Archive Project

Brainfuck/Interpreter.m

@@ -0,0 +1,130 @@
+//
+//  Interpreter.m
+//  Brainfuck
+//
+//  Created by Kim Wittenburg on 20.05.13.
+//  Copyright (c) 2013 brainfuck. All rights reserved.
+//
+
+#import "Interpreter.h"
+
+#import "Lexer.h"
+
+@implementation Interpreter {
+    NSMutableArray *a;
+    NSInteger level;
+    NSString *input;
+    NSInteger inPos;
+}
+
+@synthesize printer;
+
++ (Interpreter *)interpreter
+{
+    return [[self alloc] init];
+}
+
+- (id)init
+{
+    self = [super init];
+    if (self) {
+    }
+    return self;
+}
+
+- (void)execute:(NSString *)script withInput:(NSString *)i error:(NSError *__autoreleasing *)error
+{
+    input = i;
+    inPos = 0;
+    Lexer *lexer = [Lexer lexer];
+    NSArray *cmds = [lexer performLexingOnString:script error:error];
+    level = 0;
+    a = [NSMutableArray new];
+    [a addObject:[NSNumber numberWithInt:0]];
+    [self executeCommands:cmds];
+}
+
+- (void)executeCommands:(NSArray *)cmds
+{
+    for (id cmd in cmds) {
+        if ([cmd isKindOfClass:[NSArray class]]) {
+            [self loop:cmd];
+        } else {
+            [self executeCommand:cmd];
+        }
+    }
+}
+
+- (void)executeCommand:(NSString *)cmd
+{
+    int c = [cmd characterAtIndex:0];
+    if (c == '+') {
+        [self increment];
+    } else if (c == '-') {
+        [self decrement];
+    } else if (c == '<') {
+        [self previousCell];
+    } else if (c == '>') {
+        [self nextCell];
+    } else if (c == '.') {
+        [self printCellValue];
+    } else if (c == ',') {
+        [self readNextInput];
+    }
+}
+
+- (void)increment
+{
+    NSNumber *number = a[level];
+    number = [NSNumber numberWithInt:number.intValue+1];
+     a[level] = number;
+}
+
+- (void)decrement
+{
+    NSNumber *number = a[level];
+    number = [NSNumber numberWithInt:number.intValue-1];
+    a[level] = number;
+}
+
+- (void)nextCell
+{
+    if (++level == a.count) {
+        [a addObject:[NSNumber numberWithInt:0]];
+    }
+}
+
+- (void)previousCell
+{
+    if (--level == -1) {
+        [a insertObject:[NSNumber numberWithInt:0] atIndex:0];
+        level++;
+    }
+}
+
+- (void)printCellValue
+{
+    NSNumber *ascii = a[level];
+    NSString *text = [NSString stringWithFormat:@"%c", ascii.intValue];
+    [self.printer print:text];
+}
+
+- (void)readNextInput
+{
+    int ascii;
+    if (inPos == input.length) {
+        ascii = 0;
+    } else {
+        ascii = [input characterAtIndex:inPos++];
+    }
+    a[level] = [NSNumber numberWithInt:ascii];
+}
+
+- (void)loop:(NSArray *)cmds
+{
+    while (((NSNumber *)a[level]).intValue != 0) {
+        [self executeCommands:cmds];
+    }
+}
+
+@end