internal/core/adt: introduce HasConjunct

and use it where appropriate.

Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: I919c129b3b56b4a312bd01e2a7f9741985f30607
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1202658
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Matthew Sackman <matthew@cue.works>

cue/query.go

@@ -62,7 +62,7 @@ outer:
 				Label:  sel.sel.feature(ctx),
 			}
 			n.MatchAndInsert(ctx, x)
-			if len(x.Conjuncts) > 0 {
+			if x.HasConjuncts() {
 				x.Finalize(ctx)
 				parent = linkParent(parent, n, x)
 				n = x

internal/core/adt/composite.go

@@ -672,6 +672,11 @@ func visitAllConjuncts(a []Conjunct, f func(c Conjunct, isLeaf bool)) {
 	}
 }
 
+// HasConjuncts reports whether v has any conjuncts.
+func (v *Vertex) HasConjuncts() bool {
+	return len(v.Conjuncts) > 0
+}
+
 // SingleConjunct reports whether there is a single leaf conjunct and returns 1
 // if so. It will return 0 if there are no conjuncts or 2 if there are more than
 // 1.
@@ -736,7 +741,7 @@ func (x *Vertex) IsConcrete() bool {
 // it tells whether optional field matching and non-regular fields, like
 // definitions and hidden fields, should be ignored.
 func (v *Vertex) IsData() bool {
-	return v.isData || len(v.Conjuncts) == 0
+	return v.isData || !v.HasConjuncts()
 }
 
 // ToDataSingle creates a new Vertex that represents just the regular fields

internal/core/export/expr.go

@@ -74,7 +74,7 @@ func (e *exporter) expr(env *adt.Environment, v adt.Elem) (result ast.Expr) {
 		return nil
 
 	case *adt.Vertex:
-		if len(x.Conjuncts) == 0 || x.IsData() {
+		if x.IsData() {
 			// Treat as literal value.
 			return e.value(x)
 		} // Should this be the arcs label?
@@ -170,9 +170,9 @@ func (x *exporter) mergeValues(label adt.Feature, src *adt.Vertex, a []conjunct,
 	}
 
 	// Unify values only for one level.
-	if a := e.values.Conjuncts; len(a) > 0 {
+	if e.values.HasConjuncts() {
 		e.values.Finalize(e.ctx)
-		e.embed = append(e.embed, e.value(e.values, a...))
+		e.embed = append(e.embed, e.value(e.values, e.values.Conjuncts...))
 	}
 
 	// Collect and order set of fields.

internal/core/export/value.go

@@ -85,7 +85,7 @@ func (e *exporter) vertex(n *adt.Vertex) (result ast.Expr) {
 				result = e.structComposite(n, attrs)
 			}
 
-		case !x.IsIncomplete() || len(n.Conjuncts) == 0 || e.cfg.Final:
+		case !x.IsIncomplete() || !n.HasConjuncts() || e.cfg.Final:
 			result = e.bottom(x)
 		}
 

internal/core/subsume/vertex.go

@@ -221,7 +221,7 @@ outer:
 
 		a := &adt.Vertex{Label: f}
 		x.MatchAndInsert(ctx, a)
-		if len(a.Conjuncts) == 0 {
+		if !a.HasConjuncts() {
 			// It is accepted and has no further constraints, so all good.
 			continue
 		}
@@ -413,7 +413,7 @@ outer:
 
 		a := &adt.Vertex{Label: f}
 		x.MatchAndInsert(ctx, a)
-		if len(a.Conjuncts) == 0 {
+		if !a.HasConjuncts() {
 			// It is accepted and has no further constraints, so all good.
 			continue
 		}