encoding/jsonschema: define isTop and isBottom functions

In general, CUE does uses "top" rather than "all", and
renaming `isAll` to `isTop` makes the corresponding `isBottom`
function more obviously correspondent.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I93b172ca75e59415d60d14614f461a2a02ecc1eb
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1205768
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: rogpeppe

encoding/jsonschema/constraints_array.go

@@ -45,12 +45,12 @@ func constraintAdditionalItems(key string, n cue.Value, s *state) {
 		panic("no elements in list")
 	}
 	last := s.list.Elts[len(s.list.Elts)-1].(*ast.Ellipsis)
-	if _, isBottom := elem.(*ast.BottomLit); isBottom {
+	if isBottom(elem) {
 		// No additional elements allowed. Remove the ellipsis.
 		s.list.Elts = s.list.Elts[:len(s.list.Elts)-1]
 		return
 	}
-	if isAny(elem) {
+	if isTop(elem) {
 		// Nothing to do: there's already an ellipsis in place that
 		// allows anything.
 		return

encoding/jsonschema/constraints_object.go

@@ -142,7 +142,7 @@ func constraintProperties(key string, n cue.Value, s *state) {
 
 func constraintPropertyNames(key string, n cue.Value, s *state) {
 	// [=~pattern]: _
-	if names, _ := s.schemaState(n, cue.StringKind, nil); !isAny(names) {
+	if names, _ := s.schemaState(n, cue.StringKind, nil); !isTop(names) {
 		x := ast.NewStruct(ast.NewList(names), top())
 		s.add(n, objectType, x)
 	}

encoding/jsonschema/decode.go

@@ -378,7 +378,7 @@ func (c *constraintInfo) setTypeUsed(n cue.Value, t coreType) {
 }
 
 func (c *constraintInfo) add(n cue.Value, x ast.Expr) {
-	if !isAny(x) {
+	if !isTop(x) {
 		setPos(x, n)
 		ast.SetRelPos(x, token.NoRelPos)
 		c.constraints = append(c.constraints, x)
@@ -948,11 +948,16 @@ func boolSchema(ok bool) ast.Expr {
 	return bottom()
 }
 
-func isAny(s ast.Expr) bool {
+func isTop(s ast.Expr) bool {
 	i, ok := s.(*ast.Ident)
 	return ok && i.Name == "_"
 }
 
+func isBottom(e ast.Expr) bool {
+	_, ok := e.(*ast.BottomLit)
+	return ok
+}
+
 func addTag(field ast.Label, tag, value string) *ast.Field {
 	return &ast.Field{
 		Label: field,