pkg/aflow: support function calls in templates

Support constructs like:

{{if and .Foo .Bar}}

"and" is represented by IdentifierNode, which we need to ignore in our analysis.

Author: dvyukov

pkg/aflow/template.go

@@ -94,6 +94,7 @@ func walkTemplate(n parse.Node, used map[string]bool, errp *error) {
 		used[n.Ident[0]] = true
 	case *parse.VariableNode:
 	case *parse.TextNode:
+	case *parse.IdentifierNode:
 	default:
 		noteError(errp, "unhandled node type %T", n)
 	}

pkg/aflow/template_test.go

@@ -64,6 +64,14 @@ func TestTemplate(t *testing.T) {
 			},
 			err: "input foo is not provided",
 		},
+		{
+			template: `{{if and .foo .bar}} yes {{end}}`,
+			vars: map[string]reflect.Type{
+				"foo": reflect.TypeFor[bool](),
+				"bar": reflect.TypeFor[int](),
+			},
+			used: []string{"foo", "bar"},
+		},
 	}
 	for i, test := range tests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {