Recognize "patch" identifier in .dartp files.

lib/compiler/implementation/patch_parser.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#library("patchparser");
+#import("dart:uri");
+
+#import("tree/tree.dart", prefix: "tree");
+#import("leg.dart", prefix: 'leg');  // CompilerTask, Compiler.
+#import("apiimpl.dart");
+#import("scanner/scannerlib.dart");  // Scanner, Parsers, Listeners
+#import("elements/elements.dart");
+#import('native_handler.dart', prefix: 'native');
+
+class PatchParserTask extends leg.CompilerTask {
+  PatchParserTask(leg.Compiler compiler): super(compiler);
+  final String name = "Patching Parser";
+
+  LibraryElement loadPatchLibrary(Uri uri) {
+    bool newLibrary = false;
+    PatchLibraryElement library =
+      compiler.libraries.putIfAbsent(uri.toString(), () {
+          newLibrary = true;
+          leg.Script script = compiler.readScript(uri, null);
+          LibraryElement element =
+              new LibraryElement(script);
+          native.maybeEnableNative(compiler, element, uri);
+          return element;
+        });
+    if (newLibrary) {
+      compiler.withCurrentElement(library, () {
+        scanLibraryElements(library);
+        compiler.onLibraryLoaded(library, uri);
+      });
+    }
+    return library;
+  }
+
+  void scanLibraryElements(LibraryElement library) {
+    measure(() {
+      // TODO(lrn): Possibly recursively handle #source directives in patch.
+      leg.Script script = library.script;
+      Token tokens = new StringScanner(script.text).tokenize();
+      Function idGenerator = compiler.getNextFreeClassId;
+      PatchListener patchListener =
+          new PatchElementListener(compiler, library, idGenerator);
+      new PatchParser(patchListener).parseUnit(tokens);
+    });
+  }
+}
+
+/**
+ * Extension of the [Listener] interface to handle the extra "patch" pseudo-
+ * keyword in patch files.
+ * Patch files shouldn't have a type named "patch".
+ */
+interface PatchListener extends Listener {
+  void beginPatch(Token patch);
+  void endPatch(Token patch);
+}
+
+/**
+ * Partial parser that extends the top-level and class grammars to allow the
+ * word "patch" in front of some declarations.
+ */
+class PatchParser extends PartialParser {
+  PatchParser(PatchListener listener) : super(listener);
+
+  PatchListener get patchListener() => listener;
+
+  bool isPatch(Token token) {
+    return token.stringValue === null &&
+           token.slowToString() == "patch";
+  }
+
+  /**
+   * Parse top-level declarations, and allow "patch" in front of functions
+   * and classes.
+   */
+  Token parseTopLevelDeclaration(Token token) {
+    if (!isPatch(token)) {
+      return super.parseTopLevelDeclaration(token);
+    }
+    Token patch = token;
+    token = token.next;
+    String value = token.stringValue;
+    if (value === 'interface'
+        || value === 'typedef'
+        || value === '#'
+        || value === 'abstract') {
+      // At the top level, you can only patch functions and classes.
+      // Patch classes and functions can't be marked abstract.
+      return listener.unexpected(patch);
+    }
+    patchListener.beginPatch(patch);
+    token = super.parseTopLevelDeclaration(token.next);
+    patchListener.endPatch(patch);
+    return token;
+  }
+
+  /**
+   * Parse a class member.
+   * If the member starts with "patch", it's a member override.
+   * Only methods can be overridden, including constructors, getters and
+   * setters, but not fields. If "patch" occurs in front of a field, the error
+   * is caught elsewhere.
+   */
+  Token parseMember(Token token) {
+    if (!isPatch(token)) {
+      return super.parseMember(token);
+    }
+    Token patch = token;
+    patchListener.beginPatch(patch);
+    token = super.parseMember(token.next);
+    patchListener.endPatch(patch);
+    return token;
+  }
+}
+
+
+/**
+ * Partial parser for patch files that also handles the members of class
+ * declarations.
+ */
+class PatchClassElementParser extends PatchParser {
+  PatchClassElementParser(PatchListener listener) : super(listener);
+
+  Token parseClassBody(Token token) => fullParseClassBody(token);
+}
+
+
+/**
+ * Extension of [ElementListener] for parsing patch files.
+ */
+class PatchElementListener extends ElementListener implements PatchListener {
+  bool isMemberPatch = false;
+  bool isClassPatch = false;
+  PatchElementListener(DiagnosticListener listener,
+                       CompilationUnitElement patchElement,
+                       int idGenerator())
+    : super(listener, patchElement, idGenerator);
+
+  void beginPatch(Token token) {
+    if (token.next.stringValue === "class") {
+      isClassPatch = true;
+    } else {
+      isMemberPatch = true;
+    }
+    handleIdentifier(token);
+  }
+
+  void endPatch(Token token) {
+    if (token.next.stringValue === "class") {
+      isClassPatch = false;
+    } else {
+      isMemberPatch = false;
+    }
+  }
+
+  void pushElement(Element element) {
+    if (isMemberPatch || (isClassPatch && element is ClassElement)) {
+      element.addMetadata(popNode());
+    }
+    super.pushElement(element);
+  }
+}