shithub: pprolog

ref: ff418c798b580204f6fea5512adc36835f8b7efa
dir: /builtins.c/

#include <u.h>
#include <libc.h>

#include "dat.h"
#include "fns.h"

#define BuiltinProto(name) int name(Term *, Term *, Goal **, Choicepoint **, Binding **)
#define Match(X, Y) (runestrcmp(name, X) == 0 && arity == Y)

BuiltinProto(builtinfail);
BuiltinProto(builtincall);
BuiltinProto(builtincut);
BuiltinProto(builtinvar);
BuiltinProto(builtinatom);
BuiltinProto(builtininteger);
BuiltinProto(builtinfloat);
BuiltinProto(builtinatomic);
BuiltinProto(builtincompound);
BuiltinProto(builtinnonvar);
BuiltinProto(builtinnumber);
BuiltinProto(builtinstring);
BuiltinProto(builtincompare);

int compareterms(Term *, Term *);

Builtin
findbuiltin(Term *goal)
{
	int arity;
	Rune *name;

	switch(goal->tag){
	case AtomTerm:
		arity = 0;
		name = goal->text;
		break;
	case CompoundTerm:
		arity = goal->arity;
		name = goal->text;
		break;
	default:
		return nil;
	}

	/* Rewrite this so its not just a long if chain */
	if(Match(L"fail", 0))
		return builtinfail;
	if(Match(L"call", 1))
		return builtincall;
	if(Match(L"!", 0))
		return builtincut;
	if(Match(L"var", 1))
		return builtinvar;
	if(Match(L"atom", 1))
		return builtinatom;
	if(Match(L"integer", 1))
		return builtininteger;
	if(Match(L"float", 1))
		return builtinfloat;
	if(Match(L"atomic", 1))
		return builtinatomic;
	if(Match(L"compound", 1))
		return builtincompound;
	if(Match(L"nonvar", 1))
		return builtinnonvar;
	if(Match(L"number", 1))
		return builtinnumber;
	if(Match(L"string", 1))
		return builtinstring;
	if(Match(L"compare", 3))
		return builtincompare;

	return nil;
}

int
builtinfail(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goal);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	return 0;
}

int
builtincall(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(choicestack);
	USED(bindings);

	Goal *g = malloc(sizeof(Goal));
	g->goal = goal->children;
	g->next = *goals;
	*goals = g;

	return 1;
}

int
builtincut(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(bindings);

	Choicepoint *cp = *choicestack;

	/* Cut all choicepoints with an id larger or equal to the goal clause number, since they must have been introduced
	   after this goal's parent.
	*/
	while(cp != nil && cp->id >= goal->clausenr)
		cp = cp->next;
	*choicestack = cp;
	return 1;
}

int
builtinvar(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == VariableTerm);
}

int
builtinatom(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == AtomTerm);
}

int
builtininteger(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == NumberTerm && arg->numbertype == NumberInt);
}

int
builtinfloat(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == NumberTerm && arg->numbertype == NumberFloat);
}

int
builtinatomic(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == AtomTerm || arg->tag == NumberTerm);
}

int
builtincompound(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == CompoundTerm);
}

int
builtinnonvar(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag != VariableTerm);
}

int
builtinnumber(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == NumberTerm);
}

int
builtinstring(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	USED(bindings);
	Term *arg = goal->children;
	return (arg->tag == StringTerm);
}

#define Compare(A, B) ((A < B) ? -1 : ((A > B) ? 1 : 0))

int
compareterms(Term *t1, Term *t2)
{
	int result = 0;

	if(t1->tag != t2->tag)
		result = Compare(t1->tag, t2->tag);
	else{
		/* Same type term */
		switch(t1->tag){
		case VariableTerm:
			if(t1->clausenr == t2->clausenr)
				result = runestrcmp(t1->text, t2->text);
			else
				result = Compare(t1->clausenr, t2->clausenr);
			break;
		case NumberTerm:
			if(t1->numbertype == t2->numbertype){
				if(t1->numbertype == NumberInt)
					result = Compare(t1->ival, t2->ival);
				else
					result = Compare(t1->dval, t2->dval);
			}else
				result = Compare(t1->numbertype, t2->numbertype);
			break;
		case StringTerm:
		case AtomTerm:
			result = runestrcmp(t1->text, t2->text);
			break;
		case CompoundTerm:
			result = Compare(t1->arity, t2->arity);
			if(result != 0)
				break;

			result = runestrcmp(t1->text, t2->text);
			if(result != 0)
				break;

			t1 = t1->children;
			t2 = t2->children;
			while(t1 != nil && t2 != nil){
				result = compareterms(t1, t2);
				if(result != 0)
					break;
				else
					t1 = t1->next;
					t2 = t2->next;
			}
			break;
		}
	}
	return result;
}

int
builtincompare(Term *database, Term *goal, Goal **goals, Choicepoint **choicestack, Binding **bindings)
{
	USED(database);
	USED(goals);
	USED(choicestack);
	Term *order = goal->children;
	Term *t1 = order->next;
	Term *t2 = t1->next;

	int result = compareterms(t1, t2);

	Term *resultorder;
	if(result == -1)
		resultorder = mkatom(L"<");
	else if(result == 0)
		resultorder = mkatom(L"=");
	else
		resultorder = mkatom(L">");

	return unify(order, resultorder, bindings);
}