On Wed, Nov 12, 2008 at 6:22 PM, Ariel Rodriguez <[EMAIL PROTECTED]> wrote: > thanks Stephen for your kind response. I think i've grasp the theory, but i > am not qite sure about the best way to implement the algorithm. Perhaps to > set a flag to indicate wether the "country" object is the root one or the > nested one?
That's the basic idea. First, draw out the state machine (see the
attached PNG). Then you assign numbers to each of the states:
typedef enum _MyParserStates {
STATE_INITIAL,
STATE_EDIT_COUNTRY,
STATE_SET_COUNTRY,
STATE_SET_ID,
STATE_SET_GDP,
STATE_SET_ISO_CODE
} MyParserStates;
Then, you code the transitions in your delegate (which tracks the state).
- (void) parser:(NSXMLParser *)parser
didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qualifiedName
attributes:(NSDictionary *)attributeDict {
switch (state) {
case STATE_INITIAL:
if ([elementName isEqualToString:@"country"]) {
// create a new country object and store it somewhere
state = STATE_EDIT_COUNTRY;
}
break;
case STATE_EDIT_COUNTRY:
if ([elementName isEqualToString:@"country"]) {
state = STATE_SET_COUNTRY;
} else if ([elementName isEqualToString:@"id"]) {
state = STATE_SET_ID;
} else if () {
// you get the idea
}
break;
}
}
- (void) parser:(NSXMLParser *)parser
foundCharacters:(NSString *)string {
switch (state) {
case STATE_SET_COUNTRY:
// get the current country object
// set the country name field
break;
case STATE_SET_ID:
// get the current country object
// set the ID field
break;
// ...so on and so forth for the rest of the properties
}
}
- (void) parser:(NSXMLParser *)parser
didEndElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qName {
switch (state) {
case STATE_SET_COUNTRY:
if ([elementName isEqualToString:@"country"])
state = STATE_EDIT_COUNTRY;
break;
case STATE_SET_ID:
if ([elementName isEqualToString:@"id"])
state = STATE_EDIT_COUNTRY;
break;
// ... so on and so forth for the rest of the properties
case STATE_EDIT_COUNTRY:
if ([elementName isEqualToString:@"country"])
{
// validate the current country object
// store the current country object somewhere
// clear the current country object
state = STATE_INITIAL;
}
}
}
Pretty straight forward and fool proof!
<<attachment: coutry-state-machine.png>>
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