Move frog/leg to lib/compiler/implementation.

frog/leg/scanner/array_based_scanner.dart

-// Copyright (c) 2011, 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.
-
-class ArrayBasedScanner<S> extends AbstractScanner<S> {
-  int get charOffset() => byteOffset + extraCharOffset;
-  final Token tokens;
-  Token tail;
-  int tokenStart;
-  int byteOffset;
-
-  /** Since the input is UTF8, some characters are represented by more
-   * than one byte. [extraCharOffset] tracks the difference. */
-  int extraCharOffset;
-  Link<BeginGroupToken> groupingStack = const EmptyLink<BeginGroupToken>();
-
-  ArrayBasedScanner()
-    : this.extraCharOffset = 0,
-      this.tokenStart = -1,
-      this.byteOffset = -1,
-      this.tokens = new Token(EOF_INFO, -1) {
-    this.tail = this.tokens;
-  }
-
-  int advance() {
-    int next = nextByte();
-    return next;
-  }
-
-  int select(int choice, PrecedenceInfo yes, PrecedenceInfo no) {
-    int next = advance();
-    if (next === choice) {
-      appendPrecenceToken(yes);
-      return advance();
-    } else {
-      appendPrecenceToken(no);
-      return next;
-    }
-  }
-
-  void appendPrecenceToken(PrecedenceInfo info) {
-    tail.next = new Token(info, tokenStart);
-    tail = tail.next;
-  }
-
-  void appendStringToken(PrecedenceInfo info, String value) {
-    tail.next = new StringToken(info, value, tokenStart);
-    tail = tail.next;
-  }
-
-  void appendKeywordToken(Keyword keyword) {
-    tail.next = new KeywordToken(keyword, tokenStart);
-    tail = tail.next;
-  }
-
-  void appendEofToken() {
-    tail.next = new Token(EOF_INFO, charOffset);
-    tail = tail.next;
-    // EOF points to itself so there's always infinite look-ahead.
-    tail.next = tail;
-    discardOpenLt();
-    if (!groupingStack.isEmpty()) {
-      BeginGroupToken begin = groupingStack.head;
-      throw new MalformedInputException('Unbalanced ${begin.stringValue}',
-                                        begin);
-    }
-  }
-
-  void beginToken() {
-    tokenStart = charOffset;
-  }
-
-  Token firstToken() {
-    return tokens.next;
-  }
-
-  void addToCharOffset(int offset) {
-    extraCharOffset += offset;
-  }
-
-  void appendWhiteSpace(int next) {
-    // Do nothing, we don't collect white space.
-  }
-
-  void appendBeginGroup(PrecedenceInfo info, String value) {
-    Token token = new BeginGroupToken(info, value, tokenStart);
-    tail.next = token;
-    tail = tail.next;
-    while (info.kind !== LT_TOKEN &&
-           !groupingStack.isEmpty() &&
-           groupingStack.head.kind === LT_TOKEN) {
-      groupingStack = groupingStack.tail;
-    }
-    groupingStack = groupingStack.prepend(token);
-  }
-
-  int appendEndGroup(PrecedenceInfo info, String value, int openKind) {
-    assert(openKind !== LT_TOKEN);
-    appendStringToken(info, value);
-    discardOpenLt();
-    if (groupingStack.isEmpty()) {
-      return advance();
-    }
-    BeginGroupToken begin = groupingStack.head;
-    if (begin.kind !== openKind) {
-      if (openKind !== OPEN_CURLY_BRACKET_TOKEN ||
-          begin.kind !== STRING_INTERPOLATION_TOKEN) {
-        // Not ending string interpolation.
-        throw new MalformedInputException('Unmatched ${begin.stringValue}',
-                                          begin);
-      }
-      // We're ending an interpolated expression.
-      begin.endGroup = tail;
-      groupingStack = groupingStack.tail;
-      // Using "start-of-text" to signal that we're back in string
-      // scanning mode.
-      return $STX;
-    }
-    begin.endGroup = tail;
-    groupingStack = groupingStack.tail;
-    return advance();
-  }
-
-  void appendGt(PrecedenceInfo info, String value) {
-    appendStringToken(info, value);
-    if (groupingStack.isEmpty()) return;
-    if (groupingStack.head.kind === LT_TOKEN) {
-      groupingStack.head.endGroup = tail;
-      groupingStack = groupingStack.tail;
-    }
-  }
-
-  void appendGtGt(PrecedenceInfo info, String value) {
-    appendStringToken(info, value);
-    if (groupingStack.isEmpty()) return;
-    if (groupingStack.head.kind === LT_TOKEN) {
-      groupingStack = groupingStack.tail;
-    }
-    if (groupingStack.isEmpty()) return;
-    if (groupingStack.head.kind === LT_TOKEN) {
-      groupingStack.head.endGroup = tail;
-      groupingStack = groupingStack.tail;
-    }
-  }
-
-  void appendGtGtGt(PrecedenceInfo info, String value) {
-    appendStringToken(info, value);
-    if (groupingStack.isEmpty()) return;
-    if (groupingStack.head.kind === LT_TOKEN) {
-      groupingStack = groupingStack.tail;
-    }
-    if (groupingStack.isEmpty()) return;
-    if (groupingStack.head.kind === LT_TOKEN) {
-      groupingStack = groupingStack.tail;
-    }
-    if (groupingStack.isEmpty()) return;
-    if (groupingStack.head.kind === LT_TOKEN) {
-      groupingStack.head.endGroup = tail;
-      groupingStack = groupingStack.tail;
-    }
-  }
-
-  void discardOpenLt() {
-    while (!groupingStack.isEmpty() && groupingStack.head.kind === LT_TOKEN) {
-      groupingStack = groupingStack.tail;
-    }
-  }
-
-  // TODO(ahe): make class abstract instead of adding an abstract method.
-  abstract peek();
-}