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Unified Diff: third_party/WebKit/Source/core/layout/ng/ng_block_layout_child_iterator.h

Issue 2693193002: [LayoutNG] A different approach to multi-col. (Closed)
Patch Set: Created 3 years, 10 months ago
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Index: third_party/WebKit/Source/core/layout/ng/ng_block_layout_child_iterator.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_block_layout_child_iterator.h b/third_party/WebKit/Source/core/layout/ng/ng_block_layout_child_iterator.h
new file mode 100644
index 0000000000000000000000000000000000000000..3af4a5320800fb59129e44d92d80d34fd7844ef9
--- /dev/null
+++ b/third_party/WebKit/Source/core/layout/ng/ng_block_layout_child_iterator.h
@@ -0,0 +1,80 @@
+// 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 NGBlockLayoutChildIterator_h
+#define NGBlockLayoutChildIterator_h
+
+#include "core/layout/ng/ng_block_break_token.h"
+#include "core/layout/ng/ng_layout_input_node.h"
+
+namespace blink {
+
+class NGBlockLayoutChildIterator {
+ public:
+ NGBlockLayoutChildIterator(NGLayoutInputNode* first_child,
+ NGBlockBreakToken* break_token)
+ : child_(first_child), break_token_(break_token), child_token_idx_(0) {
+ Advance();
+ }
+
+ std::pair<NGLayoutInputNode*, NGBreakToken*> NextChild() {
+ NGLayoutInputNode* child = child_;
+ NGBreakToken* child_token = child_token_;
+ if (child_)
+ child_ = child_->NextSibling();
+ Advance();
+ return std::make_pair(child, child_token);
+ }
+
+ private:
+ //
+ void Advance() {
+ const auto& child_break_tokens = break_token_->ChildBreakTokens();
+ child_token_ = nullptr;
+
+ do {
+ NGBreakToken* next_child_token = nullptr;
+ if (break_token_ && child_token_idx_ < child_break_tokens.size()) {
+ next_child_token = break_token_->ChildBreakTokens()[child_token_idx_];
+ }
+
+ if (next_child_token && next_child_token->Node() == child_) {
+ // If we're resuming layout after a fragmentainer break, we need to skip
+ // siblings that we're done with. We may have been able to fully lay out
+ // some
+ // node(s) preceding a node that we had to break inside (and therefore
+ // were
+ // not able to fully lay out). This happens when we have parallel flows
+ // [1],
+ // which are caused by floats, overflow, etc.
+ //
+ // [1] https://drafts.csswg.org/css-break/#parallel-flows
+
+ // We may have a break token which just represents that a child has
+ // fully completed its layout.
+ if (next_child_token->IsFinished())
+ continue;
+
+ // We've found our next child, return.
+ child_token_idx_++;
+ child_token_ = next_child_token;
+ return;
+ } else {
+ // There is no break token which matches here, we've found our next
+ // child.
+ return;
+ }
+ } while ((child_ = child_->NextSibling()));
+ }
+
+ Persistent<NGLayoutInputNode> child_;
+ Persistent<NGBreakToken> child_token_;
+
+ Persistent<NGBlockBreakToken> break_token_;
+ size_t child_token_idx_;
+};
+
+} // namespace blink
+
+#endif // NGBlockLayoutChildIterator_h

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