1 //===- FormatVariadic.cpp - Format string parsing and analysis ----*-C++-*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 //===----------------------------------------------------------------------===// 7 8 #include "llvm/Support/FormatVariadic.h" 9 #include <cassert> 10 #include <optional> 11 12 using namespace llvm; 13 14 static std::optional<AlignStyle> translateLocChar(char C) { 15 switch (C) { 16 case '-': 17 return AlignStyle::Left; 18 case '=': 19 return AlignStyle::Center; 20 case '+': 21 return AlignStyle::Right; 22 default: 23 return std::nullopt; 24 } 25 LLVM_BUILTIN_UNREACHABLE; 26 } 27 28 bool formatv_object_base::consumeFieldLayout(StringRef &Spec, AlignStyle &Where, 29 size_t &Align, char &Pad) { 30 Where = AlignStyle::Right; 31 Align = 0; 32 Pad = ' '; 33 if (Spec.empty()) 34 return true; 35 36 if (Spec.size() > 1) { 37 // A maximum of 2 characters at the beginning can be used for something 38 // other 39 // than the width. 40 // If Spec[1] is a loc char, then Spec[0] is a pad char and Spec[2:...] 41 // contains the width. 42 // Otherwise, if Spec[0] is a loc char, then Spec[1:...] contains the width. 43 // Otherwise, Spec[0:...] contains the width. 44 if (auto Loc = translateLocChar(Spec[1])) { 45 Pad = Spec[0]; 46 Where = *Loc; 47 Spec = Spec.drop_front(2); 48 } else if (auto Loc = translateLocChar(Spec[0])) { 49 Where = *Loc; 50 Spec = Spec.drop_front(1); 51 } 52 } 53 54 bool Failed = Spec.consumeInteger(0, Align); 55 return !Failed; 56 } 57 58 std::optional<ReplacementItem> 59 formatv_object_base::parseReplacementItem(StringRef Spec) { 60 StringRef RepString = Spec.trim("{}"); 61 62 // If the replacement sequence does not start with a non-negative integer, 63 // this is an error. 64 char Pad = ' '; 65 std::size_t Align = 0; 66 AlignStyle Where = AlignStyle::Right; 67 StringRef Options; 68 size_t Index = 0; 69 RepString = RepString.trim(); 70 if (RepString.consumeInteger(0, Index)) { 71 assert(false && "Invalid replacement sequence index!"); 72 return ReplacementItem{}; 73 } 74 RepString = RepString.trim(); 75 if (!RepString.empty() && RepString.front() == ',') { 76 RepString = RepString.drop_front(); 77 if (!consumeFieldLayout(RepString, Where, Align, Pad)) 78 assert(false && "Invalid replacement field layout specification!"); 79 } 80 RepString = RepString.trim(); 81 if (!RepString.empty() && RepString.front() == ':') { 82 Options = RepString.drop_front().trim(); 83 RepString = StringRef(); 84 } 85 RepString = RepString.trim(); 86 if (!RepString.empty()) { 87 assert(false && "Unexpected characters found in replacement string!"); 88 } 89 90 return ReplacementItem{Spec, Index, Align, Where, Pad, Options}; 91 } 92 93 std::pair<ReplacementItem, StringRef> 94 formatv_object_base::splitLiteralAndReplacement(StringRef Fmt) { 95 while (!Fmt.empty()) { 96 // Everything up until the first brace is a literal. 97 if (Fmt.front() != '{') { 98 std::size_t BO = Fmt.find_first_of('{'); 99 return std::make_pair(ReplacementItem{Fmt.substr(0, BO)}, Fmt.substr(BO)); 100 } 101 102 StringRef Braces = Fmt.take_while([](char C) { return C == '{'; }); 103 // If there is more than one brace, then some of them are escaped. Treat 104 // these as replacements. 105 if (Braces.size() > 1) { 106 size_t NumEscapedBraces = Braces.size() / 2; 107 StringRef Middle = Fmt.take_front(NumEscapedBraces); 108 StringRef Right = Fmt.drop_front(NumEscapedBraces * 2); 109 return std::make_pair(ReplacementItem{Middle}, Right); 110 } 111 // An unterminated open brace is undefined. We treat the rest of the string 112 // as a literal replacement, but we assert to indicate that this is 113 // undefined and that we consider it an error. 114 std::size_t BC = Fmt.find_first_of('}'); 115 if (BC == StringRef::npos) { 116 assert( 117 false && 118 "Unterminated brace sequence. Escape with {{ for a literal brace."); 119 return std::make_pair(ReplacementItem{Fmt}, StringRef()); 120 } 121 122 // Even if there is a closing brace, if there is another open brace before 123 // this closing brace, treat this portion as literal, and try again with the 124 // next one. 125 std::size_t BO2 = Fmt.find_first_of('{', 1); 126 if (BO2 < BC) 127 return std::make_pair(ReplacementItem{Fmt.substr(0, BO2)}, 128 Fmt.substr(BO2)); 129 130 StringRef Spec = Fmt.slice(1, BC); 131 StringRef Right = Fmt.substr(BC + 1); 132 133 auto RI = parseReplacementItem(Spec); 134 if (RI) 135 return std::make_pair(*RI, Right); 136 137 // If there was an error parsing the replacement item, treat it as an 138 // invalid replacement spec, and just continue. 139 Fmt = Fmt.drop_front(BC + 1); 140 } 141 return std::make_pair(ReplacementItem{Fmt}, StringRef()); 142 } 143 144 SmallVector<ReplacementItem, 2> 145 formatv_object_base::parseFormatString(StringRef Fmt) { 146 SmallVector<ReplacementItem, 2> Replacements; 147 ReplacementItem I; 148 while (!Fmt.empty()) { 149 std::tie(I, Fmt) = splitLiteralAndReplacement(Fmt); 150 if (I.Type != ReplacementType::Empty) 151 Replacements.push_back(I); 152 } 153 return Replacements; 154 } 155 156 void detail::format_adapter::anchor() { } 157