cappuccino/Foundation/CPPredicate/CPPredicate.j

@import <Foundation/CPValue.j>
@import <Foundation/CPArray.j>
@import <Foundation/CPSet.j>
@import <Foundation/CPNull.j>
@import <Foundation/CPScanner.j>

/*!
    @ingroup foundation
    @class CPPredicate
    @brief The CPPredicate class is used to define logical conditions used to constrain a search either for a fetch or for in-memory filtering.

    You use predicates to represent logical conditions, used for describing objects in persistent stores and in-memory filtering of objects. Although it is common to create predicates directly from instances of CPComparisonPredicate, CPCompoundPredicate, and CPExpression, you often create predicates from a format string which is parsed by the class methods on CPPredicate. Examples of predicate format strings include:

    Simple comparisons, such as grade == "7" or firstName like "Shaffiq"\n
    Case/diacritic insensitive lookups, such as name contains[cd] "itroen"\n
    Logical operations, such as (firstName like "Mark") OR (lastName like "Adderley")\n
    “Between” predicates such as date between {$YESTERDAY, $TOMORROW}.\n

    You can create predicates for relationships, such as:

    group.name like "work*"\n
    ALL children.age > 12\n
    ANY children.age > 12\n
    You can create predicates for operations, such as @sum.items.price < 1000.

    You can also create predicates that include variables, so that the predicate can be pre-defined before substituting concrete values at runtime with evaluateWithObject:substitutionVariables: method.
*/

@implementation CPPredicate : CPObject
{
}

/*!
    Creates and returns a new predicate formed by creating a new string with a given format and parsing the result.
    @param format The format string for the new predicate.
    @param … A comma-separated list of arguments to substitute into format.
    @return A new predicate formed by creating a new string with format and parsing the result.
*/
+ (CPPredicate)predicateWithFormat:(CPString) format, ...
{
    if (!format)
        [CPException raise:CPInvalidArgumentException reason:_cmd + " the format can't be 'nil'"];

    var args = Array.prototype.slice.call(arguments, 3);
    return [self predicateWithFormat:arguments[2] argumentArray:args];
}

/*!
    Creates and returns a new predicate by substituting the values in a given array into a format string and parsing the result.
    @param format The format string for the new predicate.
    @param arguments The arguments to substitute into predicateFormat. Values are substituted into predicateFormat in the order they appear in the array.
    @return A new predicate by substituting the values in arguments into predicateFormat, and parsing the result.
*/
+ (CPPredicate)predicateWithFormat:(CPString)format argumentArray:(CPArray)args
{
    if (!format)
        [CPException raise:CPInvalidArgumentException reason:_cmd + " the format can't be 'nil'"];

    var s = [[CPPredicateScanner alloc] initWithString:format args:args],
        p = [s parse];

    return p;
}

/*!
    Creates and returns a new predicate by substituting the values in an argument list into a format string and parsing the result.
    @param format The format string for the new predicate.
    @param argList The arguments to substitute into predicateFormat. Values are substituted into predicateFormat in the order they appear in the argument list.
    @return A new predicate by substituting the values in argList into predicateFormat and parsing the result.
*/
+ (CPPredicate)predicateWithFormat:(CPString)format arguments:(va_list)argList
{
    // UNIMPLEMENTED
    return nil;
}

/*!
    Returns a copy of the receiver with the receiver’s variables substituted by values specified in a given substitution variables dictionary.
    @param variables The substitution variables dictionary. The dictionary must contain key-value pairs for all variables in the receiver.
    @return A copy of the receiver with the receiver’s variables substituted by values specified in variables.
*/
- (CPPredicate)predicateWithSubstitutionVariables:(CPDictionary)variables
{
    // IMPLEMENTED BY SUBCLASSES
}

/*!
    Creates and returns a predicate that always evaluates to a given value.
    @param value The value to which the new predicate should evaluate.
    @return A predicate that always evaluates to value.
*/
+ (CPPredicate)predicateWithValue:(BOOL)value
{
    return [[CPPredicate_BOOL alloc] initWithBool:value];
}

// Evaluating a Predicate
/*!
    Returns a Boolean value that indicates whether a given object matches the conditions specified by the receiver.
    @param object The object against which to evaluate the receiver.
    @return YES if object matches the conditions specified by the receiver, otherwise NO.
*/
- (BOOL)evaluateWithObject:(id)object
{
    // IMPLEMENTED BY SUBCLASSES
}

/*!
    Returns a Boolean value that indicates whether a given object matches the conditions specified by the receiver after substituting in the values in a given variables dictionary.
    @param object The object against which to evaluate the receiver.
    @param variables The substitution variables dictionary. The dictionary must contain key-value pairs for all variables in the receiver.
    @return YES if object matches the conditions specified by the receiver after substituting in the values in variables for any replacement tokens, otherwise NO.
*/
- (BOOL)evaluateWithObject:(id)object substitutionVariables:(CPDictionary)variables
{
    // IMPLEMENTED BY SUBCLASSES
}

// Getting Format Information
/*!
    Returns the receiver’s format string.
    @return The receiver’s format string.
*/
- (CPString)predicateFormat
{
    // IMPLEMENTED BY SUBCLASSES
}

- (CPString)description
{
    return [self predicateFormat];
}

@end

@implementation CPPredicate_BOOL : CPPredicate
{
    BOOL _value;
}

- (id)initWithBool:(BOOL)value
{
    _value = value;
    return self;
}

- (BOOL)evaluateObject:(id)object
{
    return _value;
}

- (CPString)predicateFormat
{
    return (_value) ? @"TRUEPREDICATE" : @"FALSEPREDICATE";
}

@end


@implementation CPArray (CPPredicate)

- (CPArray)filteredArrayUsingPredicate:(CPPredicate)predicate
{
    var count = [self count],
        result = [CPArray array],
        i;

    for (i = 0; i < count; i++)
    {
        var object = self[i];
        if ([predicate evaluateWithObject:object])
            result.push(object);
    }

    return result;
}

- (void)filterUsingPredicate:(CPPredicate)predicate
{
    var count = [self count];

    while (count--)
    {
        if (![predicate evaluateWithObject:self[count]])
            splice(count, 1);
    }
}

@end

@implementation CPSet (CPPredicate)

- (CPSet)filteredSetUsingPredicate:(CPPredicate)predicate
{
    var count = [self count],
        result = [CPSet set],
        i;

    for (i = 0; i < count; i++)
    {
        var object = [self objectAtIndex:i];

        if ([predicate evaluateWithObject:object])
            [result addObject:object];
    }

    return result;
}

- (void)filterUsingPredicate:(CPPredicate)predicate
{
    var count = [self count];

    while (--count >= 0)
    {
        var object = [self objectAtIndex:count];

        if (![predicate evaluateWithObject:object])
            [self removeObjectAtIndex:count];
    }
}

@end

#define REFERENCE(variable) \
function(newValue)\
{\
    var oldValue = variable;\
    if (typeof newValue != 'undefined')\
        variable = newValue;\
    return oldValue;\
}

@implementation CPPredicateScanner : CPScanner
{
    CPEnumerator    _args;
    unsigned        _retrieved;
}

- (id) initWithString:(CPString)format args:(CPArray)args
{
    self = [super initWithString:format];
    if (self != nil)
    {
        _args = [args objectEnumerator];
    }
    return self;
}

- (id) nextArg
{
    return [_args nextObject];
}

- (BOOL)scanPredicateKeyword:(CPString)key
{
    var loc = [self scanLocation];
    var c;

    [self setCaseSensitive:NO];
    if (![self scanString:key intoString:NULL])
        return NO;

    if ([self isAtEnd])
        return YES;

    c = [[self string] characterAtIndex:[self scanLocation]];
    if (![[CPCharacterSet alphanumericCharacterSet] characterIsMember:c])
        return YES;

    [self setScanLocation:loc];

    return NO;
}

- (CPPredicate) parse
{
    var r = nil;

    try
    {
        [self setCharactersToBeSkipped:[CPCharacterSet whitespaceCharacterSet]];
        r = [self parsePredicate];
    }
    catch(error)
    {
        CPLogConsole(@"Parsing failed for "+[self string]+" with " + error);
    }
    finally
    {
        if (![self isAtEnd])
            CPLogConsole(@"Format string contains extra characters: \""+[self string]+"\"");
    }

    return r;
}

- (CPPredicate) parsePredicate
{
    return [self parseAnd];
}

- (CPPredicate) parseAnd
{
    var l = [self parseOr];

    while ([self scanPredicateKeyword:@"AND"] || [self scanPredicateKeyword:@"&&"])
    {
        var r = [self parseOr];

        if ([r isKindOfClass:[CPCompoundPredicate class]] && [r compoundPredicateType] == CPAndPredicateType)
        {
            if ([l isKindOfClass:[CPCompoundPredicate class]] && [l compoundPredicateType] == CPAndPredicateType)
            {
                [[l subpredicates] addObjectsFromArray:[r subpredicates]];
            }
            else
            {
                [[r subpredicates] insertObject:l atIndex:0];
                l = r;
            }
        }
        else if ([l isKindOfClass:[CPCompoundPredicate class]] && [l compoundPredicateType] == CPAndPredicateType)
        {
            [[l subpredicates] addObject:r];
        }
        else
        {
            l = [CPCompoundPredicate andPredicateWithSubpredicates:[CPArray arrayWithObjects:l, r]];
        }
    }
    return l;
}

- (CPPredicate) parseNot
{
    if ([self scanString:@"(" intoString:NULL])
    {
        var r = [self parsePredicate];

        if (![self scanString:@")" intoString:NULL])
            [CPException raise:CPInvalidArgumentException reason:@"Missing ) in compound predicate"];

        return r;
    }

    if ([self scanPredicateKeyword:@"NOT"] || [self scanPredicateKeyword:@"!"])
    {
        return [CPCompoundPredicate notPredicateWithSubpredicate:[self parseNot]];
    }
    if ([self scanPredicateKeyword:@"TRUEPREDICATE"])
    {
        return [CPPredicate predicateWithValue:YES];
    }
    if ([self scanPredicateKeyword:@"FALSEPREDICATE"])
    {
        return [CPPredicate predicateWithValue:NO];
    }

    return [self parseComparison];
}

- (CPPredicate) parseOr
{
    var l = [self parseNot];
    while ([self scanPredicateKeyword:@"OR"] || [self scanPredicateKeyword:@"||"])
    {
        var r = [self parseNot];

        if ([r isKindOfClass:[CPCompoundPredicate class]] && [r compoundPredicateType] == CPOrPredicateType)
        {
            if ([l isKindOfClass:[CPCompoundPredicate class]] && [l compoundPredicateType] == CPOrPredicateType)
            {
                [[l subpredicates] addObjectsFromArray:[r subpredicates]];
            }
            else
            {
                [[r subpredicates] insertObject:l atIndex:0];
                l = r;
            }
        }
        else if ([l isKindOfClass:[CPCompoundPredicate class]] && [l compoundPredicateType] == CPOrPredicateType)
        {
            [[l subpredicates] addObject:r];
        }
        else
        {
            l = [CPCompoundPredicate orPredicateWithSubpredicates:[CPArray arrayWithObjects:l, r]];
        }
    }
    return l;
}

- (CPPredicate) parseComparison
{
    var modifier = CPDirectPredicateModifier,
        type = 0,
        opts = 0,
        left,
        right,
        p,
        negate = NO,
        swap = NO;

    if ([self scanPredicateKeyword:@"ANY"])
    {
        modifier = CPAnyPredicateModifier;
    }
    else if ([self scanPredicateKeyword:@"ALL"])
    {
        modifier = CPAllPredicateModifier;
    }
    else if ([self scanPredicateKeyword:@"NONE"])
    {
        modifier = CPAnyPredicateModifier;
        negate = YES;
    }
    else if ([self scanPredicateKeyword:@"SOME"])
    {
        modifier = CPAllPredicateModifier;
        negate = YES;
    }

    left = [self parseExpression];
    if ([self scanString:@"!=" intoString:NULL] || [self scanString:@"<>" intoString:NULL])
    {
        type = CPNotEqualToPredicateOperatorType;
    }
    else if ([self scanString:@"<=" intoString:NULL] || [self scanString:@"=<" intoString:NULL])
    {
        type = CPLessThanOrEqualToPredicateOperatorType;
    }
    else if ([self scanString:@">=" intoString:NULL] || [self scanString:@"=>" intoString:NULL])
    {
        type = CPGreaterThanOrEqualToPredicateOperatorType;
    }
    else if ([self scanString:@"<" intoString:NULL])
    {
        type = CPLessThanPredicateOperatorType;
    }
    else if ([self scanString:@">" intoString:NULL])
    {
        type = CPGreaterThanPredicateOperatorType;
    }
    else if ([self scanString:@"==" intoString:NULL] || [self scanString:@"=" intoString:NULL])
    {
        type = CPEqualToPredicateOperatorType;
    }
    else if ([self scanPredicateKeyword:@"MATCHES"])
    {
        type = CPMatchesPredicateOperatorType;
    }
    else if ([self scanPredicateKeyword:@"LIKE"])
    {
        type = CPLikePredicateOperatorType;
    }
    else if ([self scanPredicateKeyword:@"BEGINSWITH"])
    {
        type = CPBeginsWithPredicateOperatorType;
    }
    else if ([self scanPredicateKeyword:@"ENDSWITH"])
    {
        type = CPEndsWithPredicateOperatorType;
    }
    else if ([self scanPredicateKeyword:@"IN"])
    {
        type = CPInPredicateOperatorType;
    }
    else if ([self scanPredicateKeyword:@"CONTAINS"])
    {
        type = CPInPredicateOperatorType;
        swap = YES;
    }
    else if ([self scanPredicateKeyword:@"BETWEEN"])
    {
        var exp = [self parseSimpleExpression],
            a = [exp constantValue],
            lower, upper,
            lexp, uexp,
            lp, up;

        if (![a isKindOfClass:[CPArray class]])
            [CPException raise:CPInvalidArgumentException reason:@"BETWEEN operator requires array argument"];

        lower = [a objectAtIndex:0];
        upper = [a objectAtIndex:1];
        lexp = [CPExpression expressionForConstantValue:lower];
        uexp = [CPExpression expressionForConstantValue:upper];
        lp = [CPComparisonPredicate predicateWithLeftExpression:left
              rightExpression:lexp
              modifier:modifier
              type:CPGreaterThanPredicateOperatorType
              options:opts];
        up = [CPComparisonPredicate predicateWithLeftExpression:left
              rightExpression:uexp
              modifier:modifier
              type:CPLessThanPredicateOperatorType
              options:opts];
        return [CPCompoundPredicate andPredicateWithSubpredicates:
                [CPArray arrayWithObjects:lp, up]];
    }
    else
        [CPException raise:CPInvalidArgumentException reason:@"Invalid comparison predicate: "+ [[self string] substringFromIndex: [self scanLocation]]];

    if ([self scanString:@"[cd]" intoString:NULL])
    {
        opts = CPCaseInsensitivePredicateOption | CPDiacriticInsensitivePredicateOption;
    }
    else if ([self scanString:@"[c]" intoString:NULL])
    {
        opts = CPCaseInsensitivePredicateOption;
    }
    else if ([self scanString:@"[d]" intoString:NULL])
    {
        opts = CPDiacriticInsensitivePredicateOption;
    }

    right = [self parseExpression];

    if (swap == YES)
    {
        var tmp = left;

        left = right;
        right = tmp;
    }

    p = [CPComparisonPredicate predicateWithLeftExpression:left
         rightExpression:right
         modifier:modifier
         type:type
         options:opts];

    return negate ? [CPCompoundPredicate notPredicateWithSubpredicate:p]:p;
}

- (CPExpression) parseExpression
{
    return [self parseBinaryExpression];
}

- (CPExpression) parseSimpleExpression
{
    var identifier,
        location,
        ident,
        dbl;

    if ([self scanDouble:REFERENCE(dbl)])
        return [CPExpression expressionForConstantValue:[CPNumber numberWithDouble:dbl]];

    // FIXME: handle integer, hex constants, 0x 0o 0b
    if ([self scanString:@"-" intoString:NULL])
        return [CPExpression expressionForFunction:@"chs" arguments:[CPArray arrayWithObject:[self parseExpression]]];

    if ([self scanString:@"(" intoString:NULL])
    {
        var arg = [self parseExpression];

        if (![self scanString:@")" intoString:NULL])
            [CPException raise:CPInvalidArgumentException reason:@"Missing ) in expression"];

        return arg;
    }

    if ([self scanString:@"{" intoString:NULL])
    {
        var a = [CPMutableArray arrayWithCapacity:10];

        if ([self scanString:@"}" intoString:NULL])
            return [CPExpression expressionForConstantValue:a];

        [a addObject:[self parseExpression]];
        while ([self scanString:@"," intoString:NULL])
            [a addObject:[self parseExpression]];

        if (![self scanString:@"}" intoString:NULL])
            [CPException raise:CPInvalidArgumentException reason:@"Missing } in aggregate"];

        return [CPExpression expressionForConstantValue:a];
    }

    if ([self scanPredicateKeyword:@"NULL"] || [self scanPredicateKeyword:@"NIL"])
    {
        return [CPExpression expressionForConstantValue:[CPNull null]];
    }
    if ([self scanPredicateKeyword:@"TRUE"] || [self scanPredicateKeyword:@"YES"])
    {
        return [CPExpression expressionForConstantValue:[CPNumber numberWithBool:YES]];
    }
    if ([self scanPredicateKeyword:@"FALSE"] || [self scanPredicateKeyword:@"NO"])
    {
        return [CPExpression expressionForConstantValue:[CPNumber numberWithBool:NO]];
    }
    if ([self scanPredicateKeyword:@"SELF"])
    {
        return [CPExpression expressionForEvaluatedObject];
    }

    if ([self scanString:@"$" intoString:NULL])
    {
        var variable = [self parseExpression];

        if (![variable keyPath])
            [CPException raise:CPInvalidArgumentException reason:@"Invalid variable identifier: " + variable];

        return [CPExpression expressionForVariable:[variable keyPath]];
    }

    location = [self scanLocation];

    if ([self scanString:@"%" intoString:NULL])
    {
        if ([self isAtEnd] == NO)
        {
            var c = [[self string] characterAtIndex:[self scanLocation]];

            switch (c)
            {
                case '%':// '%%' is treated as '%'
                    location = [self scanLocation];
                    break;
                case 'K':
                    [self setScanLocation:[self scanLocation] + 1];
                    return [CPExpression expressionForKeyPath:[self nextArg]];
                case '@':
                case 'c':
                case 'C':
                case 'd':
                case 'D':
                case 'i':
                case 'o':
                case 'O':
                case 'u':
                case 'U':
                case 'x':
                case 'X':
                case 'e':
                case 'E':
                case 'f':
                case 'g':
                case 'G':
                    [self setScanLocation:[self scanLocation] + 1];
                    return [CPExpression expressionForConstantValue:[self nextArg]];
                case 'h':
                    [self scanString:@"h" intoString:NULL];
                    if ([self isAtEnd] == NO)
                    {
                        c = [[self string] characterAtIndex:[self scanLocation]];
                        if (c == 'i' || c == 'u')
                        {
                            [self setScanLocation:[self scanLocation] + 1];
                            return [CPExpression expressionForConstantValue:[self nextArg]];
                        }
                    }
                    break;
                case 'q':
                    [self scanString:@"q" intoString:NULL];
                    if ([self isAtEnd] == NO)
                    {
                        c = [[self string] characterAtIndex:[self scanLocation]];
                        if (c == 'i' || c == 'u' || c == 'x' || c == 'X')
                        {
                            [self setScanLocation:[self scanLocation] + 1];
                            return [CPExpression expressionForConstantValue:[self nextArg]];
                        }
                    }
                    break;
            }
        }

        [self setScanLocation:location];
    }

    if ([self scanString:@"\"" intoString:NULL])
    {
        var skip = [self charactersToBeSkipped],
            str;

        [self setCharactersToBeSkipped:nil];
        if ([self scanUpToString:@"\"" intoString:REFERENCE(str)] == NO)
        {
            [self setCharactersToBeSkipped:skip];
            [CPException raise:CPInvalidArgumentException reason:@"Invalid double quoted literal at "+location];
        }

        [self scanString:@"\"" intoString:NULL];
        [self setCharactersToBeSkipped:skip];

        return [CPExpression expressionForConstantValue:str];
    }
    if ([self scanString:@"'" intoString:NULL])
    {
        var skip = [self charactersToBeSkipped],
            str;

        [self setCharactersToBeSkipped:nil];
        if ([self scanUpToString:@"'" intoString:REFERENCE(str)] == NO)
        {
            [self setCharactersToBeSkipped:skip];
            [CPException raise:CPInvalidArgumentException reason:@"Invalid single quoted literal at "+location];
        }

        [self scanString:@"'" intoString:NULL];
        [self setCharactersToBeSkipped:skip];

        return [CPExpression expressionForConstantValue:str];
    }

    if ([self scanString:@"@" intoString:NULL])
    {
        var e = [self parseExpression];

        if (![e keyPath])
            [CPException raise:CPInvalidArgumentException reason:@"Invalid keypath identifier: "+e];

        return [CPExpression expressionForKeyPath:[e keyPath]+"@"];
    }

    [self scanString:@"#" intoString:NULL];
    if (!identifier)
        identifier = [CPCharacterSet characterSetWithCharactersInString:@"_$abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"];

    if (![self scanCharactersFromSet:identifier intoString:REFERENCE(ident)])
        [CPException raise:CPInvalidArgumentException reason:@"Missing identifier: "+[[self string] substringFromIndex:[self scanLocation]]];

    return [CPExpression expressionForKeyPath:ident];
}

- (CPExpression)parseFunctionalExpression
{
    var left = [self parseSimpleExpression];

    while (YES)
    {
        if ([self scanString:@"(" intoString:NULL])
        {
            // function - this parser allows for (max)(a, b, c) to be properly
            // recognized and even (%K)(a, b, c) if %K evaluates to "max"
            var args = [CPMutableArray arrayWithCapacity:5];

            if (![left keyPath])
                [CPException raise:CPInvalidArgumentException reason:@"Invalid function identifier: " + left];

            if (![self scanString:@")" intoString:NULL])
            {
                // any arguments
                // first argument
                [args addObject:[self parseExpression]];
                while ([self scanString:@"," intoString:NULL])
                {
                    // more arguments
                    [args addObject:[self parseExpression]];
                }

                if (![self scanString:@")" intoString:NULL])
                    [CPException raise:CPInvalidArgumentException reason:@"Missing ) in function arguments"];
            }
            left = [CPExpression expressionForFunction:[left keyPath] arguments:args];
        }
        else if ([self scanString:@"[" intoString:NULL])
        {
            // index expression
            if ([self scanPredicateKeyword:@"FIRST"])
            {
                left = [CPExpression expressionForFunction:@"first" arguments:[CPArray arrayWithObject:[self parseExpression]]];
            }
            else if ([self scanPredicateKeyword:@"LAST"])
            {
                left = [CPExpression expressionForFunction:@"last" arguments:[CPArray arrayWithObject:[self parseExpression]]];
            }
            else if ([self scanPredicateKeyword:@"SIZE"])
            {
                left = [CPExpression expressionForFunction:@"count" arguments:[CPArray arrayWithObject:[self parseExpression]]];
            }
            else
            {
                left = [CPExpression expressionForFunction:@"index" arguments:[CPArray arrayWithObjects:left, [self parseExpression]]];
            }
            if (![self scanString:@"]" intoString:NULL])
                [CPException raise:CPInvalidArgumentException reason:@"Missing ] in index argument"];
        }
        else if ([self scanString:@"." intoString:NULL])
        {
            // keypath - this parser allows for (a).(b.c)
            // to be properly recognized
            // and even %K.((%K)) if the first %K evaluates to "a" and the
            // second %K to "b.c"

            if (![left keyPath])
                [CPException raise:CPInvalidArgumentException reason:@"Invalid left keypath:" + left];

            var right = [self parseExpression];
            if (![right keyPath])
                [CPException raise:CPInvalidArgumentException reason:@"Invalid right keypath:" + right];

            // concatenate
            left = [CPExpression expressionForKeyPath:[left keyPath]+ "." + [right keyPath]];
        }
        else
        {
            // done with suffixes
            return left;
        }
    }
}

- (CPExpression)parsePowerExpression
{
    var left = [self parseFunctionalExpression];

    while (YES)
    {
        var right;

        if ([self scanString:@"**" intoString:NULL])
        {
            right = [self parseFunctionalExpression];
            left = [CPExpression expressionForFunction:@"pow" arguments:[CPArray arrayWithObjects:left, right]];
        }
        else
        {
            return left;
        }
    }
}

- (CPExpression)parseMultiplicationExpression
{
    var left = [self parsePowerExpression];

    while (YES)
    {
        var right;

        if ([self scanString:@"*" intoString:NULL])
        {
            right = [self parsePowerExpression];
            left = [CPExpression expressionForFunction:@"_mul" arguments:[CPArray arrayWithObjects:left, right]];
        }
        else if ([self scanString:@"/" intoString:NULL])
        {
            right = [self parsePowerExpression];
            left = [CPExpression expressionForFunction:@"_div" arguments:[CPArray arrayWithObjects:left, right]];
        }
        else
        {
            return left;
        }
    }
}

- (CPExpression)parseAdditionExpression
{
    var left = [self parseMultiplicationExpression];

    while (YES)
    {
        var right;

        if ([self scanString:@"+" intoString:NULL])
        {
            right = [self parseMultiplicationExpression];
            left = [CPExpression expressionForFunction:@"_add" arguments:[CPArray arrayWithObjects:left, right]];
        }
        else if ([self scanString:@"-" intoString:NULL])
        {
            right = [self parseMultiplicationExpression];
            left = [CPExpression expressionForFunction:@"_sub" arguments:[CPArray arrayWithObjects:left, right]];
        }
        else
        {
            return left;
        }
    }
}

- (CPExpression)parseBinaryExpression
{
    var left = [self parseAdditionExpression];

    while (YES)
    {
        var right;

        if ([self scanString:@":=" intoString:NULL])    // assignment
        {
            // check left to be a variable?
            right = [self parseAdditionExpression];
            // FIXME
        }
        else
        {
            return left;
        }
    }
}

@end

@import "CPCompoundPredicate.j"
@import "CPComparisonPredicate.j"

@import "CPExpression.j"
@import "CPExpression_operator.j"
@import "CPExpression_aggregate.j"
@import "CPExpression_assignment.j"