//
//  MPFunctionTerm.h
//  MathPad
//
//  Created by Kim Wittenburg on 12.11.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPTerm.h"

/*!
 @header
 This file contains the <code>MPFunctionTerm</code> class.
 */


/*!
    @define     MPEvaluateExpression
    @abstract   Evaluates the receiver's child at the specified index and assigns
                the evaluation result to a variable.
 
    @discussion If errors occur during evaluation this macro returns
                <code>nil</code>. Also there has to exist a <code>NSError *__autoreleasing *</code> pointer called <code>error</code>.
 
    @param      var
                The name of the variable that will be declared in this macro. It
                will be of the type <code>NSDecimalNumber *</code> and contain
                the result of the evaluation.
 
    @param      index
                The index of the child to be evaluated.
 */
#define MPEvaluateExpression(var, index) NSDecimalNumber *var = [[self expressionAtIndex:index] evaluate:error]; if (var == nil) return nil



@class MPFunctionTerm, MPFunction, MPParsedExpression;


/*!
    @class      MPFunctionTerm
    @abstract   A function term represents the term of a generic function.
 
    @discussion This class is an abstract class that can not be evaluated. It is
                the common superclass of all terms that represent <code>@link
                //apple_ref/occ/cl/MPFunction@/link</code> instances.
 */
@interface MPFunctionTerm : MPTerm

/*!
    @method     initWithFunction:errors:
    @abstract   Initializes a <code>MPFunctionTerm</code> from the specified
                <code>@link //apple_ref/occ/cl/MPFunction@/link</code> instance.
 
    @discussion This method parses the children of the specified
                <code>function</code> and stores the respective parsed
                expressions. They are accessible using the <code>@link
                //apple_ref/occ/instm/MPFunctionTerm/expressionAtIndex:@/link</code>
                method.
 
                Whether the children should contain a variable definition is
                determined using the <code>@link
                //apple_ref/occ/instm/MPFunction/expectsVariableDefinitionInChildAtIndex:@/link</code>

    @param      function
                The function to initialize the receiver with. This method parses
                the function's children. If any of them contain syntax errors
                they are returned indirectly through the <code>errors</code>
                parameter.
 
    @param      errors
                If any of the <code>function</code>'s children contain syntax
                errors they are returned indirectly through this parameter. In
                that case the method returns <code>nil</code>. If there are no
                errors the parameter is not modified. This parameter is never set
                to an empty array.
 
    @return     A new <code>MPFunctionTerm</code> instance.
 */
- (instancetype)initWithFunction:(MPFunction *)function
                          errors:(NSArray *__autoreleasing *)errors; /* designated initializer */


/*!
    @method     expressionAtIndex:
    @abstract   Returns a <code>@link
                //apple_ref/occ/cl/MPParsedExpression@/link</code> instance that
                represents the child at <code>anIndex</code> of the function that
                is represented by the receiver.
 
    @param      anIndex
                The index of the child.
 
    @return     A parsed expression that represents th
 */
- (MPParsedExpression *)expressionAtIndex:(NSUInteger)anIndex;

@end