Add support for GraphQL variables

qcode/parse.go

@@ -14,6 +14,8 @@ var (
 type parserType int16
 
 const (
+	maxNested = 50
+
 	parserError parserType = iota
 	parserEOF
 	opQuery
@@ -50,6 +52,8 @@ func (t parserType) String() string {
 		v = "node-float"
 	case nodeBool:
 		v = "node-bool"
+	case nodeVar:
+		v = "node-var"
 	case nodeObj:
 		v = "node-obj"
 	case nodeList:
@@ -253,7 +257,7 @@ func (p *Parser) parseFields() ([]*Field, int16, error) {
 			continue
 		}
 
-		if i > 500 {
+		if i > maxNested {
 			return nil, 0, errors.New("too many fields")
 		}
 

qcode/qcode.go

@@ -465,8 +465,10 @@ func (com *Compiler) compileArgID(sel *Select, arg *Arg) error {
 		ex.Type = ValInt
 	case nodeFloat:
 		ex.Type = ValFloat
+	case nodeVar:
+		ex.Type = ValVar
 	default:
-		fmt.Errorf("expecting an string, int or float")
+		fmt.Errorf("expecting a string, int, float or variable")
 	}
 
 	sel.Where = ex