import os

class AbstractDependency:
	def __init__(self, name):
		self._name = name
	
	def get_name(self):
		return self._name
	
	def check(self):
		return False

class LibDependency(AbstractDependency):
	def __init__(self, name, module):
		AbstractDependency.__init__(self, name)
		self._module = module
	
	def check(self):
		pid = os.fork()
		if not pid:
			os.execvp('pkg-config', [ 'pkg-config', '--exists', self._module ])
		return os.wait()[1] == 0

def get_installed(dependencies):
	installed = []
	for dep in dependencies:
		if dep.check():
			installed.append(dep.get_name())
	return installed