1 //===- FormatVariadic.cpp - Format string parsing and analysis ----*-C++-*-===//
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 //===----------------------------------------------------------------------===//
8 #include "llvm/Support/FormatVariadic.h"
12 static Optional<AlignStyle> translateLocChar(char C) {
15 return AlignStyle::Left;
17 return AlignStyle::Center;
19 return AlignStyle::Right;
23 LLVM_BUILTIN_UNREACHABLE;
26 bool formatv_object_base::consumeFieldLayout(StringRef &Spec, AlignStyle &Where,
27 size_t &Align, char &Pad) {
28 Where = AlignStyle::Right;
34 if (Spec.size() > 1) {
35 // A maximum of 2 characters at the beginning can be used for something
38 // If Spec[1] is a loc char, then Spec[0] is a pad char and Spec[2:...]
39 // contains the width.
40 // Otherwise, if Spec[0] is a loc char, then Spec[1:...] contains the width.
41 // Otherwise, Spec[0:...] contains the width.
42 if (auto Loc = translateLocChar(Spec[1])) {
45 Spec = Spec.drop_front(2);
46 } else if (auto Loc = translateLocChar(Spec[0])) {
48 Spec = Spec.drop_front(1);
52 bool Failed = Spec.consumeInteger(0, Align);
56 Optional<ReplacementItem>
57 formatv_object_base::parseReplacementItem(StringRef Spec) {
58 StringRef RepString = Spec.trim("{}");
60 // If the replacement sequence does not start with a non-negative integer,
63 std::size_t Align = 0;
64 AlignStyle Where = AlignStyle::Right;
67 RepString = RepString.trim();
68 if (RepString.consumeInteger(0, Index)) {
69 assert(false && "Invalid replacement sequence index!");
70 return ReplacementItem{};
72 RepString = RepString.trim();
73 if (!RepString.empty() && RepString.front() == ',') {
74 RepString = RepString.drop_front();
75 if (!consumeFieldLayout(RepString, Where, Align, Pad))
76 assert(false && "Invalid replacement field layout specification!");
78 RepString = RepString.trim();
79 if (!RepString.empty() && RepString.front() == ':') {
80 Options = RepString.drop_front().trim();
81 RepString = StringRef();
83 RepString = RepString.trim();
84 if (!RepString.empty()) {
85 assert(false && "Unexpected characters found in replacement string!");
88 return ReplacementItem{Spec, Index, Align, Where, Pad, Options};
91 std::pair<ReplacementItem, StringRef>
92 formatv_object_base::splitLiteralAndReplacement(StringRef Fmt) {
94 while (From < Fmt.size() && From != StringRef::npos) {
95 std::size_t BO = Fmt.find_first_of('{', From);
96 // Everything up until the first brace is a literal.
98 return std::make_pair(ReplacementItem{Fmt.substr(0, BO)}, Fmt.substr(BO));
101 Fmt.drop_front(BO).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.substr(BO, NumEscapedBraces);
107 StringRef Right = Fmt.drop_front(BO + NumEscapedBraces * 2);
108 return std::make_pair(ReplacementItem{Middle}, Right);
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('}', BO);
114 if (BC == StringRef::npos) {
117 "Unterminated brace sequence. Escape with {{ for a literal brace.");
118 return std::make_pair(ReplacementItem{Fmt}, StringRef());
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
124 std::size_t BO2 = Fmt.find_first_of('{', BO + 1);
126 return std::make_pair(ReplacementItem{Fmt.substr(0, BO2)},
129 StringRef Spec = Fmt.slice(BO + 1, BC);
130 StringRef Right = Fmt.substr(BC + 1);
132 auto RI = parseReplacementItem(Spec);
134 return std::make_pair(*RI, Right);
136 // If there was an error parsing the replacement item, treat it as an
137 // invalid replacement spec, and just continue.
140 return std::make_pair(ReplacementItem{Fmt}, StringRef());
143 std::vector<ReplacementItem>
144 formatv_object_base::parseFormatString(StringRef Fmt) {
145 std::vector<ReplacementItem> Replacements;
147 while (!Fmt.empty()) {
148 std::tie(I, Fmt) = splitLiteralAndReplacement(Fmt);
149 if (I.Type != ReplacementType::Empty)
150 Replacements.push_back(I);
155 void detail::format_adapter::anchor() { }