Fundamental Redesign of Evaluation

MathPad/MPElementaryFunctionTerm.m

@@ -0,0 +1,109 @@
+//
+//  MPFunctionValue.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 11.10.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPElementaryFunctionTerm.h"
+
+#import "MPParsedExpression.h"
+#import "MPPowerFunction.h"
+#import "MPProductTerm.h"
+#import "MPTokenStream.h"
+#import "MPToken.h"
+
+#import "MPExpression.h"
+#import "MPMathRules.h"
+
+@implementation MPElementaryFunctionTerm {
+    NSDecimalNumber *(^_function)(NSDecimalNumber *);
+}
+
+- (instancetype)initWithFunctionIdentifier:(NSString *)function
+                                      term:(MPTerm *)term
+{
+    self = [super init];
+    if (self) {
+        NSAssert(function != nil, @"function must not be nil.");
+        NSAssert(term != nil, @"term must not be nil.");
+        double (*func)(double);
+        BOOL takesArc = NO;
+        BOOL returnsArc = NO;
+        if ([function isEqualToString:@"sin"]) {
+            func = &sin;
+            takesArc = YES;
+        } else if ([function isEqualToString:@"cos"]) {
+            func = &cos;
+            takesArc = YES;
+        } else if ([function isEqualToString:@"tan"]) {
+            func = &tan;
+            takesArc = YES;
+        } else if ([function isEqualToString:@"asin"]) {
+            func = &asin;
+            returnsArc = YES;
+        } else if ([function isEqualToString:@"acos"]) {
+            func = &acos;
+            returnsArc = YES;
+        } else if ([function isEqualToString:@"atan"]) {
+            func = &atan;
+            returnsArc = YES;
+        } else {
+            NSAssert(true, @"function must be one of (sin, cos, tan, asin, acos, atan).");
+        }
+        [self setFunction:func
+            takesArcValue:takesArc
+          returnsArcValue:returnsArc];
+        _term = term;
+    }
+    return self;
+}
+
+- (void)setFunction:(double (*)(double))function
+      takesArcValue:(BOOL)takesArc
+    returnsArcValue:(BOOL)returnsArc
+{
+    id __weak weakSelf = self;
+    _function = ^(NSDecimalNumber *value){
+        if (takesArc) {
+            value = [weakSelf convertToRadiantsIfNecessary:value];
+        }
+        NSDecimalNumber *returnValue = [[NSDecimalNumber alloc] initWithDouble:function(value.doubleValue)];
+        if (returnsArc) {
+            returnValue = [weakSelf convertToDegreesIfNecessary:returnValue];
+        }
+        return returnValue;
+    };
+}
+
+- (NSDecimalNumber *)convertToRadiantsIfNecessary:(NSDecimalNumber *)degrees
+{
+    if ([MPMathRules sharedRules].isUsingDegrees) {
+        // * M_PI / 180
+        return [[degrees decimalNumberByMultiplyingBy:[[NSDecimalNumber alloc] initWithDouble:M_PI]] decimalNumberByDividingBy:[[NSDecimalNumber alloc] initWithInteger:180]];
+    } else {
+        return degrees;
+    }
+}
+
+- (NSDecimalNumber *)convertToDegreesIfNecessary:(NSDecimalNumber *)radiants
+{
+    if ([MPMathRules sharedRules].isUsingDegrees) {
+        // * 180 / M_PI
+        return [[radiants decimalNumberByMultiplyingBy:[[NSDecimalNumber alloc] initWithInteger:180]] decimalNumberByDividingBy:[[NSDecimalNumber alloc] initWithDouble:M_PI]];
+    } else {
+        return radiants;
+    }
+}
+
+- (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
+{
+    NSDecimalNumber *value = [self.term evaluate:error];
+    if (!value) {
+        return nil;
+    }
+    return _function(value);
+}
+
+@end