numeric_lex.h

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//
// Copyright (c) 2012 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

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

#ifndef COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
#define COMPILER_PREPROCESSOR_NUMERIC_LEX_H_

#include <sstream>

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();
}

} // namespace pp.
#endif // COMPILER_PREPROCESSOR_NUMERIC_LEX_H_