Issue 4238. Infer Element subclass from query() parameter

compiler/java/com/google/dart/compiler/type/ExternalTypeAnalyzers.java

+// 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.
+
+package com.google.dart.compiler.type;
+
+import com.google.common.collect.Maps;
+import com.google.dart.compiler.ast.DartExpression;
+import com.google.dart.compiler.ast.DartMethodInvocation;
+import com.google.dart.compiler.ast.DartStringLiteral;
+import com.google.dart.compiler.ast.DartUnqualifiedInvocation;
+import com.google.dart.compiler.resolver.Element;
+import com.google.dart.compiler.resolver.ElementKind;
+import com.google.dart.compiler.resolver.Elements;
+import com.google.dart.compiler.resolver.EnclosingElement;
+import com.google.dart.compiler.resolver.LibraryElement;
+import com.google.dart.compiler.util.apache.StringUtils;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Provides type information which can not be inferred from source itself.

[Brian Wilkerson, 2012/08/01 17:45:46]

nit: "can not" --> "cannot", here and below

+ */
+public class ExternalTypeAnalyzers {
+  private static final Map<String, String> tagToElementType = Maps.newHashMap();
+  static {
+    tagToElementType.put("A", "AnchorElement");
+    tagToElementType.put("AREA", "AreaElement");
+    tagToElementType.put("BR", "BRElement");
+    tagToElementType.put("BASE", "BaseElement");
+    tagToElementType.put("BODY", "BodyElement");
+    tagToElementType.put("BUTTON", "ButtonElement");
+    tagToElementType.put("CANVAS", "CanvasElement");
+    tagToElementType.put("DL", "DListElement");
+    tagToElementType.put("DETAILS", "DetailsElement");
+    tagToElementType.put("DIV", "DivElement");
+    tagToElementType.put("EMBED", "EmbedElement");
+    tagToElementType.put("FIELDSET", "FieldSetElement");
+    tagToElementType.put("FORM", "FormElement");
+    tagToElementType.put("HR", "HRElement");
+    tagToElementType.put("HEAD", "HeadElement");
+    tagToElementType.put("H1", "HeadingElement");
+    tagToElementType.put("H2", "HeadingElement");
+    tagToElementType.put("H3", "HeadingElement");
+    tagToElementType.put("H4", "HeadingElement");
+    tagToElementType.put("H5", "HeadingElement");
+    tagToElementType.put("H6", "HeadingElement");
+    tagToElementType.put("HTML", "HtmlElement");
+    tagToElementType.put("IFRAME", "IFrameElement");
+    tagToElementType.put("IMG", "ImageElement");
+    tagToElementType.put("INPUT", "InputElement");
+    tagToElementType.put("KEYGEN", "KeygenElement");
+    tagToElementType.put("LI", "LIElement");
+    tagToElementType.put("LABEL", "LabelElement");
+    tagToElementType.put("LEGEND", "LegendElement");
+    tagToElementType.put("LINK", "LinkElement");
+    tagToElementType.put("MAP", "MapElement");
+    tagToElementType.put("MENU", "MenuElement");
+    tagToElementType.put("METER", "MeterElement");
+    tagToElementType.put("OL", "OListElement");
+    tagToElementType.put("OBJECT", "ObjectElement");
+    tagToElementType.put("OPTGROUP", "OptGroupElement");
+    tagToElementType.put("OUTPUT", "OutputElement");
+    tagToElementType.put("P", "ParagraphElement");
+    tagToElementType.put("PARAM", "ParamElement");
+    tagToElementType.put("PRE", "PreElement");
+    tagToElementType.put("PROGRESS", "ProgressElement");
+    tagToElementType.put("SCRIPT", "ScriptElement");
+    tagToElementType.put("SOURCE", "SourceElement");
+    tagToElementType.put("SPAN", "SpanElement");
+    tagToElementType.put("STYLE", "StyleElement");
+    tagToElementType.put("CAPTION", "TableCaptionElement");
+    tagToElementType.put("TD", "TableCellElement");
+    tagToElementType.put("COL", "TableColElement");
+    tagToElementType.put("TABLE", "TableElement");
+    tagToElementType.put("TR", "TableRowElement");
+    tagToElementType.put("TEXTAREA", "TextAreaElement");
+    tagToElementType.put("TITLE", "TitleElement");
+    tagToElementType.put("TRACK", "TrackElement");
+    tagToElementType.put("UL", "UListElement");
+    tagToElementType.put("VIDEO", "VideoElement");
+    tagToElementType.put("DART_EDITOR_NO_SUCH_TYPE", "DartEditorNoSuchElement");
+  }
+
+  /**
+   * Attempts to make better guess about return type of invocation.
+   * 
+   * @return the better {@link Type} guess, may be "defaultType" if can not make better guess.
+   */
+  public static Type resolve(Types types, DartUnqualifiedInvocation invocation, Element element,
+      Type defaultType) {
+    if (element == null) {
+      return defaultType;
+    }
+    String name = element.getName();
+    List<DartExpression> arguments = invocation.getArguments();
+    LibraryElement libraryElement = Elements.getDeclaringLibrary(element);
+    // html.query(String)
+    if ("query".equals(name) && isHtmlLibraryFunction(element)) {
+      return analyzeQuery(arguments, libraryElement, defaultType);
+    }
+    // no guess
+    return defaultType;
+  }
+
+  /**
+   * Attempts to make better guess about return type of invocation.
+   * 
+   * @return the better {@link Type} guess, may be "defaultType" if can not make better guess.
+   */
+  public static Type resolve(Types types, DartMethodInvocation invocation, Element element,
+      Type defaultType) {
+    if (element == null) {
+      return defaultType;
+    }
+    String name = element.getName();
+    List<DartExpression> arguments = invocation.getArguments();
+    LibraryElement libraryElement = Elements.getDeclaringLibrary(element);
+    // NodeSelector.query(String)
+    EnclosingElement enclosingElement = element.getEnclosingElement();
+    if ("query".equals(name) && isDeclaredInHtmlLibrary(element)
+        && ElementKind.of(enclosingElement) == ElementKind.CLASS
+        && "NodeSelector".equals(enclosingElement.getName())) {
+      return analyzeQuery(arguments, libraryElement, defaultType);
+    }
+    // no guess
+    return defaultType;
+  }
+
+  private static Type analyzeQuery(List<DartExpression> arguments, LibraryElement libraryElement,
+      Type defaultType) {
+    if (arguments.size() == 1 && arguments.get(0) instanceof DartStringLiteral) {
+      String selectors = ((DartStringLiteral) arguments.get(0)).getValue();
+      // if has spaces, full parsing required, because may be: E[text='warning text']
+      if (selectors.contains(" ")) {
+        return defaultType;
+      }
+      // try to extract tag
+      // http://www.w3.org/TR/CSS2/selector.html
+      String tag = selectors;
+      tag = StringUtils.substringBefore(tag, ":");
+      tag = StringUtils.substringBefore(tag, "[");
+      tag = StringUtils.substringBefore(tag, ".");
+      tag = StringUtils.substringBefore(tag, "#");
+      tag = tag.toUpperCase();
+      // prepare Element type name
+      String tagTypeName = tagToElementType.get(tag);
+      if (tagTypeName == null) {
+        return defaultType;
+      }
+      // lookup tag Element
+      Element tagTypeElement = libraryElement.lookupLocalElement(tagTypeName);
+      if (tagTypeElement == null) {
+        return defaultType;
+      }
+      // OK, we know more specific return type
+      Type tagType = tagTypeElement.getType();
+      if (tagType != null) {
+        return tagType;
+      }
+    }
+    // no guess
+    return defaultType;
+  }
+
+  private static boolean isHtmlLibraryFunction(Element element) {
+    return ElementKind.of(element) == ElementKind.METHOD && isDeclaredInHtmlLibrary(element);
+  }
+
+  private static boolean isDeclaredInHtmlLibrary(Element element) {
+    LibraryElement libraryElement = Elements.getDeclaringLibrary(element);
+    return StringUtils.startsWith(libraryElement.getName(), "dart://html");
+  }
+}