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							9.4 KiB
						
					
					
				
			
		
		
	
	
							373 lines
						
					
					
						
							9.4 KiB
						
					
					
				"use strict"; | 
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 | 
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// These use the global symbol registry so that multiple copies of this | 
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// library can work together in case they are not deduped. | 
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const GENSYNC_START = Symbol.for("gensync:v1:start"); | 
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const GENSYNC_SUSPEND = Symbol.for("gensync:v1:suspend"); | 
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 | 
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const GENSYNC_EXPECTED_START = "GENSYNC_EXPECTED_START"; | 
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const GENSYNC_EXPECTED_SUSPEND = "GENSYNC_EXPECTED_SUSPEND"; | 
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const GENSYNC_OPTIONS_ERROR = "GENSYNC_OPTIONS_ERROR"; | 
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const GENSYNC_RACE_NONEMPTY = "GENSYNC_RACE_NONEMPTY"; | 
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const GENSYNC_ERRBACK_NO_CALLBACK = "GENSYNC_ERRBACK_NO_CALLBACK"; | 
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 | 
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module.exports = Object.assign( | 
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  function gensync(optsOrFn) { | 
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    let genFn = optsOrFn; | 
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    if (typeof optsOrFn !== "function") { | 
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      genFn = newGenerator(optsOrFn); | 
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    } else { | 
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      genFn = wrapGenerator(optsOrFn); | 
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    } | 
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 | 
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    return Object.assign(genFn, makeFunctionAPI(genFn)); | 
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  }, | 
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  { | 
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    all: buildOperation({ | 
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      name: "all", | 
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      arity: 1, | 
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      sync: function(args) { | 
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        const items = Array.from(args[0]); | 
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        return items.map(item => evaluateSync(item)); | 
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      }, | 
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      async: function(args, resolve, reject) { | 
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        const items = Array.from(args[0]); | 
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 | 
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        if (items.length === 0) { | 
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          Promise.resolve().then(() => resolve([])); | 
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          return; | 
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        } | 
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 | 
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        let count = 0; | 
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        const results = items.map(() => undefined); | 
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        items.forEach((item, i) => { | 
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          evaluateAsync( | 
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            item, | 
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            val => { | 
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              results[i] = val; | 
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              count += 1; | 
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 | 
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              if (count === results.length) resolve(results); | 
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            }, | 
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            reject | 
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          ); | 
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        }); | 
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      }, | 
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    }), | 
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    race: buildOperation({ | 
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      name: "race", | 
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      arity: 1, | 
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      sync: function(args) { | 
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        const items = Array.from(args[0]); | 
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        if (items.length === 0) { | 
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          throw makeError("Must race at least 1 item", GENSYNC_RACE_NONEMPTY); | 
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        } | 
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 | 
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        return evaluateSync(items[0]); | 
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      }, | 
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      async: function(args, resolve, reject) { | 
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        const items = Array.from(args[0]); | 
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        if (items.length === 0) { | 
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          throw makeError("Must race at least 1 item", GENSYNC_RACE_NONEMPTY); | 
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        } | 
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 | 
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        for (const item of items) { | 
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          evaluateAsync(item, resolve, reject); | 
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        } | 
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      }, | 
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    }), | 
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  } | 
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); | 
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 | 
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/** | 
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 * Given a generator function, return the standard API object that executes | 
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 * the generator and calls the callbacks. | 
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 */ | 
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function makeFunctionAPI(genFn) { | 
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  const fns = { | 
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    sync: function(...args) { | 
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      return evaluateSync(genFn.apply(this, args)); | 
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    }, | 
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    async: function(...args) { | 
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      return new Promise((resolve, reject) => { | 
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        evaluateAsync(genFn.apply(this, args), resolve, reject); | 
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      }); | 
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    }, | 
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    errback: function(...args) { | 
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      const cb = args.pop(); | 
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      if (typeof cb !== "function") { | 
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        throw makeError( | 
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          "Asynchronous function called without callback", | 
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          GENSYNC_ERRBACK_NO_CALLBACK | 
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        ); | 
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      } | 
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 | 
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      let gen; | 
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      try { | 
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        gen = genFn.apply(this, args); | 
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      } catch (err) { | 
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        cb(err); | 
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        return; | 
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      } | 
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 | 
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      evaluateAsync(gen, val => cb(undefined, val), err => cb(err)); | 
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    }, | 
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  }; | 
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  return fns; | 
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} | 
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 | 
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function assertTypeof(type, name, value, allowUndefined) { | 
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  if ( | 
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    typeof value === type || | 
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    (allowUndefined && typeof value === "undefined") | 
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  ) { | 
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    return; | 
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  } | 
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 | 
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  let msg; | 
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  if (allowUndefined) { | 
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    msg = `Expected opts.${name} to be either a ${type}, or undefined.`; | 
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  } else { | 
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    msg = `Expected opts.${name} to be a ${type}.`; | 
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  } | 
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 | 
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  throw makeError(msg, GENSYNC_OPTIONS_ERROR); | 
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} | 
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function makeError(msg, code) { | 
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  return Object.assign(new Error(msg), { code }); | 
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} | 
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 | 
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/** | 
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 * Given an options object, return a new generator that dispatches the | 
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 * correct handler based on sync or async execution. | 
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 */ | 
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function newGenerator({ name, arity, sync, async, errback }) { | 
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  assertTypeof("string", "name", name, true /* allowUndefined */); | 
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  assertTypeof("number", "arity", arity, true /* allowUndefined */); | 
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  assertTypeof("function", "sync", sync); | 
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  assertTypeof("function", "async", async, true /* allowUndefined */); | 
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  assertTypeof("function", "errback", errback, true /* allowUndefined */); | 
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  if (async && errback) { | 
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    throw makeError( | 
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      "Expected one of either opts.async or opts.errback, but got _both_.", | 
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      GENSYNC_OPTIONS_ERROR | 
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    ); | 
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  } | 
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 | 
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  if (typeof name !== "string") { | 
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    let fnName; | 
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    if (errback && errback.name && errback.name !== "errback") { | 
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      fnName = errback.name; | 
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    } | 
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    if (async && async.name && async.name !== "async") { | 
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      fnName = async.name.replace(/Async$/, ""); | 
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    } | 
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    if (sync && sync.name && sync.name !== "sync") { | 
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      fnName = sync.name.replace(/Sync$/, ""); | 
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    } | 
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 | 
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    if (typeof fnName === "string") { | 
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      name = fnName; | 
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    } | 
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  } | 
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 | 
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  if (typeof arity !== "number") { | 
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    arity = sync.length; | 
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  } | 
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 | 
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  return buildOperation({ | 
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    name, | 
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    arity, | 
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    sync: function(args) { | 
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      return sync.apply(this, args); | 
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    }, | 
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    async: function(args, resolve, reject) { | 
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      if (async) { | 
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        async.apply(this, args).then(resolve, reject); | 
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      } else if (errback) { | 
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        errback.call(this, ...args, (err, value) => { | 
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          if (err == null) resolve(value); | 
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          else reject(err); | 
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        }); | 
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      } else { | 
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        resolve(sync.apply(this, args)); | 
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      } | 
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    }, | 
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  }); | 
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} | 
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 | 
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function wrapGenerator(genFn) { | 
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  return setFunctionMetadata(genFn.name, genFn.length, function(...args) { | 
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    return genFn.apply(this, args); | 
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  }); | 
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} | 
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 | 
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function buildOperation({ name, arity, sync, async }) { | 
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  return setFunctionMetadata(name, arity, function*(...args) { | 
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    const resume = yield GENSYNC_START; | 
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    if (!resume) { | 
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      // Break the tail call to avoid a bug in V8 v6.X with --harmony enabled. | 
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      const res = sync.call(this, args); | 
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      return res; | 
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    } | 
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 | 
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    let result; | 
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    try { | 
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      async.call( | 
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        this, | 
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        args, | 
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        value => { | 
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          if (result) return; | 
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 | 
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          result = { value }; | 
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          resume(); | 
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        }, | 
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        err => { | 
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          if (result) return; | 
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 | 
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          result = { err }; | 
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          resume(); | 
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        } | 
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      ); | 
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    } catch (err) { | 
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      result = { err }; | 
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      resume(); | 
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    } | 
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 | 
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    // Suspend until the callbacks run. Will resume synchronously if the | 
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    // callback was already called. | 
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    yield GENSYNC_SUSPEND; | 
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 | 
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    if (result.hasOwnProperty("err")) { | 
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      throw result.err; | 
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    } | 
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 | 
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    return result.value; | 
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  }); | 
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} | 
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 | 
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function evaluateSync(gen) { | 
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  let value; | 
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  while (!({ value } = gen.next()).done) { | 
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    assertStart(value, gen); | 
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  } | 
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  return value; | 
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} | 
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 | 
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function evaluateAsync(gen, resolve, reject) { | 
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  (function step() { | 
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    try { | 
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      let value; | 
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      while (!({ value } = gen.next()).done) { | 
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        assertStart(value, gen); | 
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 | 
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        // If this throws, it is considered to have broken the contract | 
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        // established for async handlers. If these handlers are called | 
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        // synchronously, it is also considered bad behavior. | 
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        let sync = true; | 
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        let didSyncResume = false; | 
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        const out = gen.next(() => { | 
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          if (sync) { | 
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            didSyncResume = true; | 
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          } else { | 
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            step(); | 
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          } | 
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        }); | 
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        sync = false; | 
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 | 
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        assertSuspend(out, gen); | 
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 | 
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        if (!didSyncResume) { | 
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          // Callback wasn't called synchronously, so break out of the loop | 
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          // and let it call 'step' later. | 
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          return; | 
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        } | 
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      } | 
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 | 
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      return resolve(value); | 
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    } catch (err) { | 
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      return reject(err); | 
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    } | 
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  })(); | 
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} | 
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 | 
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function assertStart(value, gen) { | 
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  if (value === GENSYNC_START) return; | 
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 | 
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  throwError( | 
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    gen, | 
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    makeError( | 
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      `Got unexpected yielded value in gensync generator: ${JSON.stringify( | 
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        value | 
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      )}. Did you perhaps mean to use 'yield*' instead of 'yield'?`, | 
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      GENSYNC_EXPECTED_START | 
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    ) | 
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  ); | 
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} | 
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function assertSuspend({ value, done }, gen) { | 
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  if (!done && value === GENSYNC_SUSPEND) return; | 
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 | 
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  throwError( | 
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    gen, | 
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    makeError( | 
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      done | 
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        ? "Unexpected generator completion. If you get this, it is probably a gensync bug." | 
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        : `Expected GENSYNC_SUSPEND, got ${JSON.stringify( | 
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            value | 
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          )}. If you get this, it is probably a gensync bug.`, | 
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      GENSYNC_EXPECTED_SUSPEND | 
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    ) | 
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  ); | 
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} | 
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 | 
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function throwError(gen, err) { | 
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  // Call `.throw` so that users can step in a debugger to easily see which | 
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  // 'yield' passed an unexpected value. If the `.throw` call didn't throw | 
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  // back to the generator, we explicitly do it to stop the error | 
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  // from being swallowed by user code try/catches. | 
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  if (gen.throw) gen.throw(err); | 
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  throw err; | 
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} | 
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 | 
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function isIterable(value) { | 
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  return ( | 
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    !!value && | 
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    (typeof value === "object" || typeof value === "function") && | 
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    !value[Symbol.iterator] | 
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  ); | 
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} | 
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 | 
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function setFunctionMetadata(name, arity, fn) { | 
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  if (typeof name === "string") { | 
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    // This should always work on the supported Node versions, but for the | 
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    // sake of users that are compiling to older versions, we check for | 
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    // configurability so we don't throw. | 
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    const nameDesc = Object.getOwnPropertyDescriptor(fn, "name"); | 
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    if (!nameDesc || nameDesc.configurable) { | 
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      Object.defineProperty( | 
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        fn, | 
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        "name", | 
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        Object.assign(nameDesc || {}, { | 
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          configurable: true, | 
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          value: name, | 
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        }) | 
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      ); | 
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    } | 
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  } | 
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 | 
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  if (typeof arity === "number") { | 
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    const lengthDesc = Object.getOwnPropertyDescriptor(fn, "length"); | 
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    if (!lengthDesc || lengthDesc.configurable) { | 
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      Object.defineProperty( | 
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        fn, | 
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        "length", | 
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        Object.assign(lengthDesc || {}, { | 
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          configurable: true, | 
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          value: arity, | 
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        }) | 
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      ); | 
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    } | 
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  } | 
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 | 
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  return fn; | 
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}
 | 
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 |