NSFormatter+GRMustache.m

// The MIT License
//
// Copyright (c) 2014 Gwendal Roué
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#import "NSFormatter+GRMustache.h"
#import "GRMustacheTag.h"
#import "GRMustacheContext.h"

@implementation NSFormatter (GRMustache)

#pragma mark - <GRMustacheFilter>

/**
 * Support for {{ formatter(value) }}
 */
- (id)transformedValue:(id)object
{
    // [NSNumberFormatter stringForObjectValue:] and
    // [NSDateFormatter stringForObjectValue:] return nil or an empty string for
    // nil, [NSNull null], and other off-topic values.
    //
    // Since nil and empty strings do not render anything, and are false when
    // controlling boolean sections, we can safely say that formatters do not
    // have surprising behavior: just use the plain straight
    // stringForObjectValue: without any special care.
    return [self stringForObjectValue:object];
}

#pragma mark - <GRMustacheRendering>

/**
 * Support for {{# formatter }}...{{ value }}...{{ value }}...{{/ formatter }}
 */
- (NSString *)renderForMustacheTag:(GRMustacheTag *)tag context:(GRMustacheContext *)context HTMLSafe:(BOOL *)HTMLSafe error:(NSError **)error
{
    switch (tag.type) {
        case GRMustacheTagTypeVariable:
            // {{ formatter }}
            // Behave as a regular object: render self's description
            if (HTMLSafe != NULL) { *HTMLSafe = NO; }
            return [self description];
            
        case GRMustacheTagTypeSection:
            // {{# formatter }}...{{/ formatter }}
            // {{^ formatter }}...{{/ formatter }}
            
            // Render normally, but listen to all inner tags rendering, so that
            // we can format them. See mustacheTag:willRenderObject: below.
            context = [context contextByAddingTagDelegate:self];
            return [tag renderContentWithContext:context HTMLSafe:HTMLSafe error:error];
    }
}

#pragma mark - <GRMustacheTagDelegate>

/**
 * Support for {{# formatter }}...{{ value }}...{{ value }}...{{/ formatter }}
 */
- (id)mustacheTag:(GRMustacheTag *)tag willRenderObject:(id)object
{
    switch (tag.type) {
        case GRMustacheTagTypeVariable: {
            // {{ value }}
            
            NSString *formatted = [self stringForObjectValue:object];
            
            if (formatted == nil) {
                // NSFormatter documentation for stringForObjectValue: states:
                //
                // > First test the passed-in object to see if it’s of the correct
                // > class. If it isn’t, return nil; but if it is of the right class,
                // > return a properly formatted and, if necessary, localized string.
                //
                // So nil result means that object is not of the correct class. Leave
                // it untouched.
                
                return object;
            }
            
            return formatted;
        }
            
        case GRMustacheTagTypeSection:
            // {{# value }}
            // {{^ value }}
            return object;
    }
}

@end