Execute Brain****/D: Difference between revisions
(Move 2 alternate implementations from Execute Brain****. http://rosettacode.org/mw/index.php?title=Execute_Brain****&action=history) |
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{{implementation|Brainf***}}{{collection|RCBF}}
==
An implementation of Rosetta Code [[Brainfuck|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
__gshared Act[char] cmd
▲int ptr ; // mem pointer
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['.'] = {
cmd[','] = {
int c = getc(stdin);
mem[ptr] = cast(char)c;
}
void bf(in string code) {
int cp = 0
int nested = 0
Act bfAct() {
Act[] acts
while(cp < code.length)▼
case '[':▼
nested++ ;▼
acts ~= bfAct() ; // begin inner loop▼
▲ break ;
case ']': ▼
if(--nested < 0) throw new Exception("Unmatched Loops") ;▼
default:▼
▲ if(cc in cmd)
acts ~= cmd[cc] ;▼
//else ignore other non-command char▼
▲ }
return { foreach(x ; acts){x();} } ;▼
}▼
Act run = bfAct() ;▼
if(nested != 0) throw new Exception("Unmatched Loops") ;▼
run() ; // execute the whole bf program▼
printf("\n") ;▼
▲ while (cp < code.length) {
void main(string[] args) { // if no argument, demo code will be run, else ▼
▲ case '[':
else ▼
bf(">+++++++++[<+++++++++>-]<+.>+++[<----->-]"▼
"<.-.++++.>++++++[<------>-]<--.>++++++++["▼
break;
"<+++++++++>-]<+.>++[<++>-]<+.>++++++++[<-"▼
"-------->-]<------.>++++++[<++++++>-]<.>+"▼
nested--;
if (nested < 0)
return {
while (mem[ptr]) {
foreach (x; acts)
x();
};
▲ default:
if (cc in cmd)
▲ // else ignore other non-command char
}
}
return {
x();
};
▲ }
// reset memory
mem = null;
mem[0] = 0;
ptr = 0;
if (nested != 0)
}
</lang>▼
void main(in string[] args) {
// argument is treated as filename of bf source and executed.
if (args.length > 1) {
bf(readText(args[1]));
▲ } else {
++++[<------->-]<.");
}
▲}</lang>
== Implementation 2 ==
|
Revision as of 23:51, 24 March 2012
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>
Implementation 2
Alternative version, simpler and faster: <lang d>import core.stdc.stdio: getchar, putchar, EOF; import core.stdc.stdlib: exit;
void brainfuckRun(const string code) {
static pure int[int] matchBraces(const string code) 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(const string code, const int[int] loops) { 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 ',': 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>
Implementation 3
Faster partially compile-time version (code generated at compile-time, run at run time): <lang d>import core.stdc.stdio, core.stdc.stdlib;
pure string ctbf(in string code) {
string r; foreach (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 ~= "putchar(m[i]);"; break; case ',': r ~= "int d = getchar(); if (d == EOF) exit(1); m[i] = cast(char)d;"; break; default: break; } return r;
}
void main() {
char[30_000] m = '\0'; size_t i; mixin(ctbf("++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++ ++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."));
}</lang>