1 // Copyright 2016 The SwiftShader Authors. All Rights Reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 // numeric_lex.h: Functions to extract numeric values from string.
16
17 #ifndef COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
18 #define COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
19
20 #include <sstream>
21 #include <cmath>
22
23 namespace pp {
24
numeric_base_int(const std::string & str)25 inline std::ios::fmtflags numeric_base_int(const std::string& str)
26 {
27 if ((str.size() >= 2) &&
28 (str[0] == '0') &&
29 (str[1] == 'x' || str[1] == 'X'))
30 {
31 return std::ios::hex;
32 }
33 else if ((str.size() >= 1) && (str[0] == '0'))
34 {
35 return std::ios::oct;
36 }
37 return std::ios::dec;
38 }
39
40 // The following functions parse the given string to extract a numerical
41 // value of the given type. These functions assume that the string is
42 // of the correct form. They can only fail if the parsed value is too big,
43 // in which case false is returned.
44
45 template<typename IntType>
numeric_lex_int(const std::string & str,IntType * value)46 bool numeric_lex_int(const std::string& str, IntType* value)
47 {
48 std::istringstream stream(str);
49 // This should not be necessary, but MSVS has a buggy implementation.
50 // It returns incorrect results if the base is not specified.
51 stream.setf(numeric_base_int(str), std::ios::basefield);
52
53 stream >> (*value);
54 return !stream.fail();
55 }
56
57 template<typename FloatType>
numeric_lex_float(const std::string & str,FloatType * value)58 bool numeric_lex_float(const std::string& str, FloatType* value)
59 {
60 std::istringstream stream(str);
61 // Force "C" locale so that decimal character is always '.', and
62 // not dependent on the current locale.
63 stream.imbue(std::locale::classic());
64
65 stream >> (*value);
66 return !stream.fail() && std::isfinite(*value);
67 }
68
69 } // namespace pp.
70 #endif // COMPILER_PREPROCESSOR_NUMERIC_LEX_H_
71