5.6 KiB
title | id | challengeType |
---|---|---|
Execute Brain**** | 59e0a8df964e4540d5abe599 | 5 |
Description
Write a function to implement a Brain**** interpreter. The function will take a string as a parameter and should return a string as the output. More details are given below :
RCBF is a set of Brainf*** compilers and interpreters written for Rosetta Code in a variety of languages.
Below are links to each of the versions of RCBF.
An implementation need only properly implement the following instructions:
{|
!Command
!Description
|-
| style="text-align:center"| >
|| Move the pointer to the right
|-
| style="text-align:center"| <
|| Move the pointer to the left
|-
| style="text-align:center"| +
|| Increment the memory cell under the pointer
|-
| style="text-align:center"| -
|| Decrement the memory cell under the pointer
|-
| style="text-align:center"| .
|| Output the character signified by the cell at the pointer
|-
| style="text-align:center"| ,
|| Input a character and store it in the cell at the pointer
|-
| style="text-align:center"| [
|| Jump past the matching ]
if the cell under the pointer is 0
|-
| style="text-align:center"| ]
|| Jump back to the matching [
if the cell under the pointer is nonzero
|}
Any cell size is allowed, EOF (End-O-File) support is optional, as is whether you have bounded or unbounded memory.
Instructions
Tests
tests:
- text: <code>brain(bye)</code> should retuen a string
testString: assert(typeof brain(bye) === 'string', '<code>brain(bye)</code> should return a string');
- text: <code>brain("++++++[>++++++++++<-]>+++++.")</code should return "A"
testString: assert.equal(brain("++++++[>++++++++++<-]>+++++."),"A", '<code>brain("++++++[>++++++++++<-]>+++++.")</code should return "A"');
- text: <code>brain(bye)</code> should return <code>Goodbye, World!\\r\\n</code>
testString: assert.equal(brain(bye), 'Goodbye, World!\r\n', '<code>brain(bye)</code> should return <code>Goodbye, World!\\r\\n</code>');
- text: <code>brain(hello)</code> should return <code>Hello World!\\n</code>'
testString: assert.equal(brain(hello), "Hello World!\n", '<code>brain(hello)</code> should return <code>Hello World!\\n</code>');
- text: <code>brain(fib)</code> should return <code>1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89</code>
testString: assert.equal(brain(fib), "1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89", '<code>brain(fib)</code> should return <code>1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89</code>');
Challenge Seed
function brain (prog) {
// Good luck!
}
Before Test
let fib=`+
++
+++
++++
+>+>>
>>++++
+++++++
++++++++
+++++++++
++++++++++
++++++>++++
++++++++++++
+++++++++++++
+++<<<<<<[>[>>
>>>>+>+<<<<<<<-
]>>>>>>>[<<<<<<<
+>>>>>>>-]<[>++++
++++++[-<-[>>+>+<<
<-]>>>[<<<+>>>-]+<[
>[-]<[-]]>[<<[>>>+<<
<-]>>[-]]<<]>>>[>>+>+
<<<-]>>>[<<<+>>>-]+<[>
[-]<[-]]>[<<+>>[-]]<<<<
<<<]>>>>>[++++++++++++++
+++++++++++++++++++++++++
+++++++++.[-]]++++++++++<[
->-<]>+++++++++++++++++++++
+++++++++++++++++++++++++++.
[-]<<<<<<<<<<<<[>>>+>+<<<<-]>
>>>[<<<<+>>>>-]<-[>>.>.<<<[-]]
<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+
>-]>[<+>-]<<<-]`;
let hello='++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.'
let bye='++++++++++[>+>+++>++++>+++++++>++++++++>+++++++++>++++++++++>+++++++++++>++++++++++++<<<<<<<<<-]>>>>+.>>>>+..<.<++++++++.>>>+.<<+.<<<<++++.<++.>>>+++++++.>>>.+++.<+++++++.--------.<<<<<+.<+++.---.';
Solution
function brain(prog){
var output="";
var code; // formatted code
var ip = 0; // current instruction within code
var nest = 0; // current bracket nesting (for Out button)
var ahead = []; // locations of matching brackets
var data = [0]; // data array (mod by +, -)
var dp = 0; // index into data (mod by <, >)
var inp = 0; // current input character (fetch with ,)
var quit = 0;
var commands = {
'>':function() { if (++dp >= data.length) data[dp]=0 },
'<':function() { if (--dp < 0) quit++ },
'+':function() { ++data[dp] },
'-':function() { --data[dp] },
'[':function() { if (!data[dp]) ip = ahead[ip]; else ++nest },
']':function() { if ( data[dp]) ip = ahead[ip]; else --nest },
',':function() {
var c = document.getElementById("input").value.charCodeAt(inp++);
data[dp] = isNaN(c) ? 0 : c; // EOF: other options are -1 or no change
},
'.':function() {
output+=String.fromCharCode(data[dp]);
/*var s = document.getElementById("output").innerHTML)
+ String.fromCharCode(data[dp]);
s = s.replace(/\n/g,"<br>").replace(/ /g,"&nbsp;");
document.getElementById("output").innerHTML = s;*/
},
};
let ar=prog.split('');
var st = [], back, error = -1;
for (ip=0; ip<ar.length; ip++) {
switch(ar[ip]) {
case '[':
st.push(ip);
break;
case ']':
if (st.length == 0) error = ip;
back = st.pop();
ahead[ip] = back;
ahead[back] = ip;
break;
}
}
for(ip=0;ip<ar.length;ip++){
if(commands.hasOwnProperty(ar[ip]))
commands[ar[ip]]();
}
return output;
}