Improved Evaluation
This commit is contained in:
Kim Wittenburg
@@ -9,105 +9,236 @@
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#import "MPExpressionEvaluator.h"
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#import "MPExpression.h"
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#import "MPFunction.h"
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#import "MPParsedFactor.h"
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#import "MPFunction+MPParsedFactor.h"
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#import "MPMathRules.h"
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#import "MPToken.h"
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#import "MPFunction+MPToken.h"
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#import "MPTokenStream.h"
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#import "MPEvaluationContext.h"
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@interface MPExpressionEvaluator ()
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@property (readwrite, nonatomic, strong) NSString *definedVariable;
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@property (readwrite, nonatomic, copy) NSString *definedVariable;
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@property (nonatomic, strong) NSArray *tokens;
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- (void)setError:(MPParseError *)error;
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@end
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@implementation MPExpressionEvaluator {
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MPElementParser *parser;
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MPParseError *__autoreleasing *_error;
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MPTokenStream *tokenStream;
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}
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- (id)initWithExpression:(MPExpression *)expression
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{
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self = [super init];
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if (self) {
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_expression = expression;
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parser = [[MPElementParser alloc] init];
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}
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return self;
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}
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#pragma mark Evaluating Expressions
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- (NSDecimalNumber *)evaluateWithError:(MPParseError *__autoreleasing *)error
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@synthesize lexer = _lexer;
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- (void)setLexer:(MPExpressionTokenizer *)lexer
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{
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return [self evaluateVariableDefinition:NO error:error];
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_lexer = lexer;
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self.tokens = nil;
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}
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- (NSDecimalNumber *)evaluateVariableDefinition:(BOOL)flag error:(MPParseError *__autoreleasing *)error
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- (MPExpressionTokenizer *)lexer
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{
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// Empty Expression
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if (self.expression.numberOfElements == 0) {
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*error = MPParseError(NSMakeRange(0, 0), @"Expected Expression");
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if (!_lexer) {
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_lexer = [[MPExpressionTokenizer alloc] init];
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}
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return _lexer;
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}
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- (NSArray *)tokens
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{
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if (!_tokens) {
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_tokens = [self.lexer tokenizeExpression:self.expression];
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}
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return _tokens;
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}
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- (void)expressionDidChangeInRange:(NSRange)range
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replacementLength:(NSUInteger)replacementLength
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{
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self.tokens = nil;
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}
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#pragma mark Evaluating Expressions
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- (void)setError:(MPParseError *)error
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{
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if (_error) {
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error.pathToExpression = self.expression.indexPath;
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*_error = error;
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}
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}
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- (MPTerm *)parseExpectingVariable:(BOOL)flag
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error:(MPParseError *__autoreleasing *)error
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{
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_error = error;
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tokenStream = [[MPTokenStream alloc] initWithTokens:self.tokens];
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if (!tokenStream.hasMoreTokens) {
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self.error = MPParseError(NSMakeRange(0, 0), @"Empty Expression");
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return nil;
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}
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NSMutableArray *products = [[NSMutableArray alloc] init];
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MPParsedProduct *currentProduct = nil;
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for (NSUInteger elementIndex = 0; elementIndex < self.expression.numberOfElements; elementIndex++) {
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// Variable Definition
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if (flag) {
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MPToken *variableToken = [tokenStream nextToken];
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MPToken *equalsToken = [tokenStream nextTokenOfType:MPEqualsToken];
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id<MPExpressionElement> element = [self.expression elementAtIndex:elementIndex];
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if ([element isString]) {
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id<MPParsedFactor> nextFactor = nil;
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if (elementIndex < self.expression.numberOfElements - 1) {
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MPFunction *nextFunction = (MPFunction *)[self.expression elementAtIndex:elementIndex+1];
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nextFactor = nextFunction;
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}
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NSArray *newProducts;
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if (elementIndex == 0 && flag) {
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NSString *definedVariable;
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newProducts = [parser parseElement:(NSString *)element
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previousProduct:currentProduct
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nextFactor:nextFactor
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definesVariable:YES
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definedVariable:&definedVariable
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error:error];
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self.definedVariable = definedVariable;
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} else {
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newProducts = [parser parseElement:(NSString *)element
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previousProduct:currentProduct
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nextFactor:nextFactor
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error:error];
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}
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if (!newProducts) {
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return nil;
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}
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for (NSUInteger productIndex = 0; productIndex < newProducts.count-1; productIndex++) {
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[products addObject:newProducts[productIndex]];
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}
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currentProduct = newProducts.lastObject;
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elementIndex++;
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} else {
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if (!currentProduct) {
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currentProduct = [[MPParsedProduct alloc] init];
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} else if ([MPMathRules sharedRules].allowsImplicitMultiplication) {
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[currentProduct addFactor:(MPFunction *)element];
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} else {
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*error = MPParseError(NSMakeRange(((MPFunction *)element).range.location, 0), @"Implicit Multiplication not allowed");
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return nil;
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}
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}
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}
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[products addObject:currentProduct];
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NSDecimalNumber *value = [NSDecimalNumber zero];
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for (MPParsedProduct *product in products) {
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NSDecimalNumber *productValue = [product evaluateWithError:error];
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if (!productValue) {
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if (variableToken.tokenType != MPVariableToken) {
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self.error = MPParseError(variableToken.range, @"Expected Variable Definition.");
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return nil;
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}
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if (equalsToken.tokenType != MPEqualsToken) {
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self.error = MPParseError(equalsToken.range, @"Expected \"=\".");
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return nil;
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}
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self.definedVariable = variableToken.stringValue;
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}
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BOOL isAtBeginning = YES;
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NSMutableArray *summands = [[NSMutableArray alloc] init];
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NSMutableArray *currentSummand = [[NSMutableArray alloc] init];
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while (tokenStream.hasMoreTokens) {
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MPToken *multiplicationToken = [tokenStream nextTokenOfType:MPMultiplicationSymbolToken];
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MPToken *operatorToken = [tokenStream nextTokenOfType:MPOperatorListToken];
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NSRange valueRange;
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MPTerm *value = [self nextValue:&valueRange];
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if (multiplicationToken) {
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if (isAtBeginning) {
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self.error = MPParseError(multiplicationToken.range, @"Unexpected Symbol. Expected Number.");
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return nil;
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}
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if (operatorToken) {
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if (operatorToken.numberOfOperators > [[MPMathRules sharedRules] maximumOperatorChainLengthInMultiplication]) {
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self.error = MPParseError(operatorToken.range, @"Too many operators in multiplication");
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return nil;
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}
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[currentSummand addObject:[[MPTerm alloc] initWithNumber:operatorToken.operatorValue]];
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}
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if (value) {
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[currentSummand addObject:value];
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} else {
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return nil;
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}
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} else {
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if (operatorToken) {
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if (operatorToken.numberOfOperators > [[MPMathRules sharedRules] maximumOperatorChainLength]) {
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self.error = MPParseError(operatorToken.range, @"Too many operators.");
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return nil;
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}
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[summands addObject:[[MPTerm alloc] initWithFactors:currentSummand.copy]];
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currentSummand = [[NSMutableArray alloc] init];
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[currentSummand addObject:[[MPTerm alloc] initWithNumber:operatorToken.operatorValue]];
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if (value) {
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[currentSummand addObject:value];
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} else {
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return nil;
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}
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} else if (!value) {
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return nil;
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} else if (isAtBeginning || [[MPMathRules sharedRules] allowsImplicitMultiplication]) {
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[currentSummand addObject:value];
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} else {
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self.error = MPParseError(NSMakeRange(valueRange.location, 0), @"Implicit Multiplication not allowed here");
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return nil;
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}
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}
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isAtBeginning = NO;
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}
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[summands addObject:[[MPTerm alloc] initWithFactors:currentSummand.copy]];
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return [[MPTerm alloc] initWithSummands:summands.copy];
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}
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- (MPTerm *)nextValue:(NSRangePointer)range
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{
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MPToken *token = [tokenStream nextToken];
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if (range) {
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*range = token.range;
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}
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switch (token.tokenType) {
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case MPNumberToken:
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{
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return [[MPTerm alloc] initWithNumber:token.number];
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}
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case MPVariableToken:
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{
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if(![[MPEvaluationContext sharedContext] isVariableDefined:token.variable]) {
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self.error = MPParseError(token.range, @"Undefined Variable");
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return nil;
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}
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return [[MPTerm alloc] initWithVariable:token.variable];
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}
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case MPGenericFunctionToken:
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{
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return [((MPFunction *)token) parseWithError:_error];
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}
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case MPSinToken:
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{
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NSRange sinTermRange;
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MPTerm *sinTerm = [self nextValue:&sinTermRange];
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if (!sinTerm) {
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if (range) {
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*range = NSUnionRange(token.range, sinTermRange);
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}
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return nil;
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}
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return [[MPTerm alloc] initWithSinOfTerm:sinTerm];
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}
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case MPCosToken:
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{
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NSRange cosTermRange;
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MPTerm *cosTerm = [self nextValue:&cosTermRange];
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if (!cosTerm) {
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if (range) {
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*range = NSUnionRange(token.range, cosTermRange);
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}
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return nil;
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}
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return [[MPTerm alloc] initWithSinOfTerm:cosTerm];
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}
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case MPTanToken:
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{
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NSRange tanTermRange;
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MPTerm *tanTerm = [self nextValue:&tanTermRange];
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if (!tanTerm) {
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if (range) {
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*range = NSUnionRange(token.range, tanTermRange);
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}
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return nil;
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}
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return [[MPTerm alloc] initWithTanOfTerm:tanTerm];
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}
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case MPEOFToken:
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{
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self.error = MPParseError(token.range, @"Unexpected End. Expected Number.");
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return nil;
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}
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default:
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{
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self.error = MPParseError(token.range, @"Unexpected Symbol. Expected Number.");
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return nil;
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}
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value = [value decimalNumberByAdding:productValue];
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}
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return value;
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}
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@end
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