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      1 //
      2 // Copyright (c) 2012 The ANGLE Project Authors. All rights reserved.
      3 // Use of this source code is governed by a BSD-style license that can be
      4 // found in the LICENSE file.
      5 //
      6 
      7 // numeric_lex.h: Functions to extract numeric values from string.
      8 
      9 #ifndef COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
     10 #define COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
     11 
     12 #include <sstream>
     13 
     14 namespace pp {
     15 
     16 inline std::ios::fmtflags numeric_base_int(const std::string &str)
     17 {
     18     if ((str.size() >= 2) &&
     19         (str[0] == '0') &&
     20         (str[1] == 'x' || str[1] == 'X'))
     21     {
     22         return std::ios::hex;
     23     }
     24     if ((str.size() >= 1) && (str[0] == '0'))
     25     {
     26         return std::ios::oct;
     27     }
     28     return std::ios::dec;
     29 }
     30 
     31 // The following functions parse the given string to extract a numerical
     32 // value of the given type. These functions assume that the string is
     33 // of the correct form. They can only fail if the parsed value is too big,
     34 // in which case false is returned.
     35 
     36 template<typename IntType>
     37 bool numeric_lex_int(const std::string &str, IntType *value)
     38 {
     39     std::istringstream stream(str);
     40     // This should not be necessary, but MSVS has a buggy implementation.
     41     // It returns incorrect results if the base is not specified.
     42     stream.setf(numeric_base_int(str), std::ios::basefield);
     43 
     44     stream >> (*value);
     45     return !stream.fail();
     46 }
     47 
     48 template<typename FloatType>
     49 bool numeric_lex_float(const std::string &str, FloatType *value)
     50 {
     51     std::istringstream stream(str);
     52     // Force "C" locale so that decimal character is always '.', and
     53     // not dependent on the current locale.
     54     stream.imbue(std::locale::classic());
     55 
     56     stream >> (*value);
     57     return !stream.fail();
     58 }
     59 
     60 } // namespace pp.
     61 #endif // COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
     62