michael@0: //
michael@0: // Copyright (c) 2012 The ANGLE Project Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: //
michael@0: 
michael@0: // numeric_lex.h: Functions to extract numeric values from string.
michael@0: 
michael@0: #ifndef COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
michael@0: #define COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
michael@0: 
michael@0: #include <sstream>
michael@0: 
michael@0: namespace pp {
michael@0: 
michael@0: inline std::ios::fmtflags numeric_base_int(const std::string& str)
michael@0: {
michael@0:     if ((str.size() >= 2) &&
michael@0:         (str[0] == '0') &&
michael@0:         (str[1] == 'x' || str[1] == 'X'))
michael@0:     {
michael@0:         return std::ios::hex;
michael@0:     }
michael@0:     else if ((str.size() >= 1) && (str[0] == '0'))
michael@0:     {
michael@0:         return std::ios::oct;
michael@0:     }
michael@0:     return std::ios::dec;
michael@0: }
michael@0: 
michael@0: // The following functions parse the given string to extract a numerical
michael@0: // value of the given type. These functions assume that the string is
michael@0: // of the correct form. They can only fail if the parsed value is too big,
michael@0: // in which case false is returned.
michael@0: 
michael@0: template<typename IntType>
michael@0: bool numeric_lex_int(const std::string& str, IntType* value)
michael@0: {
michael@0:     std::istringstream stream(str);
michael@0:     // This should not be necessary, but MSVS has a buggy implementation.
michael@0:     // It returns incorrect results if the base is not specified.
michael@0:     stream.setf(numeric_base_int(str), std::ios::basefield);
michael@0: 
michael@0:     stream >> (*value);
michael@0:     return !stream.fail();
michael@0: }
michael@0: 
michael@0: template<typename FloatType>
michael@0: bool numeric_lex_float(const std::string& str, FloatType* value)
michael@0: {
michael@0:     std::istringstream stream(str);
michael@0:     // Force "C" locale so that decimal character is always '.', and
michael@0:     // not dependent on the current locale.
michael@0:     stream.imbue(std::locale::classic());
michael@0: 
michael@0:     stream >> (*value);
michael@0:     return !stream.fail();
michael@0: }
michael@0: 
michael@0: } // namespace pp.
michael@0: #endif // COMPILER_PREPROCESSOR_NUMERIC_LEX_H_