cam: options: Add option type handling to options parser

Extend the options parser with support for option types. All options
must now specify the type of their argument, and the parser
automatically parses the argument and handles errors internally.
Available types are none, integer or string.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/cam/main.cpp

@@ -37,10 +37,12 @@ static int parseOptions(int argc, char *argv[])
 {
 	OptionsParser parser;
 
-	parser.addOption(OptCamera, "Specify which camera to operate on",
+	parser.addOption(OptCamera, OptionString,
-			 "camera", ArgumentRequired, "camera");
+			 "Specify which camera to operate on", "camera",
-	parser.addOption(OptHelp, "Display this help message", "help");
+			 ArgumentRequired, "camera");
-	parser.addOption(OptList, "List all cameras", "list");
+	parser.addOption(OptHelp, OptionNone, "Display this help message",
+			 "help");
+	parser.addOption(OptList, OptionNone, "List all cameras", "list");
 
 	options = parser.parse(argc, argv);
 	if (!options.valid())

src/cam/options.cpp

@@ -12,6 +12,30 @@
 
 #include "options.h"
 
+/* -----------------------------------------------------------------------------
+ * Option
+ */
+
+const char *Option::typeName() const
+{
+	switch (type) {
+	case OptionNone:
+		return "none";
+
+	case OptionInteger:
+		return "integer";
+
+	case OptionString:
+		return "string";
+	}
+
+	return "unknown";
+}
+
+/* -----------------------------------------------------------------------------
+ * OptionBase<T>
+ */
+
 template <typename T>
 bool OptionsBase<T>::valid() const
 {
@@ -25,11 +49,45 @@ bool OptionsBase<T>::isSet(const T &opt) const
 }
 
 template <typename T>
-const std::string &OptionsBase<T>::operator[](const T &opt) const
+const OptionValue &OptionsBase<T>::operator[](const T &opt) const
 {
 	return values_.find(opt)->second;
 }
 
+template <typename T>
+bool OptionsBase<T>::parseValue(const T &opt, const Option &option,
+				const char *optarg)
+{
+	OptionValue value;
+
+	switch (option.type) {
+	case OptionNone:
+		break;
+
+	case OptionInteger:
+		unsigned int integer;
+
+		if (optarg) {
+			char *endptr;
+			integer = strtoul(optarg, &endptr, 10);
+			if (*endptr != '\0')
+				return false;
+		} else {
+			integer = 0;
+		}
+
+		value = OptionValue(integer);
+		break;
+
+	case OptionString:
+		value = OptionValue(optarg ? optarg : "");
+		break;
+	}
+
+	values_[opt] = value;
+	return true;
+}
+
 template <typename T>
 void OptionsBase<T>::clear()
 {
@@ -38,8 +96,53 @@ void OptionsBase<T>::clear()
 
 template class OptionsBase<int>;
 
-bool OptionsParser::addOption(int opt, const char *help, const char *name,
+/* -----------------------------------------------------------------------------
-			      OptionArgument argument, const char *argumentName)
+ * OptionValue
+ */
+
+OptionValue::OptionValue()
+	: type_(OptionNone)
+{
+}
+
+OptionValue::OptionValue(int value)
+	: type_(OptionInteger), integer_(value)
+{
+}
+
+OptionValue::OptionValue(const char *value)
+	: type_(OptionString), string_(value)
+{
+}
+
+OptionValue::OptionValue(const std::string &value)
+	: type_(OptionString), string_(value)
+{
+}
+
+OptionValue::operator int() const
+{
+	if (type_ != OptionInteger)
+		return 0;
+
+	return integer_;
+}
+
+OptionValue::operator std::string() const
+{
+	if (type_ != OptionString)
+		return std::string();
+
+	return string_;
+}
+
+/* -----------------------------------------------------------------------------
+ * OptionsParser
+ */
+
+bool OptionsParser::addOption(int opt, OptionType type, const char *help,
+			      const char *name, OptionArgument argument,
+			      const char *argumentName)
 {
 	/*
 	 * Options must have at least a short or long name, and a text message.
@@ -56,7 +159,8 @@ bool OptionsParser::addOption(int opt, const char *help, const char *name,
 	if (optionsMap_.find(opt) != optionsMap_.end())
 		return false;
 
-	options_.push_back(Option({ opt, name, argument, argumentName, help }));
+	options_.push_back(Option({ opt, type, name, argument, argumentName,
+				    help }));
 	optionsMap_[opt] = &options_.back();
 	return true;
 }
@@ -126,7 +230,13 @@ OptionsParser::Options OptionsParser::parse(int argc, char **argv)
 			break;
 		}
 
-		options.values_[c] = optarg ? optarg : "";
+		const Option &option = *optionsMap_[c];
+		if (!options.parseValue(c, option, optarg)) {
+			parseValueError(option);
+			usage();
+			options.clear();
+			break;
+		}
 	}
 
 	return options;
@@ -193,3 +303,16 @@ void OptionsParser::usage()
 		}
 	}
 }
+
+void OptionsParser::parseValueError(const Option &option)
+{
+	std::string optionName;
+
+	if (option.name)
+		optionName = "--" + std::string(option.name);
+	else
+		optionName = "-" + static_cast<char>(option.opt);
+
+	std::cerr << "Can't parse " << option.typeName()
+		  << " argument for option " << optionName << std::endl;
+}

src/cam/options.h

@@ -17,8 +17,15 @@ enum OptionArgument {
 	ArgumentOptional,
 };
 
+enum OptionType {
+	OptionNone,
+	OptionInteger,
+	OptionString,
+};
+
 struct Option {
 	int opt;
+	OptionType type;
 	const char *name;
 	OptionArgument argument;
 	const char *argumentName;
@@ -26,20 +33,45 @@ struct Option {
 
 	bool hasShortOption() const { return isalnum(opt); }
 	bool hasLongOption() const { return name != nullptr; }
+	const char *typeName() const;
 };
 
+class OptionValue;
+
 template <typename T>
 class OptionsBase
 {
 public:
 	bool valid() const;
 	bool isSet(const T &opt) const;
-	const std::string &operator[](const T &opt) const;
+	const OptionValue &operator[](const T &opt) const;
 
 private:
 	friend class OptionsParser;
-	std::map<T, std::string> values_;
+
+	bool parseValue(const T &opt, const Option &option, const char *value);
 	void clear();
+
+	std::map<T, OptionValue> values_;
+};
+
+class OptionValue
+{
+public:
+	OptionValue();
+	OptionValue(int value);
+	OptionValue(const char *value);
+	OptionValue(const std::string &value);
+
+	OptionType type() const { return type_; }
+
+	operator int() const;
+	operator std::string() const;
+
+private:
+	OptionType type_;
+	int integer_;
+	std::string string_;
 };
 
 class OptionsParser
@@ -49,7 +81,8 @@ public:
 	{
 	};
 
-	bool addOption(int opt, const char *help, const char *name = nullptr,
+	bool addOption(int opt, OptionType type, const char *help,
+		       const char *name = nullptr,
 		       OptionArgument argument = ArgumentNone,
 		       const char *argumentName = nullptr);
 
@@ -57,6 +90,8 @@ public:
 	void usage();
 
 private:
+	void parseValueError(const Option &option);
+
 	std::list<Option> options_;
 	std::map<unsigned int, Option *> optionsMap_;
 };