Created
July 24, 2022 08:04
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BF -> JS compiler
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// @ts-check | |
/** @returns {(stdin: () => number, stdout: (c: number) => void) => void} */ | |
function compile(/** @type {string} */ source) { | |
let func = | |
"const memory = new Uint8Array(30000);\n" + | |
"let ptr = 0;\n"; | |
for (let i = 0, len = source.length; i < len; ++i) { | |
let c = source.charAt(i); | |
switch (c) { | |
// move pointer right | |
case '>': func += "ptr += 1;\n"; break; | |
// move point left | |
case '<': func += "ptr -= 1;\n"; break; | |
// increment cell | |
case '+': func += "memory[ptr] += 1;\n"; break; | |
// decrement cell | |
case '-': func += "memory[ptr] -= 1;\n"; break; | |
// write cell to output | |
case '.': func += "stdout(memory[ptr]);\n"; break; | |
// read to cell from output | |
case ',': func += "memory[ptr] = stdin();\n"; break; | |
// jump to next `]` if cell is 0 | |
case '[': func += "while (memory[ptr]) {\n"; break; | |
// jump to previous `[` if cell is not 0 | |
case ']': func += "}\n"; break; | |
// ignore all other characters | |
default: break; | |
} | |
} | |
// @ts-expect-error: signature will match | |
return new Function("stdin", "stdout", func); | |
} |
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// assumes `compile` is in scope | |
// 99 bottles of beer | |
const program = ` | |
>+++++++++[<+++++++++++>-]<[>[-]>[-]<<[>+>+<<-]>>[<<+>>-]>>> | |
[-]<<<+++++++++<[>>>+<<[>+>[-]<<-]>[<+>-]>[<<++++++++++>>>+< | |
-]<<-<-]+++++++++>[<->-]>>+>[<[-]<<+>>>-]>[-]+<<[>+>-<<-]<<< | |
[>>+>+<<<-]>>>[<<<+>>>-]>[<+>-]<<-[>[-]<[-]]>>+<[>[-]<-]<+++ | |
+++++[<++++++<++++++>>-]>>>[>+>+<<-]>>[<<+>>-]<[<<<<<.>>>>>- | |
]<<<<<<.>>[-]>[-]++++[<++++++++>-]<.>++++[<++++++++>-]<++.>+ | |
++++[<+++++++++>-]<.><+++++..--------.-------.>>[>>+>+<<<-]> | |
>>[<<<+>>>-]<[<<<<++++++++++++++.>>>>-]<<<<[-]>++++[<+++++++ | |
+>-]<.>+++++++++[<+++++++++>-]<--.---------.>+++++++[<------ | |
---->-]<.>++++++[<+++++++++++>-]<.+++..+++++++++++++.>++++++ | |
++[<---------->-]<--.>+++++++++[<+++++++++>-]<--.-.>++++++++ | |
[<---------->-]<++.>++++++++[<++++++++++>-]<++++.----------- | |
-.---.>+++++++[<---------->-]<+.>++++++++[<+++++++++++>-]<-. | |
>++[<----------->-]<.+++++++++++..>+++++++++[<---------->-]< | |
-----.---.>>>[>+>+<<-]>>[<<+>>-]<[<<<<<.>>>>>-]<<<<<<.>>>+++ | |
+[<++++++>-]<--.>++++[<++++++++>-]<++.>+++++[<+++++++++>-]<. | |
><+++++..--------.-------.>>[>>+>+<<<-]>>>[<<<+>>>-]<[<<<<++ | |
++++++++++++.>>>>-]<<<<[-]>++++[<++++++++>-]<.>+++++++++[<++ | |
+++++++>-]<--.---------.>+++++++[<---------->-]<.>++++++[<++ | |
+++++++++>-]<.+++..+++++++++++++.>++++++++++[<---------->-]< | |
-.---.>+++++++[<++++++++++>-]<++++.+++++++++++++.++++++++++. | |
------.>+++++++[<---------->-]<+.>++++++++[<++++++++++>-]<-. | |
-.---------.>+++++++[<---------->-]<+.>+++++++[<++++++++++>- | |
]<--.+++++++++++.++++++++.---------.>++++++++[<---------->-] | |
<++.>+++++[<+++++++++++++>-]<.+++++++++++++.----------.>++++ | |
+++[<---------->-]<++.>++++++++[<++++++++++>-]<.>+++[<-----> | |
-]<.>+++[<++++++>-]<..>+++++++++[<--------->-]<--.>+++++++[< | |
++++++++++>-]<+++.+++++++++++.>++++++++[<----------->-]<++++ | |
.>+++++[<+++++++++++++>-]<.>+++[<++++++>-]<-.---.++++++.---- | |
---.----------.>++++++++[<----------->-]<+.---.[-]<<<->[-]>[ | |
-]<<[>+>+<<-]>>[<<+>>-]>>>[-]<<<+++++++++<[>>>+<<[>+>[-]<<-] | |
>[<+>-]>[<<++++++++++>>>+<-]<<-<-]+++++++++>[<->-]>>+>[<[-]< | |
<+>>>-]>[-]+<<[>+>-<<-]<<<[>>+>+<<<-]>>>[<<<+>>>-]<>>[<+>-]< | |
<-[>[-]<[-]]>>+<[>[-]<-]<++++++++[<++++++<++++++>>-]>>>[>+>+ | |
<<-]>>[<<+>>-]<[<<<<<.>>>>>-]<<<<<<.>>[-]>[-]++++[<++++++++> | |
-]<.>++++[<++++++++>-]<++.>+++++[<+++++++++>-]<.><+++++..--- | |
-----.-------.>>[>>+>+<<<-]>>>[<<<+>>>-]<[<<<<++++++++++++++ | |
.>>>>-]<<<<[-]>++++[<++++++++>-]<.>+++++++++[<+++++++++>-]<- | |
-.---------.>+++++++[<---------->-]<.>++++++[<+++++++++++>-] | |
<.+++..+++++++++++++.>++++++++[<---------->-]<--.>+++++++++[ | |
<+++++++++>-]<--.-.>++++++++[<---------->-]<++.>++++++++[<++ | |
++++++++>-]<++++.------------.---.>+++++++[<---------->-]<+. | |
>++++++++[<+++++++++++>-]<-.>++[<----------->-]<.+++++++++++ | |
..>+++++++++[<---------->-]<-----.---.+++.---.[-]<<<] | |
`; | |
const stdin = () => {}; | |
let buffer = ""; | |
const stdout = (c) => buffer += String.fromCharCode(c); | |
const run = compile(program); | |
run(stdin, stdout); | |
console.log(buffer); |
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