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// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "tools/gn/string_utils.h"
#include "tools/gn/err.h"
#include "tools/gn/scope.h"
#include "tools/gn/token.h"
#include "tools/gn/tokenizer.h"
#include "tools/gn/value.h"
namespace {
// Constructs an Err indicating a range inside a string. We assume that the
// token has quotes around it that are not counted by the offset.
Err ErrInsideStringToken(const Token& token, size_t offset, size_t size,
const std::string& msg,
const std::string& help = std::string()) {
// The "+1" is skipping over the " at the beginning of the token.
Location begin_loc(token.location().file(),
token.location().line_number(),
token.location().char_offset() + offset + 1);
Location end_loc(token.location().file(),
token.location().line_number(),
token.location().char_offset() + offset + 1 + size);
return Err(LocationRange(begin_loc, end_loc), msg, help);
}
// Given the character input[i] indicating the $ in a string, locates the
// identifier and places its range in |*identifier|, and updates |*i| to
// point to the last character consumed.
//
// On error returns false and sets the error.
bool LocateInlineIdenfitier(const Token& token,
const char* input, size_t size,
size_t* i,
base::StringPiece* identifier,
Err* err) {
size_t dollars_index = *i;
(*i)++;
if (*i == size) {
*err = ErrInsideStringToken(token, dollars_index, 1, "$ at end of string.",
"I was expecting an identifier after the $.");
return false;
}
bool has_brackets;
if (input[*i] == '{') {
(*i)++;
if (*i == size) {
*err = ErrInsideStringToken(token, dollars_index, 2,
"${ at end of string.",
"I was expecting an identifier inside the ${...}.");
return false;
}
has_brackets = true;
} else {
has_brackets = false;
}
// First char is special.
if (!Tokenizer::IsIdentifierFirstChar(input[*i])) {
*err = ErrInsideStringToken(
token, dollars_index, *i - dollars_index + 1,
"$ not followed by an identifier char.",
"It you want a literal $ use \"\\$\".");
return false;
}
size_t begin_offset = *i;
(*i)++;
// Find the first non-identifier char following the string.
while (*i < size && Tokenizer::IsIdentifierContinuingChar(input[*i]))
(*i)++;
size_t end_offset = *i;
// If we started with a bracket, validate that there's an ending one. Leave
// *i pointing to the last char we consumed (backing up one).
if (has_brackets) {
if (*i == size) {
*err = ErrInsideStringToken(token, dollars_index, *i - dollars_index,
"Unterminated ${...");
return false;
} else if (input[*i] != '}') {
*err = ErrInsideStringToken(token, *i, 1, "Not an identifier in string expansion.",
"The contents of ${...} should be an identifier. "
"This character is out of sorts.");
return false;
}
// We want to consume the bracket but also back up one, so *i is unchanged.
} else {
(*i)--;
}
*identifier = base::StringPiece(&input[begin_offset],
end_offset - begin_offset);
return true;
}
bool AppendIdentifierValue(Scope* scope,
const Token& token,
const base::StringPiece& identifier,
std::string* output,
Err* err) {
const Value* value = scope->GetValue(identifier, true);
if (!value) {
// We assume the identifier points inside the token.
*err = ErrInsideStringToken(
token, identifier.data() - token.value().data() - 1, identifier.size(),
"Undefined identifier in string expansion.",
std::string("\"") + identifier + "\" is not currently in scope.");
return false;
}
output->append(value->ToString());
return true;
}
} // namespace
bool ExpandStringLiteral(Scope* scope,
const Token& literal,
Value* result,
Err* err) {
DCHECK(literal.type() == Token::STRING);
DCHECK(literal.value().size() > 1); // Should include quotes.
DCHECK(result->type() == Value::STRING); // Should be already set.
// The token includes the surrounding quotes, so strip those off.
const char* input = &literal.value().data()[1];
size_t size = literal.value().size() - 2;
std::string& output = result->string_value();
output.reserve(size);
for (size_t i = 0; i < size; i++) {
if (input[i] == '\\') {
if (i < size - 1) {
switch (input[i + 1]) {
case '\\':
case '"':
case '$':
output.push_back(input[i + 1]);
i++;
continue;
default: // Everything else has no meaning: pass the literal.
break;
}
}
output.push_back(input[i]);
} else if (input[i] == '$') {
base::StringPiece identifier;
if (!LocateInlineIdenfitier(literal, input, size, &i, &identifier, err))
return false;
if (!AppendIdentifierValue(scope, literal, identifier, &output, err))
return false;
} else {
output.push_back(input[i]);
}
}
return true;
}
std::string RemovePrefix(const std::string& str, const std::string& prefix) {
CHECK(str.size() >= prefix.size() &&
str.compare(0, prefix.size(), prefix) == 0);
return str.substr(prefix.size());
}
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