// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// 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.

// numeric_lex.h: Functions to extract numeric values from string.

#ifndef COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
#define COMPILER_PREPROCESSOR_NUMERIC_LEX_H_

#include <sstream>
#include <cmath>

namespace pp {

inline std::ios::fmtflags numeric_base_int(const std::string& str)
{
	if ((str.size() >= 2) &&
		(str[0] == '0') &&
		(str[1] == 'x' || str[1] == 'X'))
	{
		return std::ios::hex;
	}
	else if ((str.size() >= 1) && (str[0] == '0'))
	{
		return std::ios::oct;
	}
	return std::ios::dec;
}

// The following functions parse the given string to extract a numerical
// value of the given type. These functions assume that the string is
// of the correct form. They can only fail if the parsed value is too big,
// in which case false is returned.

template<typename IntType>
bool numeric_lex_int(const std::string& str, IntType* value)
{
	std::istringstream stream(str);
	// This should not be necessary, but MSVS has a buggy implementation.
	// It returns incorrect results if the base is not specified.
	stream.setf(numeric_base_int(str), std::ios::basefield);

	stream >> (*value);
	return !stream.fail();
}

template<typename FloatType>
bool numeric_lex_float(const std::string& str, FloatType* value)
{
	std::istringstream stream(str);
	// Force "C" locale so that decimal character is always '.', and
	// not dependent on the current locale.
	stream.imbue(std::locale::classic());

	stream >> (*value);
	return !stream.fail() && std::isfinite(*value);
}

} // namespace pp.
#endif // COMPILER_PREPROCESSOR_NUMERIC_LEX_H_