1 files changed, 214 insertions, 0 deletions
diff --git a/js/src/util/StringBuffer.cpp b/js/src/util/StringBuffer.cpp
new file mode 100644
index 0000000000..03d9a7279c
--- /dev/null
+++ b/js/src/util/StringBuffer.cpp
@@ -0,0 +1,214 @@
+/* -*- 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/. */
+
+#include "util/StringBuffer.h"
+
+#include "mozilla/Latin1.h"
+#include "mozilla/Range.h"
+
+#include <algorithm>
+
+#include "frontend/ParserAtom.h"  // frontend::{ParserAtomsTable, TaggedParserAtomIndex
+#include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
+#include "vm/BigIntType.h"
+#include "vm/StaticStrings.h"
+
+#include "vm/JSObject-inl.h"
+#include "vm/StringType-inl.h"
+
+using namespace js;
+
+template <typename CharT, class Buffer>
+static CharT* ExtractWellSized(Buffer& cb) {
+  size_t capacity = cb.capacity();
+  size_t length = cb.length();
+  StringBufferAllocPolicy allocPolicy = cb.allocPolicy();
+
+  CharT* buf = cb.extractOrCopyRawBuffer();
+  if (!buf) {
+    return nullptr;
+  }
+
+  // For medium/big buffers, avoid wasting more than 1/4 of the memory. Very
+  // small strings will not reach here because they will have been stored in a
+  // JSInlineString. Don't bother shrinking the allocation unless at least 80
+  // bytes will be saved, which is a somewhat arbitrary number (though it does
+  // correspond to a mozjemalloc size class.)
+  MOZ_ASSERT(capacity >= length);
+  constexpr size_t minCharsToReclaim = 80 / sizeof(CharT);
+  if (capacity - length >= minCharsToReclaim &&
+      capacity - length > capacity / 4) {
+    CharT* tmp = allocPolicy.pod_realloc<CharT>(buf, capacity, length);
+    if (!tmp) {
+      allocPolicy.free_(buf);
+      return nullptr;
+    }
+    buf = tmp;
+  }
+
+  return buf;
+}
+
+char16_t* StringBuffer::stealChars() {
+  if (isLatin1() && !inflateChars()) {
+    return nullptr;
+  }
+
+  return ExtractWellSized<char16_t>(twoByteChars());
+}
+
+bool StringBuffer::inflateChars() {
+  MOZ_ASSERT(isLatin1());
+
+  TwoByteCharBuffer twoByte(latin1Chars().allocPolicy());
+
+  /*
+   * Note: we don't use Vector::capacity() because it always returns a
+   * value >= sInlineCapacity. Since Latin1CharBuffer::sInlineCapacity >
+   * TwoByteCharBuffer::sInlineCapacitychars, we'd always malloc here.
+   */
+  size_t capacity = std::max(reserved_, latin1Chars().length());
+  if (!twoByte.reserve(capacity)) {
+    return false;
+  }
+
+  twoByte.infallibleGrowByUninitialized(latin1Chars().length());
+
+  mozilla::ConvertLatin1toUtf16(mozilla::AsChars(latin1Chars()), twoByte);
+
+  cb.destroy();
+  cb.construct<TwoByteCharBuffer>(std::move(twoByte));
+  return true;
+}
+
+bool StringBuffer::append(const frontend::ParserAtomsTable& parserAtoms,
+                          frontend::TaggedParserAtomIndex atom) {
+  return parserAtoms.appendTo(*this, atom);
+}
+
+template <typename CharT>
+JSLinearString* StringBuffer::finishStringInternal(JSContext* cx,
+                                                   gc::Heap heap) {
+  size_t len = length();
+
+  if (JSAtom* staticStr = cx->staticStrings().lookup(begin<CharT>(), len)) {
+    return staticStr;
+  }
+
+  if (JSInlineString::lengthFits<CharT>(len)) {
+    mozilla::Range<const CharT> range(begin<CharT>(), len);
+    return NewInlineString<CanGC>(cx, range);
+  }
+
+  UniquePtr<CharT[], JS::FreePolicy> buf(
+      ExtractWellSized<CharT>(chars<CharT>()));
+
+  if (!buf) {
+    return nullptr;
+  }
+
+  JSLinearString* str =
+      NewStringDontDeflate<CanGC>(cx, std::move(buf), len, heap);
+  if (!str) {
+    return nullptr;
+  }
+
+  return str;
+}
+
+JSLinearString* JSStringBuilder::finishString(gc::Heap heap) {
+  MOZ_ASSERT(maybeCx_);
+
+  size_t len = length();
+  if (len == 0) {
+    return maybeCx_->names().empty_;
+  }
+
+  if (MOZ_UNLIKELY(!JSString::validateLength(maybeCx_, len))) {
+    return nullptr;
+  }
+
+  static_assert(JSFatInlineString::MAX_LENGTH_TWO_BYTE <
+                TwoByteCharBuffer::InlineLength);
+  static_assert(JSFatInlineString::MAX_LENGTH_LATIN1 <
+                Latin1CharBuffer::InlineLength);
+
+  return isLatin1() ? finishStringInternal<Latin1Char>(maybeCx_, heap)
+                    : finishStringInternal<char16_t>(maybeCx_, heap);
+}
+
+JSAtom* StringBuffer::finishAtom() {
+  MOZ_ASSERT(maybeCx_);
+
+  size_t len = length();
+  if (len == 0) {
+    return maybeCx_->names().empty_;
+  }
+
+  if (isLatin1()) {
+    JSAtom* atom = AtomizeChars(maybeCx_, latin1Chars().begin(), len);
+    latin1Chars().clear();
+    return atom;
+  }
+
+  JSAtom* atom = AtomizeChars(maybeCx_, twoByteChars().begin(), len);
+  twoByteChars().clear();
+  return atom;
+}
+
+frontend::TaggedParserAtomIndex StringBuffer::finishParserAtom(
+    frontend::ParserAtomsTable& parserAtoms, FrontendContext* fc) {
+  size_t len = length();
+  if (len == 0) {
+    return frontend::TaggedParserAtomIndex::WellKnown::empty();
+  }
+
+  if (isLatin1()) {
+    auto result = parserAtoms.internLatin1(fc, latin1Chars().begin(), len);
+    latin1Chars().clear();
+    return result;
+  }
+
+  auto result = parserAtoms.internChar16(fc, twoByteChars().begin(), len);
+  twoByteChars().clear();
+  return result;
+}
+
+bool js::ValueToStringBufferSlow(JSContext* cx, const Value& arg,
+                                 StringBuffer& sb) {
+  RootedValue v(cx, arg);
+  if (!ToPrimitive(cx, JSTYPE_STRING, &v)) {
+    return false;
+  }
+
+  if (v.isString()) {
+    return sb.append(v.toString());
+  }
+  if (v.isNumber()) {
+    return NumberValueToStringBuffer(v, sb);
+  }
+  if (v.isBoolean()) {
+    return BooleanToStringBuffer(v.toBoolean(), sb);
+  }
+  if (v.isNull()) {
+    return sb.append(cx->names().null);
+  }
+  if (v.isSymbol()) {
+    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                              JSMSG_SYMBOL_TO_STRING);
+    return false;
+  }
+  if (v.isBigInt()) {
+    RootedBigInt i(cx, v.toBigInt());
+    JSLinearString* str = BigInt::toString<CanGC>(cx, i, 10);
+    if (!str) {
+      return false;
+    }
+    return sb.append(str);
+  }
+  MOZ_ASSERT(v.isUndefined());
+  return sb.append(cx->names().undefined);
+}