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// This source code comes from http://www.odelia-technologies.com/node/200
package com.odelia.groovy.simpleworkflow
class SimpleWorkflowEngine {
def workflowMap = [:]
def context = [:]
def beforeActivityName = 'beforeActivity'
def afterActivityName = 'afterActivity'
SimpleWorkflowEngine(workflow, context = [:]) {
this.context = context
parseWorkflow(workflow)
}
def parseWorkflow(workflow) {
workflowMap = new WorkflowParser().parse(workflow)
}
def getActivityValue(activity) {
assert activity instanceof String
if (!workflowMap[activity])
throw new RuntimeException("$activity activity doesn't exist")
workflowMap[activity]
}
def execute(activity, pause) {
if (workflowMap[beforeActivityName]) {
getActivityValue(beforeActivityName)(context, activity)
}
def activityValue = getActivityValue(activity)
// Determine the next activity to execute
def nextActivity
switch (activityValue) {
case String: nextActivity = activityValue; break
case Closure: nextActivity = activityValue(context); break
case Class: nextActivity = activityValue.newInstance()(context)
}
if (workflowMap[afterActivityName]) {
getActivityValue(afterActivityName)(context, activity, nextActivity)
}
if (!pause && nextActivity)
call(nextActivity)
else
nextActivity
}
def call(activity) {
execute(activity, false)
}
def nextActivity(activity) {
execute(activity, true)
}
static void main(String[] args) {
if (args.size() != 2) {
println 'Usage: com.odelia.groovy.simpleworkflow.SimpleWorkflowEngine <dsl_filename> <activity_name>'
return
}
SimpleWorkflowEngine.newInstance(new File(args[0]))(args[1])
}
}
private class WorkflowParser {
def map = [:]
def methodMissing(String name, args) {
map[name] = args[0]
}
def parse(Closure wf) {
wf.delegate = this
wf.resolveStrategy = Closure.DELEGATE_FIRST
wf()
map
}
def workflow = { it ->
it.delegate = this
it.resolveStrategy = Closure.DELEGATE_FIRST
it()
}
def parse(File workflowDef) {
def binding = new Binding([workflow: workflow])
def shell = new GroovyShell(binding)
shell.evaluate(workflowDef)
map
}
}
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