47 lines
1.3 KiB
JavaScript
47 lines
1.3 KiB
JavaScript
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'use strict'
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function getDirectoryComponents (path, sep) {
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var components = path.split(sep)
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// Remove any trailing separators and the base component.
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var last = ''
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while (last === '') {
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last = components.pop()
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}
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return components
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}
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module.exports = function commonPathPrefix (paths, sep) {
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if (!sep) {
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var m = /(\/|\\)/.exec(paths[0])
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// The first path did not contain any directory components. Bail now.
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if (!m) return ''
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sep = m[0]
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}
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// Object to hold prefix strings formed of the directory components of each
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// path. The value for each prefix string is the number of times that prefix
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// occurred in the `paths` array.
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var prefixes = Object.create(null)
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for (var i = 0; i < paths.length; i++) {
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var dirComponents = getDirectoryComponents(paths[i], sep)
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var prefix = ''
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for (var j = 0; j < dirComponents.length; j++) {
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prefix += dirComponents[j] + sep
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prefixes[prefix] = (prefixes[prefix] || 0) + 1
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}
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}
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// Find the prefixes that occurred for each path and sort them by length
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// (longest first).
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var common = Object.keys(prefixes).filter(function (prefix) {
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return prefixes[prefix] === paths.length
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}).sort(function (a, b) {
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return b.length - a.length
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})
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// Return the longest common path prefix, or the empty string.
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return common[0] || ''
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}
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