1 //===- FormatVariadic.cpp - Format string parsing and analysis ----*-C++-*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
8
9 #include "llvm/Support/FormatVariadic.h"
10
11 using namespace llvm;
12
translateLocChar(char C)13 static Optional<AlignStyle> translateLocChar(char C) {
14 switch (C) {
15 case '-':
16 return AlignStyle::Left;
17 case '=':
18 return AlignStyle::Center;
19 case '+':
20 return AlignStyle::Right;
21 default:
22 return None;
23 }
24 LLVM_BUILTIN_UNREACHABLE;
25 }
26
consumeFieldLayout(StringRef & Spec,AlignStyle & Where,size_t & Align,char & Pad)27 bool formatv_object_base::consumeFieldLayout(StringRef &Spec, AlignStyle &Where,
28 size_t &Align, char &Pad) {
29 Where = AlignStyle::Right;
30 Align = 0;
31 Pad = ' ';
32 if (Spec.empty())
33 return true;
34
35 if (Spec.size() > 1) {
36 // A maximum of 2 characters at the beginning can be used for something
37 // other
38 // than the width.
39 // If Spec[1] is a loc char, then Spec[0] is a pad char and Spec[2:...]
40 // contains the width.
41 // Otherwise, if Spec[0] is a loc char, then Spec[1:...] contains the width.
42 // Otherwise, Spec[0:...] contains the width.
43 if (auto Loc = translateLocChar(Spec[1])) {
44 Pad = Spec[0];
45 Where = *Loc;
46 Spec = Spec.drop_front(2);
47 } else if (auto Loc = translateLocChar(Spec[0])) {
48 Where = *Loc;
49 Spec = Spec.drop_front(1);
50 }
51 }
52
53 bool Failed = Spec.consumeInteger(0, Align);
54 return !Failed;
55 }
56
57 Optional<ReplacementItem>
parseReplacementItem(StringRef Spec)58 formatv_object_base::parseReplacementItem(StringRef Spec) {
59 StringRef RepString = Spec.trim("{}");
60
61 // If the replacement sequence does not start with a non-negative integer,
62 // this is an error.
63 char Pad = ' ';
64 std::size_t Align = 0;
65 AlignStyle Where = AlignStyle::Right;
66 StringRef Options;
67 size_t Index = 0;
68 RepString = RepString.trim();
69 if (RepString.consumeInteger(0, Index)) {
70 assert(false && "Invalid replacement sequence index!");
71 return ReplacementItem{};
72 }
73 RepString = RepString.trim();
74 if (!RepString.empty() && RepString.front() == ',') {
75 RepString = RepString.drop_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>
splitLiteralAndReplacement(StringRef Fmt)93 formatv_object_base::splitLiteralAndReplacement(StringRef Fmt) {
94 std::size_t From = 0;
95 while (From < Fmt.size() && From != StringRef::npos) {
96 std::size_t BO = Fmt.find_first_of('{', From);
97 // Everything up until the first brace is a literal.
98 if (BO != 0)
99 return std::make_pair(ReplacementItem{Fmt.substr(0, BO)}, Fmt.substr(BO));
100
101 StringRef Braces =
102 Fmt.drop_front(BO).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.substr(BO, NumEscapedBraces);
108 StringRef Right = Fmt.drop_front(BO + 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('}', BO);
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('{', BO + 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(BO + 1, BC);
131 StringRef Right = Fmt.substr(BC + 1);
132
133 auto RI = parseReplacementItem(Spec);
134 if (RI.hasValue())
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 From = BC + 1;
140 }
141 return std::make_pair(ReplacementItem{Fmt}, StringRef());
142 }
143
144 std::vector<ReplacementItem>
parseFormatString(StringRef Fmt)145 formatv_object_base::parseFormatString(StringRef Fmt) {
146 std::vector<ReplacementItem> 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