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.

[ahe, 2012/06/08 07:37:36]

Doc comment.

[Roman, 2012/06/08 09:10:15]

Done.

+  static final String _INDENT = "  ";

[ahe, 2012/06/08 07:37:36]

This doesn't need to be private, so please don't make private (FYI, I don't
think our privacy mechanism works well, and is often misused).

[Roman, 2012/06/08 09:10:15]

Ok, removed underscore. Why do you think it should be public?

[ahe, 2012/06/08 09:41:57]

That is the wrong question :-)

The interesting questions are:

Why do you think it should be private?

Can you write a detailed explanation of the pros and cons of using library
privacy to demonstrate that you're fully aware of all the implications of using
library privacy? In other words, do you understand exactly how the Dart privacy
mechanism differs from, for example, default access (aka package privacy) in
Java?

Examples of problems I'm aware of regarding library privacy: you cannot access
private members from test code. Test code will be in a different library. Also,
if not being careful, using private members can cause problems if you use
implicit interfaces to mock up stuff.

Generally, library privacy is hard to use without using some of the benefits we
have built in to Dart. Your intuition from Java or C++ does not apply. You
should use library privacy much less frequently, and rely on interfaces to hide
implementation details.

+
+  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) {
+    depth = 0;
+    sb = new StringBuffer();
+    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");
+  }
+}