brainf*** interpreter with examples

brainf.py

@@ -0,0 +1,68 @@
+# brainf*** Interpreter in Python
+# Copyright (c) 2002 & 2006, James Tauber
+#
+# see http://en.wikipedia.org/wiki/Brainfuck
+
+import sys
+
+class brainf:
+
+    def __init__(self, program):
+        self.mem = [0] * 65536
+        self.p = 0
+        self.pc = 0
+        self.program = program
+
+    def run(self, stop=None):
+        if stop is None:
+            stop = len(self.program)
+
+        while self.pc < stop:
+            c = self.program[self.pc]
+            if   c == ">":   self.p += 1
+            elif c == "<":   self.p -= 1
+            elif c == "+":   self.mem[self.p] += 1
+            elif c == "-":   self.mem[self.p] -= 1
+            elif c == ".":   sys.stdout.write(chr(self.mem[self.p]))
+            elif c == ",":   self.mem[self.p] = ord(sys.stdin.read(1))
+            elif c == "[":   
+                depth = 1    
+                start = end = self.pc
+                while depth: 
+                    end += 1 
+                    if self.program[end] == "[":   depth += 1
+                    if self.program[end] == "]":   depth -= 1
+                while self.mem[self.p]:
+                    self.pc = start + 1
+                    self.run(end)
+                self.pc = end     
+            elif c == "]":   raise "unbalanced ]"
+            else:            pass
+            self.pc += 1
+
+# hello world sample
+
+hello_world = """
+>+++++++++[<++++++++>-]<.
+>+++++++[<++++>-]<+.
++++++++.
+.
++++.
+[-]>++++++++[<++++>-]<.
+>+++++++++++[<++++++++>-]<-.
+--------.
++++.
+------.
+--------.
+[-]>++++++++[<++++>-]<+.
+[-]++++++++++.
+"""
+
+# add two one-digit numbers to make a third (if one-digit)
+
+add = """
+,>++++++[<-------->-],[<+>-],<.>.
+"""
+
+brainf(hello_world).run()
+brainf(add).run()