Resolve non-imported symbols in comments [#1153] (#1298)

* Resolve non-imported symbols in comments [#1153]

@Hixie noticed, that sometimes, a library, like the Flutter rendering
library, wants to refer to another library, like the Flutter widgets
library, in the documentation, but doesn't want to introduce a
dependency in the code. Currently, there’s no mechanisms in dartdoc,
which allows that.

This commit adds that. You can use either a short name (e.g. [icon]) or
a fully qualified name (like, [material.Icon.icon]), in the HTML docs,
it always will be shown as a short name though (is that a desired
behavior?).  Dartdoc will go over all the libraries, classes, methods,
properties, constants of the package that is being documented, and will
try to resolve the symbol. If it’s successful, it will add the link to
it, same way as when the symbol is in scope.

Some outstanding questions:

* What to do in case of ambiguity here? Show a warning, crash with an
  error message, ignore?
* Do we want to show short name in case a fully qualified name is
  provided? I saw in the comments in the ticket
  (#1153 (comment))
  that @Hixie would want that.
* Anything else?

Testing: Unit tests, of course, also tried to generate Flutter docs with
that, and observed that the links for previously non-resolved symbols
work.

* Address @devoncarew feedback

* Add types to declarations
* Add filename/line number to the warnings
* Move the code for gathering all the model elements of a package to the
  package's accessor and cache it.

* Address another round of feedback

From now on, if the reference was, for example, `[key]`, we won't match
`material.Widget.key`, we will only match `material.key` (i.e. top-level
`key` symbol). If you still want to match `Widget.key`, you should use
either `[Widget.key]` or `[material.Widget.key]`.

lib/src/markdown_processor.dart

@@ -9,13 +9,7 @@ import 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart'
-    show
-        LibraryElement,
-        Element,
-        ConstructorElement,
-        ClassElement,
-        ParameterElement,
-        PropertyAccessorElement;
+    show LibraryElement, Element, ConstructorElement, ClassElement, ParameterElement, PropertyAccessorElement;
 import 'package:html/parser.dart' show parse;
 import 'package:markdown/markdown.dart' as md;
 
@@ -28,32 +22,31 @@ const List<String> _oneLinerSkipTags = const ["code", "pre"];
 
 final List<md.InlineSyntax> _markdown_syntaxes = [new _InlineCodeSyntax()];
 
+class MatchingLinkResult {
+  final ModelElement element;
+  final String label;
+  MatchingLinkResult(this.element, this.label);
+}
+
 // TODO: this is in the wrong place
 NodeList<CommentReference> _getCommentRefs(ModelElement modelElement) {
   if (modelElement == null) return null;
   if (modelElement.documentation == null && modelElement.canOverride()) {
     var melement = modelElement.overriddenElement;
-    if (melement != null &&
-        melement.element.computeNode() != null &&
-        melement.element.computeNode() is AnnotatedNode) {
-      var docComment = (melement.element.computeNode() as AnnotatedNode)
-          .documentationComment;
+    if (melement != null && melement.element.computeNode() != null && melement.element.computeNode() is AnnotatedNode) {
+      var docComment = (melement.element.computeNode() as AnnotatedNode).documentationComment;
       if (docComment != null) return docComment.references;
       return null;
     }
   }
   if (modelElement.element.computeNode() is AnnotatedNode) {
-    if ((modelElement.element.computeNode() as AnnotatedNode)
-            .documentationComment !=
-        null) {
-      return (modelElement.element.computeNode() as AnnotatedNode)
-          .documentationComment
-          .references;
+    final AnnotatedNode annotatedNode = modelElement.element.computeNode();
+    if (annotatedNode.documentationComment != null) {
+      return annotatedNode.documentationComment.references;
     }
   } else if (modelElement.element is LibraryElement) {
     // handle anonymous libraries
-    if (modelElement.element.computeNode() == null ||
-        modelElement.element.computeNode().parent == null) {
+    if (modelElement.element.computeNode() == null || modelElement.element.computeNode().parent == null) {
       return null;
     }
     var node = modelElement.element.computeNode().parent.parent;
@@ -67,84 +60,113 @@ NodeList<CommentReference> _getCommentRefs(ModelElement modelElement) {
 }
 
 /// Returns null if element is a parameter.
-ModelElement _getMatchingLinkElement(
-    String codeRef, ModelElement element, List<CommentReference> commentRefs,
+MatchingLinkResult _getMatchingLinkElement(String codeRef, ModelElement element, List<CommentReference> commentRefs,
     {bool isConstructor: false}) {
-  if (commentRefs == null) return null;
+  if (commentRefs == null) return new MatchingLinkResult(null, null);
 
   Element refElement;
   bool isEnum = false;
 
   for (CommentReference ref in commentRefs) {
     if (ref.identifier.name == codeRef) {
       bool isConstrElement = ref.identifier.staticElement is ConstructorElement;
-      if (isConstructor && isConstrElement ||
-          !isConstructor && !isConstrElement) {
+      if (isConstructor && isConstrElement || !isConstructor && !isConstrElement) {
         refElement = ref.identifier.staticElement;
         break;
       }
     }
   }
 
   // Did not find an element in scope
-  if (refElement == null) return null;
+  if (refElement == null) {
+    return _findRefElementInLibrary(codeRef, element, commentRefs);
+  }
 
   if (refElement is PropertyAccessorElement) {
     // yay we found an accessor that wraps a const, but we really
     // want the top-level field itself
     refElement = (refElement as PropertyAccessorElement).variable;
-    if (refElement.enclosingElement is ClassElement &&
-        (refElement.enclosingElement as ClassElement).isEnum) {
+    if (refElement.enclosingElement is ClassElement && (refElement.enclosingElement as ClassElement).isEnum) {
       isEnum = true;
     }
   }
 
-  if (refElement is ParameterElement) return null;
+  if (refElement is ParameterElement) return new MatchingLinkResult(null, null);
 
   // bug! this can fail to find the right library name if the element's name
   // we're looking for is the same as a name that comes in from an imported
   // library.
   //
   // Don't search through all libraries in the package, actually search
   // in the current scope.
-  Library refLibrary =
-      element.package.findLibraryFor(refElement, scopedTo: element);
+  Library refLibrary = element.package.findLibraryFor(refElement, scopedTo: element);
 
   if (refLibrary != null) {
     // Is there a way to pull this from a registry of known elements?
     // Seems like we're creating too many objects this way.
     if (isEnum) {
-      return new EnumField(refElement, refLibrary);
+      return new MatchingLinkResult(new EnumField(refElement, refLibrary), null);
     }
-    return new ModelElement.from(refElement, refLibrary);
+    return new MatchingLinkResult(new ModelElement.from(refElement, refLibrary), null);
+  }
+  return new MatchingLinkResult(null, null);
+}
+
+MatchingLinkResult _findRefElementInLibrary(String codeRef, ModelElement element, List<CommentReference> commentRefs) {
+  final Library library = element.library;
+  final Package package = library.package;
+  final Map<String, ModelElement> result = {};
+
+  for (final modelElement in package.allModelElements) {
+    if (codeRef == modelElement.fullyQualifiedName) {
+      result[modelElement.fullyQualifiedName] = modelElement;
+    }
+  }
+
+  for (final modelElement in library.allModelElements) {
+    if (codeRef == modelElement.fullyQualifiedNameWithoutLibrary) {
+      result[modelElement.fullyQualifiedName] = modelElement;
+    }
+  }
+
+  if (result.isEmpty) {
+    return new MatchingLinkResult(null, null);
+  } else if (result.length == 1) {
+    return new MatchingLinkResult(result.values.first, result.values.first.name);
+  } else {
+    // TODO: add --fatal-warning, which would make the app crash in case of ambiguous references
+    print(
+        "Ambiguous reference to [${codeRef}] in '${element.fullyQualifiedName}' (${element.sourceFileName}:${element.lineNumber}). " +
+            "We found matches to the following elements: ${result.keys.map((k) => "'${k}'").join(", ")}");
+    return new MatchingLinkResult(null, null);
   }
-  return null;
 }
 
-String _linkDocReference(String reference, ModelElement element,
-    NodeList<CommentReference> commentRefs) {
-  ModelElement linkedElement;
+String _linkDocReference(String reference, ModelElement element, NodeList<CommentReference> commentRefs) {
   // support for [new Constructor] and [new Class.namedCtr]
   var refs = reference.split(' ');
+  MatchingLinkResult result;
   if (refs.length == 2 && refs.first == 'new') {
-    linkedElement = _getMatchingLinkElement(refs[1], element, commentRefs,
-        isConstructor: true);
+    result = _getMatchingLinkElement(refs[1], element, commentRefs, isConstructor: true);
   } else {
-    linkedElement = _getMatchingLinkElement(reference, element, commentRefs);
+    result = _getMatchingLinkElement(reference, element, commentRefs);
   }
+  final ModelElement linkedElement = result.element;
+  final String label = result.label ?? reference;
   if (linkedElement != null) {
     var classContent = '';
     if (linkedElement.isDeprecated) {
       classContent = 'class="deprecated" ';
     }
     // this would be linkedElement.linkedName, but link bodies are slightly
     // different for doc references. sigh.
-    return '<a ${classContent}href="${linkedElement.href}">$reference</a>';
+    return '<a ${classContent}href="${linkedElement.href}">$label</a>';
   } else {
     if (_emitWarning) {
+      // TODO: add --fatal-warning, which would make the app crash in case of ambiguous references
       print("  warning: unresolved doc reference '$reference' (in $element)");
     }
-    return '<code>${HTML_ESCAPE.convert(reference)}</code>';
+    return '<code>${HTML_ESCAPE.convert(label)}</code>';
   }
 }
 
@@ -154,8 +176,7 @@ String _renderMarkdownToHtml(String text, [ModelElement element]) {
     return new md.Text(_linkDocReference(name, element, commentRefs));
   }
 
-  return md.markdownToHtml(text,
-      inlineSyntaxes: _markdown_syntaxes, linkResolver: _linkResolver);
+  return md.markdownToHtml(text, inlineSyntaxes: _markdown_syntaxes, linkResolver: _linkResolver);
 }
 
 class Documentation {
@@ -181,16 +202,13 @@ class Documentation {
       s.remove();
     }
     for (var pre in asHtmlDocument.querySelectorAll('pre')) {
-      if (pre.children.isNotEmpty &&
-          pre.children.length != 1 &&
-          pre.children.first.localName != 'code') {
+      if (pre.children.isNotEmpty && pre.children.length != 1 && pre.children.first.localName != 'code') {
         continue;
       }
 
       if (pre.children.isNotEmpty && pre.children.first.localName == 'code') {
         var code = pre.children.first;
-        pre.classes
-            .addAll(code.classes.where((name) => name.startsWith('language-')));
+        pre.classes.addAll(code.classes.where((name) => name.startsWith('language-')));
       }
 
       bool specifiesLanguage = pre.classes.isNotEmpty;
@@ -201,9 +219,7 @@ class Documentation {
 
     // `trim` fixes issue with line ending differences between mac and windows.
     var asHtml = asHtmlDocument.body.innerHtml?.trim();
-    var asOneLiner = asHtmlDocument.body.children.isEmpty
-        ? ''
-        : asHtmlDocument.body.children.first.innerHtml;
+    var asOneLiner = asHtmlDocument.body.children.isEmpty ? '' : asHtmlDocument.body.children.first.innerHtml;
     if (!asOneLiner.startsWith('<p>')) {
       asOneLiner = '<p>$asOneLiner</p>';
     }

lib/src/model.dart

@@ -1231,6 +1231,30 @@ class Library extends ModelElement {
       return _getPackageName(dir.parent);
     }
   }
+
+  List<ModelElement> _allModelElements;
+  List<ModelElement> get allModelElements {
+    if (_allModelElements == null) {
+      final List<ModelElement> result = [];
+      result
+        ..addAll(library.allClasses)
+        ..addAll(library.constants)
+        ..addAll(library.enums)
+        ..addAll(library.functions)
+        ..addAll(library.properties)
+        ..addAll(library.typedefs);
+
+      library.allClasses.forEach((c) {
+        result.addAll(c.allInstanceMethods);
+        result.addAll(c.allInstanceProperties);
+        result.addAll(c.allOperators);
+        result.addAll(c.staticMethods);
+        result.addAll(c.staticProperties);
+      });
+      _allModelElements = result;
+    }
+    return _allModelElements;
+  }
 }
 
 class Method extends ModelElement
@@ -1328,6 +1352,7 @@ abstract class ModelElement implements Comparable, Nameable, Documentable {
   String _linkedName;
 
   String _fullyQualifiedName;
+  String _fullyQualifiedNameWithoutLibrary;
 
   // WARNING: putting anything into the body of this seems
   // to lead to stack overflows. Need to make a registry of ModelElements
@@ -1441,6 +1466,28 @@ abstract class ModelElement implements Comparable, Nameable, Documentable {
     return (_fullyQualifiedName ??= _buildFullyQualifiedName());
   }
 
+  String get fullyQualifiedNameWithoutLibrary {
+    return (_fullyQualifiedNameWithoutLibrary ??= fullyQualifiedName.split(".").skip(1).join("."));
+  }
+
+  String get sourceFileName => element.source.fullName;
+
+  int _lineNumber;
+  bool _isLineNumberComputed = false;
+  int get lineNumber {
+    if (!_isLineNumberComputed) {
+      var node = element.computeNode();
+      if (node is Declaration && node.element != null) {
+        var element = node.element;
+        var lineNumber = lineNumberCache.lineNumber(
+            element.source.fullName, element.nameOffset);
+        _lineNumber = lineNumber + 1;
+      }
+      _isLineNumberComputed = true;
+    }
+    return _lineNumber;
+  }
+
   bool get hasAnnotations => annotations.isNotEmpty;
 
   @override
@@ -2077,6 +2124,17 @@ class Package implements Nameable, Documentable {
     }
     return new Library(e.library, this);
   }
+
+  List<ModelElement> _allModelElements;
+  List<ModelElement> get allModelElements {
+    if (_allModelElements == null) {
+      _allModelElements = [];
+      this.libraries.forEach((library) {
+        _allModelElements.addAll(library.allModelElements);
+      });
+    }
+    return _allModelElements;
+  }
 }
 
 class PackageCategory implements Comparable<PackageCategory> {
@@ -2158,6 +2216,8 @@ abstract class SourceCodeMixin {
     }
   }
 
+  int get lineNumber;
+
   Element get element;
 
   bool get hasSourceCode => config.includeSource && sourceCode.isNotEmpty;
@@ -2240,21 +2300,9 @@ abstract class SourceCodeMixin {
   }
 
   String get _crossdartUrl {
-    if (_lineNumber != null && _crossdartPath != null) {
+    if (lineNumber != null && _crossdartPath != null) {
       String url = "//www.crossdart.info/p/${_crossdartPath}.html";
-      return "${url}#line-${_lineNumber}";
-    } else {
-      return null;
-    }
-  }
-
-  int get _lineNumber {
-    var node = element.computeNode();
-    if (node is Declaration && node.element != null) {
-      var element = node.element;
-      var lineNumber = lineNumberCache.lineNumber(
-          element.source.fullName, element.nameOffset);
-      return lineNumber + 1;
+      return "${url}#line-${lineNumber}";
     } else {
       return null;
     }

test/model_test.dart

@@ -279,6 +279,14 @@ void main() {
         expect(docsAsHtml, contains('<code>doesStuff</code>'));
       });
 
+      test(
+          'link to unresolved name in the library in this package still should be linked',
+          () {
+        final Class helperClass = exLibrary.classes.firstWhere((c) => c.name == 'Helper');
+        expect(helperClass.documentationAsHtml, contains('<a href="ex/Apple-class.html">Apple</a>'));
+        expect(helperClass.documentationAsHtml, contains('<a href="ex/B-class.html">B</a>'));
+      });
+
       test(
           'link to a name of a class from an imported library that exports the name',
           () {

testing/test_package/lib/src/mylib.dart

@@ -2,6 +2,9 @@ library src.mylib;
 
 void helperFunction(String message) => print(message);
 
+/// Even unresolved references in the same library should be resolved
+/// [Apple]
+/// [ex.B]
 class Helper {
   Helper();
 

testing/test_package_docs/ex/Helper-class.html

@@ -136,6 +136,11 @@ <h5><a href="ex/ex-library.html">ex</a></h5>
 
   <div class="col-xs-12 col-sm-9 col-md-8 main-content">
 
+    <section class="desc markdown">
+      <p>Even unresolved references in the same library should be resolved
+<a href="ex/Apple-class.html">Apple</a>
+<a href="ex/B-class.html">B</a></p>
+    </section>