include/biosxml.hpp - openbmc/intel-ipmi-oem - Gitiles

 #pragma once

 #include "tinyxml2.h"

 #include <phosphor-logging/elog-errors.hpp>
 #include <phosphor-logging/log.hpp>

 #include <map>
 #include <sstream>
 #include <stack>
 #include <string>
 #include <variant>
 #include <vector>

 namespace bios
 {
 /* Can hold one 'option'
  * For example
  *  <option text="TIS" value="0x0"/>
  */
 using OptionType = std::tuple<std::string, std::variant<int64_t, std::string>>;

 /* Can hold one 'options'
  * For example
  *  <options>
  *		<option text="TIS" value="0x0"/>
  *		<option text="PTP FIFO" value="0x1"/>
  *		<option text="PTP CRB" value="0x2"/>
  *	</options>
  */
 using OptionTypeVector = std::vector<OptionType>;

 /* Can hold one 'knob'
  * For example
  *  <knob  type="scalar" setupType="oneof" name="TpmDeviceInterfaceAttempt"
  *  varstoreIndex="14" prompt="Attempt PTP TPM Device Interface"
  *  description="Attempt PTP TPM Device Interface: PTP FIFO, PTP CRB" size="1"
  *  offset="0x0005" depex="Sif( _LIST_ TpmDevice _EQU_ 0 1 ) _AND_ Sif(
  *  TpmDeviceInterfacePtpFifoSupported _EQU_ 0 OR
  *  TpmDeviceInterfacePtpCrbSupported _EQU_ 0 )" default="0x00"
  *CurrentVal="0x00"> <options> <option text="TIS" value="0x0"/> <option
  *text="PTP FIFO" value="0x1"/> <option text="PTP CRB" value="0x2"/>
  *		</options>
  *	</knob>
  */
 using BiosBaseTableTypeEntry =
     std::tuple<std::string, bool, std::string, std::string, std::string,
                std::variant<int64_t, std::string>,
                std::variant<int64_t, std::string>, OptionTypeVector>;

 /* Can hold one 'biosknobs'
  * biosknobs has array of 'knob' */
 using BiosBaseTableType = std::map<std::string, BiosBaseTableTypeEntry>;

 namespace knob
 {
 /* These are the operators we support in a 'depex' expression
  * Note: We also support '_LIST_', 'Sif', 'Gif', 'Dif', and 'NOT'. But they are
  * handeled sepeartely. */
 enum class DepexOperators
 {
     unknown = 0,
     OR,
     AND,
     GT,
     GTE,
     LTE,
     LT,
     EQU,
     NEQ,
     MODULO
 };

 namespace option
 {
 /* Can hold one 'option' */
 struct option
 {
     option(std::string text, std::string value) :
         text(std::move(text)), value(std::move(value))
     {}

     std::string text;
     std::string value;
 };
 } // namespace option

 /* Can hold one 'knob' */
 struct knob
 {
     knob(std::string nameStr, std::string currentValStr, int currentVal,
          std::string descriptionStr, std::string defaultStr,
          std::string promptStr, std::string depexStr,
          std::string& setupTypeStr) :
         nameStr(std::move(nameStr)),
         currentValStr(std::move(currentValStr)), currentVal(currentVal),
         descriptionStr(std::move(descriptionStr)),
         defaultStr(std::move(defaultStr)), promptStr(std::move(promptStr)),
         depexStr(std::move(depexStr)), depex(false),
         readOnly(("ReadOnly" == setupTypeStr) ? true : false)
     {}

     bool depex;
     bool readOnly;
     int currentVal;

     std::string nameStr;
     std::string currentValStr;
     std::string descriptionStr;
     std::string defaultStr;
     std::string promptStr;
     std::string depexStr;

     /* Can hold one 'options' */
     std::vector<option::option> options;
 };
 } // namespace knob

 /* Class capable of computing 'depex' expression. */
 class Depex
 {
   public:
     Depex(std::vector<knob::knob>& knobs) : mKnobs(knobs)
     {}

     /* Compute 'depex' expression of all knobs in 'biosknobs'. */
     void compute()
     {
         mError.clear();

         for (auto& knob : mKnobs)
         {
             /* if 'depex' == "TRUE" no need to execute expression. */
             if ("TRUE" == knob.depexStr)
             {
                 knob.depex = true;
             }
             else if (!knob.readOnly)
             {
                 int value = 0;

                 if (!evaluateExpression(knob.depexStr, value))
                 {
                     mError.emplace_back("bad depex: " + knob.depexStr +
                                         " in knob: " + knob.nameStr);
                 }
                 else
                 {
                     if (value)
                     {
                         knob.depex = true;
                     }
                 }
             }
         }
     }

     /* Returns the number of 'knob's which have a bad 'depex' expression. */
     size_t getErrorCount()
     {
         return mError.size();
     }

     /* Prints all the 'knob's which have a bad 'depex' expression. */
     void printError()
     {
         for (auto& error : mError)
         {
             phosphor::logging::log<phosphor::logging::level::ERR>(
                 error.c_str());
         }
     }

   private:
     /* Returns 'true' if the argument string is a number. */
     bool isNumber(const std::string& s)
     {
         return !s.empty() &&
                std::find_if(s.begin(), s.end(), [](unsigned char c) {
                    return !std::isdigit(c);
                }) == s.end();
     }

     /* Returns 'true' if the argument string is hex representation of a number.
      */
     bool isHexNotation(std::string const& s)
     {
         return s.compare(0, 2, "0x") == 0 && s.size() > 2 &&
                s.find_first_not_of("0123456789abcdefABCDEF", 2) ==
                    std::string::npos;
     }

     /* Function to find current value of a 'knob'
      * search is done using 'knob' attribute 'name' */
     bool getValue(std::string& variableName, int& value)
     {
         for (auto& knob : mKnobs)
         {
             if (knob.nameStr == variableName)
             {
                 value = knob.currentVal;
                 return true;
             }
         }

         std::string error =
             "Unable to find knob: " + variableName + " in knob list\n";
         phosphor::logging::log<phosphor::logging::level::ERR>(error.c_str());

         return false;
     }

     /* Get the expression enclosed within brackets, i.e., between '(' and ')' */
     bool getSubExpression(const std::string& expression,
                           std::string& subExpression, size_t& i)
     {
         int level = 1;
         subExpression.clear();

         for (; i < expression.length(); i++)
         {
             if (expression[i] == '(')
             {
                 ++level;
             }
             else if (expression[i] == ')')
             {
                 --level;
                 if (level == 0)
                 {
                     break;
                 }
             }

             subExpression.push_back(expression[i]);
         }

         if (!subExpression.empty())
         {
             return true;
         }

         return false;
     }

     /* Function to handle operator '_LIST_'
      * Convert a '_LIST_' expression to a normal expression
      * Example "_LIST_ VariableA _EQU_ 0 1" is converted to "VariableA _EQU_ 0
      * OR VariableA _EQU_ 1" */
     bool getListExpression(const std::string& expression,
                            std::string& subExpression, size_t& i)
     {
         subExpression.clear();

         int cnt = 0;
         std::string variableStr;
         std::string operatorStr;

         for (; i < expression.length(); i++)
         {
             if (expression[i] == '(')
             {
                 return false;
             }
             else if (expression[i] == ')')
             {
                 break;
             }
             else if (expression[i] == ' ')
             {
                 /* whitespace */
                 continue;
             }
             else
             {
                 std::string word;

                 /* Get the next word in expression string */
                 while ((i < expression.length()) && (expression[i] != ' '))
                 {
                     word.push_back(expression[i++]);
                 }

                 if (word == "_OR_" || word == "OR" || word == "_AND_" ||
                     word == "AND" || word == "NOT")
                 {
                     i = i - word.length();
                     break;
                 }

                 ++cnt;

                 if (cnt == 1)
                 {
                     variableStr = word;
                 }
                 else if (cnt == 2)
                 {
                     operatorStr = word;
                 }
                 else
                 {
                     if (cnt > 3)
                     {
                         subExpression += " OR ";
                     }

                     subExpression += "( ";
                     subExpression += variableStr;
                     subExpression += " ";
                     subExpression += operatorStr;
                     subExpression += " ";
                     subExpression += word;
                     subExpression += " )";
                 }
             }
         }

         if (!subExpression.empty())
         {
             return true;
         }

         return false;
     }

     /* Function to handle operator 'NOT'
      * 1) Find the variable
      * 2) apply NOT on the variable */
     bool getNotValue(const std::string& expression, size_t& i, int& value)
     {
         std::string word;

         for (; i < expression.length(); i++)
         {
             if (expression[i] == ' ')
             {
                 /* whitespace */
                 continue;
             }
             else
             {
                 /* Get the next word in expression string */
                 while ((i < expression.length()) && (expression[i] != ' '))
                 {
                     word.push_back(expression[i++]);
                 }

                 break;
             }
         }

         if (!word.empty())
         {
             if (getValue(word, value))
             {
                 value = !value;
                 return true;
             }
         }

         return false;
     }

     /* 1) Pop one operator from operator stack, example 'OR'
      * 2) Pop two variable from variable stack, example VarA and VarB
      * 3) Push back result of 'VarA OR VarB' to variable stack
      * 4) Repeat till operator stack is empty
      *
      * The last variable in variable stack is the output of the expression. */
     bool evaluateExprStack(std::stack<int>& values,
                            std::stack<knob::DepexOperators>& operators,
                            int& output)
     {
         if (values.size() != (operators.size() + 1))
         {
             return false;
         }

         while (!operators.empty())
         {
             int b = values.top();
             values.pop();

             int a = values.top();
             values.pop();

             switch (operators.top())
             {
                 case knob::DepexOperators::OR:
                     values.emplace(a | b);
                     break;

                 case knob::DepexOperators::AND:
                     values.emplace(a & b);
                     break;

                 case knob::DepexOperators::EQU:
                     if (a == b)
                     {
                         values.emplace(1);
                         break;
                     }

                     values.emplace(0);
                     break;

                 case knob::DepexOperators::NEQ:
                     if (a != b)
                     {
                         values.emplace(1);
                         break;
                     }

                     values.emplace(0);
                     break;

                 case knob::DepexOperators::LTE:
                     if (a <= b)
                     {
                         values.emplace(1);
                         break;
                     }

                     values.emplace(0);
                     break;

                 case knob::DepexOperators::LT:
                     if (a < b)
                     {
                         values.emplace(1);
                         break;
                     }

                     values.emplace(0);
                     break;

                 case knob::DepexOperators::GTE:
                     if (a >= b)
                     {
                         values.emplace(1);
                         break;
                     }

                     values.emplace(0);
                     break;

                 case knob::DepexOperators::GT:
                     if (a > b)
                     {
                         values.emplace(1);
                         break;
                     }

                     values.emplace(0);
                     break;

                 case knob::DepexOperators::MODULO:
                     if (b == 0)
                     {
                         return false;
                     }
                     values.emplace(a % b);
                     break;

                 default:
                     return false;
             }

             operators.pop();
         }

         if (values.size() == 1)
         {
             output = values.top();
             values.pop();

             return true;
         }

         return false;
     }

     /* Evaluvate one 'depex' expression
      * 1) Find a word in expression string
      * 2) If word is a variable push to variable stack
      * 3) If word is a operator push to operator stack
      *
      * Execute the stack at end to get the result of expression. */
     bool evaluateExpression(const std::string& expression, int& output)
     {
         if (expression.empty())
         {
             return false;
         }

         size_t i;
         int value;
         std::stack<int> values;
         std::stack<knob::DepexOperators> operators;
         std::string subExpression;

         for (i = 0; i < expression.length(); i++)
         {
             if (expression[i] == ' ')
             {
                 /* whitespace */
                 continue;
             }
             else
             {
                 std::string word;

                 /* Get the next word in expression string */
                 while ((i < expression.length()) && (expression[i] != ' '))
                 {
                     word.push_back(expression[i++]);
                 }

                 if (word == "_OR_" || word == "OR")
                 {
                     /* OR and AND has more precedence than other operators
                      * To handle statements like "a != b or c != d"
                      * we need to execute, for above example, both '!=' before
                      * 'or' */
                     if (!operators.empty())
                     {
                         if (!evaluateExprStack(values, operators, value))
                         {
                             return false;
                         }

                         values.emplace(value);
                     }

                     operators.emplace(knob::DepexOperators::OR);
                 }
                 else if (word == "_AND_" || word == "AND")
                 {
                     /* OR and AND has more precedence than other operators
                      * To handle statements like "a == b and c == d"
                      * we need to execute, for above example, both '==' before
                      * 'and' */
                     if (!operators.empty())
                     {
                         if (!evaluateExprStack(values, operators, value))
                         {
                             return false;
                         }

                         values.emplace(value);
                     }

                     operators.emplace(knob::DepexOperators::AND);
                 }
                 else if (word == "_LTE_")
                 {
                     operators.emplace(knob::DepexOperators::LTE);
                 }
                 else if (word == "_LT_")
                 {
                     operators.emplace(knob::DepexOperators::LT);
                 }
                 else if (word == "_GTE_")
                 {
                     operators.emplace(knob::DepexOperators::GTE);
                 }
                 else if (word == "_GT_")
                 {
                     operators.emplace(knob::DepexOperators::GT);
                 }
                 else if (word == "_NEQ_")
                 {
                     operators.emplace(knob::DepexOperators::NEQ);
                 }
                 else if (word == "_EQU_")
                 {
                     operators.emplace(knob::DepexOperators::EQU);
                 }
                 else if (word == "%")
                 {
                     operators.emplace(knob::DepexOperators::MODULO);
                 }
                 else
                 {
                     /* Handle 'Sif(', 'Gif(', 'Dif(' and '('
                      * by taking the inner/sub expression and evaluating it */
                     if (word.back() == '(')
                     {
                         if (!getSubExpression(expression, subExpression, i))
                             break;

                         if (!evaluateExpression(subExpression, value))
                             break;
                     }
                     else if (word == "_LIST_")
                     {
                         if (!getListExpression(expression, subExpression, i))
                             break;

                         --i;

                         if (!evaluateExpression(subExpression, value))
                             break;
                     }
                     else if (word == "NOT")
                     {
                         if (!getNotValue(expression, i, value))
                             break;
                     }
                     else if (isNumber(word) || isHexNotation(word))
                     {
                         try
                         {
                             value = std::stoi(word);
                         }
                         catch (const std::exception& ex)
                         {
                             phosphor::logging::log<
                                 phosphor::logging::level::ERR>(ex.what());
                             return false;
                         }
                     }
                     else
                     {
                         if (!getValue(word, value))
                             break;
                     }

                     values.emplace(value);
                 }
             }
         }

         if (i == expression.length())
         {
             if (evaluateExprStack(values, operators, output))
             {
                 return true;
             }
         }

         return false;
     }

   private:
     /* To store all 'knob's in 'biosknobs' */
     std::vector<knob::knob>& mKnobs;

     /* To store all bad 'depex' expression */
     std::vector<std::string> mError;
 };

 class Xml
 {
   public:
     Xml(const char* filePath) : mDepex(std::make_unique<Depex>(mKnobs))
     {
         if (!getKnobs(filePath))
         {
             std::string error =
                 "Unable to get knobs in file: " + std::string(filePath);
             throw std::runtime_error(error);
         }
     }

     /* Fill Bios table with all 'knob's which have output of 'depex' expression
      * as 'true' */
     bool getBaseTable(bios::BiosBaseTableType& baseTable)
     {
         baseTable.clear();

         for (auto& knob : mKnobs)
         {
             if (knob.depex)
             {
                 std::string text =
                     "xyz.openbmc_project.BIOSConfig.Manager.BoundType.OneOf";
                 bios::OptionTypeVector options;

                 for (auto& option : knob.options)
                 {
                     options.emplace_back(text, option.value);
                 }

                 bios::BiosBaseTableTypeEntry baseTableEntry = std::make_tuple(
                     "xyz.openbmc_project.BIOSConfig.Manager.AttributeType."
                     "String",
                     false, knob.nameStr, knob.descriptionStr, "./",
                     knob.currentValStr, knob.defaultStr, options);

                 baseTable.emplace(knob.nameStr, baseTableEntry);
             }
         }

         if (!baseTable.empty())
         {
             return true;
         }

         return false;
     }

     /* Execute all 'depex' expression */
     bool doDepexCompute()
     {
         mDepex->compute();

         if (mDepex->getErrorCount())
         {
             mDepex->printError();
             return false;
         }

         return true;
     }

   private:
     /* Get 'option' */
     void getOption(tinyxml2::XMLElement* pOption)
     {
         if (pOption)
         {
             std::string valueStr;
             std::string textStr;

             if (pOption->Attribute("text"))
                 valueStr = pOption->Attribute("text");

             if (pOption->Attribute("value"))
                 textStr = pOption->Attribute("value");

             mKnobs.back().options.emplace_back(pOption->Attribute("text"),
                                                pOption->Attribute("value"));
         }
     }

     /* Get 'options' */
     void getOptions(tinyxml2::XMLElement* pKnob)
     {
         uint16_t reserveCnt = 0;

         /* Get node options inside knob */
         tinyxml2::XMLElement* pOptions = pKnob->FirstChildElement("options");

         if (pOptions)
         {
             for (tinyxml2::XMLElement* pOption =
                      pOptions->FirstChildElement("option");
                  pOption; pOption = pOption->NextSiblingElement("option"))
             {
                 ++reserveCnt;
             }

             mKnobs.back().options.reserve(reserveCnt);

             /* Loop through all option inside options */
             for (tinyxml2::XMLElement* pOption =
                      pOptions->FirstChildElement("option");
                  pOption; pOption = pOption->NextSiblingElement("option"))
             {
                 getOption(pOption);
             }
         }
     }

     /* Get 'knob' */
     void getKnob(tinyxml2::XMLElement* pKnob)
     {
         if (pKnob)
         {
             int currentVal = 0;
             std::string nameStr;
             std::string currentValStr;
             std::string descriptionStr;
             std::string defaultStr;
             std::string depexStr;
             std::string promptStr;
             std::string setupTypeStr;

             if (!pKnob->Attribute("name") || !pKnob->Attribute("CurrentVal"))
             {
                 return;
             }

             nameStr = pKnob->Attribute("name");
             currentValStr = pKnob->Attribute("CurrentVal");
             std::stringstream ss;
             ss << std::hex << currentValStr;
             if (ss.good())
             {
                 ss >> currentVal;
             }
             else
             {
                 std::string error = "Invalid hex value input " + currentValStr +
                                     " for " + nameStr + "\n";
                 phosphor::logging::log<phosphor::logging::level::ERR>(
                     error.c_str());
                 return;
             }
             if (pKnob->Attribute("description"))
                 descriptionStr = pKnob->Attribute("description");

             if (pKnob->Attribute("default"))
                 defaultStr = pKnob->Attribute("default");

             if (pKnob->Attribute("depex"))
                 depexStr = pKnob->Attribute("depex");

             if (pKnob->Attribute("prompt"))
                 promptStr = pKnob->Attribute("prompt");

             if (pKnob->Attribute("setupType"))
                 setupTypeStr = pKnob->Attribute("setupType");

             mKnobs.emplace_back(nameStr, currentValStr, currentVal,
                                 descriptionStr, defaultStr, promptStr, depexStr,
                                 setupTypeStr);

             getOptions(pKnob);
         }
     }

     /* Get 'biosknobs' */
     bool getKnobs(const char* biosXmlFilePath)
     {
         uint16_t reserveCnt = 0;

         mKnobs.clear();

         tinyxml2::XMLDocument biosXml;

         /* Load the XML file into the Doc instance */
         biosXml.LoadFile(biosXmlFilePath);

         /* Get 'SYSTEM' */
         tinyxml2::XMLElement* pRootElement = biosXml.RootElement();
         if (pRootElement)
         {
             /* Get 'biosknobs' inside 'SYSTEM' */
             tinyxml2::XMLElement* pBiosknobs =
                 pRootElement->FirstChildElement("biosknobs");
             if (pBiosknobs)
             {
                 for (tinyxml2::XMLElement* pKnob =
                          pBiosknobs->FirstChildElement("knob");
                      pKnob; pKnob = pKnob->NextSiblingElement("knob"))
                 {
                     ++reserveCnt;
                 }

                 /* reserve before emplace_back will avoids realloc(s) */
                 mKnobs.reserve(reserveCnt);

                 for (tinyxml2::XMLElement* pKnob =
                          pBiosknobs->FirstChildElement("knob");
                      pKnob; pKnob = pKnob->NextSiblingElement("knob"))
                 {
                     getKnob(pKnob);
                 }
             }
         }

         if (!mKnobs.empty())
         {
             return true;
         }

         return false;
     }

   private:
     /* To store all 'knob's in 'biosknobs' */
     std::vector<knob::knob> mKnobs;

     /* Object of Depex class to compute 'depex' expression */
     std::unique_ptr<Depex> mDepex;
 };
 } // namespace bios
	#pragma once

	#include "tinyxml2.h"

	#include <phosphor-logging/elog-errors.hpp>
	#include <phosphor-logging/log.hpp>

	#include <map>
	#include <sstream>
	#include <stack>
	#include <string>
	#include <variant>
	#include <vector>

	namespace bios
	{
	/* Can hold one 'option'
	* For example
	* <option text="TIS" value="0x0"/>
	*/
	using OptionType = std::tuple<std::string, std::variant<int64_t, std::string>>;

	/* Can hold one 'options'
	* For example
	* <options>
	* <option text="TIS" value="0x0"/>
	* <option text="PTP FIFO" value="0x1"/>
	* <option text="PTP CRB" value="0x2"/>
	* </options>
	*/
	using OptionTypeVector = std::vector<OptionType>;

	/* Can hold one 'knob'
	* For example
	* <knob type="scalar" setupType="oneof" name="TpmDeviceInterfaceAttempt"
	* varstoreIndex="14" prompt="Attempt PTP TPM Device Interface"
	* description="Attempt PTP TPM Device Interface: PTP FIFO, PTP CRB" size="1"
	* offset="0x0005" depex="Sif( _LIST_ TpmDevice _EQU_ 0 1 ) _AND_ Sif(
	* TpmDeviceInterfacePtpFifoSupported _EQU_ 0 OR
	* TpmDeviceInterfacePtpCrbSupported _EQU_ 0 )" default="0x00"
	*CurrentVal="0x00"> <options> <option text="TIS" value="0x0"/> <option
	*text="PTP FIFO" value="0x1"/> <option text="PTP CRB" value="0x2"/>
	* </options>
	* </knob>
	*/
	using BiosBaseTableTypeEntry =
	std::tuple<std::string, bool, std::string, std::string, std::string,
	std::variant<int64_t, std::string>,
	std::variant<int64_t, std::string>, OptionTypeVector>;

	/* Can hold one 'biosknobs'
	* biosknobs has array of 'knob' */
	using BiosBaseTableType = std::map<std::string, BiosBaseTableTypeEntry>;

	namespace knob
	{
	/* These are the operators we support in a 'depex' expression
	* Note: We also support '_LIST_', 'Sif', 'Gif', 'Dif', and 'NOT'. But they are
	* handeled sepeartely. */
	enum class DepexOperators
	{
	unknown = 0,
	OR,
	AND,
	GT,
	GTE,
	LTE,
	LT,
	EQU,
	NEQ,
	MODULO
	};

	namespace option
	{
	/* Can hold one 'option' */
	struct option
	{
	option(std::string text, std::string value) :
	text(std::move(text)), value(std::move(value))
	{}

	std::string text;
	std::string value;
	};
	} // namespace option

	/* Can hold one 'knob' */
	struct knob
	{
	knob(std::string nameStr, std::string currentValStr, int currentVal,
	std::string descriptionStr, std::string defaultStr,
	std::string promptStr, std::string depexStr,
	std::string& setupTypeStr) :
	nameStr(std::move(nameStr)),
	currentValStr(std::move(currentValStr)), currentVal(currentVal),
	descriptionStr(std::move(descriptionStr)),
	defaultStr(std::move(defaultStr)), promptStr(std::move(promptStr)),
	depexStr(std::move(depexStr)), depex(false),
	readOnly(("ReadOnly" == setupTypeStr) ? true : false)
	{}

	bool depex;
	bool readOnly;
	int currentVal;

	std::string nameStr;
	std::string currentValStr;
	std::string descriptionStr;
	std::string defaultStr;
	std::string promptStr;
	std::string depexStr;

	/* Can hold one 'options' */
	std::vector<option::option> options;
	};
	} // namespace knob

	/* Class capable of computing 'depex' expression. */
	class Depex
	{
	public:
	Depex(std::vector<knob::knob>& knobs) : mKnobs(knobs)
	{}

	/* Compute 'depex' expression of all knobs in 'biosknobs'. */
	void compute()
	{
	mError.clear();

	for (auto& knob : mKnobs)
	{
	/* if 'depex' == "TRUE" no need to execute expression. */
	if ("TRUE" == knob.depexStr)
	{
	knob.depex = true;
	}
	else if (!knob.readOnly)
	{
	int value = 0;

	if (!evaluateExpression(knob.depexStr, value))
	{
	mError.emplace_back("bad depex: " + knob.depexStr +
	" in knob: " + knob.nameStr);
	}
	else
	{
	if (value)
	{
	knob.depex = true;
	}
	}
	}
	}
	}

	/* Returns the number of 'knob's which have a bad 'depex' expression. */
	size_t getErrorCount()
	{
	return mError.size();
	}

	/* Prints all the 'knob's which have a bad 'depex' expression. */
	void printError()
	{
	for (auto& error : mError)
	{
	phosphor::logging::log<phosphor::logging::level::ERR>(
	error.c_str());
	}
	}

	private:
	/* Returns 'true' if the argument string is a number. */
	bool isNumber(const std::string& s)
	{
	return !s.empty() &&
	std::find_if(s.begin(), s.end(), [](unsigned char c) {
	return !std::isdigit(c);
	}) == s.end();
	}

	/* Returns 'true' if the argument string is hex representation of a number.
	*/
	bool isHexNotation(std::string const& s)
	{
	return s.compare(0, 2, "0x") == 0 && s.size() > 2 &&
	s.find_first_not_of("0123456789abcdefABCDEF", 2) ==
	std::string::npos;
	}

	/* Function to find current value of a 'knob'
	* search is done using 'knob' attribute 'name' */
	bool getValue(std::string& variableName, int& value)
	{
	for (auto& knob : mKnobs)
	{
	if (knob.nameStr == variableName)
	{
	value = knob.currentVal;
	return true;
	}
	}

	std::string error =
	"Unable to find knob: " + variableName + " in knob list\n";
	phosphor::logging::log<phosphor::logging::level::ERR>(error.c_str());

	return false;
	}

	/* Get the expression enclosed within brackets, i.e., between '(' and ')' */
	bool getSubExpression(const std::string& expression,
	std::string& subExpression, size_t& i)
	{
	int level = 1;
	subExpression.clear();

	for (; i < expression.length(); i++)
	{
	if (expression[i] == '(')
	{
	++level;
	}
	else if (expression[i] == ')')
	{
	--level;
	if (level == 0)
	{
	break;
	}
	}

	subExpression.push_back(expression[i]);
	}

	if (!subExpression.empty())
	{
	return true;
	}

	return false;
	}

	/* Function to handle operator '_LIST_'
	* Convert a '_LIST_' expression to a normal expression
	* Example "_LIST_ VariableA _EQU_ 0 1" is converted to "VariableA _EQU_ 0
	* OR VariableA _EQU_ 1" */
	bool getListExpression(const std::string& expression,
	std::string& subExpression, size_t& i)
	{
	subExpression.clear();

	int cnt = 0;
	std::string variableStr;
	std::string operatorStr;

	for (; i < expression.length(); i++)
	{
	if (expression[i] == '(')
	{
	return false;
	}
	else if (expression[i] == ')')
	{
	break;
	}
	else if (expression[i] == ' ')
	{
	/* whitespace */
	continue;
	}
	else
	{
	std::string word;

	/* Get the next word in expression string */
	while ((i < expression.length()) && (expression[i] != ' '))
	{
	word.push_back(expression[i++]);
	}

	if (word == "_OR_" \|\| word == "OR" \|\| word == "_AND_" \|\|
	word == "AND" \|\| word == "NOT")
	{
	i = i - word.length();
	break;
	}

	++cnt;

	if (cnt == 1)
	{
	variableStr = word;
	}
	else if (cnt == 2)
	{
	operatorStr = word;
	}
	else
	{
	if (cnt > 3)
	{
	subExpression += " OR ";
	}

	subExpression += "( ";
	subExpression += variableStr;
	subExpression += " ";
	subExpression += operatorStr;
	subExpression += " ";
	subExpression += word;
	subExpression += " )";
	}
	}
	}

	if (!subExpression.empty())
	{
	return true;
	}

	return false;
	}

	/* Function to handle operator 'NOT'
	* 1) Find the variable
	* 2) apply NOT on the variable */
	bool getNotValue(const std::string& expression, size_t& i, int& value)
	{
	std::string word;

	for (; i < expression.length(); i++)
	{
	if (expression[i] == ' ')
	{
	/* whitespace */
	continue;
	}
	else
	{
	/* Get the next word in expression string */
	while ((i < expression.length()) && (expression[i] != ' '))
	{
	word.push_back(expression[i++]);
	}

	break;
	}
	}

	if (!word.empty())
	{
	if (getValue(word, value))
	{
	value = !value;
	return true;
	}
	}

	return false;
	}

	/* 1) Pop one operator from operator stack, example 'OR'
	* 2) Pop two variable from variable stack, example VarA and VarB
	* 3) Push back result of 'VarA OR VarB' to variable stack
	* 4) Repeat till operator stack is empty
	*
	* The last variable in variable stack is the output of the expression. */
	bool evaluateExprStack(std::stack<int>& values,
	std::stack<knob::DepexOperators>& operators,
	int& output)
	{
	if (values.size() != (operators.size() + 1))
	{
	return false;
	}

	while (!operators.empty())
	{
	int b = values.top();
	values.pop();

	int a = values.top();
	values.pop();

	switch (operators.top())
	{
	case knob::DepexOperators::OR:
	values.emplace(a \| b);
	break;

	case knob::DepexOperators::AND:
	values.emplace(a & b);
	break;

	case knob::DepexOperators::EQU:
	if (a == b)
	{
	values.emplace(1);
	break;
	}

	values.emplace(0);
	break;

	case knob::DepexOperators::NEQ:
	if (a != b)
	{
	values.emplace(1);
	break;
	}

	values.emplace(0);
	break;

	case knob::DepexOperators::LTE:
	if (a <= b)
	{
	values.emplace(1);
	break;
	}

	values.emplace(0);
	break;

	case knob::DepexOperators::LT:
	if (a < b)
	{
	values.emplace(1);
	break;
	}

	values.emplace(0);
	break;

	case knob::DepexOperators::GTE:
	if (a >= b)
	{
	values.emplace(1);
	break;
	}

	values.emplace(0);
	break;

	case knob::DepexOperators::GT:
	if (a > b)
	{
	values.emplace(1);
	break;
	}

	values.emplace(0);
	break;

	case knob::DepexOperators::MODULO:
	if (b == 0)
	{
	return false;
	}
	values.emplace(a % b);
	break;

	default:
	return false;
	}

	operators.pop();
	}

	if (values.size() == 1)
	{
	output = values.top();
	values.pop();

	return true;
	}

	return false;
	}

	/* Evaluvate one 'depex' expression
	* 1) Find a word in expression string
	* 2) If word is a variable push to variable stack
	* 3) If word is a operator push to operator stack
	*
	* Execute the stack at end to get the result of expression. */
	bool evaluateExpression(const std::string& expression, int& output)
	{
	if (expression.empty())
	{
	return false;
	}

	size_t i;
	int value;
	std::stack<int> values;
	std::stack<knob::DepexOperators> operators;
	std::string subExpression;

	for (i = 0; i < expression.length(); i++)
	{
	if (expression[i] == ' ')
	{
	/* whitespace */
	continue;
	}
	else
	{
	std::string word;

	/* Get the next word in expression string */
	while ((i < expression.length()) && (expression[i] != ' '))
	{
	word.push_back(expression[i++]);
	}

	if (word == "_OR_" \|\| word == "OR")
	{
	/* OR and AND has more precedence than other operators
	* To handle statements like "a != b or c != d"
	* we need to execute, for above example, both '!=' before
	* 'or' */
	if (!operators.empty())
	{
	if (!evaluateExprStack(values, operators, value))
	{
	return false;
	}

	values.emplace(value);
	}

	operators.emplace(knob::DepexOperators::OR);
	}
	else if (word == "_AND_" \|\| word == "AND")
	{
	/* OR and AND has more precedence than other operators
	* To handle statements like "a == b and c == d"
	* we need to execute, for above example, both '==' before
	* 'and' */
	if (!operators.empty())
	{
	if (!evaluateExprStack(values, operators, value))
	{
	return false;
	}

	values.emplace(value);
	}

	operators.emplace(knob::DepexOperators::AND);
	}
	else if (word == "_LTE_")
	{
	operators.emplace(knob::DepexOperators::LTE);
	}
	else if (word == "_LT_")
	{
	operators.emplace(knob::DepexOperators::LT);
	}
	else if (word == "_GTE_")
	{
	operators.emplace(knob::DepexOperators::GTE);
	}
	else if (word == "_GT_")
	{
	operators.emplace(knob::DepexOperators::GT);
	}
	else if (word == "_NEQ_")
	{
	operators.emplace(knob::DepexOperators::NEQ);
	}
	else if (word == "_EQU_")
	{
	operators.emplace(knob::DepexOperators::EQU);
	}
	else if (word == "%")
	{
	operators.emplace(knob::DepexOperators::MODULO);
	}
	else
	{
	/* Handle 'Sif(', 'Gif(', 'Dif(' and '('
	* by taking the inner/sub expression and evaluating it */
	if (word.back() == '(')
	{
	if (!getSubExpression(expression, subExpression, i))
	break;

	if (!evaluateExpression(subExpression, value))
	break;
	}
	else if (word == "_LIST_")
	{
	if (!getListExpression(expression, subExpression, i))
	break;

	--i;

	if (!evaluateExpression(subExpression, value))
	break;
	}
	else if (word == "NOT")
	{
	if (!getNotValue(expression, i, value))
	break;
	}
	else if (isNumber(word) \|\| isHexNotation(word))
	{
	try
	{
	value = std::stoi(word);
	}
	catch (const std::exception& ex)
	{
	phosphor::logging::log<
	phosphor::logging::level::ERR>(ex.what());
	return false;
	}
	}
	else
	{
	if (!getValue(word, value))
	break;
	}

	values.emplace(value);
	}
	}
	}

	if (i == expression.length())
	{
	if (evaluateExprStack(values, operators, output))
	{
	return true;
	}
	}

	return false;
	}

	private:
	/* To store all 'knob's in 'biosknobs' */
	std::vector<knob::knob>& mKnobs;

	/* To store all bad 'depex' expression */
	std::vector<std::string> mError;
	};

	class Xml
	{
	public:
	Xml(const char* filePath) : mDepex(std::make_unique<Depex>(mKnobs))
	{
	if (!getKnobs(filePath))
	{
	std::string error =
	"Unable to get knobs in file: " + std::string(filePath);
	throw std::runtime_error(error);
	}
	}

	/* Fill Bios table with all 'knob's which have output of 'depex' expression
	* as 'true' */
	bool getBaseTable(bios::BiosBaseTableType& baseTable)
	{
	baseTable.clear();

	for (auto& knob : mKnobs)
	{
	if (knob.depex)
	{
	std::string text =
	"xyz.openbmc_project.BIOSConfig.Manager.BoundType.OneOf";
	bios::OptionTypeVector options;

	for (auto& option : knob.options)
	{
	options.emplace_back(text, option.value);
	}

	bios::BiosBaseTableTypeEntry baseTableEntry = std::make_tuple(
	"xyz.openbmc_project.BIOSConfig.Manager.AttributeType."
	"String",
	false, knob.nameStr, knob.descriptionStr, "./",
	knob.currentValStr, knob.defaultStr, options);

	baseTable.emplace(knob.nameStr, baseTableEntry);
	}
	}

	if (!baseTable.empty())
	{
	return true;
	}

	return false;
	}

	/* Execute all 'depex' expression */
	bool doDepexCompute()
	{
	mDepex->compute();

	if (mDepex->getErrorCount())
	{
	mDepex->printError();
	return false;
	}

	return true;
	}

	private:
	/* Get 'option' */
	void getOption(tinyxml2::XMLElement* pOption)
	{
	if (pOption)
	{
	std::string valueStr;
	std::string textStr;

	if (pOption->Attribute("text"))
	valueStr = pOption->Attribute("text");

	if (pOption->Attribute("value"))
	textStr = pOption->Attribute("value");

	mKnobs.back().options.emplace_back(pOption->Attribute("text"),
	pOption->Attribute("value"));
	}
	}

	/* Get 'options' */
	void getOptions(tinyxml2::XMLElement* pKnob)
	{
	uint16_t reserveCnt = 0;

	/* Get node options inside knob */
	tinyxml2::XMLElement* pOptions = pKnob->FirstChildElement("options");

	if (pOptions)
	{
	for (tinyxml2::XMLElement* pOption =
	pOptions->FirstChildElement("option");
	pOption; pOption = pOption->NextSiblingElement("option"))
	{
	++reserveCnt;
	}

	mKnobs.back().options.reserve(reserveCnt);

	/* Loop through all option inside options */
	for (tinyxml2::XMLElement* pOption =
	pOptions->FirstChildElement("option");
	pOption; pOption = pOption->NextSiblingElement("option"))
	{
	getOption(pOption);
	}
	}
	}

	/* Get 'knob' */
	void getKnob(tinyxml2::XMLElement* pKnob)
	{
	if (pKnob)
	{
	int currentVal = 0;
	std::string nameStr;
	std::string currentValStr;
	std::string descriptionStr;
	std::string defaultStr;
	std::string depexStr;
	std::string promptStr;
	std::string setupTypeStr;

	if (!pKnob->Attribute("name") \|\| !pKnob->Attribute("CurrentVal"))
	{
	return;
	}

	nameStr = pKnob->Attribute("name");
	currentValStr = pKnob->Attribute("CurrentVal");
	std::stringstream ss;
	ss << std::hex << currentValStr;
	if (ss.good())
	{
	ss >> currentVal;
	}
	else
	{
	std::string error = "Invalid hex value input " + currentValStr +
	" for " + nameStr + "\n";
	phosphor::logging::log<phosphor::logging::level::ERR>(
	error.c_str());
	return;
	}
	if (pKnob->Attribute("description"))
	descriptionStr = pKnob->Attribute("description");

	if (pKnob->Attribute("default"))
	defaultStr = pKnob->Attribute("default");

	if (pKnob->Attribute("depex"))
	depexStr = pKnob->Attribute("depex");

	if (pKnob->Attribute("prompt"))
	promptStr = pKnob->Attribute("prompt");

	if (pKnob->Attribute("setupType"))
	setupTypeStr = pKnob->Attribute("setupType");

	mKnobs.emplace_back(nameStr, currentValStr, currentVal,
	descriptionStr, defaultStr, promptStr, depexStr,
	setupTypeStr);

	getOptions(pKnob);
	}
	}

	/* Get 'biosknobs' */
	bool getKnobs(const char* biosXmlFilePath)
	{
	uint16_t reserveCnt = 0;

	mKnobs.clear();

	tinyxml2::XMLDocument biosXml;

	/* Load the XML file into the Doc instance */
	biosXml.LoadFile(biosXmlFilePath);

	/* Get 'SYSTEM' */
	tinyxml2::XMLElement* pRootElement = biosXml.RootElement();
	if (pRootElement)
	{
	/* Get 'biosknobs' inside 'SYSTEM' */
	tinyxml2::XMLElement* pBiosknobs =
	pRootElement->FirstChildElement("biosknobs");
	if (pBiosknobs)
	{
	for (tinyxml2::XMLElement* pKnob =
	pBiosknobs->FirstChildElement("knob");
	pKnob; pKnob = pKnob->NextSiblingElement("knob"))
	{
	++reserveCnt;
	}

	/* reserve before emplace_back will avoids realloc(s) */
	mKnobs.reserve(reserveCnt);

	for (tinyxml2::XMLElement* pKnob =
	pBiosknobs->FirstChildElement("knob");
	pKnob; pKnob = pKnob->NextSiblingElement("knob"))
	{
	getKnob(pKnob);
	}
	}
	}

	if (!mKnobs.empty())
	{
	return true;
	}

	return false;
	}

	private:
	/* To store all 'knob's in 'biosknobs' */
	std::vector<knob::knob> mKnobs;

	/* Object of Depex class to compute 'depex' expression */
	std::unique_ptr<Depex> mDepex;
	};
	} // namespace bios