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'use strict'
const fs = require('fs')
const path = require('path')
const YError = require('./yerror')
let previouslyVisitedConfigs = []
function checkForCircularExtends (cfgPath) {
if (previouslyVisitedConfigs.indexOf(cfgPath) > -1) {
throw new YError(`Circular extended configurations: '${cfgPath}'.`)
}
}
function getPathToDefaultConfig (cwd, pathToExtend) {
return path.resolve(cwd, pathToExtend)
}
function mergeDeep (config1, config2) {
const target = {}
const isObject = obj => obj && typeof obj === 'object' && !Array.isArray(obj)
Object.assign(target, config1)
for (let key of Object.keys(config2)) {
if (isObject(config2[key]) && isObject(target[key])) {
target[key] = mergeDeep(config1[key], config2[key])
} else {
target[key] = config2[key]
}
}
return target
}
function applyExtends (config, cwd, mergeExtends) {
let defaultConfig = {}
if (Object.prototype.hasOwnProperty.call(config, 'extends')) {
if (typeof config.extends !== 'string') return defaultConfig
const isPath = /\.json|\..*rc$/.test(config.extends)
let pathToDefault = null
if (!isPath) {
try {
pathToDefault = require.resolve(config.extends)
} catch (err) {
// most likely this simply isn't a module.
}
} else {
pathToDefault = getPathToDefaultConfig(cwd, config.extends)
}
// maybe the module uses key for some other reason,
// err on side of caution.
if (!pathToDefault && !isPath) return config
checkForCircularExtends(pathToDefault)
previouslyVisitedConfigs.push(pathToDefault)
defaultConfig = isPath ? JSON.parse(fs.readFileSync(pathToDefault, 'utf8')) : require(config.extends)
delete config.extends
defaultConfig = applyExtends(defaultConfig, path.dirname(pathToDefault), mergeExtends)
}
previouslyVisitedConfigs = []
return mergeExtends ? mergeDeep(defaultConfig, config) : Object.assign({}, defaultConfig, config)
}
module.exports = applyExtends
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