1/* 2 * Copyright (C) 2013 Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are 6 * met: 7 * 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above 11 * copyright notice, this list of conditions and the following disclaimer 12 * in the documentation and/or other materials provided with the 13 * distribution. 14 * * Neither the name of Google Inc. nor the names of its 15 * contributors may be used to endorse or promote products derived from 16 * this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#ifndef HTMLImport_h 32#define HTMLImport_h 33 34#include "core/html/imports/HTMLImportState.h" 35#include "platform/heap/Handle.h" 36#include "wtf/TreeNode.h" 37 38namespace blink { 39 40class Document; 41class LocalFrame; 42class HTMLImportChild; 43class HTMLImportLoader; 44class HTMLImportsController; 45class KURL; 46 47// 48// # Basic Data Structure and Algorithms of HTML Imports implemenation. 49// 50// ## The Import Tree 51// 52// HTML Imports form a tree: 53// 54// * The root of the tree is HTMLImportTreeRoot. 55// 56// * The HTMLImportTreeRoot is owned HTMLImportsController, which is owned by the master 57// document as a DocumentSupplement. 58// 59// * The non-root nodes are HTMLImportChild. They are all owned by HTMLImporTreeRoot. 60// LinkStyle is wired into HTMLImportChild by implementing HTMLImportChildClient interface 61// 62// * Both HTMLImportTreeRoot and HTMLImportChild are derived from HTMLImport superclass 63// that models the tree data structure using WTF::TreeNode and provides a set of 64// virtual functions. 65// 66// HTMLImportsController also owns all loaders in the tree and manages their lifetime through it. 67// One assumption is that the tree is append-only and nodes are never inserted in the middle of the tree nor removed. 68// 69// Full diagram is here: 70// https://docs.google.com/drawings/d/1jFQrO0IupWrlykTNzQ3Nv2SdiBiSz4UE9-V3-vDgBb0/ 71// 72// # Import Sharing and HTMLImportLoader 73// 74// The HTML Imports spec calls for de-dup mechanism to share already loaded imports. 75// To implement this, the actual loading machinery is split out from HTMLImportChild to 76// HTMLImportLoader, and each loader shares HTMLImportLoader with other loader if the URL is same. 77// Check around HTMLImportsController::findLink() for more detail. 78// 79// HTMLImportLoader can be shared by multiple imports. 80// 81// HTMLImportChild (1)-->(*) HTMLImportLoader 82// 83// 84// # Script Blocking 85// 86// - An import blocks the HTML parser of its own imported document from running <script> 87// until all of its children are loaded. 88// Note that dynamically added import won't block the parser. 89// 90// - An import under loading also blocks imported documents that follow from being created. 91// This is because an import can include another import that has same URLs of following ones. 92// In such case, the preceding import should be loaded and following ones should be de-duped. 93// 94 95// The superclass of HTMLImportTreeRoot and HTMLImportChild 96// This represents the import tree data structure. 97class HTMLImport : public NoBaseWillBeGarbageCollectedFinalized<HTMLImport>, public TreeNode<HTMLImport> { 98public: 99 enum SyncMode { 100 Sync = 0, 101 Async = 1 102 }; 103 104 virtual ~HTMLImport() { } 105 106 // FIXME: Consider returning HTMLImportTreeRoot. 107 HTMLImport* root(); 108 bool precedes(HTMLImport*); 109 bool isRoot() const { return !parent(); } 110 bool isSync() const { return SyncMode(m_sync) == Sync; } 111 bool formsCycle() const; 112 const HTMLImportState& state() const { return m_state; } 113 114 void appendImport(HTMLImport*); 115 116 virtual Document* document() const = 0; 117 virtual bool isDone() const = 0; // FIXME: Should be renamed to haveFinishedLoading() 118 virtual HTMLImportLoader* loader() const { return 0; } 119 virtual void stateWillChange() { } 120 virtual void stateDidChange(); 121 122 virtual void trace(Visitor*) { } 123 124protected: 125 // Stating from most conservative state. 126 // It will be corrected through state update flow. 127 explicit HTMLImport(SyncMode sync) 128 : m_sync(sync) 129 { } 130 131 static void recalcTreeState(HTMLImport* root); 132 133#if !defined(NDEBUG) 134 void show(); 135 void showTree(HTMLImport* highlight, unsigned depth); 136 virtual void showThis(); 137#endif 138 139private: 140 HTMLImportState m_state; 141 unsigned m_sync : 1; 142}; 143 144} // namespace blink 145 146#endif // HTMLImport_h 147