Issue 23018. Fix for inlining multiline strings with leading whitespaces.

pkg/analyzer/lib/src/generated/ast.dart

 // Copyright (c) 2014, 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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.ast;
 
 import 'dart:collection';
@@ skipping 10842 matching lines @@
   @override
   Token get beginToken => contents;
 
   @override
   Iterable get childEntities => new ChildEntities()..add(contents);
 
   /**
    * Return the offset of the after-last contents character.
    */
   int get contentsEnd {
-    int end = contents.end;
     String lexeme = contents.lexeme;
-    if (StringUtilities.endsWith3(lexeme, 0x22, 0x22, 0x22) ||
-        StringUtilities.endsWith3(lexeme, 0x27, 0x27, 0x27)) {
-      end -= 3;
-    } else {
-      end -= 1;
-    }
-    return end;
+    return offset + new StringLexemeHelper(lexeme, true, true).end;
   }
 
   /**
    * Return the offset of the first contents character.
    */
   int get contentsOffset {
     int offset = contents.offset;
     String lexeme = contents.lexeme;
-    if (lexeme.codeUnitAt(0) == 0x72) {
-      offset += 1;
-    }
-    if (StringUtilities.startsWith3(lexeme, offset, 0x22, 0x22, 0x22) ||
-        StringUtilities.startsWith3(lexeme, offset, 0x27, 0x27, 0x27)) {
-      offset += 3;
-    } else {
-      offset += 1;
-    }
-    return offset;
+    return offset + new StringLexemeHelper(lexeme, true, true).start;
   }
 
   @override
   Token get endToken => contents;
 
   /**
    * Return the value of the literal.
    */
   String get value => _value;
 
@@ skipping 5586 matching lines @@
     _value = StringUtilities.intern(value);
   }
 
   @override
   Token get beginToken => literal;
 
   @override
   Iterable get childEntities => new ChildEntities()..add(literal);
 
   @override
-  int get contentsEnd {
-    if (isMultiline) {
-      return end - 3;
-    }
-    return end - 1;
-  }
+  int get contentsEnd => offset + _helper.end;
 
   @override
-  int get contentsOffset {
-    int contentsOffset = 0;
-    if (isRaw) {
-      contentsOffset += 1;
-    }
-    if (isMultiline) {
-      contentsOffset += 3;
-    } else {
-      contentsOffset += 1;
-    }
-    return offset + contentsOffset;
-  }
+  int get contentsOffset => offset + _helper.start;
 
   @override
   Token get endToken => literal;
 
   @override
-  bool get isMultiline {
-    String lexeme = literal.lexeme;
-    if (lexeme.length < 3) {
-      return false;
-    }
-    // skip 'r'
-    int offset = 0;
-    if (isRaw) {
-      offset = 1;
-    }
-    // check prefix
-    return StringUtilities.startsWith3(lexeme, offset, 0x22, 0x22, 0x22) ||
-        StringUtilities.startsWith3(lexeme, offset, 0x27, 0x27, 0x27);
-  }
+  bool get isMultiline => _helper.isMultiline;
 
   @override
-  bool get isRaw => literal.lexeme.codeUnitAt(0) == 0x72;
+  bool get isRaw => _helper.isRaw;
 
   @override
-  bool get isSingleQuoted {
-    String lexeme = literal.lexeme;
-    if (lexeme.isEmpty) {
-      return false;
-    }
-    int codeZero = lexeme.codeUnitAt(0);
-    if (codeZero == 0x72) {
-      return lexeme.length > 1 && lexeme.codeUnitAt(1) == 0x27;
-    }
-    return codeZero == 0x27;
-  }
+  bool get isSingleQuoted => _helper.isSingleQuoted;
 
   @override
   bool get isSynthetic => literal.isSynthetic;
 
   /**
    * Return the value of the literal.
    */
   String get value => _value;
 
   /**
    * Set the value of the literal to the given [string].
    */
   void set value(String string) {
     _value = StringUtilities.intern(_value);
   }
 
+  StringLexemeHelper get _helper {

[Brian Wilkerson, 2015/03/28 00:38:20]

Use '=>'?

+    return new StringLexemeHelper(literal.lexeme, true, true);
+  }
+
   @override
   accept(AstVisitor visitor) => visitor.visitSimpleStringLiteral(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     // There are no children to visit.
   }
 
   @override
   void _appendStringValue(StringBuffer buffer) {
     buffer.write(value);
   }
 }
 
 /**
  * A single string literal expression.
  *
  * > singleStringLiteral ::=
  * >     [SimpleStringLiteral]
  * >   | [StringInterpolation]
  */
 abstract class SingleStringLiteral extends StringLiteral {
   /**
    * Return the offset of the after-last contents character.
    */
   int get contentsEnd;
 
   /**
    * Return the offset of the first contents character.
+   * If the string is multiline, then leading whitespaces are skipped.
    */
   int get contentsOffset;
 
   /**
    * Return `true` if this string literal is a multi-line string.
    */
   bool get isMultiline;
 
   /**
    * Return `true` if this string literal is a raw string.
@@ skipping 74 matching lines @@
 
   /**
    * Return the elements that will be composed to produce the resulting string.
    */
   NodeList<InterpolationElement> get elements => _elements;
 
   @override
   Token get endToken => _elements.endToken;
 
   @override
-  bool get isMultiline {
-    InterpolationString element = _elements.first;
-    String lexeme = element.contents.lexeme;
-    if (lexeme.length < 3) {
-      return false;
-    }
-    return StringUtilities.startsWith3(lexeme, 0, 0x22, 0x22, 0x22) ||
-        StringUtilities.startsWith3(lexeme, 0, 0x27, 0x27, 0x27);
-  }
+  bool get isMultiline => _firstHelper.isMultiline;
 
   @override
   bool get isRaw => false;
 
   @override
-  bool get isSingleQuoted {
+  bool get isSingleQuoted => _firstHelper.isSingleQuoted;
+
+  StringLexemeHelper get _firstHelper {
     InterpolationString lastString = _elements.first;
     String lexeme = lastString.contents.lexeme;
-    return StringUtilities.startsWithChar(lexeme, 0x27);
+    return new StringLexemeHelper(lexeme, true, false);
   }
 
   @override
   accept(AstVisitor visitor) => visitor.visitStringInterpolation(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _elements.accept(visitor);
   }
 
   @override
   void _appendStringValue(StringBuffer buffer) {
     throw new IllegalArgumentException();
   }
 }
 
 /**
+ * A helper for analyzing string lexemes.
+ */
+class StringLexemeHelper {
+  final String lexeme;
+  final bool isFirst;
+  final bool isLast;
+
+  bool isRaw = false;
+  bool isSingleQuoted = false;
+  bool isMultiline = false;
+  int start = 0;
+  int end;
+
+  StringLexemeHelper(this.lexeme, this.isFirst, this.isLast) {
+    isRaw = StringUtilities.startsWithChar(lexeme, 0x72);
+    if (isRaw) {
+      start++;
+    }
+    if (StringUtilities.startsWith3(lexeme, start, 0x27, 0x27, 0x27)) {
+      isSingleQuoted = true;
+      isMultiline = true;
+      start += 3;
+      start = _trimInitialWhitespace(start);
+    } else if (StringUtilities.startsWith3(lexeme, start, 0x22, 0x22, 0x22)) {
+      isSingleQuoted = false;
+      isMultiline = true;
+      start += 3;
+      start = _trimInitialWhitespace(start);
+    } else if (start < lexeme.length && lexeme.codeUnitAt(start) == 0x27) {
+      isSingleQuoted = true;
+      isMultiline = false;
+      start++;
+    } else if (start < lexeme.length && lexeme.codeUnitAt(start) == 0x22) {
+      isSingleQuoted = false;
+      isMultiline = false;
+      start++;
+    }
+    end = lexeme.length;
+    if (isLast) {
+      if (StringUtilities.endsWith3(lexeme, 0x22, 0x22, 0x22) ||
+          StringUtilities.endsWith3(lexeme, 0x27, 0x27, 0x27)) {
+        end -= 3;
+      } else if (StringUtilities.endsWithChar(lexeme, 0x22) ||
+          StringUtilities.endsWithChar(lexeme, 0x27)) {
+        end -= 1;
+      }
+    }
+  }
+
+  /**
+   * Given the [lexeme] for a multi-line string whose content begins at the
+   * given [start] index, return the index of the first character that is
+   * included in the value of the string. According to the specification:
+   *
+   * If the first line of a multiline string consists solely of the whitespace
+   * characters defined by the production WHITESPACE 20.1), possibly prefixed
+   * by \, then that line is ignored, including the new line at its end.
+   */
+  int _trimInitialWhitespace(int start) {
+    int length = lexeme.length;
+    int index = start;
+    while (index < length) {
+      int currentChar = lexeme.codeUnitAt(index);
+      if (currentChar == 0x0D) {
+        if (index + 1 < length && lexeme.codeUnitAt(index + 1) == 0x0A) {
+          return index + 2;
+        }
+        return index + 1;
+      } else if (currentChar == 0x0A) {
+        return index + 1;
+      } else if (currentChar == 0x5C) {
+        if (index + 1 >= length) {
+          return start;
+        }
+        currentChar = lexeme.codeUnitAt(index + 1);
+        if (currentChar != 0x0D &&
+            currentChar != 0x0A &&
+            currentChar != 0x09 &&
+            currentChar != 0x20) {
+          return start;
+        }
+      } else if (currentChar != 0x09 && currentChar != 0x20) {
+        return start;
+      }
+      index++;
+    }
+    return start;
+  }
+}
+
+/**
  * A string literal expression.
  *
  * > stringLiteral ::=
  * >     [SimpleStringLiteral]
  * >   | [AdjacentStrings]
  * >   | [StringInterpolation]
  */
 abstract class StringLiteral extends Literal {
   /**
    * Return the value of the string literal, or `null` if the string is not a
@@ skipping 3352 matching lines @@
   }
 
   @override
   accept(AstVisitor visitor) => visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _safelyVisitChild(_expression, visitor);
   }
 }