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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef builtin_intl_StringAsciiChars_h
#define builtin_intl_StringAsciiChars_h
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/Span.h"
#include <stddef.h>
#include "js/GCAPI.h"
#include "js/TypeDecls.h"
#include "js/Vector.h"
#include "vm/StringType.h"
namespace js::intl {
/**
* String view of an ASCII-only string.
*
* This holds a reference to a JSLinearString and can produce a string view
* into that string. If the string is represented by Latin1 characters, the
* span is returned directly. If the string is represented by UTF-16
* characters, it copies the char16_t characters into a char array, and then
* returns a span based on the copy.
*
* This allows us to avoid copying for the common use case that the ASCII
* characters are represented in Latin1.
*/
class MOZ_STACK_CLASS StringAsciiChars final {
// When copying string characters, use this many bytes of inline storage.
static const size_t InlineCapacity = 24;
JS::AutoCheckCannotGC nogc_;
JSLinearString* str_;
mozilla::Maybe<Vector<Latin1Char, InlineCapacity>> ownChars_;
public:
explicit StringAsciiChars(JSLinearString* str) : str_(str) {
MOZ_ASSERT(StringIsAscii(str));
}
operator mozilla::Span<const char>() const {
if (str_->hasLatin1Chars()) {
return mozilla::AsChars(str_->latin1Range(nogc_));
}
return mozilla::AsChars(mozilla::Span<const Latin1Char>(*ownChars_));
}
[[nodiscard]] bool init(JSContext* cx) {
if (str_->hasLatin1Chars()) {
return true;
}
ownChars_.emplace(cx);
if (!ownChars_->resize(str_->length())) {
return false;
}
js::CopyChars(ownChars_->begin(), *str_);
return true;
}
};
} // namespace js::intl
#endif // builtin_intl_StringAsciiChars_h
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