feat(logic): add atomic_list_concat/2 predicate

ccamel · ccamel · commit 44daf95f7c08 · 2024-10-13T18:26:26.000+02:00
diff --git a/x/logic/interpreter/registry.go b/x/logic/interpreter/registry.go
@@ -119,6 +119,7 @@ var registry = orderedmap.New[string, any](
 		{Key: "ecdsa_verify/4", Value: predicate.ECDSAVerify},
 		{Key: "string_bytes/3", Value: predicate.StringBytes},
 		{Key: "term_to_atom/2", Value: predicate.TermToAtom},
+		{Key: "atomic_list_concat/2", Value: predicate.AtomicListConcat2},
 	}...),
 )
 
diff --git a/x/logic/predicate/atom.go b/x/logic/predicate/atom.go
@@ -26,14 +26,14 @@ import (
 //
 //	# Convert the atom to a term.
 //	- term_to_atom(foo, foo).
-func TermToAtom(vm *engine.VM, term, atom engine.Term, cont engine.Cont, env *engine.Env) *engine.Promise {
+func TermToAtom(vm *engine.VM, term, atom engine.Term, k engine.Cont, env *engine.Env) *engine.Promise {
 	switch {
 	case prolog.IsGround(term, env):
 		var strBuilder strings.Builder
 		os := engine.NewOutputTextStream(&strBuilder)
 		return engine.WriteTerm(vm, os, term, engine.List(engine.NewAtom("quoted").Apply(prolog.AtomTrue)),
 			func(env *engine.Env) *engine.Promise {
-				return engine.Unify(vm, prolog.StringToAtom(strBuilder.String()), atom, cont, env)
+				return engine.Unify(vm, prolog.StringToAtom(strBuilder.String()), atom, k, env)
 			}, env)
 	case prolog.IsGround(atom, env):
 		atom, err := prolog.AssertAtom(atom, env)
@@ -44,9 +44,42 @@ func TermToAtom(vm *engine.VM, term, atom engine.Term, cont engine.Cont, env *en
 		parsedAtom := engine.NewVariable()
 		return engine.ReadTerm(vm, is, parsedAtom, engine.List(),
 			func(env *engine.Env) *engine.Promise {
-				return engine.Unify(vm, term, parsedAtom, cont, env)
+				return engine.Unify(vm, term, parsedAtom, k, env)
 			}, env)
 	}
 
 	return engine.Error(engine.InstantiationError(env))
 }
+
+// AtomicListConcat2 is a predicate that unifies an Atom with the concatenated elements of a List.
+//
+// # Signature
+//
+//	atomic_list_concat(+List, ?Atom)
+//
+// where:
+//   - List is a list of strings, atoms, integers, floating point numbers or non-integer rationals
+//   - Atom is an Atom representing the concatenation of the elements of List
+func AtomicListConcat2(vm *engine.VM, list, atom engine.Term, k engine.Cont, env *engine.Env) *engine.Promise {
+	if !prolog.IsGround(list, env) {
+		return engine.Error(engine.InstantiationError(env))
+	}
+
+	it, err := prolog.ListIterator(list, env)
+	if err != nil {
+		return engine.Error(err)
+	}
+
+	switch {
+	case !it.Next():
+		return engine.Unify(vm, prolog.AtomEmpty, atom, k, env)
+	default:
+		headAtom := engine.NewVariable()
+		return TermToAtom(vm, it.Current(), headAtom, func(env *engine.Env) *engine.Promise {
+			tailAtom := engine.NewVariable()
+			return AtomicListConcat2(vm, it.Suffix(), tailAtom, func(env *engine.Env) *engine.Promise {
+				return engine.AtomConcat(vm, headAtom, tailAtom, atom, k, env)
+			}, env)
+		}, env)
+	}
+}

Original file line number	Diff line number	Diff line change
`@@ -119,6 +119,7 @@ var registry = orderedmap.New[string, any](`
`119`	`119`	`{Key: "ecdsa_verify/4", Value: predicate.ECDSAVerify},`
`120`	`120`	`{Key: "string_bytes/3", Value: predicate.StringBytes},`
`121`	`121`	`{Key: "term_to_atom/2", Value: predicate.TermToAtom},`
	`122`	`+ {Key: "atomic_list_concat/2", Value: predicate.AtomicListConcat2},`
`122`	`123`	`}...),`
`123`	`124`	`)`
`124`	`125`