var concatMap = require('concat-map');
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var balanced = require('balanced-match');
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module.exports = expandTop;
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var escSlash = '\0SLASH'+Math.random()+'\0';
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var escOpen = '\0OPEN'+Math.random()+'\0';
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var escClose = '\0CLOSE'+Math.random()+'\0';
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var escComma = '\0COMMA'+Math.random()+'\0';
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var escPeriod = '\0PERIOD'+Math.random()+'\0';
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function numeric(str) {
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return parseInt(str, 10) == str
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? parseInt(str, 10)
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: str.charCodeAt(0);
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}
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function escapeBraces(str) {
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return str.split('\\\\').join(escSlash)
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.split('\\{').join(escOpen)
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.split('\\}').join(escClose)
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.split('\\,').join(escComma)
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.split('\\.').join(escPeriod);
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}
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function unescapeBraces(str) {
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return str.split(escSlash).join('\\')
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.split(escOpen).join('{')
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.split(escClose).join('}')
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.split(escComma).join(',')
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.split(escPeriod).join('.');
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}
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// Basically just str.split(","), but handling cases
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// where we have nested braced sections, which should be
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// treated as individual members, like {a,{b,c},d}
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function parseCommaParts(str) {
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if (!str)
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return [''];
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var parts = [];
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var m = balanced('{', '}', str);
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if (!m)
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return str.split(',');
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var pre = m.pre;
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var body = m.body;
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var post = m.post;
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var p = pre.split(',');
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p[p.length-1] += '{' + body + '}';
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var postParts = parseCommaParts(post);
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if (post.length) {
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p[p.length-1] += postParts.shift();
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p.push.apply(p, postParts);
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}
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parts.push.apply(parts, p);
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return parts;
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}
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function expandTop(str) {
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if (!str)
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return [];
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// I don't know why Bash 4.3 does this, but it does.
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// Anything starting with {} will have the first two bytes preserved
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// but *only* at the top level, so {},a}b will not expand to anything,
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// but a{},b}c will be expanded to [a}c,abc].
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// One could argue that this is a bug in Bash, but since the goal of
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// this module is to match Bash's rules, we escape a leading {}
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if (str.substr(0, 2) === '{}') {
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str = '\\{\\}' + str.substr(2);
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}
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return expand(escapeBraces(str), true).map(unescapeBraces);
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}
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function identity(e) {
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return e;
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}
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function embrace(str) {
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return '{' + str + '}';
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}
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function isPadded(el) {
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return /^-?0\d/.test(el);
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}
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function lte(i, y) {
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return i <= y;
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}
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function gte(i, y) {
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return i >= y;
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}
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function expand(str, isTop) {
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var expansions = [];
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var m = balanced('{', '}', str);
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if (!m || /\$$/.test(m.pre)) return [str];
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var isNumericSequence = /^-?\d+\.\.-?\d+(?:\.\.-?\d+)?$/.test(m.body);
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var isAlphaSequence = /^[a-zA-Z]\.\.[a-zA-Z](?:\.\.-?\d+)?$/.test(m.body);
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var isSequence = isNumericSequence || isAlphaSequence;
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var isOptions = m.body.indexOf(',') >= 0;
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if (!isSequence && !isOptions) {
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// {a},b}
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if (m.post.match(/,.*\}/)) {
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str = m.pre + '{' + m.body + escClose + m.post;
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return expand(str);
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}
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return [str];
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}
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var n;
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if (isSequence) {
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n = m.body.split(/\.\./);
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} else {
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n = parseCommaParts(m.body);
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if (n.length === 1) {
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// x{{a,b}}y ==> x{a}y x{b}y
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n = expand(n[0], false).map(embrace);
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if (n.length === 1) {
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var post = m.post.length
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? expand(m.post, false)
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: [''];
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return post.map(function(p) {
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return m.pre + n[0] + p;
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});
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}
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}
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}
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// at this point, n is the parts, and we know it's not a comma set
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// with a single entry.
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// no need to expand pre, since it is guaranteed to be free of brace-sets
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var pre = m.pre;
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var post = m.post.length
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? expand(m.post, false)
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: [''];
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var N;
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if (isSequence) {
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var x = numeric(n[0]);
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var y = numeric(n[1]);
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var width = Math.max(n[0].length, n[1].length)
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var incr = n.length == 3
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? Math.abs(numeric(n[2]))
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: 1;
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var test = lte;
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var reverse = y < x;
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if (reverse) {
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incr *= -1;
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test = gte;
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}
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var pad = n.some(isPadded);
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N = [];
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for (var i = x; test(i, y); i += incr) {
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var c;
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if (isAlphaSequence) {
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c = String.fromCharCode(i);
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if (c === '\\')
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c = '';
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} else {
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c = String(i);
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if (pad) {
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var need = width - c.length;
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if (need > 0) {
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var z = new Array(need + 1).join('0');
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if (i < 0)
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c = '-' + z + c.slice(1);
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else
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c = z + c;
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}
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}
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}
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N.push(c);
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}
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} else {
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N = concatMap(n, function(el) { return expand(el, false) });
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}
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for (var j = 0; j < N.length; j++) {
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for (var k = 0; k < post.length; k++) {
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var expansion = pre + N[j] + post[k];
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if (!isTop || isSequence || expansion)
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expansions.push(expansion);
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}
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}
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return expansions;
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}
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