| // |
| // ANTLRLookaheadStream.m |
| // ANTLR |
| // |
| // Created by Ian Michell on 26/04/2010. |
| // [The "BSD licence"] |
| // Copyright (c) 2010 Ian Michell 2010 Alan Condit |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions |
| // are met: |
| // 1. Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // 2. Redistributions in binary form must reproduce the above copyright |
| // notice, this list of conditions and the following disclaimer in the |
| // documentation and/or other materials provided with the distribution. |
| // 3. The name of the author may not be used to endorse or promote products |
| // derived from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| // IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #import "ANTLRLookaheadStream.h" |
| #import "ANTLRError.h" |
| #import "ANTLRRecognitionException.h" |
| #import "ANTLRCommonToken.h" |
| #import "ANTLRRuntimeException.h" |
| |
| @implementation ANTLRLookaheadStream |
| |
| @synthesize eof; |
| @synthesize index; |
| @synthesize eofElementIndex; |
| @synthesize lastMarker; |
| @synthesize markDepth; |
| @synthesize prevElement; |
| |
| -(id) init |
| { |
| self = [super init]; |
| if ( self != nil ) { |
| eof = [[ANTLRCommonToken eofToken] retain]; |
| eofElementIndex = UNITIALIZED_EOF_ELEMENT_INDEX; |
| markDepth = 0; |
| index = 0; |
| } |
| return self; |
| } |
| |
| -(id) initWithEOF:(id)obj |
| { |
| if ((self = [super init]) != nil) { |
| self.eof = obj; |
| if ( self.eof ) [self.eof retain]; |
| } |
| return self; |
| } |
| |
| - (void) reset |
| { |
| [super reset]; |
| index = 0; |
| p = 0; |
| prevElement = nil; |
| eofElementIndex = UNITIALIZED_EOF_ELEMENT_INDEX; |
| } |
| |
| -(id) nextElement |
| { |
| // [self doesNotRecognizeSelector:_cmd]; |
| return nil; |
| } |
| |
| - (id) remove |
| { |
| id obj = [self objectAtIndex:0]; |
| p++; |
| // have we hit end of buffer and not backtracking? |
| if ( p == [data count] && markDepth==0 ) { |
| // if so, it's an opportunity to start filling at index 0 again |
| [self clear]; // size goes to 0, but retains memory |
| } |
| [obj release]; |
| return obj; |
| } |
| |
| -(void) consume |
| { |
| [self sync:1]; |
| prevElement = [self remove]; |
| index++; |
| } |
| |
| -(void) sync:(NSInteger) need |
| { |
| NSInteger n = (p + need - 1) - [data count] + 1; |
| if ( n > 0 ) { |
| [self fill:n]; |
| } |
| } |
| |
| -(void) fill:(NSInteger) n |
| { |
| id obj; |
| for (NSInteger i = 1; i <= n; i++) { |
| obj = [self nextElement]; |
| if ( obj == eof ) { |
| [data addObject:self.eof]; |
| eofElementIndex = [data count] - 1; |
| } |
| else { |
| [data addObject:obj]; |
| } |
| } |
| } |
| |
| -(NSUInteger) count |
| { |
| @throw [NSException exceptionWithName:@"ANTLRUnsupportedOperationException" reason:@"Streams have no defined size" userInfo:nil]; |
| } |
| |
| -(id) LT:(NSInteger) k |
| { |
| if (k == 0) { |
| return nil; |
| } |
| if (k < 0) { |
| return [self LB:-k]; |
| } |
| if ((p + k - 1) >= eofElementIndex) { |
| return self.eof; |
| } |
| [self sync:k]; |
| return [self objectAtIndex:(k - 1)]; |
| } |
| |
| -(id) LB:(NSInteger) k |
| { |
| if (k == 1) { |
| return prevElement; |
| } |
| @throw [ANTLRNoSuchElementException newException:@"can't look backwards more than one token in this stream"]; |
| } |
| |
| -(id) getCurrentSymbol |
| { |
| return [self LT:1]; |
| } |
| |
| -(NSInteger) mark |
| { |
| markDepth++; |
| lastMarker = p; |
| return lastMarker; |
| } |
| |
| -(void) release:(NSInteger) marker |
| { |
| // no resources to release |
| } |
| |
| -(void) rewind:(NSInteger) marker |
| { |
| markDepth--; |
| [self seek:marker]; |
| // if (marker == 0) [self reset]; |
| } |
| |
| -(void) rewind |
| { |
| [self seek:lastMarker]; |
| // if (lastMarker == 0) [self reset]; |
| } |
| |
| -(void) seek:(NSInteger) anIndex |
| { |
| p = anIndex; |
| } |
| |
| - (id) getEof |
| { |
| return eof; |
| } |
| |
| - (void) setEof:(id) anID |
| { |
| eof = anID; |
| } |
| |
| - (NSInteger) getEofElementIndex |
| { |
| return eofElementIndex; |
| } |
| |
| - (void) setEofElementIndex:(NSInteger) anInt |
| { |
| eofElementIndex = anInt; |
| } |
| |
| - (NSInteger) getLastMarker |
| { |
| return lastMarker; |
| } |
| |
| - (void) setLastMarker:(NSInteger) anInt |
| { |
| lastMarker = anInt; |
| } |
| |
| - (NSInteger) getMarkDepthlastMarker |
| { |
| return markDepth; |
| } |
| |
| - (void) setMarkDepth:(NSInteger) anInt |
| { |
| markDepth = anInt; |
| } |
| |
| @end |