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34 #include "core/html/imports/HTMLImportState.h"
35 #include "wtf/TreeNode.h"
36 #include "wtf/Vector.h"
42 class HTMLImportChild;
43 class HTMLImportLoader;
44 class HTMLImportsController;
48 // # Basic Data Structure and Algorithms of HTML Imports implemenation.
52 // HTML Imports form a tree:
54 // * The root of the tree is HTMLImportsController, which is owned by the master
55 // document as a DocumentSupplement.
57 // * The non-root nodes are HTMLImportChild, which is owned by LinkStyle, that is owned by HTMLLinkElement.
58 // LinkStyle is wired into HTMLImportChild by implementing HTMLImportChildClient interface
60 // * Both HTMLImportsController and HTMLImportChild are derived from HTMLImport superclass
61 // that models the tree data structure using WTF::TreeNode and provides a set of
64 // HTMLImportsController also owns all loaders in the tree and manages their lifetime through it.
65 // One assumption is that the tree is append-only and nodes are never inserted in the middle of the tree nor removed.
68 // HTMLImport <|- HTMLImportsController <- Document
71 // <|- HTMLImportChild <- LinkStyle <- HTMLLinkElement
74 // # Import Sharing and HTMLImportLoader
76 // The HTML Imports spec calls for de-dup mechanism to share already loaded imports.
77 // To implement this, the actual loading machinery is split out from HTMLImportChild to
78 // HTMLImportLoader, and each loader shares HTMLImportLoader with other loader if the URL is same.
79 // Check around HTMLImportsController::findLink() for more detail.
81 // HTMLImportLoader can be shared by multiple imports.
83 // HTMLImportChild (1)-->(*) HTMLImportLoader
88 // - An import blocks the HTML parser of its own imported document from running <script>
89 // until all of its children are loaded.
90 // Note that dynamically added import won't block the parser.
92 // - An import under loading also blocks imported documents that follow from being created.
93 // This is because an import can include another import that has same URLs of following ones.
94 // In such case, the preceding import should be loaded and following ones should be de-duped.
97 // The superclass of HTMLImportsController and HTMLImportChild
98 // This represents the import tree data structure.
99 class HTMLImport : public TreeNode<HTMLImport> {
106 virtual ~HTMLImport() { }
109 bool precedes(HTMLImport*);
110 bool isRoot() const { return !isChild(); }
111 bool isSync() const { return SyncMode(m_sync) == Sync; }
112 bool formsCycle() const;
113 const HTMLImportState& state() const { return m_state; }
115 void appendImport(HTMLImport*);
117 virtual bool isChild() const { return false; }
118 virtual Document* document() const = 0;
119 virtual bool isDone() const = 0; // FIXME: Should be renamed to haveFinishedLoading()
120 virtual HTMLImportLoader* loader() const { return 0; }
121 virtual void stateWillChange() { }
122 virtual void stateDidChange();
125 // Stating from most conservative state.
126 // It will be corrected through state update flow.
127 explicit HTMLImport(SyncMode sync)
131 static void recalcTreeState(HTMLImport* root);
135 void showTree(HTMLImport* highlight, unsigned depth);
136 virtual void showThis();
140 HTMLImportState m_state;
144 } // namespace WebCore
146 #endif // HTMLImport_h