uri-template-router/util/range.js

Match a URI to a pattern in a collection of URI Templates

'use strict';

// Get all the characters described by a charclass like [a-z0-9]
function *range(str){
	for(var i=0; i<str.length; i++){
		const chr = str[i];
		if(chr === '-'){
			yield chr;
		}else if(str[i+1]==='-' && str[i+2]){
			for(var j=str.charCodeAt(i), end=str.charCodeAt(i+2); j<=end; j++){
				yield String.fromCharCode(j);
			}
			i += 2;
		}else{
			yield chr;
		}
	}
}

function toRangeString(chars){
	var str = '';
	chars = chars.slice().sort();
	for(var i=0; i<chars.length; i++){
		if(chars[i].length !== 1) throw new Error('Invalid symbol size');
		const startCode = chars[i].charCodeAt();
		for(var j=0; i+j+1<chars.length && chars[i+j+1].charCodeAt() !== startCode+j+1; j++);
		if(j===0){
			str += chars[i];
		}else if(j===1){
			str += chars[i] + chars[i+1];
		}else{
			str += chars[i] + '-' + chars[i+j];
		}
		i += j;
	}
	return str;
}

function normalize(str){
	return toRangeString([...range(str)]);
}