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

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

Index: pkg/analyzer/lib/src/generated/parser.dart
diff --git a/pkg/analyzer/lib/src/generated/parser.dart b/pkg/analyzer/lib/src/generated/parser.dart
index de44f48971e65f2b8fc457763da74fdd3be2dee2..824dc1908dc41ef3e2fc162350f15323836771b5 100644
--- a/pkg/analyzer/lib/src/generated/parser.dart
+++ b/pkg/analyzer/lib/src/generated/parser.dart
@@ -3435,41 +3435,15 @@ class Parser {
    * `true` if this is the last token in a string literal.
    */
   String _computeStringValue(String lexeme, bool isFirst, bool isLast) {
-    bool isRaw = false;
-    int start = 0;
-    if (isFirst) {
-      if (StringUtilities.startsWith4(lexeme, 0, 0x72, 0x22, 0x22, 0x22) ||
-          StringUtilities.startsWith4(lexeme, 0, 0x72, 0x27, 0x27, 0x27)) {
-        isRaw = true;
-        start = _trimInitialWhitespace(lexeme, start + 4);
-      } else if (StringUtilities.startsWith2(lexeme, 0, 0x72, 0x22) ||
-          StringUtilities.startsWith2(lexeme, 0, 0x72, 0x27)) {
-        isRaw = true;
-        start += 2;
-      } else if (StringUtilities.startsWith3(lexeme, 0, 0x22, 0x22, 0x22) ||
-          StringUtilities.startsWith3(lexeme, 0, 0x27, 0x27, 0x27)) {
-        start = _trimInitialWhitespace(lexeme, start + 3);
-      } else if (StringUtilities.startsWithChar(lexeme, 0x22) ||
-          StringUtilities.startsWithChar(lexeme, 0x27)) {
-        start += 1;
-      }
-    }
-    int 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;
-      }
-    }
+    StringLexemeHelper helper = new StringLexemeHelper(lexeme, isFirst, isLast);
+    int start = helper.start;
+    int end = helper.end;
     if (end - start + 1 < 0) {
       AnalysisEngine.instance.logger.logError(
           "Internal error: computeStringValue($lexeme, $isFirst, $isLast)");
       return "";
     }
-    if (isRaw) {
+    if (helper.isRaw) {
       return lexeme.substring(start, end);
     }
     StringBuffer buffer = new StringBuffer();
@@ -3481,46 +3455,6 @@ class Parser {
   }
 
   /**
-   * 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(String lexeme, 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;
-  }
-
-  /**
    * Convert the given [method] declaration into the nearest valid top-level
    * function declaration (that is, the function declaration that most closely
    * captures the components of the given method declaration).