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.consume_front(",")) { 76 if (!consumeFieldLayout(RepString, Where, Align, Pad)) 77 assert(false && "Invalid replacement field layout specification!"); 78 } 79 RepString = RepString.trim(); 80 if (!RepString.empty() && RepString.front() == ':') { 81 Options = RepString.drop_front().trim(); 82 RepString = StringRef(); 83 } 84 RepString = RepString.trim(); 85 if (!RepString.empty()) { 86 assert(false && "Unexpected characters found in replacement string!"); 87 } 88 89 return ReplacementItem{Spec, Index, Align, Where, Pad, Options}; 90 } 91 92 std::pair<ReplacementItem, StringRef> 93 formatv_object_base::splitLiteralAndReplacement(StringRef Fmt) { 94 while (!Fmt.empty()) { 95 // Everything up until the first brace is a literal. 96 if (Fmt.front() != '{') { 97 std::size_t BO = Fmt.find_first_of('{'); 98 return std::make_pair(ReplacementItem{Fmt.substr(0, BO)}, Fmt.substr(BO)); 99 } 100 101 StringRef Braces = Fmt.take_while([](char C) { return C == '{'; }); 102 // If there is more than one brace, then some of them are escaped. Treat 103 // these as replacements. 104 if (Braces.size() > 1) { 105 size_t NumEscapedBraces = Braces.size() / 2; 106 StringRef Middle = Fmt.take_front(NumEscapedBraces); 107 StringRef Right = Fmt.drop_front(NumEscapedBraces * 2); 108 return std::make_pair(ReplacementItem{Middle}, Right); 109 } 110 // An unterminated open brace is undefined. We treat the rest of the string 111 // as a literal replacement, but we assert to indicate that this is 112 // undefined and that we consider it an error. 113 std::size_t BC = Fmt.find_first_of('}'); 114 if (BC == StringRef::npos) { 115 assert( 116 false && 117 "Unterminated brace sequence. Escape with {{ for a literal brace."); 118 return std::make_pair(ReplacementItem{Fmt}, StringRef()); 119 } 120 121 // Even if there is a closing brace, if there is another open brace before 122 // this closing brace, treat this portion as literal, and try again with the 123 // next one. 124 std::size_t BO2 = Fmt.find_first_of('{', 1); 125 if (BO2 < BC) 126 return std::make_pair(ReplacementItem{Fmt.substr(0, BO2)}, 127 Fmt.substr(BO2)); 128 129 StringRef Spec = Fmt.slice(1, BC); 130 StringRef Right = Fmt.substr(BC + 1); 131 132 auto RI = parseReplacementItem(Spec); 133 if (RI) 134 return std::make_pair(*RI, Right); 135 136 // If there was an error parsing the replacement item, treat it as an 137 // invalid replacement spec, and just continue. 138 Fmt = Fmt.drop_front(BC + 1); 139 } 140 return std::make_pair(ReplacementItem{Fmt}, StringRef()); 141 } 142 143 SmallVector<ReplacementItem, 2> 144 formatv_object_base::parseFormatString(StringRef Fmt) { 145 SmallVector<ReplacementItem, 2> Replacements; 146 ReplacementItem I; 147 while (!Fmt.empty()) { 148 std::tie(I, Fmt) = splitLiteralAndReplacement(Fmt); 149 if (I.Type != ReplacementType::Empty) 150 Replacements.push_back(I); 151 } 152 return Replacements; 153 } 154 155 void detail::format_adapter::anchor() { } 156