D言語おもすれー

module brainfuck;
const(ubyte)[] brainfuck(const(char)[] code)(in const(ubyte)[] input = []) {
ubyte[] output, mem = new ubyte[100];
uint ptr, readptr;
mixin(_brainfuck(code));
return output;
}
private const(char)[] _brainfuck(const(char)[] code) {
char[] o = "".dup;
foreach(c; code) {
switch(c) {
case '>': o ~= "if(++ptr >= mem.length) mem.length = mem.length * 2;"; break;
case '<': o ~= "--ptr;"; break;
case '+': o ~= "++mem[ptr];"; break;
case '-': o ~= "--mem[ptr];"; break;
case '.': o ~= "output ~= mem[ptr];"; break;
case ',': o ~= "mem[ptr] = readptr < input.length ? input[readptr++] : 0;"; break;
case '[': o ~= "while(mem[ptr] != 0) {"; break;
case ']': o ~= "}"; break;
default: break;
}
}
return o;
}
unittest {
assert(brainfuck!("+++++++++[>++++++++>+++++++++++>+++++<<<-]>.>++.+++++++..+++.>-.
------------.<++++++++.--------.+++.------.--------.>+.") == cast(ubyte[])"Hello, world!");
}