{"id":5,"date":"2012-06-30T16:36:17","date_gmt":"2012-06-30T16:36:17","guid":{"rendered":"http:\/\/opisthokonta.net\/?p=5"},"modified":"2012-12-13T17:57:04","modified_gmt":"2012-12-13T17:57:04","slug":"a-brainfuck-interpreter-in-python","status":"publish","type":"post","link":"https:\/\/opisthokonta.net\/?p=5","title":{"rendered":"A brainfuck interpreter in Python."},"content":{"rendered":"<p>So I implemented this small <a href=\"http:\/\/en.wikipedia.org\/wiki\/Brainfuck\">brainfuck<\/a> interpreter in python. This implementation uses 8-bit memory cells and does not allow for for values outside the 0-255 range. If this happens a ValueError will be raised. By default, the memory tape is 5000 cells long, but this can be set by the user. <\/p>\n<p>Python 2.6 or later is required.<\/p>\n<p>Example:<\/p>\n<pre class=\"brush: python; title: ; notranslate\" title=\"\">\r\nbf = Brainfuck(100) #only 100 cells on the tape\r\ntwoPlusThree = &quot;++&gt;+++&lt;[&gt;+&lt;-]&quot;\r\nbf.run_command(twoPlusThree)\r\n<\/pre>\n<p>And here is the implementation:<\/p>\n<pre class=\"brush: python; title: ; notranslate\" title=\"\">\r\nclass Brainfuck:\r\n\tdef __init__(self, tape_length=5000):\r\n\t\tself.tape = bytearray(tape_length)\r\n\t\tself.tape_pointer = 0\r\n\t\t\r\n\tdef run_command(self, cmd):\r\n\t\tcmd_pointer = 0\r\n\r\n\t\trunning = True\r\n\t\twhile running:\r\n\t\t\tif self.tape_pointer &gt; len(self.tape) or self.tape_pointer &lt; 0 or cmd_pointer &lt; 0 or cmd_pointer &gt; len(cmd) -1:\r\n\t\t\t\tbreak\r\n\r\n\t\t\tif cmd[cmd_pointer] == &quot;+&quot;:\r\n\t\t\t\tself.tape[self.tape_pointer] += 1\r\n\t\t\telif cmd[cmd_pointer] == &quot;-&quot;:\r\n\t\t\t\tself.tape[self.tape_pointer] -= 1\r\n\t\t\telif cmd[cmd_pointer] == &quot;&lt;&quot;:\r\n\t\t\t\tself.tape_pointer -= 1\r\n\t\t\telif cmd[cmd_pointer] == &quot;&gt;&quot;:\r\n\t\t\t\tself.tape_pointer += 1\r\n\t\t\telif cmd[cmd_pointer] == &quot;.&quot;:\r\n\t\t\t\tprint(chr(self.tape[self.tape_pointer]))\r\n\t\t\telif cmd[cmd_pointer] == &quot;,&quot;:\r\n\t\t\t\tself.tape[self.tape_pointer] = int(raw_input())\r\n\t\t\telif cmd[cmd_pointer] == &quot;[&quot;:\r\n\t\t\t\tif int(self.tape[self.tape_pointer]) == 0:\r\n\t\t\t\t\tlbcounter = 0\r\n\t\t\t\t\tsearching = True\t\t\t\r\n\t\t\t\t\twhile searching:\r\n\t\t\t\t\t\tcmdpointer +=1\r\n\t\t\t\t\t\tif cmd[cmd_pointer] == &quot;[&quot;:\r\n\t\t\t\t\t\t\tlbcounter += 1\r\n\t\t\t\t\t\telif lbcounter == 0 and cmd[cmd_pointer] == &quot;]&quot;:\r\n\t\t\t\t\t\t\tsearching = False \r\n\t\t\t\t\t\telif cmd[cmd_pointer] == &quot;]&quot;:\r\n\t\t\t\t\t\t\tlbcounter -= 1\r\n\t\t\telif cmd[cmd_pointer] == &quot;]&quot;:\r\n\t\t\t\tif int(self.tape[self.tape_pointer]) != 0:\r\n\t\t\t\t\trbcounter = 0\r\n\t\t\t\t\tsearching = True\t\t\t\r\n\t\t\t\t\twhile searching:\r\n\t\t\t\t\t\tcmd_pointer -=1\r\n\t\t\t\t\t\tif cmd[cmd_pointer] == &quot;]&quot;:\r\n\t\t\t\t\t\t\trbcounter += 1\r\n\t\t\t\t\t\telif rbcounter == 0 and cmd[cmd_pointer] == &quot;[&quot;:\r\n\t\t\t\t\t\t\tsearching = False\r\n\t\t\t\t\t\telif cmd[cmd_pointer] == &quot;[&quot;:\r\n\t\t\t\t\t\t\trbcounter -= 1\r\n\t\t\t\r\n\t\t\tcmd_pointer += 1\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>So I implemented this small brainfuck interpreter in python. This implementation uses 8-bit memory cells and does not allow for for values outside the 0-255 range. If this happens a ValueError will be raised. By default, the memory tape is &hellip; <a href=\"https:\/\/opisthokonta.net\/?p=5\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[4,49],"class_list":["post-5","post","type-post","status-publish","format-standard","hentry","category-python","tag-brainfuck","tag-python"],"_links":{"self":[{"href":"https:\/\/opisthokonta.net\/index.php?rest_route=\/wp\/v2\/posts\/5","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opisthokonta.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/opisthokonta.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/opisthokonta.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/opisthokonta.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5"}],"version-history":[{"count":12,"href":"https:\/\/opisthokonta.net\/index.php?rest_route=\/wp\/v2\/posts\/5\/revisions"}],"predecessor-version":[{"id":17,"href":"https:\/\/opisthokonta.net\/index.php?rest_route=\/wp\/v2\/posts\/5\/revisions\/17"}],"wp:attachment":[{"href":"https:\/\/opisthokonta.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/opisthokonta.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/opisthokonta.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}