Expose NSAttributedString Parser about interfacss

[tbrannam]

Found that if the attributed string parser is used in this context, variable references are not handled.

ParcoaParser* attributedStringAttributesParser = [[Parcoa iss_parameterString] transform:^id(NSArray* values) {
    NSMutableDictionary* attributes = [NSMutableDictionary dictionary];
    for(NSString* pairString in values) {
        NSArray* components = [pairString iss_trimmedSplit:@":"];
        if( components.count == 2 && [components[0] iss_hasData] && [components[1] iss_hasData] ) {
            // Get property def
            ISSPropertyDefinition* def = attributedStringProperties[[components[0] lowercaseString]];
            if( def ) {


                // Potential fix to standalone use - this seems to get executed by another parser if used when parsing CSS file
                // Is this costly to do here also?
                id value =[self replaceVariableReferences:components[1]];

                // Parse value
                value = [blockSelf parsePropertyValue:value ofType:def.type];

                if( value ) {
                    // Use standard method in ISSPropertyDefinition to set value (using custom setter block)
                    [def setValue:value onTarget:attributes andParameters:nil withPrefixKeyPath:nil];
                } else {
                    ISSLogWarning(@"Unknown attributed string value `%@` for property `%@`", components[1], components[0]);
                }
            } else {
                ISSLogWarning(@"Unknown attributed string property: `%@`", components[0]);
            }
        }
    }
    return attributes;
} name:@"attributedStringAttributesParser"];

[tolo]

The protocol ISSStyleSheetParser actually already provides methods ([ISSStyleSheetParser transformValue:asPropertyType] for instance) for making it possible to manually transform a property value of a specific property type. The only missing bit was the variable substitution, but that is resolved in 1b69da4.