//

// StringFeed.m

// ANHTML

//

// Created by Alex Nichol on 11/17/11.

// Copyright (c) 2011 __MyCompanyName__. All rights reserved.

//

#import "StringFeed.h"

@implementation StringFeed

#pragma mark Initialization

- (id)initWithString:(NSString *)string {

if ((self = [super init])) {

if (!string) {

return nil;

}

feedString = string;

offsetStack = [[NSMutableArray alloc] init];

}

return self;

}

- (id)initWithStringData:(NSData *)data {

if ((self = [super init])) {

const NSStringEncoding encodings[] = {

NSUTF8StringEncoding,

NSUTF16StringEncoding,

NSUTF32StringEncoding,

NSWindowsCP1252StringEncoding

};

const int encodingsSize = 4;

for (int i = 0; i < encodingsSize; i++) {

feedString = [[NSString alloc] initWithData:data encoding:encodings[i]];

if (feedString) break;

}

if (!feedString) return nil;

offsetStack = [[NSMutableArray alloc] init];

}

return self;

}

- (id)initWithStringData:(NSData *)data encoding:(NSStringEncoding)encoding {

if ((self = [super init])) {

feedString = [[NSString alloc] initWithData:data encoding:encoding];

if (!feedString) {

return nil;

}

offsetStack = [[NSMutableArray alloc] init];

}

return self;

}

#pragma mark Length

- (NSUInteger)length {

return [feedString length];

}

- (BOOL)isFinished {

return (offset >= [feedString length]);

}

#pragma mark Reading

- (unichar)getCharacter {

if ([self isFinished]) {

@throw [NSException exceptionWithName:BufferUnderflowException

reason:@"No characters are left to read."

userInfo:nil];

}

unichar c = [feedString characterAtIndex:offset++];

return c;

}

- (NSString *)getString:(NSUInteger)length {

if (offset + length > [feedString length]) {

@throw [NSException exceptionWithName:BufferUnderflowException

reason:@"Less characters are available than the number specified to read."

userInfo:nil];

}

NSString * str = [feedString substringWithRange:NSMakeRange(offset, length)];

offset += length;

return str;

}

#pragma mark - Chunking -

#pragma mark Strings

- (BOOL)stringFollows:(NSString *)aString {

if (offset + [aString length] > [feedString length]) {

return NO;

}

NSString * following = [feedString substringWithRange:NSMakeRange(offset, [aString length])];

return [following isEqualToString:aString];

}

- (NSString *)readUntil:(NSString *)ending {

NSRange remaining = NSMakeRange(offset, [feedString length] - offset);

NSRange termRange = [feedString rangeOfString:ending options:0 range:remaining];

if (termRange.location == NSNotFound) {

return nil;

}

NSString * str = [feedString substringWithRange:NSMakeRange(offset, termRange.location - offset)];

offset = termRange.location + termRange.length;

return str;

}

- (BOOL)skipUntil:(NSString *)ending {

NSRange remaining = NSMakeRange(offset, [feedString length] - offset);

NSRange termRange = [feedString rangeOfString:ending options:0 range:remaining];

if (termRange.location == NSNotFound) {

return NO;

}

offset = termRange.location + termRange.length;

return YES;

}

- (NSString *)readUntil:(NSString *)ending notEncountering:(NSString *)invalidStr {

NSRange remaining = NSMakeRange(offset, [feedString length] - offset);

NSRange termRange = [feedString rangeOfString:ending options:0 range:remaining];

NSRange invalidRange = [feedString rangeOfString:invalidStr options:0 range:remaining];

if (termRange.location == NSNotFound) {

return nil;

}

if (invalidRange.location != NSNotFound && invalidRange.location < termRange.location) {

// found invalid string, therefore the read was faulty

return nil;

}

NSString * str = [feedString substringWithRange:NSMakeRange(offset, termRange.location - offset)];

offset = termRange.location + termRange.length;

return str;

}

#pragma mark Character Sets

- (NSString *)readUntilCharacterInSet:(NSCharacterSet *)charSet {

NSMutableString * builtString = [NSMutableString string];

while (![self isFinished]) {

unichar token = [self getCharacter];

if ([charSet characterIsMember:token]) {

break;

}

[builtString appendFormat:@"%C", token];

}

return [builtString copy]; // immutable copy

}

- (void)skipUntilCharacterInSet:(NSCharacterSet *)charSet {

while (![self isFinished]) {

unichar token = [self getCharacter];

if ([charSet characterIsMember:token]) {

return;

}

}

}

- (void)consumeCharactersInSet:(NSCharacterSet *)charSet {

while (![self isFinished]) {

unichar token = [self getCharacter];

if (![charSet characterIsMember:token]) {

offset--;

return;

}

}

}

#pragma mark - Offsets -

#pragma mark Offset Property

- (NSUInteger)offset {

return offset;

}

- (void)setOffset:(NSUInteger)_offset {

if (_offset > [self length]) {

@throw [NSException exceptionWithName:BufferUnderflowException

reason:@"The given offset exceeds the bounds of the buffer"

userInfo:nil];

}

offset = _offset;

}

#pragma mark Offset Stack

- (void)pushCurrentOffset {

[offsetStack addObject:[NSNumber numberWithUnsignedInteger:offset]];

}

- (void)restoreOffset {

if ([offsetStack count] == 0) {

@throw [NSException exceptionWithName:OffsetStackEmptyException

reason:@"Cannot pop from empty stack."

userInfo:nil];

}

NSNumber * offsetObj = [offsetStack lastObject];

[offsetStack removeLastObject];

[self setOffset:[offsetObj unsignedIntegerValue]];

}

- (void)skipOffset {

if ([offsetStack count] == 0) {

@throw [NSException exceptionWithName:OffsetStackEmptyException

reason:@"Cannot pop from empty stack."

userInfo:nil];

}

[offsetStack removeLastObject];

}

@end