module stmts;

import phl::lang::io;

/* LinkedList --> Each element contains a condition */
struct @ConditionalChain {
	field @Boolean cond;
	field @ConditionalChain next;
	
	@ConditionalChain init(@Boolean cond, @ConditionalChain next) [
		this::cond = cond;
		this::next = next;
		
		return this;
	]
	
	/*
	 *	If the condition is true executes the closure and returns a false element, otherwise returns the next condition
	 *	
	 *	Execution starts from the first element, and iterates until the right element is found.
	 */
	@ConditionalChain then(@Closure<@Void> closure) [
		if (isNull(next())) return new @ConditionalChain.init(false, null);
		if (cond()) {
			closure();
			return new @ConditionalChain.init(false, null);
		}
		else return next();
	]

	/* Operators create a cool look */	
	@ConditionalChain operator then(@Closure<@Void> closure) alias @ConditionalChain.then;
	@ConditionalChain operator else1(@Closure<@Void> closure) alias @ConditionalChain.then;
	@ConditionalChain operator else2(@Closure<@Void> closure) alias @ConditionalChain.then;
	@ConditionalChain operator orElse(@Closure<@Void> closure) alias @ConditionalChain.then;
};

/* Returns linked list [a && b, a, b, true] */
@ConditionalChain if2(@Boolean a, @Boolean b) [
	return new @ConditionalChain.init(a && b, new @ConditionalChain.init(a, new @ConditionalChain.init(b, new @ConditionalChain.init(true, null))));
]

@Void main [
	if2(false, true) then [
		println("Not this!");
	] else1 [
		println("Not this!");
	] else2 [
		println("This!");
	] orElse [
		println("Not this!");
	];
]