126 lines
3.1 KiB
JavaScript
126 lines
3.1 KiB
JavaScript
function noop(value) {
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return value;
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}
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function generateMultiplier(multiplier) {
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if (multiplier.min === 0 && multiplier.max === 0) {
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return '*';
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}
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if (multiplier.min === 0 && multiplier.max === 1) {
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return '?';
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}
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if (multiplier.min === 1 && multiplier.max === 0) {
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return multiplier.comma ? '#' : '+';
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}
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if (multiplier.min === 1 && multiplier.max === 1) {
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return '';
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}
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return (
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(multiplier.comma ? '#' : '') +
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(multiplier.min === multiplier.max
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? '{' + multiplier.min + '}'
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: '{' + multiplier.min + ',' + (multiplier.max !== 0 ? multiplier.max : '') + '}'
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)
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);
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}
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function generateTypeOpts(node) {
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switch (node.type) {
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case 'Range':
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return (
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' [' +
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(node.min === null ? '-∞' : node.min) +
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',' +
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(node.max === null ? '∞' : node.max) +
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']'
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);
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default:
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throw new Error('Unknown node type `' + node.type + '`');
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}
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}
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function generateSequence(node, forceBraces, decorate) {
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var result = node.terms.map(function(term) {
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return generate(term, forceBraces, decorate);
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}).join(node.combinator === ' ' ? ' ' : ' ' + node.combinator + ' ');
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if (node.explicit || forceBraces) {
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result = (result[0] !== ',' ? '[ ' : '[') + result + ' ]';
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}
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return result;
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}
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function generate(node, forceBraces, decorate) {
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var result;
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switch (node.type) {
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case 'Group':
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result =
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generateSequence(node, forceBraces, decorate) +
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(node.disallowEmpty ? '!' : '');
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break;
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case 'Multiplier':
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// return since node is a composition
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return (
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generate(node.term, forceBraces, decorate) +
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decorate(generateMultiplier(node), node)
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);
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case 'Type':
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result = '<' + node.name + (node.opts ? decorate(generateTypeOpts(node.opts), node.opts) : '') + '>';
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break;
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case 'Property':
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result = '<\'' + node.name + '\'>';
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break;
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case 'Keyword':
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result = node.name;
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break;
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case 'AtKeyword':
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result = '@' + node.name;
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break;
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case 'Function':
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result = node.name + '(';
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break;
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case 'String':
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case 'Token':
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result = node.value;
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break;
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case 'Comma':
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result = ',';
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break;
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default:
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throw new Error('Unknown node type `' + node.type + '`');
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}
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return decorate(result, node);
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}
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module.exports = function(node, options) {
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var decorate = noop;
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var forceBraces = false;
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if (typeof options === 'function') {
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decorate = options;
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} else if (options) {
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forceBraces = Boolean(options.forceBraces);
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if (typeof options.decorate === 'function') {
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decorate = options.decorate;
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}
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}
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return generate(node, forceBraces, decorate);
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};
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