Formatter check-point (blank-space preservation experiment).

pkg/analyzer_experimental/lib/src/services/formatter_impl.dart

 // Copyright (c) 2013, 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.
 
 library formatter_impl;
 
 
 import 'dart:io';
 
 import 'package:analyzer_experimental/analyzer.dart';
@@ skipping 33 matching lines @@
   final message;
 
   /// Creates a new FormatterException with an optional error [message].
   const FormatterException([this.message = '']);
 
   FormatterException.forError(List<AnalysisError> errors) :
     // TODO(pquitslund): add descriptive message based on errors
     message = 'an analysis error occured during format';
 
   String toString() => 'FormatterException: $message';
-
 }
 
 /// Specifies the kind of code snippet to format.
 class CodeKind {
 
   final index;
 
   const CodeKind(this.index);
 
   /// A compilation unit snippet.
@@ skipping 15 matching lines @@
   String format(CodeKind kind, String source, {int offset, int end,
     int indentationLevel:0});
 
 }
 
 class CodeFormatterImpl implements CodeFormatter, AnalysisErrorListener {
 
   final FormatterOptions options;
   final errors = <AnalysisError>[];
 
+  LineInfo lineInfo;
+
   CodeFormatterImpl(this.options);
 
   String format(CodeKind kind, String source, {int offset, int end,
       int indentationLevel:0}) {
 
     var start = tokenize(source);
     checkForErrors();
 
     var node = parse(kind, start);
     checkForErrors();
 
-    var formatter = new SourceVisitor(options);
+    var formatter = new SourceVisitor(options, lineInfo);
     node.accept(formatter);
 
     return formatter.writer.toString();
   }
 
   ASTNode parse(CodeKind kind, Token start) {
 
     var parser = new Parser(null, this);
 
     switch (kind) {
@@ skipping 11 matching lines @@
       throw new FormatterException.forError(errors);
     }
   }
 
   void onError(AnalysisError error) {
     errors.add(error);
   }
 
   Token tokenize(String source) {
     var scanner = new StringScanner(null, source, this);
-    return scanner.tokenize();
+    var token = scanner.tokenize();
+    lineInfo = new LineInfo(scanner.lineStarts);
+    return token;
   }
 
 }
 
 
 
 /// An AST visitor that drives formatting heuristics.
 class SourceVisitor implements ASTVisitor {
 
   /// The writer to which the source is to be written.
   SourceWriter writer;
 
+  LineInfo lineInfo;
+
   /// Initialize a newly created visitor to write source code representing
   /// the visited nodes to the given [writer].
-  SourceVisitor(FormatterOptions options) :
+  SourceVisitor(FormatterOptions options, this.lineInfo) :
       writer = new SourceWriter(indentCount: options.initialIndentationLevel,
                                 lineSeparator: options.lineSeparator);
 
   visitAdjacentStrings(AdjacentStrings node) {
     visitList(node.strings, ' ');
   }
 
   visitAnnotation(Annotation node) {
     writer.print('@');
     visit(node.name);
@@ skipping 127 matching lines @@
 
   visitCommentReference(CommentReference node) => null;
 
   visitCompilationUnit(CompilationUnit node) {
     var scriptTag = node.scriptTag;
     var directives = node.directives;
     visit(scriptTag);
     var prefix = scriptTag == null ? '' : ' ';
     visitPrefixedList(prefix, directives, ' ');
     prefix = scriptTag == null && directives.isEmpty ? '' : ' ';
-    visitPrefixedList(prefix, node.declarations, ' ');
+    visitPrefixedListWithBlanks(prefix, node.declarations);
+
+    //TODO(pquitslund): move this?
+    writer.newline();
   }
 
   visitConditionalExpression(ConditionalExpression node) {
     visit(node.condition);
     writer.print(' ? ');
     visit(node.thenExpression);
     writer.print(' : ');
     visit(node.elseExpression);
   }
 
@@ skipping 332 matching lines @@
     }
     visit(node.methodName);
     visit(node.argumentList);
   }
 
   visitNamedExpression(NamedExpression node) {
     visit(node.name);
     visitPrefixed(' ', node.expression);
   }
 
+  visitNativeClause(NativeClause node) {
+    writer.print("native ");
+    visit(node.name);
+  }
+
   visitNativeFunctionBody(NativeFunctionBody node) {
     writer.print('native ');
     visit(node.stringLiteral);
     writer.print(';');
   }
 
   visitNullLiteral(NullLiteral node) {
     writer.print('null');
   }
 
@@ skipping 276 matching lines @@
         for (var i = 0; i < size; i++) {
           if (i > 0) {
             writer.print(separator);
           }
           nodes[i].accept(this);
         }
       }
     }
   }
 
+  /// Print a list of [nodes], preserving blanklines between nodes.

[Brian Wilkerson, 2013/07/17 21:25:09]

nit: "blanklines" --> "blank lines"

[pquitslund, 2013/07/17 21:44:13]

Fixed!

+  visitPrefixedListWithBlanks(String prefix,
+      NodeList<ASTNode> nodes) {
+    if (nodes != null) {
+      var size = nodes.length;
+      if (size > 0) {
+        writer.print(prefix);
+        for (var i = 0; i < size; i++) {
+          if (i > 0) {
+            // Emit blanks lines
+            var lastLine =
+                lineInfo.getLocation(nodes[i-1].endToken.offset).lineNumber;
+            var currentLine =
+                lineInfo.getLocation(nodes[i].beginToken.offset).lineNumber;
+            var blanks = currentLine - lastLine;
+            for (var i = 0; i < blanks; i++) {
+              writer.newline();
+            }
+          }
+          nodes[i].accept(this);
+        }
+      }
+    }
+  }
+
 }