Follow a consistent user model

pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart

 // Copyright (c) 2017, 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 services.src.completion.statement;
 
 import 'dart:async';
+import 'dart:math';
 
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/source_buffer.dart';
 import 'package:analysis_server/src/services/correction/source_range.dart';
 import 'package:analysis_server/src/services/correction/util.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/error.dart' as engine;
 import 'package:analyzer/src/dart/ast/utilities.dart';
 import 'package:analyzer/src/dart/error/hint_codes.dart';
 import 'package:analyzer/src/dart/error/syntactic_errors.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 /**
  * An enumeration of possible statement completion kinds.
  */
 class DartStatementCompletion {
   static const NO_COMPLETION =
       const StatementCompletionKind('No_COMPLETION', 'No completion available');
@@ skipping 162 matching lines @@
     }
     for (engine.AnalysisError error in statementContext.errors) {
       if (error.offset >= node.offset &&
           error.offset <= node.offset + node.length) {
         if (error.errorCode is! HintCode) {
           errors.add(error);
         }
       }
     }
 
+    _checkExpressions();
     if (node is Statement) {
       if (errors.isEmpty) {
         if (_complete_ifStatement() ||
             _complete_forStatement() ||
             _complete_forEachStatement() ||
             _complete_whileStatement() ||
             _complete_controlFlowBlock()) {
           return completion;
         }
       } else {
@@ skipping 64 matching lines @@
   }
 
   String _baseNodeText(AstNode astNode) {
     String text = utils.getNodeText(astNode);
     if (text.endsWith(eol)) {
       text = text.substring(0, text.length - eol.length);
     }
     return text;
   }
 
+  void _checkExpressions() {
+    // Note: This may queue edits that have to be accounted for later.
+    // See _lengthOfInsertions().
+    AstNode errorMatching(errorCode, {partialMatch = null}) {
+      var error = _findError(errorCode, partialMatch: partialMatch);
+      if (error == null) {
+        return null;
+      }
+      AstNode expr = _selectedNode();
+      return (expr.getAncestor((n) => n is StringInterpolation) == null)
+          ? expr
+          : null;
+    }
+
+    var expr = errorMatching(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+    if (expr != null) {
+      String source = utils.getNodeText(expr);
+      String content = source;
+      int char = content.codeUnitAt(0);
+      if (char == 'r'.codeUnitAt(0)) {
+        content = source.substring(1);
+        char = content.codeUnitAt(0);
+      }
+      String delimiter;
+      int loc;
+      if (content.length >= 3 &&
+          char == content.codeUnitAt(1) &&
+          char == content.codeUnitAt(2)) {
+        // multi-line string
+        delimiter = content.substring(0, 3);
+        int newlineLoc = source.indexOf(eol, selectionOffset - expr.offset);
+        if (newlineLoc < 0) {
+          newlineLoc = source.length;
+        }
+        loc = newlineLoc + expr.offset;
+      } else {
+        // add first char of src
+        delimiter = content.substring(0, 1);
+        loc = expr.offset + source.length;
+      }
+      _removeError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+      _addInsertEdit(loc, delimiter);
+    }
+    expr = errorMatching(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "']'");
+    if (expr != null) {
+      expr = expr.getAncestor((n) => n is ListLiteral);
+      if (expr != null) {
+        ListLiteral lit = expr;
+        if (lit.rightBracket.isSynthetic) {
+          String src = utils.getNodeText(expr).trim();
+          int loc = expr.offset + src.length;
+          if (src.contains(eol)) {
+            String indent = utils.getNodePrefix(node);
+            _addInsertEdit(loc, ',' + eol + indent + ']');
+          } else {
+            _addInsertEdit(loc, ']');
+          }
+          _removeError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "']'");
+          var ms =
+              _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
+          if (ms != null) {
+            // Ensure the semicolon gets inserted in the correct location.
+            ms.offset = loc - 1;
+          }
+        }
+      }
+    }
+    // The following code is similar to the code for ']' but does not work well.
+    // A closing brace is recognized as belong to the map even if it is intended
+    // to close a block of code.
+    /*
+    expr = errorMatching(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "'}'");
+    if (expr != null) {
+      expr = expr.getAncestor((n) => n is MapLiteral);
+      if (expr != null) {
+        MapLiteral lit = expr;
+        String src = utils.getNodeText(expr).trim();
+        int loc = expr.offset + src.length;
+        if (lit.entries.last.separator.isSynthetic) {
+          _addInsertEdit(loc, ': ');
+        }
+        if (!src.endsWith('}')/*lit.rightBracket.isSynthetic*/) {
+          _addInsertEdit(loc, '}');
+        }
+        _removeError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "'}'");
+        var ms =
+          _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
+        if (ms != null) {
+          // Ensure the semicolon gets inserted in the correct location.
+          ms.offset = loc - 1;
+        }
+      }
+    }
+    */
+  }
+
   bool _complete_classDeclaration() {
     if (node is! ClassDeclaration) {
       return false;
     }
     ClassDeclaration decl = node;
     if (decl.leftBracket.isSynthetic && errors.length == 1) {
       // The space before the left brace is assumed to exist, even if it does not.
       SourceBuilder sb = new SourceBuilder(file, decl.end - 1);
       sb.append(' ');
       _appendEmptyBraces(sb, true);
@@ skipping 17 matching lines @@
       return false;
     }
     AstNode outer = node.parent.parent;
     if (!(outer is DoStatement ||
         outer is ForStatement ||
         outer is ForEachStatement ||
         outer is IfStatement ||
         outer is WhileStatement)) {
       return false;
     }
+    int previousInsertions = _lengthOfInsertions();
     int delta = 0;
     if (errors.isNotEmpty) {
       var error =
           _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
       if (error != null) {
         int insertOffset;
         if (expr == null || expr.isSynthetic) {
           if (node is ReturnStatement) {
             insertOffset = (node as ReturnStatement).returnKeyword.end;
           } else if (node is ExpressionStatement) {
             insertOffset =
                 ((node as ExpressionStatement).expression as ThrowExpression)
                     .throwKeyword
                     .end;
           } else {
             insertOffset = node.end; // Not reached.
           }
         } else {
           insertOffset = expr.end;
         }
         //TODO(messick) Uncomment the following line when error location is fixed.
         //insertOffset = error.offset + error.length;
         _addInsertEdit(insertOffset, ';');
         delta = 1;
       }
     }
     int offset = _appendNewlinePlusIndentAt(node.parent.end);
-    exitPosition = new Position(file, offset + delta);
+    exitPosition = new Position(file, offset + delta + previousInsertions);
     _setCompletion(DartStatementCompletion.COMPLETE_CONTROL_FLOW_BLOCK);
     return true;
   }
 
   bool _complete_doStatement() {
     if (node is! DoStatement) {
       return false;
     }
     DoStatement statement = node;
     SourceBuilder sb = _sourceBuilderAfterKeyword(statement.doKeyword);
@@ skipping 115 matching lines @@
     _setCompletion(DartStatementCompletion.COMPLETE_FOR_EACH_STMT);
     return true;
   }
 
   bool _complete_forStatement() {
     if (node is! ForStatement) {
       return false;
     }
     ForStatement forNode = node;
     SourceBuilder sb;
-    int delta = 0;
+    int replacementLength = 0;
     if (forNode.leftParenthesis.isSynthetic) {
       if (!forNode.rightParenthesis.isSynthetic) {
         return false;
       }
       // keywordOnly (unit test name suffix that exercises this branch)
       sb = _sourceBuilderAfterKeyword(forNode.forKeyword);
       sb.append('(');
       sb.setExitOffset();
       sb.append(')');
     } else {
       if (!forNode.rightSeparator.isSynthetic) {
         // Fully-defined init, cond, updaters so nothing more needed here.
-        // emptyParts
+        // emptyParts, noError
         sb = new SourceBuilder(file, forNode.rightParenthesis.offset + 1);
       } else if (!forNode.leftSeparator.isSynthetic) {
         if (_isSyntheticExpression(forNode.condition)) {
-          exitPosition = _newPosition(forNode.leftSeparator.offset + 1);
           String text = utils
               .getNodeText(forNode)
               .substring(forNode.leftSeparator.offset - forNode.offset);
-          if (text.startsWith(new RegExp(r';\s*\)'))) {
-            // emptyCondition
-            int end = text.indexOf(')');
+          Match match =
+              new RegExp(r';\s*(/\*.*\*/\s*)?\)[ \t]*').matchAsPrefix(text);
+          if (match != null) {
+            // emptyCondition, emptyInitializersEmptyCondition
+            replacementLength = match.end - match.start;
             sb = new SourceBuilder(file, forNode.leftSeparator.offset);
-            _addReplaceEdit(rangeStartLength(sb.offset, end), '; ; ');
-            delta = end - '; '.length;
+            sb.append('; ${match.group(1) == null ? '' : match.group(1)}; )');
+            String suffix = text.substring(match.end);
+            if (suffix.trim().isNotEmpty) {
+              sb.append(' ');
+              sb.append(suffix.trim());
+              replacementLength += suffix.length;
+              if (suffix.endsWith(eol)) {
+                // emptyCondition
+                replacementLength -= eol.length;
+              }
+            }
+            exitPosition = _newPosition(forNode.leftSeparator.offset + 2);
           } else {
-            // emptyInitializersEmptyCondition
-            exitPosition = _newPosition(forNode.rightParenthesis.offset);
-            sb = new SourceBuilder(file, forNode.rightParenthesis.offset);
+            return false; // Line comment in condition
           }
         } else {
           // emptyUpdaters
-          exitPosition = _newPosition(forNode.rightSeparator.offset);
-          sb = new SourceBuilder(file, forNode.rightSeparator.offset);
-          _addReplaceEdit(rangeStartLength(sb.offset, 0), '; ');
-          delta = -'; '.length;
+          sb = new SourceBuilder(file, forNode.rightParenthesis.offset);
+          replacementLength = 1;
+          sb.append('; )');
+          exitPosition = _newPosition(forNode.rightSeparator.offset + 2);
         }
       } else if (_isSyntheticExpression(forNode.initialization)) {
         // emptyInitializers
         exitPosition = _newPosition(forNode.rightParenthesis.offset);
         sb = new SourceBuilder(file, forNode.rightParenthesis.offset);
       } else {
         int start = forNode.condition.offset + forNode.condition.length;
         String text =
             utils.getNodeText(forNode).substring(start - forNode.offset);
         if (text.startsWith(new RegExp(r'\s*\)'))) {
           // missingLeftSeparator
           int end = text.indexOf(')');
           sb = new SourceBuilder(file, start);
-          _addReplaceEdit(rangeStartLength(start, end), '; ');
-          delta = end - '; '.length;
-          exitPosition = new Position(file, start);
+          _addReplaceEdit(rangeStartLength(start, end), '; ; ');
+          exitPosition = new Position(file, start - (end - '; '.length));
         } else {
           // Not possible; any comment following init is attached to init.
           exitPosition = _newPosition(forNode.rightParenthesis.offset);
           sb = new SourceBuilder(file, forNode.rightParenthesis.offset);
         }
       }
     }
     if (!_statementHasValidBody(forNode.forKeyword, forNode.body)) {
       // keywordOnly, noError
       sb.append(' ');
-      _appendEmptyBraces(sb, exitPosition == null);
+      _appendEmptyBraces(sb, true /*exitPosition == null*/);
+    } else if (forNode.body is Block) {
+      Block body = forNode.body;
+      if (body.rightBracket.end <= selectionOffset) {
+        // emptyInitializersAfterBody
+        errors = []; // Ignore errors; they are for previous statement.
+        return false; // If cursor is after closing brace just add newline.
+      }
     }
-    if (delta != 0 && exitPosition != null) {
-      // missingLeftSeparator
-      exitPosition = new Position(file, exitPosition.offset - delta);
-    }
-    _insertBuilder(sb);
+    _insertBuilder(sb, replacementLength);
     _setCompletion(DartStatementCompletion.COMPLETE_FOR_STMT);
     return true;
   }
 
   bool _complete_functionDeclaration() {
     if (node is! MethodDeclaration && node is! FunctionDeclaration) {
       return false;
     }
-    SourceBuilder sb = new SourceBuilder(file, node.end - 1);
+    bool needsParen = false;
+    int computeExitPos(FormalParameterList parameters) {
+      if (needsParen = parameters.rightParenthesis.isSynthetic) {
+        var error = _findError(ParserErrorCode.MISSING_CLOSING_PARENTHESIS);
+        if (error != null) {
+          return error.offset - 1;
+        }
+      }
+      return node.end - 1;
+    }
+
+    int paramListEnd;
+    if (node is FunctionDeclaration) {
+      FunctionDeclaration func = node;
+      paramListEnd = computeExitPos(func.functionExpression.parameters);
+    } else {
+      MethodDeclaration meth = node;
+      paramListEnd = computeExitPos(meth.parameters);
+    }
+    SourceBuilder sb = new SourceBuilder(file, paramListEnd);
+    if (needsParen) {
+      sb.append(')');
+    }
     sb.append(' ');
     _appendEmptyBraces(sb, true);
     _insertBuilder(sb);
     _setCompletion(DartStatementCompletion.COMPLETE_FUNCTION_DECLARATION);
     return true;
   }
 
   bool _complete_functionDeclarationStatement() {
     if (node is! FunctionDeclarationStatement) {
       return false;
@@ skipping 35 matching lines @@
 
   bool _complete_ifOrWhileStatement(
       _KeywordConditionBlockStructure statement, StatementCompletionKind kind) {
     if (_statementHasValidBody(statement.keyword, statement.block)) {
       return false;
     }
     SourceBuilder sb = _complete_keywordCondition(statement);
     if (sb == null) {
       return false;
     }
+    int overshoot = _lengthOfDeletions();
     sb.append(' ');
     _appendEmptyBraces(sb, exitPosition == null);
     _insertBuilder(sb);
+    if (overshoot != 0) {
+      exitPosition = _newPosition(exitPosition.offset - overshoot);
+    }
     _setCompletion(kind);
     return true;
   }
 
   bool _complete_ifStatement() {
     if (node is! IfStatement) {
       return false;
     }
     IfStatement ifNode = node;
     if (ifNode.elseKeyword != null) {
+      if (selectionOffset >= ifNode.elseKeyword.end &&
+          ifNode.elseStatement is EmptyStatement) {
+        SourceBuilder sb = new SourceBuilder(file, selectionOffset);
+        String src = utils.getNodeText(ifNode);
+        if (!src
+            .substring(ifNode.elseKeyword.end - node.offset)
+            .startsWith(new RegExp(r'[ \t]'))) {
+          sb.append(' ');
+        }
+        _appendEmptyBraces(sb, true);
+        _insertBuilder(sb);
+        _setCompletion(DartStatementCompletion.COMPLETE_IF_STMT);
+        return true;
+      }
       return false;
     }
     var stmt = new _KeywordConditionBlockStructure(
         ifNode.ifKeyword,
         ifNode.leftParenthesis,
         ifNode.condition,
         ifNode.rightParenthesis,
         ifNode.thenStatement);
     return _complete_ifOrWhileStatement(
         stmt, DartStatementCompletion.COMPLETE_IF_STMT);
   }
 
   SourceBuilder _complete_keywordCondition(
       _KeywordConditionBlockStructure statement) {
     SourceBuilder sb;
     if (statement.leftParenthesis.isSynthetic) {
       if (!statement.rightParenthesis.isSynthetic) {
         // Quite unlikely to see this so don't try to fix it.
         return null;
       }
       sb = _sourceBuilderAfterKeyword(statement.keyword);
       sb.append('(');
       sb.setExitOffset();
       sb.append(')');
     } else {
       if (_isSyntheticExpression(statement.condition)) {
         exitPosition = _newPosition(statement.leftParenthesis.offset + 1);
         sb = new SourceBuilder(file, statement.rightParenthesis.offset + 1);
       } else {
-        sb = new SourceBuilder(file, statement.rightParenthesis.offset + 1);
+        int afterParen = statement.rightParenthesis.offset + 1;
+        if (utils
+            .getNodeText(node)
+            .substring(afterParen - node.offset)
+            .startsWith(new RegExp(r'[ \t]'))) {
+          _addReplaceEdit(rangeStartLength(afterParen, 1), '');
+          sb = new SourceBuilder(file, afterParen + 1);
+        } else {
+          sb = new SourceBuilder(file, afterParen);
+        }
       }
     }
     return sb;
   }
 
   bool _complete_methodCall() {
     var parenError =
         _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "')'");
     if (parenError == null) {
       return false;
     }
-    AstNode argList = _selectedNode(at: parenError.offset - 1)
+    AstNode argList = _selectedNode(at: selectionOffset)
         .getAncestor((n) => n is ArgumentList);
+    if (argList == null) {
+      argList = _selectedNode(at: parenError.offset)
+          .getAncestor((n) => n is ArgumentList);
+    }
     if (argList?.getAncestor((n) => n == node) == null) {
       return false;
     }
-    int loc = argList.end - 1;
+    int previousInsertions = _lengthOfInsertions();
+    int loc = min(selectionOffset, argList.end - 1);
     int delta = 1;
     var semicolonError =
         _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
     if (semicolonError == null) {
       loc += 1;
       delta = 0;
     }
     _addInsertEdit(loc, ')');
     if (semicolonError != null) {
       _addInsertEdit(loc, ';');
     }
     String indent = utils.getLinePrefix(selectionOffset);
     int exit = utils.getLineNext(selectionOffset);
     _addInsertEdit(exit, indent + eol);
-    exit += indent.length + eol.length;
+    exit += indent.length + eol.length + previousInsertions;
 
     _setCompletionAt(DartStatementCompletion.SIMPLE_ENTER, exit + delta);
     return true;
   }
 
   bool _complete_simpleEnter() {
     int offset;
     if (!errors.isEmpty) {
       offset = selectionOffset;
     } else {
       String indent = utils.getLinePrefix(selectionOffset);
       int loc = utils.getLineNext(selectionOffset);
       _addInsertEdit(loc, indent + eol);
-      offset = loc + indent.length + eol.length;
+      offset = loc + indent.length;
     }
     _setCompletionAt(DartStatementCompletion.SIMPLE_ENTER, offset);
     return true;
   }
 
   bool _complete_simpleSemicolon() {
     if (errors.length != 1) {
       return false;
     }
     var error = _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
     if (error != null) {
+      int previousInsertions = _lengthOfInsertions();
       // TODO(messick) Fix this to find the correct place in all cases.
       int insertOffset = error.offset + error.length;
       _addInsertEdit(insertOffset, ';');
-      int offset = _appendNewlinePlusIndent() + 1 /* ';' */;
+      int offset = _appendNewlinePlusIndent() + 1 /*';'*/ + previousInsertions;
       _setCompletionAt(DartStatementCompletion.SIMPLE_SEMICOLON, offset);
       return true;
     }
     return false;
   }
 
   bool _complete_switchStatement() {
     if (node is! SwitchStatement) {
       return false;
     }
@@ skipping 63 matching lines @@
         // keywordOnly
         sb = new SourceBuilder(file, tryNode.tryKeyword.end);
         sb.append(' ');
       }
       _appendEmptyBraces(sb, true);
       _insertBuilder(sb);
       sb = null;
     } else if ((catchNode = _findInvalidElement(tryNode.catchClauses)) !=
         null) {
       if (catchNode.onKeyword != null) {
-        if (catchNode.exceptionType.length == 0) {
+        if (catchNode.exceptionType.length == 0 ||
+            null !=
+                _findError(StaticWarningCode.NON_TYPE_IN_CATCH_CLAUSE,
+                    partialMatch: "name 'catch")) {
           String src = utils.getNodeText(catchNode);
           if (src.startsWith(new RegExp(r'on[ \t]+'))) {
             if (src.startsWith(new RegExp(r'on[ \t][ \t]+'))) {
               // onSpaces
               exitPosition = new Position(file, catchNode.onKeyword.end + 1);
               sb = new SourceBuilder(file, catchNode.onKeyword.end + 2);
               addSpace = false;
             } else {
               // onSpace
               sb = new SourceBuilder(file, catchNode.onKeyword.end + 1);
@@ skipping 140 matching lines @@
       return true;
     }
     AstNode p = n.parent;
     return p is! Statement && p?.parent is! Statement;
   }
 
   bool _isSyntheticExpression(Expression expr) {
     return expr is SimpleIdentifier && expr.isSynthetic;
   }
 
+  int _lengthOfDeletions() {
+    if (change.edits.isEmpty) {
+      return 0;
+    }
+    int length = 0;
+    for (SourceFileEdit edit in change.edits) {
+      for (SourceEdit srcEdit in edit.edits) {
+        if (srcEdit.length > 0) {
+          length += srcEdit.length - srcEdit.replacement.length;
+        }
+      }
+    }
+    return length;
+  }
+
+  int _lengthOfInsertions() {
+    // Any _complete_*() that may follow changes made by _checkExpressions()
+    // must cache the result of this method and add that value to its
+    // exit position. That's assuming all edits are done in increasing position.
+    // There are currently no editing sequences that produce both insertions and
+    // deletions, but if there were this approach would have to be generalized.
+    if (change.edits.isEmpty) {
+      return 0;
+    }
+    int length = 0;
+    for (SourceFileEdit edit in change.edits) {
+      for (SourceEdit srcEdit in edit.edits) {
+        if (srcEdit.length == 0) {
+          length += srcEdit.replacement.length;
+        }
+      }
+    }
+    return length;
+  }
+
   Position _newPosition(int offset) {
     return new Position(file, offset);
   }
 
+  void _removeError(errorCode, {partialMatch = null}) {
+    var error = _findError(errorCode, partialMatch: partialMatch);
+    if (error != null) {
+      errors.remove(error);
+    }
+  }
+
   AstNode _selectedNode({int at: null}) =>
       new NodeLocator(at == null ? selectionOffset : at).searchWithin(unit);
 
   void _setCompletion(StatementCompletionKind kind, [List args]) {
     assert(exitPosition != null);
     change.selection = exitPosition;
     change.message = formatList(kind.message, args);
     linkedPositionGroups.values
         .forEach((group) => change.addLinkedEditGroup(group));
     completion = new StatementCompletion(kind, change);
   }
 
   void _setCompletionAt(StatementCompletionKind kind, int offset, [List args]) {
     exitPosition = _newPosition(offset);
     _setCompletion(kind, args);
   }
 
   SourceBuilder _sourceBuilderAfterKeyword(Token keyword) {
     SourceBuilder sb;
     String text = _baseNodeText(node);
     text = text.substring(keyword.offset - node.offset);
     int len = keyword.length;
-    if (text.length == len ||
-        !text.substring(len, len + 1).contains(new RegExp(r'\s'))) {
+    if (text.length == len || // onCatchComment
+        !text.substring(len, len + 1).contains(new RegExp(r'[ \t]'))) {
       sb = new SourceBuilder(file, keyword.offset + len);
       sb.append(' ');
     } else {
       sb = new SourceBuilder(file, keyword.offset + len + 1);
     }
     return sb;
   }
 
   bool _statementHasValidBody(Token keyword, Statement body) {
     // A "valid" body is either a non-synthetic block or a single statement
@@ skipping 15 matching lines @@
   final Token keyword;
   final Token leftParenthesis, rightParenthesis;
   final Expression condition;
   final Statement block;
 
   _KeywordConditionBlockStructure(this.keyword, this.leftParenthesis,
       this.condition, this.rightParenthesis, this.block);
 
   int get offset => keyword.offset;
 }