monitor: add cli11 argument parsing

Replace our custom argument parser with one from CLIUtils.

This results in a number of minor behavioral differences.
 - The -? option is no longer recognized as an alias for -h/--help.
 - The original parser returned EXIT_FAILURE in all cases, but CLIUtils
   uses different non-zero error codes in different situations.
 - Minor changes to help text descriptions:
----new----
Usage: build/phosphor-unit-failure-monitor.new [OPTIONS]

Options:
  -h,--help                   Print this help message and exit
  -s,--source TEXT REQUIRED
  -t,--target TEXT REQUIRED
  -a,--action ENUM:value in {start->0,stop->1} OR {0,1} REQUIRED

----old----
Usage: build/phosphor-unit-failure-monitor [options]
Options:
    --help             Print this menu
    --source=<source>  The source unit to monitor
    --target=<target>  The target unit to start or stop
    --action=<action>  Target unit action - start or stop

 - The original parser displays the full help text on error, CLIUtils
   does not:

----new----
$ phosphor-unit-failure-monitor
--source is required
Run with --help for more information.

----old----
$ phosphor-unit-failure-monitor
ERROR: Source not specified
Usage: build/phosphor-unit-failure-monitor [options]
Options:
    --help             Print this menu
    --source=<source>  The source unit to monitor
    --target=<target>  The target unit to start or stop
    --action=<action>  Target unit action - start or stop

Change-Id: I2417d9c857c6d8fc04807fe4729d2fa154e746a3
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/fail-monitor/argument.cpp b/fail-monitor/argument.cpp
deleted file mode 100644
index 33194ce..0000000
--- a/fail-monitor/argument.cpp
+++ /dev/null
@@ -1,91 +0,0 @@
-/**
- * Copyright © 2017 IBM Corporation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-#include "argument.hpp"
-
-#include <algorithm>
-#include <iostream>
-#include <iterator>
-
-namespace phosphor
-{
-namespace unit
-{
-namespace failure
-{
-
-ArgumentParser::ArgumentParser(int argc, char** argv)
-{
-    int option = 0;
-    while (-1 != (option = getopt_long(argc, argv, optionStr, options, NULL)))
-    {
-        if ((option == '?') || (option == 'h'))
-        {
-            usage(argv);
-            exit(-1);
-        }
-
-        auto i = &options[0];
-        while ((i->val != option) && (i->val != 0))
-        {
-            ++i;
-        }
-
-        if (i->val)
-        {
-            arguments[i->name] = (i->has_arg ? optarg : trueString);
-        }
-    }
-}
-
-const std::string& ArgumentParser::operator[](const std::string& opt)
-{
-    auto i = arguments.find(opt);
-    if (i == arguments.end())
-    {
-        return emptyString;
-    }
-    else
-    {
-        return i->second;
-    }
-}
-
-void ArgumentParser::usage(char** argv)
-{
-    std::cerr << "Usage: " << argv[0] << " [options]\n";
-    std::cerr << "Options:\n";
-    std::cerr << "    --help             Print this menu\n";
-    std::cerr << "    --source=<source>  The source unit to monitor\n";
-    std::cerr << "    --target=<target>  The target unit to start or stop\n";
-    std::cerr << "    --action=<action>  Target unit action - start or stop\n";
-    std::cerr << std::flush;
-}
-
-const option ArgumentParser::options[] = {
-    {"source", required_argument, NULL, 's'},
-    {"action", required_argument, NULL, 'a'},
-    {"target", required_argument, NULL, 't'},
-    {"help", no_argument, NULL, 'h'},
-    {0, 0, 0, 0},
-};
-
-const char* ArgumentParser::optionStr = "s:a:t:h?";
-
-const std::string ArgumentParser::trueString = "true";
-const std::string ArgumentParser::emptyString = "";
-} // namespace failure
-} // namespace unit
-} // namespace phosphor
diff --git a/fail-monitor/argument.hpp b/fail-monitor/argument.hpp
deleted file mode 100644
index 8648ddd..0000000
--- a/fail-monitor/argument.hpp
+++ /dev/null
@@ -1,68 +0,0 @@
-#pragma once
-
-#include <getopt.h>
-
-#include <map>
-#include <string>
-
-namespace phosphor
-{
-namespace unit
-{
-namespace failure
-{
-
-/** @brief Class - Encapsulates parsing command line options and
- *                 populating arguments
- */
-class ArgumentParser
-{
-  public:
-    ArgumentParser() = delete;
-    ~ArgumentParser() = default;
-    ArgumentParser(const ArgumentParser&) = delete;
-    ArgumentParser& operator=(const ArgumentParser&) = delete;
-    ArgumentParser(ArgumentParser&&) = default;
-    ArgumentParser& operator=(ArgumentParser&&) = default;
-
-    /** @brief Contructs Argument object
-     *
-     *  @param argc - the main function's argc passed as is
-     *  @param argv - the main function's argv passed as is
-     *  @return Object constructed
-     */
-    ArgumentParser(int argc, char** argv);
-
-    /** @brief Given an option, returns its argument(optarg)
-     *
-     *  @param opt - command line option string
-     *
-     *  @return argument which is a standard optarg
-     */
-    const std::string& operator[](const std::string& opt);
-
-    /** @brief Displays usage
-     *
-     *  @param argv - the main function's argv passed as is
-     */
-    static void usage(char** argv);
-
-    /** @brief Set to 'true' when an option is passed */
-    static const std::string trueString;
-
-    /** @brief Set to '' when an option is not passed */
-    static const std::string emptyString;
-
-  private:
-    /** @brief Option to argument mapping */
-    std::map<const std::string, std::string> arguments;
-
-    /** @brief Array of struct options as needed by getopt_long */
-    static const option options[];
-
-    /** @brief optstring as needed by getopt_long */
-    static const char* optionStr;
-};
-} // namespace failure
-} // namespace unit
-} // namespace phosphor
diff --git a/fail-monitor/main.cpp b/fail-monitor/main.cpp
index 90c6126..c383a67 100644
--- a/fail-monitor/main.cpp
+++ b/fail-monitor/main.cpp
@@ -20,53 +20,35 @@
  * then it will either stop or start the target unit, depending
  * on the command line arguments.
  */
-#include "argument.hpp"
 #include "monitor.hpp"
 
-#include <iostream>
+#include <CLI/CLI.hpp>
+
 #include <map>
+#include <string>
 
 using namespace phosphor::unit::failure;
 
-/**
- * Prints usage and exits the program
- *
- * @param[in] err - the error message to print
- * @param[in] argv - argv from main()
- */
-void exitWithError(const char* err, char** argv)
-{
-    std::cerr << "ERROR: " << err << "\n";
-    ArgumentParser::usage(argv);
-    exit(EXIT_FAILURE);
-}
-
 static const std::map<std::string, Monitor::Action> actions = {
     {"start", Monitor::Action::start}, {"stop", Monitor::Action::stop}};
 
 int main(int argc, char** argv)
 {
-    ArgumentParser args(argc, argv);
+    CLI::App app;
+    std::string source;
+    std::string target;
+    Monitor::Action action{Monitor::Action::start};
 
-    auto source = args["source"];
-    if (source == ArgumentParser::emptyString)
-    {
-        exitWithError("Source not specified", argv);
-    }
+    app.add_option("-s,--source", source, "The source unit to monitor")
+        ->required();
+    app.add_option("-t,--target", target, "The target unit to start or stop")
+        ->required();
+    app.add_option("-a,--action", action, "Target unit action - start or stop")
+        ->required()
+        ->transform(CLI::CheckedTransformer(actions, CLI::ignore_space));
 
-    auto target = args["target"];
-    if (target == ArgumentParser::emptyString)
-    {
-        exitWithError("Target not specified", argv);
-    }
-
-    auto a = actions.find(args["action"]);
-    if (a == actions.end())
-    {
-        exitWithError("Missing or invalid action specified", argv);
-    }
-
-    Monitor monitor{source, target, a->second};
+    CLI11_PARSE(app, argc, argv);
+    Monitor monitor{source, target, action};
 
     monitor.analyze();
 
diff --git a/meson.build b/meson.build
index 209c49f..a7f3a4f 100644
--- a/meson.build
+++ b/meson.build
@@ -12,6 +12,13 @@
     version: '1.0',
 )
 
+cxx = meson.get_compiler('cpp')
+
+if cxx.has_header('CLI/CLI.hpp')
+    cli11_dep = declare_dependency()
+else
+    cli11_dep = dependency('cli11')
+endif
 phosphor_logging = dependency('phosphor-logging')
 phosphor_dbus_interfaces = dependency('phosphor-dbus-interfaces')
 sdbusplus = dependency('sdbusplus')
@@ -104,11 +111,11 @@
 executable(
     'phosphor-unit-failure-monitor',
     [
-        'fail-monitor/argument.cpp',
         'fail-monitor/main.cpp',
         'fail-monitor/monitor.cpp',
     ],
     dependencies: [
+        cli11_dep,
         phosphor_logging,
     ],
     install: true
diff --git a/subprojects/CLI11.wrap b/subprojects/CLI11.wrap
new file mode 100644
index 0000000..2e5a95b
--- /dev/null
+++ b/subprojects/CLI11.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+url = https://github.com/CLIUtils/CLI11.git
+revision = HEAD
+
+[provide]
+CLI11 = CLI11_dep