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JavaScript

/*!
* to-regex-range <https://github.com/jonschlinkert/to-regex-range>
*
* Copyright (c) 2015, 2017, Jon Schlinkert.
* Released under the MIT License.
*/
'use strict';
var repeat = require('repeat-string');
var isNumber = require('is-number');
var cache = {};
function toRegexRange(min, max, options) {
if (isNumber(min) === false) {
throw new RangeError('toRegexRange: first argument is invalid.');
}
if (typeof max === 'undefined' || min === max) {
return String(min);
}
if (isNumber(max) === false) {
throw new RangeError('toRegexRange: second argument is invalid.');
}
options = options || {};
var relax = String(options.relaxZeros);
var shorthand = String(options.shorthand);
var capture = String(options.capture);
var key = min + ':' + max + '=' + relax + shorthand + capture;
if (cache.hasOwnProperty(key)) {
return cache[key].result;
}
var a = Math.min(min, max);
var b = Math.max(min, max);
if (Math.abs(a - b) === 1) {
var result = min + '|' + max;
if (options.capture) {
return '(' + result + ')';
}
return result;
}
var isPadded = padding(min) || padding(max);
var positives = [];
var negatives = [];
var tok = {min: min, max: max, a: a, b: b};
if (isPadded) {
tok.isPadded = isPadded;
tok.maxLen = String(tok.max).length;
}
if (a < 0) {
var newMin = b < 0 ? Math.abs(b) : 1;
var newMax = Math.abs(a);
negatives = splitToPatterns(newMin, newMax, tok, options);
a = tok.a = 0;
}
if (b >= 0) {
positives = splitToPatterns(a, b, tok, options);
}
tok.negatives = negatives;
tok.positives = positives;
tok.result = siftPatterns(negatives, positives, options);
if (options.capture && (positives.length + negatives.length) > 1) {
tok.result = '(' + tok.result + ')';
}
cache[key] = tok;
return tok.result;
}
function siftPatterns(neg, pos, options) {
var onlyNegative = filterPatterns(neg, pos, '-', false, options) || [];
var onlyPositive = filterPatterns(pos, neg, '', false, options) || [];
var intersected = filterPatterns(neg, pos, '-?', true, options) || [];
var subpatterns = onlyNegative.concat(intersected).concat(onlyPositive);
return subpatterns.join('|');
}
function splitToRanges(min, max) {
min = Number(min);
max = Number(max);
var nines = 1;
var stops = [max];
var stop = +countNines(min, nines);
while (min <= stop && stop <= max) {
stops = push(stops, stop);
nines += 1;
stop = +countNines(min, nines);
}
var zeros = 1;
stop = countZeros(max + 1, zeros) - 1;
while (min < stop && stop <= max) {
stops = push(stops, stop);
zeros += 1;
stop = countZeros(max + 1, zeros) - 1;
}
stops.sort(compare);
return stops;
}
/**
* Convert a range to a regex pattern
* @param {Number} `start`
* @param {Number} `stop`
* @return {String}
*/
function rangeToPattern(start, stop, options) {
if (start === stop) {
return {pattern: String(start), digits: []};
}
var zipped = zip(String(start), String(stop));
var len = zipped.length, i = -1;
var pattern = '';
var digits = 0;
while (++i < len) {
var numbers = zipped[i];
var startDigit = numbers[0];
var stopDigit = numbers[1];
if (startDigit === stopDigit) {
pattern += startDigit;
} else if (startDigit !== '0' || stopDigit !== '9') {
pattern += toCharacterClass(startDigit, stopDigit);
} else {
digits += 1;
}
}
if (digits) {
pattern += options.shorthand ? '\\d' : '[0-9]';
}
return { pattern: pattern, digits: [digits] };
}
function splitToPatterns(min, max, tok, options) {
var ranges = splitToRanges(min, max);
var len = ranges.length;
var idx = -1;
var tokens = [];
var start = min;
var prev;
while (++idx < len) {
var range = ranges[idx];
var obj = rangeToPattern(start, range, options);
var zeros = '';
if (!tok.isPadded && prev && prev.pattern === obj.pattern) {
if (prev.digits.length > 1) {
prev.digits.pop();
}
prev.digits.push(obj.digits[0]);
prev.string = prev.pattern + toQuantifier(prev.digits);
start = range + 1;
continue;
}
if (tok.isPadded) {
zeros = padZeros(range, tok);
}
obj.string = zeros + obj.pattern + toQuantifier(obj.digits);
tokens.push(obj);
start = range + 1;
prev = obj;
}
return tokens;
}
function filterPatterns(arr, comparison, prefix, intersection, options) {
var res = [];
for (var i = 0; i < arr.length; i++) {
var tok = arr[i];
var ele = tok.string;
if (options.relaxZeros !== false) {
if (prefix === '-' && ele.charAt(0) === '0') {
if (ele.charAt(1) === '{') {
ele = '0*' + ele.replace(/^0\{\d+\}/, '');
} else {
ele = '0*' + ele.slice(1);
}
}
}
if (!intersection && !contains(comparison, 'string', ele)) {
res.push(prefix + ele);
}
if (intersection && contains(comparison, 'string', ele)) {
res.push(prefix + ele);
}
}
return res;
}
/**
* Zip strings (`for in` can be used on string characters)
*/
function zip(a, b) {
var arr = [];
for (var ch in a) arr.push([a[ch], b[ch]]);
return arr;
}
function compare(a, b) {
return a > b ? 1 : b > a ? -1 : 0;
}
function push(arr, ele) {
if (arr.indexOf(ele) === -1) arr.push(ele);
return arr;
}
function contains(arr, key, val) {
for (var i = 0; i < arr.length; i++) {
if (arr[i][key] === val) {
return true;
}
}
return false;
}
function countNines(min, len) {
return String(min).slice(0, -len) + repeat('9', len);
}
function countZeros(integer, zeros) {
return integer - (integer % Math.pow(10, zeros));
}
function toQuantifier(digits) {
var start = digits[0];
var stop = digits[1] ? (',' + digits[1]) : '';
if (!stop && (!start || start === 1)) {
return '';
}
return '{' + start + stop + '}';
}
function toCharacterClass(a, b) {
return '[' + a + ((b - a === 1) ? '' : '-') + b + ']';
}
function padding(str) {
return /^-?(0+)\d/.exec(str);
}
function padZeros(val, tok) {
if (tok.isPadded) {
var diff = Math.abs(tok.maxLen - String(val).length);
switch (diff) {
case 0:
return '';
case 1:
return '0';
default: {
return '0{' + diff + '}';
}
}
}
return val;
}
/**
* Expose `toRegexRange`
*/
module.exports = toRegexRange;