1 files changed, 145 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SyntaxTreeVisitor.java b/src/main/java/com/google/devtools/build/lib/syntax/SyntaxTreeVisitor.java
new file mode 100644
index 0000000000..5a9502637e
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SyntaxTreeVisitor.java
@@ -0,0 +1,145 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.syntax;
+
+import com.google.devtools.build.lib.syntax.DictionaryLiteral.DictionaryEntryLiteral;
+import com.google.devtools.build.lib.syntax.IfStatement.ConditionalStatements;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A visitor for visiting the nodes in the syntax tree left to right, top to
+ * bottom.
+ */
+public class SyntaxTreeVisitor {
+
+  public void visit(ASTNode node) {
+    // dispatch to the node specific method
+    node.accept(this);
+  }
+
+  public void visitAll(List<? extends ASTNode> nodes) {
+    for (ASTNode node : nodes) {
+      visit(node);
+    }
+  }
+
+  // node specific visit methods
+  public void visit(Argument node) {
+    if (node.isNamed()) {
+      visit(node.getName());
+    }
+    if (node.hasValue()) {
+      visit(node.getValue());
+    }
+  }
+
+  public void visit(BuildFileAST node) {
+    visitAll(node.getStatements());
+    visitAll(node.getComments());
+  }
+
+  public void visit(BinaryOperatorExpression node) {
+    visit(node.getLhs());
+    visit(node.getRhs());
+  }
+
+  public void visit(FuncallExpression node) {
+    visit(node.getFunction());
+    visitAll(node.getArguments());
+  }
+
+  public void visit(Ident node) {
+  }
+
+  public void visit(ListComprehension node) {
+    visit(node.getElementExpression());
+    for (Map.Entry<Ident, Expression> list : node.getLists()) {
+      visit(list.getKey());
+      visit(list.getValue());
+    }
+  }
+
+  public void accept(DictComprehension node) {
+    visit(node.getKeyExpression());
+    visit(node.getValueExpression());
+    visit(node.getLoopVar());
+    visit(node.getListExpression());
+  }
+
+  public void visit(ListLiteral node) {
+    visitAll(node.getElements());
+  }
+
+  public void visit(IntegerLiteral node) {
+  }
+
+  public void visit(StringLiteral node) {
+  }
+
+  public void visit(AssignmentStatement node) {
+    visit(node.getLValue());
+    visit(node.getExpression());
+  }
+
+  public void visit(ExpressionStatement node) {
+    visit(node.getExpression());
+  }
+
+  public void visit(IfStatement node) {
+    for (ConditionalStatements stmt : node.getThenBlocks()) {
+      visit(stmt);
+    }
+    for (Statement stmt : node.getElseBlock()) {
+      visit(stmt);
+    }
+  }
+
+  public void visit(ConditionalStatements node) {
+    visit(node.getCondition());
+    for (Statement stmt : node.getStmts()) {
+      visit(stmt);
+    }
+  }
+
+  public void visit(FunctionDefStatement node) {
+    visit(node.getIdent());
+    for (Argument arg : node.getArgs()) {
+      visit(arg);
+    }
+    for (Statement stmt : node.getStatements()) {
+      visit(stmt);
+    }
+  }
+
+  public void visit(DictionaryLiteral node) {
+    for (DictionaryEntryLiteral entry : node.getEntries()) {
+      visit(entry);
+    }
+  }
+
+  public void visit(DictionaryEntryLiteral node) {
+    visit(node.getKey());
+    visit(node.getValue());
+  }
+
+  public void visit(NotExpression node) {
+    visit(node.getExpression());
+  }
+
+  public void visit(Comment node) {
+  }
+
+}