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LibRegex: Correct the alternative matching order when one is empty

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Previously we were compiling `/a|/` into what effectively would be
`/|a`, which is clearly incorrect.
This commit is contained in:
Ali Mohammad Pur 2022-02-14 12:03:33 +03:30 • committed by Andreas Kling
parent 76e99fa6c8
commit 3b0943d24c
2 changed files with 22 additions and 7 deletions
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14
Userland/Libraries/LibRegex/RegexOptimizer.cpp
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@ -450,17 +450,17 @@ void Optimizer::append_alternation(ByteCode& target, ByteCode&& left, ByteCode&&
if (left_is_empty && right_is_empty)
return;
// ForkJump right (+ left.size() + 2 + right.size())
// (left)
// Jump end (+ right.size())
// ForkJump left (+ 2 + right.size())
// (right)
// Jump end (+ left.size())
// (left)
// LABEL end
target.append(static_cast<ByteCodeValueType>(OpCodeId::ForkJump));
target.append(left.size() + 2 + right.size());
target.extend(move(left));
target.append(static_cast<ByteCodeValueType>(OpCodeId::Jump));
target.append(right.size());
target.append(2 + right.size());
target.extend(move(right));
target.append(static_cast<ByteCodeValueType>(OpCodeId::Jump));
target.append(left.size());
target.extend(move(left));
return;
}