Using jrunscript as a build tool

In my last post, i've described how to use jrunscript to create a build script.
As olivier wrote in the comments, the build process is usually a dependency graph and jrunscript doesn't do that by default.
But javascript is far more powerful than XML thus it's easy to create commands that enable to declare dependencies betweeen functions as Ant or make does.

I propose the following commands:

1. depends_on that declares a set of dependencies of a function.
2. run_targets that explores the graph from a function in a dependency first order.

Javascript enables to put data in an existing object even a one like Object or Function. In fact, objects are considered as an hashtable of couples property/value so the dependencies of a function can be stored in the function itself.

The build script:

function test1() {
  echo("test 1");
}

function test2() {
  echo("test 2");
}
test2.depends_on(test1);

function test3() {
  echo("test 3");
}
test3.depends_on(test1,test2);

run_targets(test3);

And the script that creates the two commands :

function depends_on() {
  var dependencies=new Array();
  for (var i=0;i<arguments.length;i++) {
    dependencies.push(arguments[i]);
  }
  this.dependencies=dependencies;
}
Function.prototype.depends_on=depends_on;

function run_targets(target) {
  run_targets_internal(target,new Object())
}

function run_targets_internal(target,markers) {
  if (markers[target]=="X")
    return
    
  markers[target]="X"
  for each(dependency in target.dependencies) {
    run_targets_internal(dependency,markers);
  }
  
  echo("target "+target.name);
  target();
}

Now, it's time to drop Ant :)