/*
     NSFNanoPredicate.h
     NanoStore
     
     Copyright (c) 2010 Webbo, L.L.C. All rights reserved.
     
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     provided that the following conditions are met:
     
     * Redistributions of source code must retain the above copyright notice, this list of conditions
     and the following disclaimer.
     * Redistributions in binary form must reproduce the above copyright notice, this list of conditions
     and the following disclaimer in the documentation and/or other materials provided with the distribution.
     * Neither the name of Webbo nor the names of its contributors may be used to endorse or promote
     products derived from this software without specific prior written permission.
     
     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
     WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
     PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY
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 */

/*! @file NSFNanoPredicate.h
 @brief A predicate is an element of an expression used to perform complex queries.
 */

/** @class NSFNanoPredicate
 * A predicate is an element of an expression used to perform complex queries.
 *
 * @note
 * A predicate must be added to a NSFNanoExpression.
 *
 * @details <b>Example:</b>
 @code
 // Instantiate a NanoStore and open it
 NSFNanoStore *nanoStore = [NSFNanoStore createAndOpenStoreWithType:NSFMemoryStoreType path:nil error:nil];
 
 // Add some data to the document store
 NSDictionary *info = ...;
 NSFNanoObject *object = [NSFNanoObject nanoObjectWithDictionary:info];
 [nanoStore addObject:object error:nil];
 
 // Prepare the expression
 NSFNanoPredicate *attribute = [NSFNanoPredicate predicateWithColumn:NSFAttributeColumn matching:NSFEqualTo value:@"FirstName"];
 NSFNanoPredicate *value = [NSFNanoPredicate predicateWithColumn:NSFValueColumn matching:NSFEqualTo value:@"Hobbes"];
 NSFNanoExpression *expression = [NSFNanoExpression expressionWithPredicate:predicateAttribute];
 [expression addPredicate:predicateValue withOperator:NSFAnd];
 
 // Setup the search with the document store and a given expression
 NSFNanoSearch *search = [NSFNanoSearch searchWithStore:nanoStore];
 [search setExpressions:[NSArray arrayWithObject:expression]];
 
 // Obtain the matching objects
 NSDictionary *searchResults = [search searchObjectsWithReturnType:NSFReturnObjects error:nil];
 
 // Close the document store
 [nanoStore closeWithError:nil];
 @endcode
 *
 * @see \link NSFNanoExpression::expressionWithPredicate: + (NSFNanoExpression*)expressionWithPredicate:(NSFNanoPredicate *)thePredicate \endlink
 * @see \link NSFNanoExpression::initWithPredicate: - (id)initWithPredicate:(NSFNanoPredicate *)thePredicate \endlink
 * @see \link NSFNanoExpression::addPredicate:withOperator: - (void)addPredicate:(NSFNanoPredicate *)thePredicate withOperator:(NSFOperator)theOperator \endlink
 */

#import <Foundation/Foundation.h>

#import "NSFNanoGlobals.h"

@interface NSFNanoPredicate : NSObject

/** * The type of column being referenced. */
@property (nonatomic, assign, readonly) NSFTableColumnType column;
/** * The comparison operator to be used. */
@property (nonatomic, assign, readonly) NSFMatchType match;
/** * The value to be used for comparison.  */
@property (nonatomic, copy, readonly) NSString *value;

/** @name Creating and Initializing a Predicate
 */

//@{

/** * Creates and returns a predicate.
 * @param theType is the column type. Can be \link Globals::NSFKeyColumn NSFKeyColumn \endlink, \link Globals::NSFAttributeColumn NSFAttributeColumn \endlink or \link Globals::NSFValueColumn NSFValueColumn \endlink.
 * @param theMatch is the match operator.
 * @param theValue is the value.
 * @return A predicate which can be used in an NSFNanoExpression.
 * @see \link initWithColumn:matching:value: - (id)initWithColumn:(NSFTableColumnType)theType matching:(NSFMatchType)theMatch value:(NSString *)theValue \endlink
 */

+ (NSFNanoPredicate*)predicateWithColumn:(NSFTableColumnType)theType matching:(NSFMatchType)theMatch value:(NSString *)theValue;

/** * Initializes a newly allocated predicate.
 * @param theType is the column type. Can be \link Globals::NSFKeyColumn NSFKeyColumn \endlink, \link Globals::NSFAttributeColumn NSFAttributeColumn \endlink or \link Globals::NSFValueColumn NSFValueColumn \endlink.
 * @param theMatch is the match operator.
 * @param theValue is the value.
 * @return A predicate which can be used in an NSFNanoExpression.
 * @see \link predicateWithColumn:matching:value: + (NSFNanoPredicate*)predicateWithColumn:(NSFTableColumnType)theType matching:(NSFMatchType)theMatch value:(NSString *)theValue \endlink
 */

- (id)initWithColumn:(NSFTableColumnType)theType matching:(NSFMatchType)theMatch value:(NSString *)theValue;

//@}

/** @name Miscellaneous
 */

//@{

/** * Returns a string representation of the predicate.
 * @note Check properties column, match and value to find out the current state of the predicate.
 * @see \link description - (NSString *)description \endlink
 */

- (NSString *)description;

//@}

@end