Execute Brain****/D
Execute Brain****/D is an implementation of Brainf***.
Other implementations of Brainf***.
Execute Brain****/D is part of RCBF. You may find other members of RCBF at Category:RCBF.
Version 1
An implementation of Rosetta Code BrainF*ck interpreter in D.
Implement notes:
- Memory is represented by an associative array, so that negative addresses are allowed, though it is not efficient.
- Input and output are in character mode, rather than in numerical.
- Nesting level is checked during parsing, and if loops/brackets are not matched, an error is thrown before executing the code.
<lang d>import core.stdc.stdio, core.stdc.stdlib, std.file;
alias void delegate() Act;
__gshared char[int] mem; // memory __gshared int ptr; // mem pointer __gshared Act[char] cmd; // bf command except loop-control
static this() {
cmd['>'] = { if (!(++ptr in mem)) mem[ptr] = 0; }; cmd['<'] = { if (!(--ptr in mem)) mem[ptr] = 0; }; cmd['+'] = { mem[ptr]++; }; cmd['-'] = { mem[ptr]--; }; cmd['.'] = { putchar(mem[ptr]); }; cmd[','] = { int c = getc(stdin); if (c == EOF) exit(1); mem[ptr] = cast(char)c; };
}
void bf(in string code) {
int cp = 0; // code pointer int nested = 0; // nested loop level
Act bfAct() { Act[] acts; // store commands of current nesting level char cc;
while (cp < code.length) { // cc get next command and code pointer cp is advanced cc = code[cp]; cp++; switch (cc) { case '[': nested++; acts ~= bfAct(); // begin inner loop break;
case ']': nested--; if (nested < 0) throw new Exception("Unmatched Loops"); return { while (mem[ptr]) { foreach (x; acts) x(); } };
default: if (cc in cmd) acts ~= cmd[cc]; // else ignore other non-command char } }
return { foreach (x; acts) x(); }; }
// reset memory mem = null; mem[0] = 0; ptr = 0;
Act run = bfAct(); if (nested != 0) throw new Exception("Unmatched Loops"); run(); // execute the whole bf program printf("\n");
}
void main(in string[] args) {
// if no argument, demo code will be run, else the first // argument is treated as filename of bf source and executed. if (args.length > 1) { bf(readText(args[1])); } else { bf(">+++++++++[<+++++++++>-]<+.>+++[<----->-] <.-.++++.>++++++[<------>-]<--.>++++++++[ <+++++++++>-]<+.>++[<++>-]<+.>++++++++[<- -------->-]<------.>++++++[<++++++>-]<.>+ ++++[<------->-]<."); }
}</lang>
Version 2
Simpler and faster: <lang d>import core.stdc.stdio, core.stdc.stdlib;
void brainfuckRun(in string code) nothrow {
static int[int] matchBraces(in string code) pure nothrow out(result) { foreach (k, v; result) { assert(k >=0 && k < code.length); assert(v >=0 && v < code.length); assert(v in result); } } body { int[int] loops; int[] loopStack;
foreach (i, instruction; code) { if (instruction == '[') loopStack ~= i; else if (instruction == ']') { assert(loopStack.length); loops[i] = loopStack[$ - 1]; loopStack.length -= 1; loops[loops[i]] = i; } }
assert(!loopStack.length); return loops; }
static void runCode(in string code, in int[int] loops) nothrow { enum char empty = '\0'; char[30_000] tape = empty; int cell, index;
while (index < cast(int)code.length) { immutable int instruction = code[index];
switch (instruction) { case '>': cell++; assert(cell < tape.length); break; case '<': cell--; assert(cell >= 0); break; case '+': tape[cell]++; break; case '-': tape[cell]--; break; case '.': putchar(tape[cell]); break; case ',': immutable int c = getchar(); if (c == EOF) exit(1); tape[cell] = cast(char)c; break; case '[': if (tape[cell] == empty) index = loops[index]; break; case ']': if (tape[cell] != empty) index = loops[index]; break; default: break; }
index++; } }
int[int] loops = matchBraces(code); runCode(code, loops);
}
void main() {
brainfuckRun("++++++++++[>+++++++>++++++++++>+++>+<<<<-] >++.>+.+++++++..+++.>++.<<+++++++++++++++.>. +++.------.--------.>+.>.");
}</lang>
Version 3
Faster version, code generated at compile-time, run at run-time: <lang d>string ctbf(in string code) pure nothrow {
string r; foreach (immutable c; code) switch (c) { case '>': r ~= "i++; assert(i < m.length);"; break; case '<': r ~= "i--; assert(i >= 0);"; break; case '+': r ~= "m[i]++;"; break; case '-': r ~= "m[i]--;"; break; case '[': r ~= "while (m[i]) {"; break; case ']': r ~= "}"; break; case '.': r ~= "m[i].putchar;"; break; case ',': r ~= "{ int d = getchar; if (d == EOF) exit(1); m[i] = cast(char)d; }"; break; default: break; } return r;
}
void main() {
import core.stdc.stdio, core.stdc.stdlib;
char[30_000] m = '\0'; size_t i; mixin(ctbf("++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++ ++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."));
}</lang>