Revert recent parser fixes

Commit 1f9b5c1 causes tests to fail
in angular when rolled into internal sources; the other two commits
need to be reverted as well to avoid merge conflicts.

This reverts commit 1f9b5c1.
This reverts commit c40b24d.
This reverts commit 96df1f9.

Change-Id: Ic4e55181ef60e825ce4409a9a9528ecbf19c39c4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/147822
Reviewed-by: Mike Fairhurst <mfairhurst@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

Author: stereotype441

pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart

@@ -3120,8 +3120,6 @@ class Parser {
     return token.type.isReservedWord;
   }
 
-  /// Whether [token] (the token right after a potential name) indicates it to
-  /// be a method or field definition.
   bool indicatesMethodOrField(Token token) {
     String value = token.stringValue;
     if (identical(value, ';') ||
@@ -4927,8 +4925,7 @@ class Parser {
   Token parseLiteralListSuffix(Token token, Token constKeyword) {
     Token beforeToken = token;
     Token beginToken = token = token.next;
-    assert(optional('[', token) || optional('[]', token),
-        "Token isn't as expected: ${token?.lexeme}");
+    assert(optional('[', token) || optional('[]', token));
     int count = 0;
     if (optional('[]', token)) {
       token = rewriteSquareBrackets(beforeToken).next;

pkg/_fe_analyzer_shared/lib/src/scanner/abstract_scanner.dart

@@ -27,7 +27,6 @@ import 'characters.dart';
 import 'error_token.dart'
     show
         NonAsciiIdentifierToken,
-        UnmatchedEndToken,
         UnmatchedToken,
         UnsupportedOperator,
         UnterminatedString,
@@ -125,35 +124,15 @@ abstract class AbstractScanner implements Scanner {
    */
   Link<BeginToken> groupingStack = const Link<BeginToken>();
 
-  final bool inRecoveryOption;
-  int recoveryCount = 0;
-
   AbstractScanner(ScannerConfiguration config, this.includeComments,
       this.languageVersionChanged,
       {int numberOfBytesHint})
-      : lineStarts = new LineStarts(numberOfBytesHint),
-        inRecoveryOption = false {
+      : lineStarts = new LineStarts(numberOfBytesHint) {
     this.tail = this.tokens;
     this.errorTail = this.tokens;
     this.configuration = config;
   }
 
-  AbstractScanner createRecoveryOptionScanner();
-
-  AbstractScanner.recoveryOptionScanner(AbstractScanner copyFrom)
-      : lineStarts = [],
-        includeComments = false,
-        languageVersionChanged = null,
-        inRecoveryOption = true {
-    this.tail = this.tokens;
-    this.errorTail = this.tokens;
-    this._enableExtensionMethods = copyFrom._enableExtensionMethods;
-    this._enableNonNullable = copyFrom._enableNonNullable;
-    this._enableTripleShift = copyFrom._enableTripleShift;
-    this.tokenStart = copyFrom.tokenStart;
-    this.groupingStack = copyFrom.groupingStack;
-  }
-
   @override
   set configuration(ScannerConfiguration config) {
     if (config != null) {
@@ -383,22 +362,9 @@ abstract class AbstractScanner implements Scanner {
    */
   int appendEndGroup(TokenType type, int openKind) {
     assert(!identical(openKind, LT_TOKEN)); // openKind is < for > and >>
-    bool foundMatchingBrace = discardBeginGroupUntil(openKind);
-    return appendEndGroupInternal(foundMatchingBrace, type, openKind);
-  }
-
-  /// Append the end group (parenthesis, bracket etc).
-  /// If [foundMatchingBrace] is true the grouping stack (stack of parenthesis
-  /// etc) is updated, otherwise it's left alone.
-  /// In effect, if [foundMatchingBrace] is false this end token is basically
-  /// ignored, i.e. not really seen as an end group.
-  int appendEndGroupInternal(
-      bool foundMatchingBrace, TokenType type, int openKind) {
-    if (!foundMatchingBrace) {
-      // No begin group. Leave the grouping stack alone and just continue.
-      Token ignoredToken = new Token(type, tokenStart, comments);
-      appendToken(ignoredToken);
-      prependErrorToken(new UnmatchedEndToken(ignoredToken));
+    if (!discardBeginGroupUntil(openKind)) {
+      // No begin group found. Just continue.
+      appendPrecedenceToken(type);
       return advance();
     }
     appendPrecedenceToken(type);
@@ -506,7 +472,7 @@ abstract class AbstractScanner implements Scanner {
    * then discard begin group tokens up to that match and return `true`,
    * otherwise return `false`.
    * This recovers nicely from from situations like "{[}" and "{foo());}",
-   * but not "foo(() {bar());});"
+   * but not "foo(() {bar());});
    */
   bool discardBeginGroupUntil(int openKind) {
     Link<BeginToken> originalStack = groupingStack;
@@ -533,8 +499,6 @@ abstract class AbstractScanner implements Scanner {
       groupingStack = groupingStack.tail;
     } while (!groupingStack.isEmpty);
 
-    recoveryCount++;
-
     // If the stack does not have any opener of the given type,
     // then return without discarding anything.
     // This recovers nicely from from situations like "{foo());}".
@@ -543,90 +507,16 @@ abstract class AbstractScanner implements Scanner {
       return false;
     }
 
-    // We found a matching group somewhere in the stack, but generally don't
-    // know if we should recover by inserting synthetic closers or
-    // basically ignore the current token.
-    // We're in a recovery setting so we're allowed to be 'relatively slow' ---
-    // try both and see which is better (i.e. gives fewest rewrites later).
-    // To not get exponential runtime we will not do this nested though.
-    // E.g. we can recover "{[}" as "{[]}" (better) or (with . for ignored
-    // tokens) "{[.".
-    // Or we can recover "[(])]" as "[()].." or "[(.)]" (better).
-    if (!inRecoveryOption) {
-      TokenType type;
-      switch (openKind) {
-        case OPEN_SQUARE_BRACKET_TOKEN:
-          type = TokenType.CLOSE_SQUARE_BRACKET;
-          break;
-        case OPEN_CURLY_BRACKET_TOKEN:
-          type = TokenType.CLOSE_CURLY_BRACKET;
-          break;
-        case OPEN_PAREN_TOKEN:
-          type = TokenType.CLOSE_PAREN;
-          break;
-        default:
-          throw new StateError("Unexpected openKind");
-      }
-
-      // Option #1: Insert synthetic closers.
-      int option1Recoveries;
-      {
-        AbstractScanner option1 = createRecoveryOptionScanner();
-        option1.insertSyntheticClosers(originalStack, groupingStack);
-        option1Recoveries =
-            option1.recoveryOptionTokenizer(option1.appendEndGroupInternal(
-                /* foundMatchingBrace = */ true,
-                type,
-                openKind));
-        option1Recoveries += option1.groupingStack.slowLength();
-      }
-
-      // Option #2: ignore this token.
-      int option2Recoveries;
-      {
-        AbstractScanner option2 = createRecoveryOptionScanner();
-        option2.groupingStack = originalStack;
-        option2Recoveries =
-            option2.recoveryOptionTokenizer(option2.appendEndGroupInternal(
-                /* foundMatchingBrace = */ false,
-                type,
-                openKind));
-        // We add 1 to make this option pay for ignoring this token.
-        option2Recoveries += option2.groupingStack.slowLength() + 1;
-      }
-
-      // The option-runs might have set invalid endGroup pointers. Reset them.
-      for (Link<BeginToken> link = originalStack;
-          link.isNotEmpty;
-          link = link.tail) {
-        link.head.endToken = null;
-      }
-
-      if (option2Recoveries < option1Recoveries) {
-        // Perform option #2 recovery.
-        groupingStack = originalStack;
-        return false;
-      }
-      // option #1 is the default, so fall though.
-    }
-
-    // Insert synthetic closers and report errors for any unbalanced openers.
-    // This recovers nicely from from situations like "{[}".
-    insertSyntheticClosers(originalStack, groupingStack);
-    return true;
-  }
-
-  void insertSyntheticClosers(
-      Link<BeginToken> originalStack, Link<BeginToken> entryToUse) {
     // Insert synthetic closers and report errors for any unbalanced openers.
     // This recovers nicely from from situations like "{[}".
-    while (!identical(originalStack, entryToUse)) {
+    while (!identical(originalStack, groupingStack)) {
       // Don't report unmatched errors for <; it is also the less-than operator.
-      if (!identical(entryToUse.head.kind, LT_TOKEN)) {
+      if (!identical(groupingStack.head.kind, LT_TOKEN)) {
         unmatchedBeginGroup(originalStack.head);
       }
       originalStack = originalStack.tail;
     }
+    return true;
   }
 
   /**
@@ -711,7 +601,6 @@ abstract class AbstractScanner implements Scanner {
     appendToken(new SyntheticToken(type, tokenStart)..beforeSynthetic = tail);
     begin.endGroup = tail;
     prependErrorToken(new UnmatchedToken(begin));
-    recoveryCount++;
   }
 
   /// Return true when at EOF.
@@ -751,26 +640,6 @@ abstract class AbstractScanner implements Scanner {
     return firstToken();
   }
 
-  /// Tokenize a (small) part of the data. Used for recovery "option testing".
-  ///
-  /// Returns the number of recoveries performed.
-  int recoveryOptionTokenizer(int next) {
-    int iterations = 0;
-    while (!atEndOfFile()) {
-      while (!identical(next, $EOF)) {
-        // TODO(jensj): Look at number of lines, tokens, parenthesis stack,
-        // semi-colon etc, not just number of iterations.
-        next = bigSwitch(next);
-        iterations++;
-
-        if (iterations > 100) {
-          break;
-        }
-      }
-    }
-    return recoveryCount;
-  }
-
   int bigHeaderSwitch(int next) {
     if (!identical(next, $SLASH)) {
       return bigSwitch(next);

pkg/_fe_analyzer_shared/lib/src/scanner/error_token.dart

@@ -16,7 +16,7 @@ import '../messages/codes.dart'
         templateUnsupportedOperator,
         templateUnterminatedString;
 
-import 'recover.dart' show closeBraceFor, closeQuoteFor, openBraceFor;
+import 'recover.dart' show closeBraceFor, closeQuoteFor;
 
 import 'scanner.dart' show Token, unicodeReplacementCharacter;
 
@@ -215,20 +215,3 @@ class UnmatchedToken extends ErrorToken {
   Message get assertionMessage =>
       templateUnmatchedToken.withArguments(closeBraceFor(begin.lexeme), begin);
 }
-
-/// Represents a close brace without a matching open brace.
-///
-/// In this case, brace means any of `)`, `}`, `]`, parenthesis, curly
-/// brace and square brace, respectively.
-class UnmatchedEndToken extends ErrorToken {
-  final Token endToken;
-
-  UnmatchedEndToken(Token endToken)
-      : this.endToken = endToken,
-        super(endToken.charOffset);
-
-  String toString() => "UnmatchedEndToken(${endToken.lexeme})";
-
-  Message get assertionMessage => templateUnmatchedToken.withArguments(
-      openBraceFor(endToken.lexeme), endToken);
-}

pkg/_fe_analyzer_shared/lib/src/scanner/errors.dart

@@ -2,16 +2,10 @@
 // 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.
 
-import '../base/errors.dart' show ErrorCode, ErrorSeverity, ErrorType;
-
-import '../messages/codes.dart'
-    show Code, codeUnexpectedDollarInString, codeUnmatchedToken;
-
-import 'error_token.dart'
-    show ErrorToken, UnmatchedEndToken, UnsupportedOperator;
-
-import 'token_constants.dart' show BAD_INPUT_TOKEN;
-
+import '../base/errors.dart';
+import '../messages/codes.dart';
+import 'error_token.dart';
+import 'token_constants.dart';
 import 'token.dart' show Token, TokenType;
 
 /**
@@ -25,13 +19,6 @@ class ScannerErrorCode extends ErrorCode {
   static const ScannerErrorCode EXPECTED_TOKEN =
       const ScannerErrorCode('EXPECTED_TOKEN', "Expected to find '{0}'.");
 
-  /**
-   * Parameters:
-   * 0: the token that was unexpected but found
-   */
-  static const ScannerErrorCode UNEXPECTED_TOKEN =
-      const ScannerErrorCode('UNEXPECTED_TOKEN', "Unexpected text '{0}'.");
-
   /**
    * Parameters:
    * 0: the illegal character
@@ -163,11 +150,6 @@ void translateErrorToken(ErrorToken token, ReportError reportError) {
 
     default:
       if (errorCode == codeUnmatchedToken) {
-        if (token is UnmatchedEndToken) {
-          charOffset = token.endToken.charOffset;
-          return _makeError(
-              ScannerErrorCode.UNEXPECTED_TOKEN, [token.endToken.lexeme]);
-        }
         charOffset = token.begin.endToken.charOffset;
         TokenType type = token.begin?.type;
         if (type == TokenType.OPEN_CURLY_BRACKET ||

pkg/_fe_analyzer_shared/lib/src/scanner/recover.dart

@@ -70,14 +70,6 @@ String closeBraceFor(String openBrace) {
   }[openBrace];
 }
 
-String openBraceFor(String closeBrace) {
-  return const {
-    ')': '(',
-    ']': '[',
-    '}': '{',
-  }[closeBrace];
-}
-
 String closeQuoteFor(String openQuote) {
   return const {
     '"': '"',

pkg/_fe_analyzer_shared/lib/src/scanner/string_scanner.dart

@@ -34,16 +34,6 @@ class StringScanner extends AbstractScanner {
       : string = ensureZeroTermination(string),
         super(configuration, includeComments, languageVersionChanged);
 
-  StringScanner.recoveryOptionScanner(StringScanner copyFrom)
-      : super.recoveryOptionScanner(copyFrom) {
-    string = copyFrom.string;
-    scanOffset = copyFrom.scanOffset;
-  }
-
-  StringScanner createRecoveryOptionScanner() {
-    return new StringScanner.recoveryOptionScanner(this);
-  }
-
   static String ensureZeroTermination(String string) {
     return (string.isEmpty || string.codeUnitAt(string.length - 1) != 0)
         // TODO(lry): abort instead of copying the array, or warn?

pkg/_fe_analyzer_shared/lib/src/scanner/utf8_bytes_scanner.dart

@@ -97,19 +97,6 @@ class Utf8BytesScanner extends AbstractScanner {
     }
   }
 
-  Utf8BytesScanner.createRecoveryOptionScanner(Utf8BytesScanner copyFrom)
-      : super.recoveryOptionScanner(copyFrom) {
-    this.bytes = copyFrom.bytes;
-    this.byteOffset = copyFrom.byteOffset;
-    this.scanSlack = copyFrom.scanSlack;
-    this.scanSlackOffset = copyFrom.scanSlackOffset;
-    this.utf8Slack = copyFrom.utf8Slack;
-  }
-
-  Utf8BytesScanner createRecoveryOptionScanner() {
-    return new Utf8BytesScanner.createRecoveryOptionScanner(this);
-  }
-
   bool containsBomAt(int offset) {
     const List<int> BOM_UTF8 = const [0xEF, 0xBB, 0xBF];
 

pkg/analyzer/lib/error/error.dart

@@ -681,7 +681,6 @@ const List<ErrorCode> errorCodeValues = [
   ScannerErrorCode.MISSING_QUOTE,
   ScannerErrorCode.UNABLE_GET_CONTENT,
   ScannerErrorCode.UNEXPECTED_DOLLAR_IN_STRING,
-  ScannerErrorCode.UNEXPECTED_TOKEN,
   ScannerErrorCode.UNSUPPORTED_OPERATOR,
   ScannerErrorCode.UNTERMINATED_MULTI_LINE_COMMENT,
   ScannerErrorCode.UNTERMINATED_STRING_LITERAL,

pkg/analyzer/lib/src/dart/scanner/scanner.dart

@@ -133,7 +133,7 @@ class Scanner {
   void reportError(
       ScannerErrorCode errorCode, int offset, List<Object> arguments) {
     _errorListener
-        ?.onError(AnalysisError(source, offset, 1, errorCode, arguments));
+        .onError(AnalysisError(source, offset, 1, errorCode, arguments));
   }
 
   void setSourceStart(int line, int column) {