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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_EARLY_BREAK_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_EARLY_BREAK_H_
#include "base/check_op.h"
#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/core/layout/block_node.h"
#include "third_party/blink/renderer/core/layout/break_appeal.h"
#include "third_party/blink/renderer/platform/wtf/gc_plugin.h"
namespace blink {
// Possible early unforced breakpoint. This represents a possible (and good)
// location to break. In cases where we run out of space at an unideal location,
// we may want to go back and break here instead.
class EarlyBreak : public GarbageCollected<EarlyBreak> {
public:
enum BreakType {
kLine, // Break before a specified line number.
kBlock // Break before or inside a specified child block.
};
explicit EarlyBreak(BlockNode block,
BreakAppeal break_appeal,
const EarlyBreak* break_inside_child = nullptr)
: box_(block.GetLayoutBox()),
break_inside_child_(break_inside_child),
const_type_(kBlock),
break_appeal_(break_appeal) {}
explicit EarlyBreak(int line_number, BreakAppeal break_appeal)
: line_number_(line_number),
const_type_(kLine),
break_appeal_(break_appeal) {}
BreakType Type() const { return static_cast<BreakType>(const_type_); }
bool IsBreakBefore() const { return !break_inside_child_; }
BlockNode GetBlockNode() const {
CHECK_EQ(const_type_, kBlock);
return BlockNode(box_);
}
int LineNumber() const {
DCHECK_EQ(const_type_, kLine);
return line_number_;
}
const EarlyBreak* BreakInside() const { return break_inside_child_.Get(); }
BreakAppeal GetBreakAppeal() const {
return static_cast<BreakAppeal>(break_appeal_);
}
void Trace(Visitor* visitor) const {
// It is safe to check |const_type_| here because it is a const value.
if (const_type_ == kBlock)
visitor->Trace(box_);
visitor->Trace(break_inside_child_);
}
private:
union {
GC_PLUGIN_IGNORE("https://crbug.com/1146383")
Member<LayoutBox> box_; // Set if const_type_ == kBlock
int line_number_; // Set if const_type_ == kLine
};
Member<const EarlyBreak> break_inside_child_;
const unsigned const_type_ : 1; // BreakType
unsigned break_appeal_ : kBreakAppealBitsNeeded; // BreakAppeal
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_EARLY_BREAK_H_
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