Add list support for Pipeline to AST

pipeline/tick/ast.go

@@ -1,9 +1,23 @@
 package tick
 
 import (
+	"bytes"
+
 	"github.com/influxdata/kapacitor/tick/ast"
 )
 
+// AST converts a pipeline into an AST
+type AST struct {
+	Node ast.Node
+}
+
+// TICKScript produces a TICKScript from the AST
+func (a *AST) TICKScript() string {
+	var buf bytes.Buffer
+	a.Node.Format(&buf, "", false)
+	return buf.String()
+}
+
 // PipeFunction produces an ast.FunctionNode within a Pipe Chain.  May return
 // the left node if all args evaluate to the zero value
 func PipeFunction(left ast.Node, name string, args ...interface{}) (ast.Node, error) {
@@ -87,9 +101,10 @@ func Function(name string, args ...interface{}) (ast.Node, error) {
 	astArgs := []ast.Node{}
 	for _, arg := range args {
 		// Skip zero values as they don't need to be rendered
-		if arg == ast.ZeroValue(ast.TypeOf(arg)) {
+		if IsZero(arg) {
 			continue
 		}
+
 		lit, err := Literal(arg)
 		if err != nil {
 			return nil, err
@@ -108,6 +123,14 @@ func Function(name string, args ...interface{}) (ast.Node, error) {
 	}, nil
 }
 
+func IsZero(arg interface{}) bool {
+	typeOf := ast.TypeOf(arg)
+	if typeOf == ast.TList {
+		return len(arg.([]interface{})) == 0
+	}
+	return arg == ast.ZeroValue(typeOf)
+}
+
 // Literal produces an ast Literal (NumberNode, etc).
 func Literal(lit interface{}) (ast.Node, error) {
 	return ast.ValueToLiteralNode(&NullPosition{}, lit)

pipeline/tick/window.go

@@ -1,24 +1,9 @@
 package tick
 
 import (
-	"bytes"
-
 	"github.com/influxdata/kapacitor/pipeline"
-	"github.com/influxdata/kapacitor/tick/ast"
 )
 
-// AST converts a pipeline into an AST
-type AST struct {
-	Node ast.Node
-}
-
-// TICKScript produces a TICKScript from the AST
-func (a *AST) TICKScript() string {
-	var buf bytes.Buffer
-	a.Node.Format(&buf, "", false)
-	return buf.String()
-}
-
 // Window converts the window pipeline node into the TICKScript AST
 func (a *AST) Window(w *pipeline.WindowNode) *AST {
 	// TODO: Handle the err

tick/ast/types.go

@@ -165,6 +165,10 @@ func ValueToLiteralNode(pos Position, v interface{}) (Node, error) {
 			position:   p,
 			Expression: e,
 		}, nil
+	case *StarNode:
+		return &StarNode{
+			position: p,
+		}, nil
 	case []interface{}:
 		nodes := make([]Node, len(value))
 		var err error