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 38 namespace blink { 39 40 class Document; 41 class LocalFrame; 42 class HTMLImportChild; 43 class HTMLImportLoader; 44 class HTMLImportsController; 45 class 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. 97 class HTMLImport : public NoBaseWillBeGarbageCollectedFinalized<HTMLImport>, public TreeNode<HTMLImport> { 98 public: 99 enum SyncMode { 100 Sync = 0, 101 Async = 1 102 }; 103 ~HTMLImport()104 virtual ~HTMLImport() { } 105 106 // FIXME: Consider returning HTMLImportTreeRoot. 107 HTMLImport* root(); 108 bool precedes(HTMLImport*); isRoot()109 bool isRoot() const { return !parent(); } isSync()110 bool isSync() const { return SyncMode(m_sync) == Sync; } 111 bool formsCycle() const; state()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() loader()118 virtual HTMLImportLoader* loader() const { return 0; } stateWillChange()119 virtual void stateWillChange() { } 120 virtual void stateDidChange(); 121 trace(Visitor *)122 virtual void trace(Visitor*) { } 123 124 protected: 125 // Stating from most conservative state. 126 // It will be corrected through state update flow. HTMLImport(SyncMode sync)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 138 139 private: 140 HTMLImportState m_state; 141 unsigned m_sync : 1; 142 }; 143 144 } // namespace blink 145 146 #endif // HTMLImport_h 147