR', debug=yaccdebug, module=None, tabmodule=tab_module, start=None, |
| check_recursion=1, optimize=0, write_tables=1, debugfile=debug_file,outputdir='', |
| debuglog=None, errorlog = None, picklefile=None): |
| |
| global parse # Reference to the parsing method of the last built parser |
| |
| # If pickling is enabled, table files are not created |
| |
| if picklefile: |
| write_tables = 0 |
| |
| if errorlog is None: |
| errorlog = PlyLogger(sys.stderr) |
| |
| # Get the module dictionary used for the parser |
| if module: |
| _items = [(k,getattr(module,k)) for k in dir(module)] |
| pdict = dict(_items) |
| else: |
| pdict = get_caller_module_dict(2) |
| |
| # Collect parser information from the dictionary |
| pinfo = ParserReflect(pdict,log=errorlog) |
| pinfo.get_all() |
| |
| if pinfo.error: |
| raise YaccError("Unable to build parser") |
| |
| # Check signature against table files (if any) |
| signature = pinfo.signature() |
| |
| # Read the tables |
| try: |
| lr = LRTable() |
| if picklefile: |
| read_signature = lr.read_pickle(picklefile) |
| else: |
| read_signature = lr.read_table(tabmodule) |
| if optimize or (read_signature == signature): |
| try: |
| lr.bind_callables(pinfo.pdict) |
| parser = LRParser(lr,pinfo.error_func) |
| parse = parser.parse |
| return parser |
| except Exception: |
| e = sys.exc_info()[1] |
| errorlog.warning("There was a problem loading the table file: %s", repr(e)) |
| except VersionError: |
| e = sys.exc_info() |
| errorlog.warning(str(e)) |
| except Exception: |
| pass |
| |
| if debuglog is None: |
| if debug: |
| debuglog = PlyLogger(open(debugfile,"w")) |
| else: |
| debuglog = NullLogger() |
| |
| debuglog.info("Created by PLY version %s (http://www.dabeaz.com/ply)", __version__) |
| |
| |
| errors = 0 |
| |
| # Validate the parser information |
| if pinfo.validate_all(): |
| raise YaccError("Unable to build parser") |
| |
| if not pinfo.error_func: |
| errorlog.warning("no p_error() function is defined") |
| |
| # Create a grammar object |
| grammar = Grammar(pinfo.tokens) |
| |
| # Set precedence level for terminals |
| for term, assoc, level in pinfo.preclist: |
| try: |
| grammar.set_precedence(term,assoc,level) |
| except GrammarError: |
| e = sys.exc_info()[1] |
| errorlog.warning("%s",str(e)) |
| |
| # Add productions to the grammar |
| for funcname, gram in pinfo.grammar: |
| file, line, prodname, syms = gram |
| try: |
| grammar.add_production(prodname,syms,funcname,file,line) |
| except GrammarError: |
| e = sys.exc_info()[1] |
| errorlog.error("%s",str(e)) |
| errors = 1 |
| |
| # Set the grammar start symbols |
| try: |
| if start is None: |
| grammar.set_start(pinfo.start) |
| else: |
| grammar.set_start(start) |
| except GrammarError: |
| e = sys.exc_info()[1] |
| errorlog.error(str(e)) |
| errors = 1 |
| |
| if errors: |
| raise YaccError("Unable to build parser") |
| |
| # Verify the grammar structure |
| undefined_symbols = grammar.undefined_symbols() |
| for sym, prod in undefined_symbols: |
| errorlog.error("%s:%d: Symbol '%s' used, but not defined as a token or a rule",prod.file,prod.line,sym) |
| errors = 1 |
| |
| unused_terminals = grammar.unused_terminals() |
| if unused_terminals: |
| debuglog.info("") |
| debuglog.info("Unused terminals:") |
| debuglog.info("") |
| for term in unused_terminals: |
| errorlog.warning("Token '%s' defined, but not used", term) |
| debuglog.info(" %s", term) |
| |
| # Print out all productions to the debug log |
| if debug: |
| debuglog.info("") |
| debuglog.info("Grammar") |
| debuglog.info("") |
| for n,p in enumerate(grammar.Productions): |
| debuglog.info("Rule %-5d %s", n, p) |
| |
| # Find unused non-terminals |
| unused_rules = grammar.unused_rules() |
| for prod in unused_rules: |
| errorlog.warning("%s:%d: Rule '%s' defined, but not used", prod.file, prod.line, prod.name) |
| |
| if len(unused_terminals) == 1: |
| errorlog.warning("There is 1 unused token") |
| if len(unused_terminals) > 1: |
| errorlog.warning("There are %d unused tokens", len(unused_terminals)) |
| |
| if len(unused_rules) == 1: |
| errorlog.warning("There is 1 unused rule") |
| if len(unused_rules) > 1: |
| errorlog.warning("There are %d unused rules", len(unused_rules)) |
| |
| if debug: |
| debuglog.info("") |
| debuglog.info("Terminals, with rules where they appear") |
| debuglog.info("") |
| terms = list(grammar.Terminals) |
| terms.sort() |
| for term in terms: |
| debuglog.info("%-20s : %s", term, " ".join([str(s) for s in grammar.Terminals[term]])) |
| |
| debuglog.info("") |
| debuglog.info("Nonterminals, with rules where they appear") |
| debuglog.info("") |
| nonterms = list(grammar.Nonterminals) |
| nonterms.sort() |
| for nonterm in nonterms: |
| debuglog.info("%-20s : %s", nonterm, " ".join([str(s) for s in grammar.Nonterminals[nonterm]])) |
| debuglog.info("") |
| |
| if check_recursion: |
| unreachable = grammar.find_unreachable() |
| for u in unreachable: |
| errorlog.warning("Symbol '%s' is unreachable",u) |
| |
| infinite = grammar.infinite_cycles() |
| for inf in infinite: |
| errorlog.error("Infinite recursion detected for symbol '%s'", inf) |
| errors = 1 |
| |
| unused_prec = grammar.unused_precedence() |
| for term, assoc in unused_prec: |
| errorlog.error("Precedence rule '%s' defined for unknown symbol '%s'", assoc, term) |
| errors = 1 |
| |
| if errors: |
| raise YaccError("Unable to build parser") |
| |
| # Run the LRGeneratedTable on the grammar |
| if debug: |
| errorlog.debug("Generating %s tables", method) |
| |
| lr = LRGeneratedTable(grammar,method,debuglog) |
| |
| if debug: |
| num_sr = len(lr.sr_conflicts) |
| |
| # Report shift/reduce and reduce/reduce conflicts |
| if num_sr == 1: |
| errorlog.warning("1 shift/reduce conflict") |
| elif num_sr > 1: |
| errorlog.warning("%d shift/reduce conflicts", num_sr) |
| |
| num_rr = len(lr.rr_conflicts) |
| if num_rr == 1: |
| errorlog.warning("1 reduce/reduce conflict") |
| elif num_rr > 1: |
| errorlog.warning("%d reduce/reduce conflicts", num_rr) |
| |
| # Write out conflicts to the output file |
| if debug and (lr.sr_conflicts or lr.rr_conflicts): |
| debuglog.warning("") |
| debuglog.warning("Conflicts:") |
| debuglog.warning("") |
| |
| for state, tok, resolution in lr.sr_conflicts: |
| debuglog.warning("shift/reduce conflict for %s in state %d resolved as %s", tok, state, resolution) |
| |
| already_reported = {} |
| for state, rule, rejected in lr.rr_conflicts: |
| if (state,id(rule),id(rejected)) in already_reported: |
| continue |
| debuglog.warning("reduce/reduce conflict in state %d resolved using rule (%s)", state, rule) |
| debuglog.warning("rejected rule (%s) in state %d", rejected,state) |
| errorlog.warning("reduce/reduce conflict in state %d resolved using rule (%s)", state, rule) |
| errorlog.warning("rejected rule (%s) in state %d", rejected, state) |
| already_reported[state,id(rule),id(rejected)] = 1 |
| |
| warned_never = [] |
| for state, rule, rejected in lr.rr_conflicts: |
| if not rejected.reduced and (rejected not in warned_never): |
| debuglog.warning("Rule (%s) is never reduced", rejected) |
| errorlog.warning("Rule (%s) is never reduced", rejected) |
| warned_never.append(rejected) |
| |
| # Write the table file if requested |
| if write_tables: |
| lr.write_table(tabmodule,outputdir,signature) |
| |
| # Write a pickled version of the tables |
| if picklefile: |
| lr.pickle_table(picklefile,signature) |
| |
| # Build the parser |
| lr.bind_callables(pinfo.pdict) |
| parser = LRParser(lr,pinfo.error_func) |
| |
| parse = parser.parse |
| return parser |