Add CSS Selectors Parser implementation

2015-11-28 21:11:16 +01:00
parent 94fed8afa1
commit 13b8fe7808
2 changed files with 384 additions and 0 deletions
@@ -0,0 +1,17 @@
+//
+//  CSSSelectorParser.h
+//  HTMLKit
+//
+//  Created by Iska on 02/10/15.
+//  Copyright © 2015 BrainCookie. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@class CSSSelector;
+
+@interface CSSSelectorParser : NSObject
+
+ (CSSSelector *)parseSelector:(NSString *)string error:(NSError **)error;
+
+@end
@@ -0,0 +1,367 @@
+//
+//  CSSSelectorParser.m
+//  HTMLKit
+//
+//  Created by Iska on 02/10/15.
+//  Copyright © 2015 BrainCookie. All rights reserved.
+//
+
+#import "CSSSelectorParser.h"
+#import "CSSInputStream.h"
+#import "CSSCodePoints.h"
+#import "CSSSelectors.h"
+#import "NSString+HTMLKit.h"
+#import "NSCharacterSet+HTMLKit.h"
+#import "CSSNthExpressionParser.h"
+#import "CSSCompoundSelector.h"
+#import "HTMLKitErrorDomain.h"
+
+@interface CSSSelectorParser ()
+{
+	NSString *_string;
+	CSSInputStream *_inputStream;
+	NSUInteger _location;
+
+	NSMutableArray *_selectors;
+}
+@end
+
+@implementation CSSSelectorParser
+
+ (CSSSelector *)parseSelector:(NSString *)string error:(NSError * __autoreleasing *)error
+{
+	CSSSelectorParser *parser = [[CSSSelectorParser alloc] initWithString:string];
+	CSSSelector *selector = [parser parse:error];
+
+	return selector;
+}
+
+#pragma mark - Init
+
+- (instancetype)initWithString:(NSString *)string
+{
+	self = [super init];
+	if (self) {
+		_string = [self preprocessInput:string];
+		_location = 0;
+	}
+	return self;
+}
+
+- (NSString *)preprocessInput:(NSString *)string
+{
+	string = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
+	string = [string stringByReplacingOccurrencesOfString:@"\r\n" withString:@"\n"];
+	string = [string stringByReplacingOccurrencesOfString:@"\r" withString:@"\n"];
+	string = [string stringByReplacingOccurrencesOfString:@"\f" withString:@"\n"];
+	string = [string stringByReplacingOccurrencesOfString:@"\0" withString:@"\uFFFD"];
+
+	return string;
+}
+
+#pragma mark - Errors
+
+- (void)emitError:(NSError * __autoreleasing *)error reason:(NSString *)reason location:(NSUInteger)location
+{
+	NSDictionary *userInfo = @{
+							   NSLocalizedDescriptionKey: @"Error parsing selector",
+							   NSLocalizedFailureReasonErrorKey: reason,
+							   CSSSelectorStringKey: _string,
+							   CSSSelectorErrorLocationKey: @(location)
+							   };
+
+	if(error) {
+		*error = [NSError errorWithDomain:HTMLKitSelectorErrorDomain code:HTMLKitSelectorParseError userInfo:userInfo];
+	}
+}
+
+#pragma mark - Parsing
+
+- (CSSSelector *)parse:(NSError * __autoreleasing *)error
+{
+	if (_string.length == 0) {
+		[self emitError:error reason:@"Empty selector" location:0];
+		return nil;
+	}
+
+	NSArray *allSubSelectors = [_string componentsSeparatedByString:@","];
+	NSMutableArray *parsed = [NSMutableArray array];
+
+	for (NSString *subSelector in allSubSelectors) {
+		if ([subSelector isEqualToString:@""]) {
+			[self emitError:error reason:@"Empty selector" location:_location];
+			break;
+		}
+
+		CSSSelector *selector = [self parseSelector:subSelector error:error];
+		if (selector == nil) {
+			break;
+		}
+		[parsed addObject:selector];
+
+		_location += subSelector.length;
+	}
+
+	if (*error != nil) {
+		return nil;
+	}
+
+	if (parsed.count > 1) {
+		return anyOf(parsed);
+	}
+
+	return parsed.firstObject;
+}
+
+- (CSSSelector *)parseSelector:(NSString *)selectorString error:(NSError * __autoreleasing *)error
+{
+	_inputStream = [[CSSInputStream alloc] initWithString:selectorString];
+	[_inputStream consumeWhitespace];
+
+	CSSSelector *result = nil;
+
+	while (YES) {
+		CSSSelector *selector = [self parseSequenceOfSimpleSelectors:error];
+		if (selector == nil) {
+			break;
+		}
+
+		result = result ? allOf(@[result, selector]) : selector;
+
+		UTF32Char next = _inputStream.nextInputCharacter;
+
+		if (isCombinator(next)) {
+			NSString *combinator = [_inputStream consumeCombinator];
+
+			if ([combinator isEqualToString:@""]) {
+				result = descendantOfElementSelector(result);
+			} else if ([combinator isEqualToString:@">"]) {
+				result = childOfElementSelector(result);
+			} else if ([combinator isEqualToString:@"+"]) {
+				result = adjacentSiblingSelector(result);
+			} else if ([combinator isEqualToString:@"~"]) {
+				result = generalSiblingSelector(result);
+			}
+		}
+	}
+
+	return result;
+}
+
+- (CSSSelector *)parseSequenceOfSimpleSelectors:(NSError * __autoreleasing *)error
+{
+	NSMutableArray *selectors = [NSMutableArray array];
+
+	CSSSelector *typeSelector = [self parseTypeSelector:error];
+	if (typeSelector != nil) {
+		[selectors addObject:typeSelector];
+	}
+
+	while (YES) {
+		UTF32Char next = _inputStream.nextInputCharacter;
+		if (next == EOF || isCombinator(next)) {
+			break;
+		}
+
+		CSSSelector *simpleSelector = [self parseSimpleSelector:error];
+		if (simpleSelector == nil) {
+			return nil;
+		}
+		[selectors addObject:simpleSelector];
+	}
+
+	if (selectors.count > 1) {
+		return allOf(selectors);
+	}
+
+	return selectors.firstObject;
+}
+
+- (CSSSelector *)parseTypeSelector:(NSError * __autoreleasing *)error
+{
+	NSString *identifier = [_inputStream consumeIdentifier];
+	if (identifier != nil) {
+		return typeSelector(identifier);
+	}
+
+	if ([_inputStream consumeCharacter:ASTERIX]) {
+		return universalSelector();
+	}
+
+	return nil;
+}
+
+- (CSSSelector *)parseSimpleSelector:(NSError * __autoreleasing *)error
+{
+	CSSSelector *typeSelector = [self parseTypeSelector:error];
+	if (typeSelector != nil) {
+		return typeSelector;
+	}
+
+	UTF32Char codePoint = [_inputStream consumeNextInputCharacter];
+	switch (codePoint) {
+		case NUMBER_SIGN:
+		{
+			NSString *elementId = [_inputStream consumeIdentifier];
+			if (elementId == nil) {
+				[self emitError:error reason:@"Invalid character" location:_location + _inputStream.currentLocation];
+				return nil;
+			}
+			return  idSelector(elementId);
+		}
+		case FULL_STOP:
+		{
+			NSString *className = [_inputStream consumeIdentifier];
+			if (className == nil) {
+				[self emitError:error reason:@"Invalid character" location:_location + _inputStream.currentLocation];
+				return nil;
+			}
+			return classSelector(className);
+		}
+		case LEFT_SQUARE_BRACKET:
+		{
+			return [self parseAttributeSelector:error];
+		}
+		case COLON:
+		{
+			return [self parsePseudoSelector:error];
+		}
+		default:
+		{
+			[self emitError:error reason:@"Invalid character" location:_location + _inputStream.currentLocation];
+			return nil;
+		}
+	}
+}
+
+- (CSSSelector *)parseAttributeSelector:(NSError * __autoreleasing *)error
+{
+	NSString *attribute = [_inputStream consumeIdentifier];
+	if (attribute == nil) {
+		[self emitError:error reason:@"Invalid character" location:_location + _inputStream.currentLocation + 1];
+		return nil;
+	}
+	[_inputStream consumeWhitespace];
+
+	CSSAttributeSelectorType type = CSSAttributeSelectorExists;
+
+	NSString *operator = [_inputStream consumeCharactersInString:@"=~|^$*!"];
+
+	if ([operator isEqualToString:@"="]) {
+		type = CSSAttributeSelectorExactMatch;
+	} else if ([operator isEqualToString:@"~="]) {
+		type = CSSAttributeSelectorIncludes;
+	} else if ([operator isEqualToString:@"|="]) {
+		type = CSSAttributeSelectorHyphen;
+	} else if ([operator isEqualToString:@"^="]) {
+		type = CSSAttributeSelectorBegins;
+	} else if ([operator isEqualToString:@"$="]) {
+		type = CSSAttributeSelectorEnds;
+	} else if ([operator isEqualToString:@"*="]) {
+		type = CSSAttributeSelectorContains;
+	} else if ([operator isEqualToString:@"!="]) {
+		type = CSSAttributeSelectorNot;
+	}
+
+	NSString *value = nil;
+	[_inputStream consumeWhitespace];
+
+	UTF32Char next = _inputStream.nextInputCharacter;
+	if (isQuote(next)) {
+		UTF32Char quote = [_inputStream consumeNextInputCharacter];
+		value =  [_inputStream consumeStringWithEndingCodePoint:quote];
+	} else {
+		value = [_inputStream consumeIdentifier];
+	}
+
+	[_inputStream consumeWhitespace];
+
+	// Consume RIGHT_SQUARE_BRACKET
+	if (![_inputStream consumeCharacter:RIGHT_SQUARE_BRACKET]) {
+		[self emitError:error reason:@"Expected closing right square bracket ']'" location:_location + _inputStream.currentLocation];
+	}
+
+	if (type == CSSAttributeSelectorExists) {
+		return hasAttributeSelector(attribute);
+	}
+
+	return attributeSelector(type, attribute, value);
+}
+
+- (CSSSelector *)parsePseudoSelector:(NSError * __autoreleasing *)error
+{
+	NSString *pseudoClass = [_inputStream consumeIdentifier];
+
+	if ([pseudoClass hasPrefix:@"nth"]) {
+		[_inputStream consumeWhitespace];
+		if (![_inputStream consumeCharacter:LEFT_PARENTHESIS]) {
+			[self emitError:error reason:@"Expected opening left parenthesis '('" location:_location + _inputStream.currentLocation];
+		}
+
+		NSString *functionExpression = [_inputStream consumeCharactersUpToString:@")"];
+		CSSNthExpression expression = [CSSNthExpressionParser parseExpression:functionExpression];
+
+		[_inputStream consumeWhitespace];
+		if (![_inputStream consumeCharacter:RIGHT_PARENTHESIS]) {
+			[self emitError:error reason:@"Expected closing right parenthesis ')'" location:_location + _inputStream.currentLocation];
+		}
+
+		if ([pseudoClass isEqualToString:@"nth-child"]) {
+			return nthChildSelector(expression);
+		} else if ([pseudoClass isEqualToString:@"nth-last-child"]) {
+			return nthLastChildSelector(expression);
+		} else if ([pseudoClass isEqualToString:@"nth-of-type"]) {
+			return nthOfTypeSelector(expression);
+		} else if ([pseudoClass isEqualToString:@"nth-last-of-type"]) {
+			return nthLastOfTypeSelector(expression);
+		}
+	} else if ([pseudoClass isEqualToString:@"not"]) {
+		[_inputStream consumeWhitespace];
+		if (![_inputStream consumeCharacter:LEFT_PARENTHESIS]) {
+			[self emitError:error reason:@"Expected opening left parenthesis '('" location:_location + _inputStream.currentLocation];
+		}
+
+		CSSSelector *subSelector = [self parseSimpleSelector:error];
+		[_inputStream consumeWhitespace];
+		if (![_inputStream consumeCharacter:RIGHT_PARENTHESIS]) {
+			[self emitError:error reason:@"Expected closing right parenthesis ')'" location:_location + _inputStream.currentLocation];
+		}
+
+		return nay(subSelector);
+	} else {
+		if ([pseudoClass isEqualToString:@"even"]) {
+			return evenSlector();
+		} else if ([pseudoClass isEqualToString:@"odd"]) {
+			return oddSelector();
+		} else if ([pseudoClass isEqualToString:@"first-child"]) {
+			return firstChildSelector();
+		} else if ([pseudoClass isEqualToString:@"last-child"]) {
+			return lastChildSelector();
+		} else if ([pseudoClass isEqualToString:@"first-of-type"]) {
+			return firstOfTypeSelector();
+		} else if ([pseudoClass isEqualToString:@"last-of-type"]) {
+			return lastOfTypeSelector();
+		} else if ([pseudoClass isEqualToString:@"only-child"]) {
+			return onlyChildSelector();
+		} else if ([pseudoClass isEqualToString:@"only-of-type"]) {
+			return onlyOfTypeSelector();
+		} else if ([pseudoClass isEqualToString:@"root"]) {
+			return rootSelector();
+		} else if ([pseudoClass isEqualToString:@"empty"]) {
+			return emptySelector();
+		} else if ([pseudoClass isEqualToString:@"link"]) {
+			return linkSelector();
+		} else if ([pseudoClass isEqualToString:@"enabled"]) {
+			return enabledSelector();
+		} else if ([pseudoClass isEqualToString:@"disabled"]) {
+			return disabledSelector();
+		} else if ([pseudoClass isEqualToString:@"checked"]) {
+			return checkedSelector();
+		}
+	}
+	NSString *reason = [NSString stringWithFormat:@"Unknown pseudo class: %@", pseudoClass];
+	[self emitError:error reason:reason location:_location + _inputStream.currentLocation];
+	return nil;
+}
+
+@end