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// Copyright 2017 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.
#ifndef NGOffsetMappingBuilder_h
#define NGOffsetMappingBuilder_h
#include "base/auto_reset.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/layout/ng/inline/ng_offset_mapping.h"
#include "third_party/blink/renderer/platform/wtf/allocator.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
namespace blink {
class LayoutObject;
// This is the helper class for constructing the DOM-to-TextContent offset
// mapping. It holds an offset mapping, and provides APIs to modify the mapping
// step by step until the construction is finished.
// Design doc: https://goo.gl/CJbxky
// TODO(xiaochengh): Change the mock implemetation to a real one.
class CORE_EXPORT NGOffsetMappingBuilder {
STACK_ALLOCATED();
public:
// A scope-like object that, mappings appended inside the scope are marked as
// from the given source node. When multiple scopes nest, only the inner-most
// scope is effective. Note that at most one of the nested scopes may have a
// non-null node.
//
// Example:
//
// NGOffsetMappingBuilder builder;
//
// {
// NGOffsetMappingBuilder::SourceNodeScope scope(&builder, node);
//
// // These 3 characters are marked as from source node |node|.
// builder.AppendIdentity(3);
//
// {
// NGOffsetMappingBuilder::SourceNodeScope unset_scope(&builder, nullptr);
//
// // This character is marked as having no source node.
// builder.AppendCollapsed(1);
// }
//
// // These 2 characters are marked as from source node |node|.
// builder.AppendIdentity(2);
//
// // Not allowed.
// // NGOffsetMappingBuilder::SourceNodeScope scope(&builder, node2);
// }
//
// // This character is marked as having no source node.
// builder.AppendIdentity(1);
class SourceNodeScope {
STACK_ALLOCATED();
public:
SourceNodeScope(NGOffsetMappingBuilder* builder, const LayoutObject* node);
~SourceNodeScope();
private:
NGOffsetMappingBuilder* const builder_ = nullptr;
base::AutoReset<Persistent<const Node>> layout_object_auto_reset_;
base::AutoReset<unsigned> appended_length_auto_reset_;
DISALLOW_COPY_AND_ASSIGN(SourceNodeScope);
};
NGOffsetMappingBuilder();
void ReserveCapacity(unsigned capacity);
// Append an identity offset mapping of the specified length with null
// annotation to the builder.
void AppendIdentityMapping(unsigned length);
// Append a collapsed offset mapping from the specified length with null
// annotation to the builder.
void AppendCollapsedMapping(unsigned length);
// TODO(xiaochengh): Add the following API when we start to fix offset mapping
// for text-transform.
// Append an expanded offset mapping to the specified length with null
// annotation to the builder.
// void AppendExpandedMapping(unsigned length);
// This function should only be called by NGInlineItemsBuilder during
// whitespace collapsing, and in the case that the target string of the
// currently held mapping:
// (i) has at least |space_offset + 1| characters,
// (ii) character at |space_offset| in destination string is a collapsible
// whitespace,
// This function changes the space into collapsed.
void CollapseTrailingSpace(unsigned space_offset);
// Concatenate the offset mapping held by another builder to this builder.
// TODO(xiaochengh): Implement when adding support for 'text-transform'
// void Concatenate(const NGOffsetMappingBuilder&);
// Composite the offset mapping held by another builder to this builder.
// TODO(xiaochengh): Implement when adding support for 'text-transform'
// void Composite(const NGOffsetMappingBuilder&);
// Set the destination string of the offset mapping.
void SetDestinationString(String);
// Called when entering a non-atomic inline node (e.g., SPAN), before
// collecting any of its inline descendants.
void EnterInline(const LayoutObject&);
// Called when exiting a non-atomic inline node (e.g., SPAN), after having
// collected all of its inline descendants.
void ExitInline(const LayoutObject&);
// Finalize and return the offset mapping.
// This method can only be called once, as it can invalidate the stored data.
NGOffsetMapping Build();
private:
// Helper function for CollapseTrailingSpace() to maintain unit ranges.
void ShiftRanges(unsigned position, int delta);
Persistent<const Node> current_node_ = nullptr;
unsigned current_offset_ = 0;
bool has_open_unit_ = false;
#if DCHECK_IS_ON()
bool has_nonnull_node_scope_ = false;
#endif
// Length of the current destination string.
unsigned destination_length_ = 0;
// Mapping units of the current mapping function.
Vector<NGOffsetMappingUnit> mapping_units_;
// Unit ranges of the current mapping function.
NGOffsetMapping::RangeMap unit_ranges_;
// Unit range starts of currently entered inline elements.
Vector<unsigned> open_inlines_;
// The destination string of the offset mapping.
String destination_string_;
friend class SourceNodeScope;
DISALLOW_COPY_AND_ASSIGN(NGOffsetMappingBuilder);
};
} // namespace blink
#endif // OffsetMappingBuilder_h
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