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Last active December 23, 2015 10:39
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Brainfuck interpreter
Raw
README.md

Brainfuck interpreter

Fully featured with loops, input, output and comments.

139bytes!

Chrome and Firefox only

Raw
annotated.js
(
a, // brainfuck input and later used as brainfuck "register"
b, // function to use for user input and output
// if any data is passed, it is printed out,
// otherwise b returns user input
c // placeholder index argument
) => eval(
// replace every char
a.replace(
// use regex as register
a = /./g,
// mapping table from identifiers to javascript
d => '1=-~101=~-10while1{0}0c++0c--0b101=b()'
// saving some space
.replace(/1/g, '(a[c])')
.split(0)['+-[]><.,'.indexOf(d)]
// add semicolon to separate statements
+ ';',
// reset index
c = 0)
)
Raw
index.js
(a,b,c)=>eval(a.replace(a=/./g,d=>'1=-~101=~-10while1{0}0c++0c--0b101=b()'.replace(/1/g,'(a[c])').split(0)['+-[]><.,'.indexOf(d)]+';',c=0))
Raw
LICENSE.txt
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
Version 2, December 2004
Copyright (C) 2013 Johan Hillerström <https://github.com/hillerstorm>
Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. You just DO WHAT THE FUCK YOU WANT TO.
Raw
package.json
{
"name": "brainfuck",
"description": "Executes a brainfuck program.",
"keywords": [
"brainfuck",
"interpreter",
"compiler"
]
}
Raw
test.html
<!DOCTYPE html>
<title>Brainfuck interpreter</title>
<div>Expected Value: <b>Hello World!
</b></div>
<div>Actual value: <b id="ret"></b></div>
<script>
var brainfuck = (a,b,c)=>eval(a.replace(a=/./g,d=>'1=-~101=~-10while1{0}0c++0c--0b101=b()'.replace(/1/g,'(a[c])').split(0)['+-[]><.,'.indexOf(d)]+';',c=0));
brainfuck(
'++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.',
function (output) {
// if no output is given, read user input instead
if (typeof output === 'undefined') {
return prompt().charCodeAt();
}
// else buffer the char
document.getElementById('ret').innerHTML += String.fromCharCode(output);
});
</script>
@hillerstorm
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Author

I guess I can give up my dream to be able to parse commented code and instead go for 140b by restricting the input to valid BF identifiers :)

@atk
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atk commented Sep 24, 2013

We could reluctantly externalize the main command string to go below 140bytes (114, to be precise). It's a bit of a gray area that I have used for my JS syntax highlighter and base64 decoder, too.

function(a,i,s,b,c){for(b in a)c+=';'+s.replace(/1/g,'(a[b])').split(0)['+-[]><.,'.indexOf(a[b])];a=[b=0];eval(c)}
// i=function(b,u){return b==u?prompt().charCodeAt():document.getElementById('output').innerHTML+=String.fromCharCode(b)}, 
// s='1=-~101=~-10while1{0}0b++0b--0i101=i()'

Let's keep the version with 151bytes as a great learning example, anyway.

@hillerstorm
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It could even be 82b if the command string is the complete array, with the 1's already replaced with a[b]:

function(a,i,s,b,c){for(b in a)c+=';'+s['+-[]><.,'.indexOf(a[b])];a=[b=0];eval(c)}
// s=['a[b]=-~a[b]','a[b]=~-a[b]','while(a[b]){','}','b++','b--','i(a[b])','a[b]=i()']

but that actually feels like too much of a gray area for my taste :D
not at all plug-and-play! as much code outside as there is inside the function

@atk
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atk commented Sep 25, 2013

I wholeheartedly agree. Maybe we'll find a solution after all. Until then, we do have a gray area solution and another one that's too big.

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