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Mirror: The magical sticky regex-based parser generator 🧙
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1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768const syntaxError = (char) => { throw new SyntaxError('Unexpected token "' + char + '"');};
export const parse = (quasis, expressions) => { let quasiIndex = 0; let stackIndex = 0;
const sequenceStack = []; const rootSequence = [];
let currentGroup = null; let lastMatch; let currentSequence = rootSequence; let capture;
for ( let quasiIndex = 0, stackIndex = 0; stackIndex < quasis.length + expressions.length; stackIndex++ ) { if (stackIndex % 2 !== 0) { const expression = expressions[stackIndex++ >> 1]; currentSequence.push({ expression, capture }); capture = undefined; }
const quasi = quasis[stackIndex >> 1]; for (quasiIndex = 0; quasiIndex < quasi.length; ) { const char = quasi[quasiIndex++]; if (char === ' ' || char === '\t' || char === '\r' || char === '\n') { } else if (char === '|' && currentSequence.length) { currentSequence = currentSequence.alternation = []; } else if (char === ')' && currentSequence.length) { currentGroup = null; currentSequence = sequenceStack.pop(); if (!currentSequence) syntaxError(char); } else if (char === '(') { sequenceStack.push(currentSequence); currentSequence.push((currentGroup = { sequence: [], capture })); currentSequence = currentGroup.sequence; capture = undefined; } else if (char === ':' || char === '=' || char === '!') { capture = char; const nextChar = quasi[quasiIndex]; if (quasi[quasiIndex] && quasi[quasiIndex] !== '(') syntaxError(char); } else if (char === '?' && !currentSequence.length && currentGroup) { capture = quasi[quasiIndex++]; if (capture === ':' || capture === '=' || capture === '!') { currentGroup.capture = capture; capture = undefined; } else { syntaxError(char); } } else if ( (char === '?' || char === '+' || char === '*') && (lastMatch = currentSequence[currentSequence.length - 1]) ) { lastMatch.quantifier = char; } else { syntaxError(char); } } }
return rootSequence;};