New Prettyprinter class that converts Node-tree to string.

lib/compiler/implementation/tree/prettyprint.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.
+
+/**
+ * Pretty-prints Node tree in XML-like format.
+ *
+ * TODO(smok): Add main() to run from command-line to print out tree for given
+ * .dart file.
+ */
+class PrettyPrinter implements Visitor {
+
+  /** String used to represent one level of indent. */
+  static final String INDENT = "  ";
+
+  StringBuffer sb;
+  int depth;
+  
+  PrettyPrinter() : sb = new StringBuffer(), depth = 0;
+
+  /**
+   * Adds given string to result string.
+   */
+  void add(SourceString string) {
+    string.printOn(sb);
+  }
+
+  /**
+   * Adds given node type to result string, increasing current depth by 1.
+   * The method "opens" the node, meaning that all output after calling
+   * this method and before calling closeNode() will represent contents
+   * of given node.
+   */
+  void openNode(String type, [Map params]) {
+    addCurrentIndent();
+    sb.add("<");
+    addTypeWithParams(type, params);
+    sb.add(">\n");
+    depth++;
+  }
+
+  /**
+   * Adds given node to result string, depth is not affected.
+   */
+  void openAndCloseNode(String type, [Map params]) {
+    addCurrentIndent();
+    sb.add("<");
+    addTypeWithParams(type, params);
+    sb.add("/>\n");
+  }
+
+  /**
+   * Closes given node type, decreasing current depth by 1.
+   */
+  void closeNode(String type, [Map params]) {
+    depth--;
+    addCurrentIndent();
+    sb.add("</");
+    addTypeWithParams(type, params);
+    sb.add(">\n");
+  }
+
+  void addTypeWithParams(String type, [Map params]) {
+    sb.add("${type}");
+    if (params != null) {
+      // TODO(smok): Escape doublequotes in values.
+      params.forEach((k, v) => sb.add(' $k="$v"'));
+    }
+  }
+
+  void addCurrentIndent() {
+    for (int i = 0; i < depth; i++) {
+      sb.add(INDENT);
+    }
+  }
+
+  /**
+   * Pretty-prints given node tree into string.
+   */
+  String prettyPrint(Node node) {

[ahe, 2012/06/08 09:45:31]

I'm not really sure I understand the purpose of this method. It is not
re-entrant, so why would I want to call prettyPrint twice on the same
PrettyPrinter. Why not turn this into a static method:

static String prettyPrint(Node node) {
  var p = new PrettyPrinter();
  node.accept(p);
  return p.sb.toString();
}

[Roman, 2012/06/08 09:56:33]

Yes, this is great. Done.

+    depth = 0;
+    sb.clear();
+    node.accept(this);
+    return sb.toString();
+  }
+
+  visitNodeWithChildren(Node node, String type) {
+    openNode(type);
+    node.visitChildren(this);
+    closeNode(type);
+  }
+
+  visitBlock(Block node) {
+    visitNodeWithChildren(node, "Block");
+  }
+
+  visitBreakStatement(BreakStatement node) {
+    visitNodeWithChildren(node, "BreakStatement");
+  }
+
+  visitCascade(Cascade node) {
+    visitNodeWithChildren(node, "Cascade");
+  }
+
+  visitCascadeReceiver(CascadeReceiver node) {
+    visitNodeWithChildren(node, "CascadeReceiver");
+  }
+
+  visitCaseMatch(CaseMatch node) {
+    visitNodeWithChildren(node, "CaseMatch");
+  }
+
+  visitCatchBlock(CatchBlock node) {
+    visitNodeWithChildren(node, "CatchBlock");
+  }
+
+  visitClassNode(ClassNode node) {
+    visitNodeWithChildren(node, "ClassNode");
+  }
+
+  visitConditional(Conditional node) {
+    visitNodeWithChildren(node, "Conditional");
+  }
+
+  visitContinueStatement(ContinueStatement node) {
+    visitNodeWithChildren(node, "ContinueStatement");
+  }
+
+  visitDoWhile(DoWhile node) {
+    visitNodeWithChildren(node, "DoWhile");
+  }
+
+  visitEmptyStatement(EmptyStatement node) {
+    visitNodeWithChildren(node, "EmptyStatement");
+  }
+
+  visitExpressionStatement(ExpressionStatement node) {
+    visitNodeWithChildren(node, "ExpressionStatement");
+  }
+
+  visitFor(For node) {
+    visitNodeWithChildren(node, "For");
+  }
+
+  visitForIn(ForIn node) {
+    visitNodeWithChildren(node, "ForIn");
+  }
+
+  visitFunctionDeclaration(FunctionDeclaration node) {
+    visitNodeWithChildren(node, "FunctionDeclaration");
+  }
+
+  visitFunctionExpression(FunctionExpression node) {
+    visitNodeWithChildren(node, "FunctionExpression");
+  }
+
+  visitIdentifier(Identifier node) {
+    openAndCloseNode("Identifier", {"token" : node.token.slowToString()});
+  }
+
+  visitIf(If node) {
+    visitNodeWithChildren(node, "If");
+  }
+
+  visitLabel(Label node) {
+    visitNodeWithChildren(node, "Label");
+  }
+
+  visitLabeledStatement(LabeledStatement node) {
+    visitNodeWithChildren(node, "LabeledStatement");
+  }
+
+  // Custom.
+  visitLiteral(Literal node, String type) {
+    openAndCloseNode(type, {"value" : node.value.toString()});
+  }
+
+  visitLiteralBool(LiteralBool node) {
+    visitLiteral(node, "LiteralBool");
+  }
+
+  visitLiteralDouble(LiteralDouble node) {
+    visitLiteral(node, "LiteralDouble");
+  }
+
+  visitLiteralInt(LiteralInt node) {
+    visitLiteral(node, "LiteralInt");
+  }
+
+  visitLiteralList(LiteralList node) {
+    visitNodeWithChildren(node, "LiteralList");
+  }
+
+  visitLiteralMap(LiteralMap node) {
+    visitNodeWithChildren(node, "LiteralMap");
+  }
+
+  visitLiteralMapEntry(LiteralMapEntry node) {
+    visitNodeWithChildren(node, "LiteralMapEntry");
+  }
+
+  visitLiteralNull(LiteralNull node) {
+    visitLiteral(node, "LiteralNull");
+  }
+
+  visitLiteralString(LiteralString node) {
+    openAndCloseNode("LiteralString", {"value" : node.token.slowToString()});
+  }
+
+  visitModifiers(Modifiers node) {
+    visitNodeWithChildren(node, "Modifiers");
+  }
+
+  visitNamedArgument(NamedArgument node) {
+    visitNodeWithChildren(node, "NamedArgument");
+  }
+
+  visitNewExpression(NewExpression node) {
+    visitNodeWithChildren(node, "NewExpression");
+  }
+
+  visitNodeList(NodeList node) {
+    if (node.nodes.toList().length == 0) {
+      openAndCloseNode("NodeList");
+    } else {
+      visitNodeWithChildren(node, "NodeList");
+    }
+  }
+
+  visitOperator(Operator node) {
+    openAndCloseNode("Operator", {"value" : node.token.slowToString()});
+  }
+
+  visitParenthesizedExpression(ParenthesizedExpression node) {
+    visitNodeWithChildren(node, "ParenthesizedExpression");
+  }
+
+  visitReturn(Return node) {
+    visitNodeWithChildren(node, "Return");
+  }
+
+  visitScriptTag(ScriptTag node) {
+    visitNodeWithChildren(node, "ScriptTag");
+  }
+
+  visitSend(Send node) {
+    visitNodeWithChildren(node, "Send");
+  }
+
+  visitSendSet(SendSet node) {
+    visitNodeWithChildren(node, "SendSet");
+  }
+
+  visitStringInterpolation(StringInterpolation node) {
+    visitNodeWithChildren(node, "StringInterpolation");
+  }
+
+  visitStringInterpolationPart(StringInterpolationPart node) {
+    visitNodeWithChildren(node, "StringInterpolationPart");
+  }
+
+  visitStringJuxtaposition(StringJuxtaposition node) {
+    visitNodeWithChildren(node, "StringJuxtaposition");
+  }
+
+  visitSwitchCase(SwitchCase node) {
+    visitNodeWithChildren(node, "SwitchCase");
+  }
+
+  visitSwitchStatement(SwitchStatement node) {
+    visitNodeWithChildren(node, "SwitchStatement");
+  }
+
+  visitThrow(Throw node) {
+    visitNodeWithChildren(node, "Throw");
+  }
+
+  visitTryStatement(TryStatement node) {
+    visitNodeWithChildren(node, "TryStatement");
+  }
+
+  visitTypeAnnotation(TypeAnnotation node) {
+    visitNodeWithChildren(node, "TypeAnnotation");
+  }
+
+  visitTypedef(Typedef node) {
+    visitNodeWithChildren(node, "Typedef");
+  }
+
+  visitTypeVariable(TypeVariable node) {
+    visitNodeWithChildren(node, "TypeVariable");
+  }
+
+  visitVariableDefinitions(VariableDefinitions node) {
+    visitNodeWithChildren(node, "VariableDefinitions");
+  }
+
+  visitWhile(While node) {
+    visitNodeWithChildren(node, "While");
+  }
+}