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94 lines
2.0 KiB
94 lines
2.0 KiB
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/**
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* Module dependencies.
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*/
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const debug = require('debug')('koa-mount')
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const compose = require('koa-compose')
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const assert = require('assert')
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/**
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* Expose `mount()`.
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*/
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module.exports = mount
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/**
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* Mount `app` with `prefix`, `app`
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* may be a Koa application or
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* middleware function.
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*
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* @param {String|Application|Function} prefix, app, or function
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* @param {Application|Function} [app or function]
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* @return {Function}
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* @api public
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*/
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function mount (prefix, app) {
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if (typeof prefix !== 'string') {
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app = prefix
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prefix = '/'
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}
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assert.equal(prefix[0], '/', 'mount path must begin with "/"')
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// compose
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const downstream = app.middleware
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? compose(app.middleware)
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: app
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// don't need to do mounting here
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if (prefix === '/') return downstream
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const trailingSlash = prefix.slice(-1) === '/'
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const name = app.name || 'unnamed'
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debug('mount %s %s', prefix, name)
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return async function (ctx, upstream) {
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const prev = ctx.path
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const newPath = match(prev)
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debug('mount %s %s -> %s', prefix, name, newPath)
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if (!newPath) return await upstream()
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ctx.mountPath = prefix
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ctx.path = newPath
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debug('enter %s -> %s', prev, ctx.path)
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await downstream(ctx, async () => {
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ctx.path = prev
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await upstream()
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ctx.path = newPath
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})
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debug('leave %s -> %s', prev, ctx.path)
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ctx.path = prev
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}
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/**
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* Check if `prefix` satisfies a `path`.
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* Returns the new path.
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*
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* match('/images/', '/lkajsldkjf') => false
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* match('/images', '/images') => /
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* match('/images/', '/images') => false
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* match('/images/', '/images/asdf') => /asdf
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*
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* @param {String} prefix
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* @param {String} path
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* @return {String|Boolean}
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* @api private
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*/
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function match (path) {
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// does not match prefix at all
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if (path.indexOf(prefix) !== 0) return false
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const newPath = path.replace(prefix, '') || '/'
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if (trailingSlash) return newPath
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// `/mount` does not match `/mountlkjalskjdf`
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if (newPath[0] !== '/') return false
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return newPath
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}
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}
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