1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "tools/gn/string_utils.h"
7 #include "tools/gn/err.h"
8 #include "tools/gn/scope.h"
9 #include "tools/gn/token.h"
10 #include "tools/gn/tokenizer.h"
11 #include "tools/gn/value.h"
15 // Constructs an Err indicating a range inside a string. We assume that the
16 // token has quotes around it that are not counted by the offset.
17 Err ErrInsideStringToken(const Token& token, size_t offset, size_t size,
18 const std::string& msg,
19 const std::string& help = std::string()) {
20 // The "+1" is skipping over the " at the beginning of the token.
21 int int_offset = static_cast<int>(offset);
22 Location begin_loc(token.location().file(),
23 token.location().line_number(),
24 token.location().char_offset() + int_offset + 1);
25 Location end_loc(token.location().file(),
26 token.location().line_number(),
27 token.location().char_offset() + int_offset + 1 +
28 static_cast<int>(size));
29 return Err(LocationRange(begin_loc, end_loc), msg, help);
32 // Given the character input[i] indicating the $ in a string, locates the
33 // identifier and places its range in |*identifier|, and updates |*i| to
34 // point to the last character consumed.
36 // On error returns false and sets the error.
37 bool LocateInlineIdenfitier(const Token& token,
38 const char* input, size_t size,
40 base::StringPiece* identifier,
42 size_t dollars_index = *i;
45 *err = ErrInsideStringToken(token, dollars_index, 1, "$ at end of string.",
46 "I was expecting an identifier after the $.");
51 if (input[*i] == '{') {
54 *err = ErrInsideStringToken(token, dollars_index, 2,
55 "${ at end of string.",
56 "I was expecting an identifier inside the ${...}.");
64 // First char is special.
65 if (!Tokenizer::IsIdentifierFirstChar(input[*i])) {
66 *err = ErrInsideStringToken(
67 token, dollars_index, *i - dollars_index + 1,
68 "$ not followed by an identifier char.",
69 "It you want a literal $ use \"\\$\".");
72 size_t begin_offset = *i;
75 // Find the first non-identifier char following the string.
76 while (*i < size && Tokenizer::IsIdentifierContinuingChar(input[*i]))
78 size_t end_offset = *i;
80 // If we started with a bracket, validate that there's an ending one. Leave
81 // *i pointing to the last char we consumed (backing up one).
84 *err = ErrInsideStringToken(token, dollars_index, *i - dollars_index,
85 "Unterminated ${...");
87 } else if (input[*i] != '}') {
88 *err = ErrInsideStringToken(token, *i, 1, "Not an identifier in string expansion.",
89 "The contents of ${...} should be an identifier. "
90 "This character is out of sorts.");
93 // We want to consume the bracket but also back up one, so *i is unchanged.
98 *identifier = base::StringPiece(&input[begin_offset],
99 end_offset - begin_offset);
103 bool AppendIdentifierValue(Scope* scope,
105 const base::StringPiece& identifier,
108 const Value* value = scope->GetValue(identifier, true);
110 // We assume the identifier points inside the token.
111 *err = ErrInsideStringToken(
112 token, identifier.data() - token.value().data() - 1, identifier.size(),
113 "Undefined identifier in string expansion.",
114 std::string("\"") + identifier + "\" is not currently in scope.");
118 output->append(value->ToString(false));
124 bool ExpandStringLiteral(Scope* scope,
125 const Token& literal,
128 DCHECK(literal.type() == Token::STRING);
129 DCHECK(literal.value().size() > 1); // Should include quotes.
130 DCHECK(result->type() == Value::STRING); // Should be already set.
132 // The token includes the surrounding quotes, so strip those off.
133 const char* input = &literal.value().data()[1];
134 size_t size = literal.value().size() - 2;
136 std::string& output = result->string_value();
137 output.reserve(size);
138 for (size_t i = 0; i < size; i++) {
139 if (input[i] == '\\') {
141 switch (input[i + 1]) {
145 output.push_back(input[i + 1]);
148 default: // Everything else has no meaning: pass the literal.
152 output.push_back(input[i]);
153 } else if (input[i] == '$') {
154 base::StringPiece identifier;
155 if (!LocateInlineIdenfitier(literal, input, size, &i, &identifier, err))
157 if (!AppendIdentifierValue(scope, literal, identifier, &output, err))
160 output.push_back(input[i]);
166 std::string RemovePrefix(const std::string& str, const std::string& prefix) {
167 CHECK(str.size() >= prefix.size() &&
168 str.compare(0, prefix.size(), prefix) == 0);
169 return str.substr(prefix.size());