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Add better syntax checking in brainfuck

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This commit is contained in:
Nilay Majorwar 2022-01-22 21:23:00 +05:30
parent 94dce5bfa9
commit 694d3133fc
1 changed files with 19 additions and 4 deletions
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23
engines/brainfuck/runtime.ts
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@ -1,5 +1,5 @@
import { DocumentRange, LanguageEngine, StepExecutionResult } from "../types"; import { DocumentRange, LanguageEngine, StepExecutionResult } from "../types";
import { RuntimeError } from "../worker-errors"; import { ParseError, RuntimeError } from "../worker-errors";
import { BFAstStep, BFInstruction, BFRS, BF_OP } from "./common"; import { BFAstStep, BFInstruction, BFRS, BF_OP } from "./common";
// Default values for internal states // Default values for internal states
@ -75,14 +75,19 @@ export default class BrainfuckLanguageEngine implements LanguageEngine<BFRS> {
if (!OP_CHARS.includes(char as BF_OP)) return; if (!OP_CHARS.includes(char as BF_OP)) return;
// Update loop-tracking stack if it's a loop-char // Update loop-tracking stack if it's a loop-char
let jumpTarget = undefined; let jumpTarget: number | undefined = undefined;
if (char === BF_OP.LOOPIN) { if (char === BF_OP.LOOPIN) {
// Push loop start into stack // Push loop start into stack
// Opposite end location will be added at loop close // Opposite end location will be added at loop close
loopStack.push(ast.length); loopStack.push(ast.length);
} else if (char === BF_OP.LOOPOUT) { } else if (char === BF_OP.LOOPOUT) {
// Get location of loop-opener // Check and add jump target to loop-opener
jumpTarget = loopStack.pop()!; jumpTarget = loopStack.pop();
if (jumpTarget == null)
throw new ParseError("Unmatched ']'", {
line: lIdx,
charRange: { start: cIdx, end: cIdx + 1 },
});
// Add closing end location to loop-opener // Add closing end location to loop-opener
ast[jumpTarget].instr.param = ast.length; ast[jumpTarget].instr.param = ast.length;
} }
@ -95,6 +100,16 @@ export default class BrainfuckLanguageEngine implements LanguageEngine<BFRS> {
}); });
}); });
// Ensure that we ended with an empty loop stack
if (loopStack.length !== 0) {
const opener = loopStack[loopStack.length - 1];
const location = ast[opener].location;
throw new ParseError("Unmatched '['", {
line: location.line,
charRange: { start: location.char, end: location.char + 1 },
});
}
return ast; return ast;
} }