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
10using namespace llvm;
11
12static Optional<AlignStyle> translateLocChar(char C) {
13  switch (C) {
14  case '-':
15    return AlignStyle::Left;
16  case '=':
17    return AlignStyle::Center;
18  case '+':
19    return AlignStyle::Right;
20  default:
21    return None;
22  }
23  LLVM_BUILTIN_UNREACHABLE;
24}
25
26bool formatv_object_base::consumeFieldLayout(StringRef &Spec, AlignStyle &Where,
27                                             size_t &Align, char &Pad) {
28  Where = AlignStyle::Right;
29  Align = 0;
30  Pad = ' ';
31  if (Spec.empty())
32    return true;
33
34  if (Spec.size() > 1) {
35    // A maximum of 2 characters at the beginning can be used for something
36    // other
37    // than the width.
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])) {
43      Pad = Spec[0];
44      Where = *Loc;
45      Spec = Spec.drop_front(2);
46    } else if (auto Loc = translateLocChar(Spec[0])) {
47      Where = *Loc;
48      Spec = Spec.drop_front(1);
49    }
50  }
51
52  bool Failed = Spec.consumeInteger(0, Align);
53  return !Failed;
54}
55
56Optional<ReplacementItem>
57formatv_object_base::parseReplacementItem(StringRef Spec) {
58  StringRef RepString = Spec.trim("{}");
59
60  // If the replacement sequence does not start with a non-negative integer,
61  // this is an error.
62  char Pad = ' ';
63  std::size_t Align = 0;
64  AlignStyle Where = AlignStyle::Right;
65  StringRef Options;
66  size_t Index = 0;
67  RepString = RepString.trim();
68  if (RepString.consumeInteger(0, Index)) {
69    assert(false && "Invalid replacement sequence index!");
70    return ReplacementItem{};
71  }
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!");
77  }
78  RepString = RepString.trim();
79  if (!RepString.empty() && RepString.front() == ':') {
80    Options = RepString.drop_front().trim();
81    RepString = StringRef();
82  }
83  RepString = RepString.trim();
84  if (!RepString.empty()) {
85    assert(false && "Unexpected characters found in replacement string!");
86  }
87
88  return ReplacementItem{Spec, Index, Align, Where, Pad, Options};
89}
90
91std::pair<ReplacementItem, StringRef>
92formatv_object_base::splitLiteralAndReplacement(StringRef Fmt) {
93  std::size_t From = 0;
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.
97    if (BO != 0)
98      return std::make_pair(ReplacementItem{Fmt.substr(0, BO)}, Fmt.substr(BO));
99
100    StringRef Braces =
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);
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('}', BO);
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('{', BO + 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(BO + 1, BC);
130    StringRef Right = Fmt.substr(BC + 1);
131
132    auto RI = parseReplacementItem(Spec);
133    if (RI.hasValue())
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    From = BC + 1;
139  }
140  return std::make_pair(ReplacementItem{Fmt}, StringRef());
141}
142
143std::vector<ReplacementItem>
144formatv_object_base::parseFormatString(StringRef Fmt) {
145  std::vector<ReplacementItem> 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
155void detail::format_adapter::anchor() { }
156