1 /* Copyright (c) 2016-2019 The Khronos Group Inc. 2 * Copyright (c) 2016-2019 Valve Corporation 3 * Copyright (c) 2016-2019 LunarG, Inc. 4 * Copyright (c) 2016-2019 Google Inc. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 #ifndef PARAMETER_NAME_H 19 #define PARAMETER_NAME_H 20 21 #include <cassert> 22 #include <sstream> 23 #include <string> 24 #include <vector> 25 26 /** 27 * Parameter name string supporting deferred formatting for array subscripts. 28 * 29 * Custom parameter name class with support for deferred formatting of names containing array subscripts. The class stores 30 * a format string and a pointer to an array of index values, and performs string formatting when an accessor function is called to 31 * retrieve the name string. This class was primarily designed to be used with validation functions that receive a parameter name 32 * string and value as arguments, and print an error message that includes the parameter name when the value fails a validation 33 * test. Using standard strings with these validation functions requires that parameter names containing array subscripts be 34 * formatted before each validation function is called, performing the string formatting even when the value passes validation 35 * and the string is not used: 36 * sprintf(name, "pCreateInfo[%d].sType", i); 37 * validate_stype(name, pCreateInfo[i].sType); 38 * 39 * With the ParameterName class, a format string and a pointer to an array of format values are stored by the ParameterName object 40 * that is provided to the validation function. String formatting is then performed only when the validation function retrieves the 41 * name string from the ParameterName object: 42 * validate_stype(ParameterName("pCreateInfo[%i].sType", IndexVector{ i }), pCreateInfo[i].sType); 43 * 44 * Since the IndexVector is not copied into the object, the lifetime of the ParameterName should not outlast the lifetime of 45 * the IndexVector, but that's fine given how it is used in parameter validation. 46 */ 47 class ParameterName { 48 public: 49 /// Container for index values to be used with parameter name string formatting. 50 typedef std::initializer_list<size_t> IndexVector; 51 52 /// Format specifier for the parameter name string, to be replaced by an index value. The parameter name string must contain 53 /// one format specifier for each index value specified. 54 const char *const IndexFormatSpecifier = "%i"; 55 56 public: 57 /** 58 * Construct a ParameterName object from a string literal, without formatting. 59 * 60 * @param source Paramater name string without format specifiers. 61 * 62 * @pre The source string must not contain the %i format specifier. 63 */ 64 ParameterName(const char *source) : source_(source), num_indices_(0) { assert(IsValid()); } 65 66 /** 67 * Construct a ParameterName object from a string literal, with formatting. 68 * 69 * @param source Paramater name string with format specifiers. 70 * @param args Array index values to be used for formatting. 71 * 72 * @pre The number of %i format specifiers contained by the source string must match the number of elements contained 73 * by the index vector. 74 */ 75 ParameterName(const char *source, const IndexVector &args) 76 : source_(source), args_(args.size() ? args.begin() : (const size_t *)nullptr), num_indices_(args.size()) { 77 assert(IsValid()); 78 } 79 80 /// Retrive the formatted name string. 81 std::string get_name() const { return (num_indices_ == 0) ? std::string(source_) : Format(); } 82 83 private: 84 /// Replace the %i format specifiers in the source string with the values from the index vector. 85 std::string Format() const { 86 std::string::size_type current = 0; 87 std::string::size_type last = 0; 88 std::stringstream format; 89 90 std::string source(source_); 91 92 for (size_t i = 0; i < num_indices_; ++i) { 93 auto index = args_[i]; 94 current = source.find(IndexFormatSpecifier, last); 95 if (current == std::string::npos) { 96 break; 97 } 98 format << source.substr(last, (current - last)) << index; 99 last = current + strlen(IndexFormatSpecifier); 100 } 101 102 format << source.substr(last, std::string::npos); 103 104 return format.str(); 105 } 106 107 /// Check that the number of %i format specifiers in the source string matches the number of elements in the index vector. 108 bool IsValid() { 109 // Count the number of occurances of the format specifier 110 uint32_t count = 0; 111 112 std::string source(source_); 113 114 std::string::size_type pos = source.find(IndexFormatSpecifier); 115 116 while (pos != std::string::npos) { 117 ++count; 118 pos = source.find(IndexFormatSpecifier, pos + 1); 119 } 120 121 return (count == num_indices_); 122 } 123 124 private: 125 const char *source_; ///< Format string. 126 const size_t *args_; ///< Array index values for formatting. 127 size_t num_indices_; ///< Number of array index values. 128 }; 129 130 #endif // PARAMETER_NAME_H 131
