OpalXMLResourceParser.m

//
//  OpalXMLResourceParser.m
//  Opal
//
//  Created by Christian Niles on 5/22/10.
//  Copyright 2010 Christian Niles. All rights reserved.
//

#import "OpalXMLResourceParser.h"
#import "OpalXMLScanner.h"
#import "OpalXMLParser.h"
#import "OpalXMLEvent.h"
#import "RegexKitLite.h"

@interface OpalXMLResourceParser ()
+ (NSDateFormatter *)dateFormatter;
@end


@implementation OpalXMLResourceParser

+ (NSDictionary *)parseResourceFromString:(NSString *)resourceXML
{
	OpalXMLParser *parser = [OpalXMLParser parserWithString:resourceXML];
	return [self parseResource:parser];
}

+ (NSDictionary *)parseResource:(OpalXMLParser *)parser
{
	OpalXMLEvent *event = [parser nextStartTag];
	if (event != nil) {
		id value = [self parseResourceValue:parser];
		return [NSDictionary dictionaryWithObject:value forKey:event.tagName];
	} else {
		return [NSDictionary dictionary];
	}
}

+ (id)parseResourceValue:(OpalXMLParser *)parser
{
	OpalXMLEvent *startTag = [parser currentEvent];
	if (![startTag isStartTag]) return [NSNull null];
	
	id value;
	NSString *type = [startTag valueForAttribute:@"type"];
	if (type && [type caseInsensitiveCompare:@"integer"] == NSOrderedSame) {
		value = [self parseIntegerValue:parser];
	} else if (type && [type caseInsensitiveCompare:@"datetime"] == NSOrderedSame) {
		value = [self parseDateValue:parser];
	} else if (type && [type caseInsensitiveCompare:@"array"] == NSOrderedSame) {
		value = [self parseArrayValue:parser];
	} else {
		value = [self parseUntypedValue:parser];
	}
	
	if (value == nil) value = [NSNull null];
	return value;
}

+ (NSNumber *)parseIntegerValue:(OpalXMLParser *)parser
{
	// get the start tag's text value, then convert it to an integer
	NSMutableString *content = [parser readElementText];
	NSString *numberText = [content stringByMatching:@"\\d+"];
	if (numberText) {
		long long integer = [numberText longLongValue];
		return [NSNumber numberWithLongLong:integer];
	} else {
		return nil;
	}
}

+ (NSDate *)parseDateValue:(OpalXMLParser *)parser
{
	NSString *content = [parser readElementText];
	content = [content stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
	// DateFormatter doesn't seem to like 'UTC'
	content = [content stringByReplacingOccurrencesOfString:@"UTC" withString:@"GMT"];
	
	return [[self dateFormatter] dateFromString:content];
}

+ (NSDateFormatter *)dateFormatter
{
	NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
	[formatter setDateFormat:@"yyyy/M/d HH:mm:ss zzz"];
	return formatter;
}

+ (NSMutableArray *)parseArrayValue:(OpalXMLParser *)parser
{
	// parse each item into an array
	NSMutableArray *arrayContent = [NSMutableArray arrayWithCapacity:1];
	OpalXMLEvent *item;
	do {
		item = [parser nextContentEvent];
		if ([item isStartTag]) {
			[arrayContent addObject:[self parseResourceValue:parser]];
		}
	} while (![item isEndTag]);
	return arrayContent;	
}


+ (id)parseUntypedValue:(OpalXMLParser *)parser
{
	// examine the content, look for simple or complex content
	OpalXMLEvent *contentEvent = [parser nextContentEvent];
	if ([contentEvent isEndTag]) {
		return nil;
	} else if ([contentEvent isText]) {
		NSString *simpleContent;
		if ([[parser peek] isEndTag]) {
			simpleContent = [contentEvent content];
			[parser nextEvent];
		} else {
			// multiple values?
			NSMutableString *mutableContent = [parser readElementText];
			[mutableContent insertString:[contentEvent content] atIndex:0];
			simpleContent = mutableContent;
		}
		return [simpleContent stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
	} else {
		// start tag
		NSMutableDictionary *complexContent = [NSMutableDictionary dictionaryWithCapacity:1];
		do {
			NSString *fieldName = [contentEvent tagName];
			id fieldValue = [self parseResourceValue:parser];
			
			id existingValue = [complexContent objectForKey:fieldName];
			if (existingValue == nil) {
				// this is the first value, so create the key
				[complexContent setObject:fieldValue forKey:[contentEvent tagName]];
			} else if ([existingValue isKindOfClass:[NSMutableArray class]]) {
				// this is the 3+ value, so append to the existing array
				[existingValue addObject:fieldValue];
			} else {
				// this is the second value, so create an array
				NSMutableArray *multipleValues = [NSMutableArray arrayWithCapacity:2];
				[multipleValues addObject:existingValue];
				[multipleValues addObject:fieldValue];
				[complexContent setObject:multipleValues forKey:fieldName];
			}
			contentEvent = [parser nextContentEvent];
		} while (![contentEvent isEndTag]);
		return complexContent;
	}
}

#pragma mark -
#pragma mark XML Serialization

+ (void)writeResource:(id)resource
          toXMLString:(NSMutableString *)xmlString
{
  if (resource == nil || resource == [NSNull null]) { return; }
  
  if ([resource isKindOfClass:[NSString class]]) {
    [xmlString appendString:[OpalXMLScanner escapeString:resource]];
  } else if ([resource isKindOfClass:[NSDictionary class]]) {
    [self writeResourceData:(NSDictionary *)resource 
                toXMLString:xmlString];
  } else if ([resource isKindOfClass:[NSArray class]]) {
    [self writeResources:[(NSArray *)resource objectEnumerator]
             toXMLString:xmlString];
  } else if ([resource respondsToSelector:@selector(stringValue)]) {
    [xmlString appendString:[resource stringValue]];
  } else {
    [xmlString appendString:[OpalXMLScanner escapeString:[resource description]]];
  }
}

+ (void)writeResourceData:(NSDictionary *)resourceData
              toXMLString:(NSMutableString *)xmlString
{
  NSEnumerator *keyEnumerator = [resourceData keyEnumerator];
  for (NSString *key in keyEnumerator) {
    id resourceValue = [resourceData objectForKey:key];
    
    NSString *typeString = nil;
    if ([resourceValue isKindOfClass:[NSArray class]]) {
      typeString = @"array";
    } else if ([resourceValue isKindOfClass:[NSDate class]]) {
      typeString = @"datetime";
    } else if ([resourceValue isKindOfClass:[NSNumber class]]) {
      NSNumber *number = resourceValue;
      const char *valueType = [number objCType];
      switch (*valueType) {
        case 'f':
        case 'd':
          typeString = @"float";
          break;
        default:
          typeString = @"integer";
          break;
      }
    }
    
    if (typeString) {
      [xmlString appendFormat:@"<%@ type='%@'>", key, typeString];
    } else {
      [xmlString appendFormat:@"<%@>", key];
    }
    
    [self writeResource:resourceValue toXMLString:xmlString];
    [xmlString appendFormat:@"</%@>", key];
  }
}

+ (void)writeResources:(NSEnumerator *)resourceEnumerator
           toXMLString:(NSMutableString *)xmlString
{
  for (id resource in resourceEnumerator) {
    [self writeResource:resource toXMLString:xmlString];
  }
}

@end