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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/text//bidi_paragraph.h"
#include "third_party/blink/renderer/platform/text/icu_error.h"
#include "third_party/blink/renderer/platform/wtf/text/character_names.h"
#include "third_party/blink/renderer/platform/wtf/text/string_builder.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
namespace blink {
bool BidiParagraph::SetParagraph(const String& text,
std::optional<TextDirection> base_direction) {
DCHECK(!text.IsNull());
DCHECK(!ubidi_);
ubidi_ = UBidiPtr(ubidi_open());
UBiDiLevel para_level;
if (base_direction) {
base_direction_ = *base_direction;
para_level = IsLtr(base_direction_) ? UBIDI_LTR : UBIDI_RTL;
} else {
para_level = UBIDI_DEFAULT_LTR;
}
ICUError error;
ubidi_setPara(ubidi_.get(), text.Span16().data(), text.length(), para_level,
nullptr, &error);
if (U_FAILURE(error)) {
NOTREACHED();
}
if (!base_direction) {
base_direction_ = DirectionFromLevel(ubidi_getParaLevel(ubidi_.get()));
}
return true;
}
// static
template <>
std::optional<TextDirection> BidiParagraph::BaseDirectionForString(
base::span<const LChar> text,
bool (*stop_at)(UChar)) {
for (const LChar ch : text) {
if (u_charDirection(ch) == U_LEFT_TO_RIGHT) {
return TextDirection::kLtr;
}
if (stop_at && stop_at(ch)) {
break;
}
}
return std::nullopt;
}
// static
template <>
std::optional<TextDirection> BidiParagraph::BaseDirectionForString(
base::span<const UChar> text,
bool (*stop_at)(UChar)) {
const UChar* data = text.data();
const size_t len = text.size();
for (size_t i = 0; i < len;) {
UChar32 ch;
UNSAFE_TODO(U16_NEXT(data, i, len, ch));
switch (u_charDirection(ch)) {
case U_LEFT_TO_RIGHT:
return TextDirection::kLtr;
case U_RIGHT_TO_LEFT:
case U_RIGHT_TO_LEFT_ARABIC:
return TextDirection::kRtl;
default:
break;
}
if (stop_at && stop_at(ch)) {
break;
}
}
return std::nullopt;
}
// static
std::optional<TextDirection> BidiParagraph::BaseDirectionForString(
const StringView& text,
bool (*stop_at)(UChar)) {
return text.Is8Bit() ? BaseDirectionForString(text.Span8(), stop_at)
: BaseDirectionForString(text.Span16(), stop_at);
}
// static
String BidiParagraph::StringWithDirectionalOverride(const StringView& text,
TextDirection direction) {
StringBuilder builder;
builder.Reserve16BitCapacity(text.length() + 2);
builder.Append(IsLtr(direction) ? kLeftToRightOverrideCharacter
: kRightToLeftOverrideCharacter);
builder.Append(text);
builder.Append(kPopDirectionalFormattingCharacter);
return builder.ToString();
}
unsigned BidiParagraph::GetLogicalRun(unsigned start, UBiDiLevel* level) const {
int32_t end;
ubidi_getLogicalRun(ubidi_.get(), start, &end, level);
return end;
}
void BidiParagraph::GetLogicalRuns(const String& text, Runs* runs) const {
DCHECK(runs->empty());
for (unsigned start = 0; start < text.length();) {
UBiDiLevel level;
unsigned end = GetLogicalRun(start, &level);
DCHECK_GT(end, start);
runs->emplace_back(start, end, level);
start = end;
}
}
void BidiParagraph::GetVisualRuns(const String& text, Runs* runs) const {
DCHECK(runs->empty());
Runs logical_runs;
GetLogicalRuns(text, &logical_runs);
Vector<UBiDiLevel, 32> levels;
levels.ReserveInitialCapacity(logical_runs.size());
for (const Run& run : logical_runs) {
levels.push_back(run.level);
}
Vector<int32_t, 32> indices_in_visual_order(logical_runs.size());
IndicesInVisualOrder(levels, &indices_in_visual_order);
for (int32_t index : indices_in_visual_order) {
runs->push_back(logical_runs[index]);
}
}
// static
void BidiParagraph::IndicesInVisualOrder(
const Vector<UBiDiLevel, 32>& levels,
Vector<int32_t, 32>* indices_in_visual_order_out) {
// Check the size before passing the raw pointers to ICU.
CHECK_EQ(levels.size(), indices_in_visual_order_out->size());
ubidi_reorderVisual(levels.data(), levels.size(),
indices_in_visual_order_out->data());
}
} // namespace blink
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