Template parser

utils/template/tree.dart

+// Copyright (c) 2011, 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.
+/**
+ * The base type for all nodes in a dart abstract syntax tree.
+ */
+class ASTNode {
+  /** The source code this [ASTNode] represents. */
+  SourceSpan span;
+
+  ASTNode(this.span) {}
+
+  /** Classic double-dispatch visitor for implementing passes. */
+  abstract visit(TreeVisitor visitor);
+
+  /** A multiline string showing the node and its children. */
+  String toDebugString() {
+    var to = new TreeOutput();
+    var tp = new TreePrinter(to);
+    this.visit(tp);
+    return to.buf.toString();
+  }
+}
+
+// TODO(jimhug): Clean-up and factor out of core.
+/** Simple class to provide a textual dump of trees for debugging. */
+class TreeOutput {
+  int depth;
+  StringBuffer buf;
+
+  var printer;
+
+  static void dump(ASTNode node) {
+    var o = new TreeOutput();
+    node.visit(new TreePrinter(o));
+    print(o.buf);
+  }
+
+  TreeOutput(): this.depth = 0, this.buf = new StringBuffer() {
+  }
+
+  void write(String s) {
+    for (int i=0; i < depth; i++) {
+      buf.add(' ');
+    }
+    buf.add(s);
+  }
+
+  void writeln(String s) {
+    write(s);
+    buf.add('\n');
+  }
+
+  void heading(String name, span) {
+    write(name);
+    buf.add('  (${span.locationText})');
+    buf.add('\n');
+  }
+
+  String toValue(value) {
+    if (value == null) return 'null';
+    else if (value is Identifier) return value.name;
+    else return value.toString();
+  }
+
+  void writeNode(String label, ASTNode node) {
+    write(label + ': ');
+    depth += 1;
+    if (node != null) node.visit(printer);
+    else writeln('null');
+    depth -= 1;
+  }
+
+  void writeValue(String label, value) {
+    var v = toValue(value);
+    writeln('${label}: ${v}');
+  }
+
+  void writeList(String label, List list) {
+    write(label + ': ');
+    if (list == null) {
+      buf.add('null');
+      buf.add('\n');
+    } else {
+      for (var item in list) {
+        buf.add(item.toString());
+        buf.add(', ');
+      }
+      buf.add('\n');
+    }
+  }
+
+  void writeNodeList(String label, List list) {
+    writeln('${label} [');
+    if (list != null) {
+      depth += 1;
+      for (var node in list) {
+        if (node != null) {
+          node.visit(printer);
+        } else {
+          writeln('null');
+        }
+      }
+      depth -= 1;
+      writeln(']');
+    }
+  }
+}