Create LineLayout api

Source/core/layout/api/LineLayoutItem.h

+// Copyright 2015 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 LineLayoutItem_h
+#define LineLayoutItem_h
+
+#include "core/layout/LayoutObject.h"
+
+#include "platform/LayoutUnit.h"
+
+namespace blink {
+
+class ComputedStyle;
+class Document;
+class LayoutObject;

[esprehn, 2015/06/23 21:57:18]

You don't need this forward decl, you include LayoutObject.h

+
+class LineLayoutItem {
+public:
+    explicit LineLayoutItem(LayoutObject* layoutObject)
+        : m_layoutObject(layoutObject)
+    {
+    }
+
+    explicit LineLayoutItem(const LineLayoutItem& item) : m_layoutObject(item.m_layoutObject) { }

[leviw_travelin_and_unemployed, 2015/06/24 19:10:51]

The jyasskin took a look and this is the problem: you don't actually want an
explicit copy constructor. This is preventing the code from being able to return
a valid value, as that would require a copy.

The only constructors that need the explicit are the ones that take Layout____*
types.

+    explicit LineLayoutItem() : m_layoutObject(0) { }

[leviw_travelin_and_unemployed, 2015/06/23 21:51:46]

You don't need the explicit here... maybe try removing that to see if it fixes
the issue?

+
+    // TODO: Remove this. It's only here to make things compile before
+    // switching all of core/layout/line to using the API.
+    // https://crbug.com/499321
+    operator LayoutObject*() const { return m_layoutObject; }
+
+    LineLayoutItem* operator->() { return this; }
+
+    bool hasLayoutObject() const

[esprehn, 2015/06/23 21:57:18]

isNull(), but I think you want to just use the UnspecifiedBool pattern and allow
implicit conversion of LineLayoutItem to a boolean.

+    {
+        return m_layoutObject;
+    }
+
+    LineLayoutItem parent() const
+    {
+        return LineLayoutItem(m_layoutObject->parent());

[leviw_travelin_and_unemployed, 2015/06/23 21:51:46]

../../third_party/WebKit/Source/core/layout/api/LineLayoutItem.h:42:16: error:
no matching constructor for initialization of 'blink::LineLayoutItem'
        return LineLayoutItem(m_layoutObject->parent());
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'm actually confused about why this doesn't work.

LineLayoutItem has a constructor that takes a LayoutObject*.
m_layoutObject->parent() returns a LayoutObject*.

I need a life line. I think jyasskin is OOO today, but I'm gonna bother him
about it tomorrow.

+    }
+
+    LineLayoutItem nextSibling() const
+    {
+        return LineLayoutItem(m_layoutObject->nextSibling());
+    }
+
+    LineLayoutItem previousSibling() const
+    {
+        return LineLayoutItem(m_layoutObject->previousSibling());
+    }
+
+    LineLayoutItem slowFirstChild() const
+    {
+        return LineLayoutItem(m_layoutObject->slowFirstChild());
+    }
+
+    LineLayoutItem slowLastChild() const
+    {
+        return LineLayoutItem(m_layoutObject->slowLastChild());
+    }
+
+    const ComputedStyle* style() const
+    {
+        return m_layoutObject->style();
+    }
+
+    const ComputedStyle& styleRef() const
+    {
+        return m_layoutObject->styleRef();
+    }
+
+    Document& document() const
+    {
+        return m_layoutObject->document();
+    }
+
+    bool preservesNewline() const
+    {
+        return m_layoutObject->preservesNewline();
+    }
+
+    unsigned length() const
+    {
+        return m_layoutObject->length();
+    }
+
+    bool isFloatingOrOutOfFlowPositioned() const
+    {
+        return m_layoutObject->isFloatingOrOutOfFlowPositioned();
+    }
+
+    bool isFloating() const
+    {
+        return m_layoutObject->isFloating();
+    }
+
+    bool isOutOfFlowPositioned() const
+    {
+        return m_layoutObject->isOutOfFlowPositioned();
+    }
+
+    bool isBox() const
+    {
+        return m_layoutObject->isBox();
+    }
+
+    bool isBR() const
+    {
+        return m_layoutObject->isBR();
+    }
+
+    bool isHorizontalWritingMode() const
+    {
+        return m_layoutObject->isHorizontalWritingMode();
+    }
+
+    bool isImage() const
+    {
+        return m_layoutObject->isImage();
+    }
+
+    bool isLayoutBlockFlow() const
+    {
+        return m_layoutObject->isLayoutBlockFlow();
+    }
+
+    bool isLayoutInline() const
+    {
+        return m_layoutObject->isLayoutInline();
+    }
+
+    bool isListMarker() const
+    {
+        return m_layoutObject->isListMarker();
+    }
+
+    bool isReplaced() const
+    {
+        return m_layoutObject->isReplaced();
+    }
+
+    bool isRubyRun() const
+    {
+        return m_layoutObject->isRubyRun();
+    }
+
+    bool isSVGInlineText() const
+    {
+        return m_layoutObject->isSVGInlineText();
+    }
+
+    bool isTableCell() const
+    {
+        return m_layoutObject->isTableCell();
+    }
+
+    bool isText() const
+    {
+        return m_layoutObject->isText();
+    }
+
+protected:
+    LayoutObject* layoutObject() { return m_layoutObject; }
+    const LayoutObject* layoutObject() const { return m_layoutObject; }
+
+private:
+    LayoutObject* m_layoutObject;
+};
+
+} // namespace blink
+
+#endif // LineLayoutItem_h