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'use strict'
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const fs = require('fs')
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const path = require('path')
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const YError = require('./yerror')
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let previouslyVisitedConfigs = []
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function checkForCircularExtends (cfgPath) {
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if (previouslyVisitedConfigs.indexOf(cfgPath) > -1) {
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throw new YError(`Circular extended configurations: '${cfgPath}'.`)
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}
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}
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function getPathToDefaultConfig (cwd, pathToExtend) {
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return path.resolve(cwd, pathToExtend)
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}
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function applyExtends (config, cwd) {
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let defaultConfig = {}
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if (config.hasOwnProperty('extends')) {
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if (typeof config.extends !== 'string') return defaultConfig
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const isPath = /\.json|\..*rc$/.test(config.extends)
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let pathToDefault = null
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if (!isPath) {
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try {
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pathToDefault = require.resolve(config.extends)
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} catch (err) {
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// most likely this simply isn't a module.
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}
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} else {
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pathToDefault = getPathToDefaultConfig(cwd, config.extends)
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}
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// maybe the module uses key for some other reason,
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// err on side of caution.
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if (!pathToDefault && !isPath) return config
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checkForCircularExtends(pathToDefault)
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previouslyVisitedConfigs.push(pathToDefault)
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defaultConfig = isPath ? JSON.parse(fs.readFileSync(pathToDefault, 'utf8')) : require(config.extends)
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delete config.extends
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defaultConfig = applyExtends(defaultConfig, path.dirname(pathToDefault))
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}
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previouslyVisitedConfigs = []
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return Object.assign({}, defaultConfig, config)
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}
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module.exports = applyExtends
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