/* @flow */
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const MAX_STACK_DEPTH = 800
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const noop = _ => _
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const defer = typeof process !== 'undefined' && process.nextTick
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? process.nextTick
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: typeof Promise !== 'undefined'
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? fn => Promise.resolve().then(fn)
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: typeof setTimeout !== 'undefined'
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? setTimeout
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: noop
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if (defer === noop) {
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throw new Error(
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'Your JavaScript runtime does not support any asynchronous primitives ' +
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'that are required by vue-server-renderer. Please use a polyfill for ' +
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'either Promise or setTimeout.'
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)
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}
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export function createWriteFunction (
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write: (text: string, next: Function) => boolean,
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onError: Function
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): Function {
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let stackDepth = 0
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const cachedWrite = (text, next) => {
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if (text && cachedWrite.caching) {
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cachedWrite.cacheBuffer[cachedWrite.cacheBuffer.length - 1] += text
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}
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const waitForNext = write(text, next)
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if (waitForNext !== true) {
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if (stackDepth >= MAX_STACK_DEPTH) {
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defer(() => {
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try { next() } catch (e) {
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onError(e)
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}
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})
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} else {
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stackDepth++
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next()
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stackDepth--
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}
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}
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}
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cachedWrite.caching = false
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cachedWrite.cacheBuffer = []
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cachedWrite.componentBuffer = []
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return cachedWrite
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}
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