TclArgParser.hh

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#ifndef TCLARGPARSER_HH
#define TCLARGPARSER_HH
 
#include "CommandException.hh"
#include "TclObject.hh"
#include <functional>
#include <optional>
#include <span>
#include <string_view>
#include <vector>
 
namespace openmsx {
 
namespace detail {
        template<typename T> struct GetArg;
 
        template<> struct GetArg<bool> {
                void operator()(Interpreter& interp, const TclObject& obj, bool& result) const {
                        result = obj.getBoolean(interp);
                }
        };
        template<> struct GetArg<int> {
                void operator()(Interpreter& interp, const TclObject& obj, int& result) const {
                        result = obj.getInt(interp);
                }
        };
        template<> struct GetArg<double> {
                void operator()(Interpreter& interp, const TclObject& obj, double& result) const {
                        result = obj.getDouble(interp);
                }
        };
        template<> struct GetArg<std::string_view> {
                void operator()(Interpreter& /*interp*/, const TclObject& obj, std::string_view& result) const {
                        result = obj.getString();
                }
        };
        template<> struct GetArg<std::string> {
                void operator()(Interpreter& /*interp*/, const TclObject& obj, std::string& result) const {
                        result = std::string(obj.getString());
                }
        };
        template<> struct GetArg<TclObject> {
                void operator()(Interpreter& /*interp*/, const TclObject& obj, TclObject& result) const {
                        result = obj;
                }
        };
 
        template<typename T> struct GetArg<std::optional<T>> {
                void operator()(Interpreter& interp, const TclObject& obj, std::optional<T>& result) const {
                        T t;
                        GetArg<T>{}(interp, obj, t);
                        result = std::move(t);
                }
        };
 
        template<typename T> struct GetArg<std::vector<T>> {
                void operator()(Interpreter& interp, const TclObject& obj, std::vector<T>& result) const {
                        result.emplace_back();
                        GetArg<T>{}(interp, obj, result.back());
                }
        };
}
 
// A Tcl-argument-parser description is made out of ArgsInfo objects
struct ArgsInfo
{
        std::string_view name;
        std::function<unsigned(Interpreter&, std::span<const TclObject>)> func;
};
 
// Parse a flag.
[[nodiscard]] inline ArgsInfo flagArg(std::string_view name, bool& flag)
{
        return {
                name,
                [&flag](Interpreter& /*interp*/, std::span<const TclObject> /*args*/) {
                        flag = true;
                        return 0;
                }
        };
}
 
// Option with a single value, handled by a callback
[[nodiscard]] inline ArgsInfo funcArg(
        std::string_view name,
        std::function<void(Interpreter&, const TclObject&)> func)
{
        return {
                name,
                [name, func = std::move(func)](Interpreter& interp, std::span<const TclObject> args) {
                        if (args.empty()) {
                                throw CommandException("missing argument for ", name);
                        }
                        func(interp, args.front());
                        return 1;
                }
        };
}
 
// Parse a value (like a flag but with associated value).
template<typename T>
[[nodiscard]] ArgsInfo valueArg(std::string_view name, T& value)
{
        return funcArg(name, [&value](Interpreter& interp, const TclObject& arg) {
                detail::GetArg<T>{}(interp, arg, value);
        });
}
 
// Parse the given 'inArgs' arguments.
// The recognized flags/values are described in 'table'.
// The result of this parser is the collection of non-flag arguments.
// See src/unittest/TclArgParser.cc for example usages.
[[nodiscard]] std::vector<TclObject> parseTclArgs(
        Interpreter& interp, std::span<const TclObject> inArgs, std::span<const ArgsInfo> table);
 
} // namespace openmsx
 
#endif