stream: clone stream before execution

internal/expr/functions/builtins.go

@@ -127,6 +127,12 @@ type TypeOf struct {
 	Expr expr.Expr
 }
 
+func (t *TypeOf) Clone() expr.Expr {
+	return &TypeOf{
+		Expr: expr.Clone(t.Expr),
+	}
+}
+
 func (t *TypeOf) Eval(env *environment.Environment) (types.Value, error) {
 	v, err := t.Expr.Eval(env)
 	if err != nil {
@@ -175,6 +181,14 @@ func NewCount(e expr.Expr) *Count {
 	}
 }
 
+func (t *Count) Clone() expr.Expr {
+	return &Count{
+		Expr:     expr.Clone(t.Expr),
+		wildcard: t.wildcard,
+		Count:    t.Count,
+	}
+}
+
 func (c *Count) Eval(env *environment.Environment) (types.Value, error) {
 	d, ok := env.GetRow()
 	if !ok {
@@ -250,6 +264,12 @@ type Min struct {
 	Expr expr.Expr
 }
 
+func (t *Min) Clone() expr.Expr {
+	return &Min{
+		Expr: expr.Clone(t.Expr),
+	}
+}
+
 // Eval extracts the min value from the given object and returns it.
 func (m *Min) Eval(env *environment.Environment) (types.Value, error) {
 	r, ok := env.GetRow()
@@ -354,6 +374,12 @@ type Max struct {
 	Expr expr.Expr
 }
 
+func (t *Max) Clone() expr.Expr {
+	return &Max{
+		Expr: expr.Clone(t.Expr),
+	}
+}
+
 // Eval extracts the max value from the given object and returns it.
 func (m *Max) Eval(env *environment.Environment) (types.Value, error) {
 	r, ok := env.GetRow()
@@ -453,6 +479,12 @@ type Sum struct {
 	Expr expr.Expr
 }
 
+func (t *Sum) Clone() expr.Expr {
+	return &Sum{
+		Expr: expr.Clone(t.Expr),
+	}
+}
+
 // Eval extracts the sum value from the given object and returns it.
 func (s *Sum) Eval(env *environment.Environment) (types.Value, error) {
 	r, ok := env.GetRow()
@@ -564,6 +596,12 @@ type Avg struct {
 	Expr expr.Expr
 }
 
+func (t *Avg) Clone() expr.Expr {
+	return &Avg{
+		Expr: expr.Clone(t.Expr),
+	}
+}
+
 // Eval extracts the average value from the given object and returns it.
 func (s *Avg) Eval(env *environment.Environment) (types.Value, error) {
 	r, ok := env.GetRow()
@@ -651,6 +689,12 @@ type Len struct {
 	Expr expr.Expr
 }
 
+func (t *Len) Clone() expr.Expr {
+	return &Len{
+		Expr: expr.Clone(t.Expr),
+	}
+}
+
 // Eval extracts the average value from the given object and returns it.
 func (s *Len) Eval(env *environment.Environment) (types.Value, error) {
 	val, err := s.Expr.Eval(env)
@@ -694,6 +738,16 @@ type Coalesce struct {
 	Exprs []expr.Expr
 }
 
+func (c *Coalesce) Clone() expr.Expr {
+	var clone Coalesce
+	clone.Exprs = make([]expr.Expr, 0, len(c.Exprs))
+	for _, e := range c.Exprs {
+		clone.Exprs = append(clone.Exprs, expr.Clone(e))
+	}
+
+	return &clone
+}
+
 func (c *Coalesce) Eval(e *environment.Environment) (types.Value, error) {
 	for _, exp := range c.Exprs {
 		v, err := exp.Eval(e)
@@ -717,6 +771,10 @@ func (c *Coalesce) Params() []expr.Expr {
 
 type Now struct{}
 
+func (n *Now) Clone() expr.Expr {
+	return &Now{}
+}
+
 func (n *Now) Eval(env *environment.Environment) (types.Value, error) {
 	tx := env.GetTx()
 	if tx == nil {

internal/expr/functions/scalar_definition.go

@@ -56,6 +56,18 @@ type ScalarFunction struct {
 	params []expr.Expr
 }
 
+func (sf *ScalarFunction) Clone() expr.Expr {
+	exprs := make([]expr.Expr, 0, len(sf.params))
+	for _, e := range sf.params {
+		exprs = append(exprs, expr.Clone(e))
+	}
+
+	return &ScalarFunction{
+		def:    sf.def,
+		params: exprs,
+	}
+}
+
 // Eval returns a row.Value based on the given environment and the underlying function
 // definition.
 func (sf *ScalarFunction) Eval(env *environment.Environment) (types.Value, error) {

internal/expr/functions/strings.go

@@ -15,6 +15,12 @@ type Lower struct {
 	Expr expr.Expr
 }
 
+func (s *Lower) Clone() expr.Expr {
+	return &Lower{
+		Expr: expr.Clone(s.Expr),
+	}
+}
+
 func (s *Lower) Eval(env *environment.Environment) (types.Value, error) {
 	val, err := s.Expr.Eval(env)
 	if err != nil {
@@ -55,6 +61,12 @@ type Upper struct {
 	Expr expr.Expr
 }
 
+func (s *Upper) Clone() expr.Expr {
+	return &Upper{
+		Expr: expr.Clone(s.Expr),
+	}
+}
+
 func (s *Upper) Eval(env *environment.Environment) (types.Value, error) {
 	val, err := s.Expr.Eval(env)
 	if err != nil {
@@ -101,6 +113,18 @@ type Trim struct {
 
 type TrimFunc func(string, string) string
 
+func (s *Trim) Clone() expr.Expr {
+	exprs := make([]expr.Expr, len(s.Expr))
+	for i := range s.Expr {
+		exprs[i] = expr.Clone(s.Expr[i])
+	}
+	return &Trim{
+		Expr:     exprs,
+		TrimFunc: s.TrimFunc,
+		Name:     s.Name,
+	}
+}
+
 func (s *Trim) Eval(env *environment.Environment) (types.Value, error) {
 	if len(s.Expr) > 2 {
 		return nil, fmt.Errorf("misuse of string function %v()", s.Name)