Add the constaint that Matchers can only operate on Trees.

Allowing things like Matcher<List<Statement>> made it impossible to provide the
matcher with a VisitorState with the correct path. This also de-duplicates the
MultiMatcher implementations and ensures that they use correct TreePaths.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=80664674

core/src/main/java/com/google/errorprone/bugpatterns/ChainingConstructorIgnoresParameter.java

@@ -23,7 +23,6 @@
 import static com.google.errorprone.fixes.SuggestedFix.replace;
 import static com.google.errorprone.matchers.Description.NO_MATCH;
 import static com.google.errorprone.matchers.Matchers.hasIdentifier;
-import static com.google.errorprone.matchers.MultiMatcher.MatchType.ANY;
 import static com.google.errorprone.util.ASTHelpers.getSymbol;
 import static com.google.errorprone.util.ASTHelpers.getType;
 import static com.sun.source.tree.Tree.Kind.IDENTIFIER;
@@ -212,7 +211,7 @@ public boolean matches(IdentifierTree tree, VisitorState state) {
         return isIdentifierWithName(tree, name);
       }
     };
-    return hasIdentifier(ANY, identifierMatcher).matches(tree, state);
+    return hasIdentifier(identifierMatcher).matches(tree, state);
   }
 
   private static boolean isIdentifierWithName(ExpressionTree tree, String name) {

core/src/main/java/com/google/errorprone/bugpatterns/ClassCanBeStatic.java

@@ -26,7 +26,6 @@
 import static com.google.errorprone.matchers.Matchers.nestingKind;
 import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.parentNode;
-import static com.google.errorprone.matchers.MultiMatcher.MatchType.ANY;
 
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
@@ -80,7 +79,7 @@ public boolean matches(ClassTree classTree, VisitorState state) {
           anyOf(
               parentNode(nestingKind(NestingKind.TOP_LEVEL)),
               parentNode(Matchers.<ClassTree>hasModifier(Modifier.STATIC))),
-          not(hasIdentifier(ANY, referenceEnclosing(classTree, state.getTypes())))
+          not(hasIdentifier(referenceEnclosing(classTree, state.getTypes())))
         ).matches(classTree, state);
       }
     };

core/src/main/java/com/google/errorprone/bugpatterns/DeadException.java

@@ -25,7 +25,6 @@
 import static com.google.errorprone.matchers.Matchers.enclosingMethod;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.kindIs;
-import static com.google.errorprone.matchers.Matchers.lastStatement;
 import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.parentNode;
 import static com.google.errorprone.suppliers.Suppliers.EXCEPTION_TYPE;
@@ -38,8 +37,9 @@
 import com.google.errorprone.bugpatterns.BugChecker.NewClassTreeMatcher;
 import com.google.errorprone.fixes.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.ChildMultiMatcher;
+import com.google.errorprone.matchers.ChildMultiMatcher.MatchType;
 import com.google.errorprone.matchers.Description;
-import com.google.errorprone.matchers.Enclosing;
 import com.google.errorprone.matchers.JUnitMatchers;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.matchers.Matchers;
@@ -50,8 +50,6 @@
 import com.sun.source.tree.StatementTree;
 import com.sun.source.tree.Tree;
 
-import java.util.List;
-
 /**
  * @author alexeagle@google.com (Alex Eagle)
  */
@@ -78,12 +76,9 @@ public Description matchNewClass(NewClassTree newClassTree, VisitorState state)
 
     StatementTree parent = (StatementTree) state.getPath().getParentPath().getLeaf();
 
-    Matcher<List<StatementTree>> isLastStatementOfList =
-        lastStatement(Matchers.<StatementTree>isSame(parent));
     boolean isLastStatement = anyOf(
-        new Enclosing.BlockOrCase<>(
-            inBlockWhereStatement(isLastStatementOfList),
-            inCaseWhereStatement(isLastStatementOfList)),
+        new ChildOfBlockOrCase<>(ChildMultiMatcher.MatchType.LAST,
+            Matchers.<StatementTree>isSame(parent)),
         // it could also be a bare if statement with no braces
         parentNode(parentNode(kindIs(IF))))
         .matches(newClassTree, state);
@@ -97,37 +92,27 @@ public Description matchNewClass(NewClassTree newClassTree, VisitorState state)
 
     return describeMatch(newClassTree, fix);
   }
+
+  private static class ChildOfBlockOrCase<T extends Tree> 
+      extends ChildMultiMatcher<T, StatementTree> {
+    public ChildOfBlockOrCase(MatchType matchType, Matcher<StatementTree> nodeMatcher) {
+      super(matchType, nodeMatcher);
+    }
 
-  /*
-   * state.getTreePath() is set incorrectly by the following classes in their call to
-   * statementsMatcher. The problem is that it's weird to have to choose a proper path for the
-   * multiple statements that statementsMatcher expects. The best approach might be to pick the path
-   * of an arbitrary statement, but of course that has its own problems. Plus, the block might be
-   * empty. Fortunately, in this case, we use only lastStatement, which doesn't use the TreePath.
-   * Thus, it doesn't matter if the TreePath is wrong. But this problem casts suspicion on the use
-   * of any Matcher<NotATree>, since without a unique tree, we can't have a unique TreePath in the
-   * VisitorState passed to its match() method.
-   */
-
-  private static Matcher<BlockTree> inBlockWhereStatement(
-      final Matcher<List<StatementTree>> statementsMatcher) {
-    return new Matcher<BlockTree>() {
-      @Override
-      public boolean matches(BlockTree t, VisitorState state) {
-        // state.getTreePath() will be wrong for statementsMatcher. See doc above.
-        return statementsMatcher.matches(ImmutableList.copyOf(t.getStatements()), state);
+    @Override
+    protected Iterable<? extends StatementTree> getChildNodes(T tree, VisitorState state) {
+      Tree enclosing = state.findEnclosing(CaseTree.class, BlockTree.class);
+      if (enclosing == null) {
+        return ImmutableList.of();
       }
-    };
-  }
-
-  private static Matcher<CaseTree> inCaseWhereStatement(
-      final Matcher<List<StatementTree>> statementsMatcher) {
-    return new Matcher<CaseTree>() {
-      @Override
-      public boolean matches(CaseTree t, VisitorState state) {
-        // state.getTreePath() will be wrong for statementsMatcher. See doc above.
-        return statementsMatcher.matches(ImmutableList.copyOf(t.getStatements()), state);
+      if (enclosing instanceof BlockTree) {
+        return ((BlockTree) enclosing).getStatements();
+      } else if (enclosing instanceof CaseTree) {
+        return ((CaseTree) enclosing).getStatements();
+      } else {
+        // findEnclosing given two types must return something of one of those types
+        throw new IllegalStateException("enclosing tree not a BlockTree or CaseTree");
       }
-    };
+    }
   }
 }

core/src/main/java/com/google/errorprone/bugpatterns/GuiceAssistedInjectScoping.java

@@ -19,12 +19,12 @@
 import static com.google.errorprone.BugPattern.Category.GUICE;
 import static com.google.errorprone.BugPattern.MaturityLevel.MATURE;
 import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.ANY;
 import static com.google.errorprone.matchers.Matchers.allOf;
 import static com.google.errorprone.matchers.Matchers.annotations;
 import static com.google.errorprone.matchers.Matchers.constructor;
 import static com.google.errorprone.matchers.Matchers.hasAnnotation;
 import static com.google.errorprone.matchers.Matchers.methodHasParameters;
-import static com.google.errorprone.matchers.MultiMatcher.MatchType.ANY;
 
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;

core/src/main/java/com/google/errorprone/bugpatterns/GuiceInjectOnFinalField.java

@@ -26,10 +26,10 @@
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
 import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.ChildMultiMatcher.MatchType;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.matchers.MultiMatcher;
-import com.google.errorprone.matchers.MultiMatcher.MatchType;
 import com.google.errorprone.util.ASTHelpers;
 
 import com.sun.source.tree.AnnotationTree;

core/src/main/java/com/google/errorprone/bugpatterns/InjectAssistedInjectAndInjectOnConstructors.java

@@ -19,13 +19,13 @@
 import static com.google.errorprone.BugPattern.Category.INJECT;
 import static com.google.errorprone.BugPattern.MaturityLevel.EXPERIMENTAL;
 import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
-import static com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.ANY;
 import static com.google.errorprone.matchers.Matchers.constructor;
 import static com.google.errorprone.matchers.Matchers.hasAnnotation;
-import static com.google.errorprone.matchers.MultiMatcher.MatchType.ANY;
 
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;

core/src/main/java/com/google/errorprone/matchers/Annotation.java

@@ -16,9 +16,6 @@
 
 package com.google.errorprone.matchers;
 
-import static com.google.errorprone.matchers.MultiMatcher.MatchType.ALL;
-import static com.google.errorprone.matchers.MultiMatcher.MatchType.ANY;
-
 import com.google.errorprone.VisitorState;
 
 import com.sun.source.tree.AnnotationTree;
@@ -28,46 +25,31 @@
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.VariableTree;
 
-import java.util.List;
-
 /**
  * Matches if the given annotation matcher matches all of or any of the annotations on the tree
  * node.
  *
  * @author eaftan@google.com (Eddie Aftandilian)
  */
-public class Annotation<T extends Tree> extends MultiMatcher<T, AnnotationTree> {
+public class Annotation<T extends Tree> extends ChildMultiMatcher<T, AnnotationTree> {
 
   public Annotation(MatchType matchType, Matcher<AnnotationTree> nodeMatcher) {
     super(matchType, nodeMatcher);
   }
 
   @Override
-  public boolean matches(T tree, VisitorState state) {
-    List<? extends AnnotationTree> annotations;
+  protected Iterable<? extends AnnotationTree> getChildNodes(T tree, VisitorState state) {
     if (tree instanceof ClassTree) {
-      annotations = ((ClassTree) tree).getModifiers().getAnnotations();
+      return ((ClassTree) tree).getModifiers().getAnnotations();
     } else if (tree instanceof VariableTree) {
-      annotations = ((VariableTree) tree).getModifiers().getAnnotations();
+      return ((VariableTree) tree).getModifiers().getAnnotations();
     } else if (tree instanceof MethodTree) {
-      annotations = ((MethodTree) tree).getModifiers().getAnnotations();
+      return ((MethodTree) tree).getModifiers().getAnnotations();
     } else if (tree instanceof CompilationUnitTree) {
-      annotations = ((CompilationUnitTree) tree).getPackageAnnotations();
+      return ((CompilationUnitTree) tree).getPackageAnnotations();
     } else {
-      throw new IllegalArgumentException("Cannot access annotations from tree of type "
-          + tree.getClass());
-    }
-
-    for (AnnotationTree annotation : annotations) {
-      boolean matches = nodeMatcher.matches(annotation, state);
-      if (matchType == ANY && matches) {
-        matchingNode = annotation;
-        return true;
-      }
-      if (matchType == ALL && !matches) {
-        return false;
-      }
+      throw new IllegalArgumentException(
+          "Cannot access annotations from tree of type " + tree.getClass());
     }
-    return matchType == ALL && annotations.size() >= 1;
   }
 }