Roll Observatory packages and add a roll script

analyzer/lib/src/generated/incremental_scanner.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.
-
-library engine.incremental_scanner;
-
-import "dart:math" as math;
-
-import 'package:analyzer/src/generated/engine.dart';
-
-import 'error.dart';
-import 'scanner.dart';
-import 'source.dart';
-import 'utilities_collection.dart' show TokenMap;
-
-/**
- * An `IncrementalScanner` is a scanner that scans a subset of a string and
- * inserts the resulting tokens into the middle of an existing token stream.
- */
-class IncrementalScanner {
-  /**
-   * The source being scanned.
-   */
-  final Source source;
-
-  /**
-   * The reader used to access the characters in the source.
-   */
-  final CharacterReader reader;
-
-  /**
-   * The error listener that will be informed of any errors that are found
-   * during the scan.
-   *
-   * TODO(brianwilkerson) Replace this with a list of errors so that we can
-   * update the errors.
-   */
-  final AnalysisErrorListener errorListener;
-
-  final AnalysisOptions _options;
-
-  /**
-   * A map from tokens that were copied to the copies of the tokens.
-   */
-  TokenMap _tokenMap = new TokenMap();
-
-  /**
-   * The token immediately to the left of the range of tokens that were
-   * modified.
-   */
-  Token leftToken;
-
-  /**
-   * The token immediately to the right of the range of tokens that were
-   * modified.
-   */
-  Token rightToken;
-
-  /**
-   * A flag indicating whether there were any non-comment tokens changed (other
-   * than having their position updated) as a result of the modification.
-   */
-  bool hasNonWhitespaceChange = false;
-
-  /**
-   * Initialize a newly created scanner to scan characters within the given
-   * [source]. The content of the source can be read using the given [reader].
-   * Any errors that are found will be reported to the given [errorListener].
-   * [_options] will determine how scanning is to be performed.
-   */
-  IncrementalScanner(
-      this.source, this.reader, this.errorListener, this._options);
-
-  /**
-   * Return a map from tokens that were copied to the copies of the tokens.
-   *
-   * @return a map from tokens that were copied to the copies of the tokens
-   */
-  TokenMap get tokenMap => _tokenMap;
-
-  /**
-   * Given the [stream] of tokens scanned from the original source, the modified
-   * source (the result of replacing one contiguous range of characters with
-   * another string of characters), and a specification of the modification that
-   * was made, update the token stream to reflect the modified source. Return
-   * the first token in the updated token stream.
-   *
-   * The [stream] is expected to be the first non-EOF token in the token stream.
-   *
-   * The modification is specified by the [index] of the first character in both
-   * the original and modified source that was affected by the modification, the
-   * number of characters removed from the original source (the [removedLength])
-   * and the number of characters added to the modified source (the
-   * [insertedLength]).
-   */
-  Token rescan(Token stream, int index, int removedLength, int insertedLength) {
-    Token leftEof = stream.previous;
-    //
-    // Compute the delta between the character index of characters after the
-    // modified region in the original source and the index of the corresponding
-    // character in the modified source.
-    //
-    int delta = insertedLength - removedLength;
-    //
-    // Skip past the tokens whose end is less than the replacement start. (If
-    // the replacement start is equal to the end of an existing token, then it
-    // means that the existing token might have been modified, so we need to
-    // rescan it.)
-    //
-    while (stream.type != TokenType.EOF && stream.end < index) {
-      _tokenMap.put(stream, stream);
-      stream = stream.next;
-    }
-    Token oldFirst = stream;
-    Token oldLeftToken = stream.previous;
-    leftToken = oldLeftToken;
-    //
-    // Skip past tokens until we find a token whose offset is greater than the
-    // end of the removed region. (If the end of the removed region is equal to
-    // the beginning of an existing token, then it means that the existing token
-    // might have been modified, so we need to rescan it.)
-    //
-    int removedEnd = index + (removedLength == 0 ? 0 : removedLength - 1);
-    while (stream.type != TokenType.EOF && stream.offset <= removedEnd) {
-      stream = stream.next;
-    }
-    //
-    // Figure out which region of characters actually needs to be re-scanned.
-    //
-    Token oldLast;
-    Token oldRightToken;
-    if (stream.type != TokenType.EOF && removedEnd + 1 == stream.offset) {
-      oldLast = stream;
-      stream = stream.next;
-      oldRightToken = stream;
-    } else {
-      oldLast = stream.previous;
-      oldRightToken = stream;
-    }
-    //
-    // Compute the range of characters that are known to need to be rescanned.
-    // If the index is within an existing token, then we need to start at the
-    // beginning of the token.
-    //
-    int scanStart = math.max(oldLeftToken.end, 0);
-    int scanEnd = oldRightToken.offset + delta;
-    //
-    // Rescan the characters that need to be rescanned.
-    //
-    Token replacementStart = _scanRange(scanStart, scanEnd);
-    oldLeftToken.setNext(replacementStart);
-    Token replacementEnd = _findEof(replacementStart).previous;
-    replacementEnd.setNext(stream);
-    //
-    // Apply the delta to the tokens after the last new token.
-    //
-    _updateOffsets(stream, delta);
-    rightToken = stream;
-    //
-    // If the index is immediately after an existing token and the inserted
-    // characters did not change that original token, then adjust the leftToken
-    // to be the next token. For example, in "a; c;" --> "a;b c;", the leftToken
-    // was ";", but this code advances it to "b" since "b" is the first new
-    // token.
-    //
-    Token newFirst = leftToken.next;
-    while (!identical(newFirst, rightToken) &&
-        !identical(oldFirst, oldRightToken) &&
-        newFirst.type != TokenType.EOF &&
-        _equalTokens(oldFirst, newFirst)) {
-      _tokenMap.put(oldFirst, newFirst);
-      oldLeftToken = oldFirst;
-      oldFirst = oldFirst.next;
-      leftToken = newFirst;
-      newFirst = newFirst.next;
-    }
-    Token newLast = rightToken.previous;
-    while (!identical(newLast, leftToken) &&
-        !identical(oldLast, oldLeftToken) &&
-        newLast.type != TokenType.EOF &&
-        _equalTokens(oldLast, newLast)) {
-      _tokenMap.put(oldLast, newLast);
-      oldRightToken = oldLast;
-      oldLast = oldLast.previous;
-      rightToken = newLast;
-      newLast = newLast.previous;
-    }
-    hasNonWhitespaceChange = !identical(leftToken.next, rightToken) ||
-        !identical(oldLeftToken.next, oldRightToken);
-    //
-    // TODO(brianwilkerson) Begin tokens are not getting associated with the
-    // corresponding end tokens (because the end tokens have not been copied
-    // when we're copying the begin tokens). This could have implications for
-    // parsing.
-    // TODO(brianwilkerson) Update the lineInfo.
-    //
-    return leftEof.next;
-  }
-
-  /**
-   * Return `true` if the [oldToken] and the [newToken] are equal to each other.
-   * For the purposes of the incremental scanner, two tokens are equal if they
-   * have the same type and lexeme.
-   */
-  bool _equalTokens(Token oldToken, Token newToken) =>
-      oldToken.type == newToken.type &&
-          oldToken.length == newToken.length &&
-          oldToken.lexeme == newToken.lexeme;
-
-  /**
-   * Given a [token], return the EOF token that follows the token.
-   */
-  Token _findEof(Token token) {
-    while (token.type != TokenType.EOF) {
-      token = token.next;
-    }
-    return token;
-  }
-
-  /**
-   * Scan the token between the [start] (inclusive) and [end] (exclusive)
-   * offsets.
-   */
-  Token _scanRange(int start, int end) {
-    Scanner scanner = new Scanner(
-        source, new CharacterRangeReader(reader, start, end), errorListener);
-    return scanner.tokenize();
-  }
-
-  /**
-   * Update the offsets of every token from the given [token] to the end of the
-   * stream by adding the given [delta].
-   */
-  void _updateOffsets(Token token, int delta) {
-    while (token.type != TokenType.EOF) {
-      _tokenMap.put(token, token);
-      token.offset += delta;
-      Token comment = token.precedingComments;
-      while (comment != null) {
-        comment.offset += delta;
-        comment = comment.next;
-      }
-      token = token.next;
-    }
-    _tokenMap.put(token, token);
-    token.offset += delta;
-  }
-}