reduce type asserts

Author: James Cor

sql/plan/filter.go

@@ -15,8 +15,6 @@
 package plan
 
 import (
-	"fmt"
-
 	"github.com/dolthub/go-mysql-server/sql"
 )
 
@@ -106,6 +104,9 @@ func (f *Filter) Expressions() []sql.Expression {
 type FilterIter struct {
 	cond      sql.Expression
 	childIter sql.RowIter
+
+	cond2      sql.Expression2
+	childIter2 sql.RowIter2
 }
 
 // NewFilterIter creates a new FilterIter.
@@ -136,23 +137,12 @@ func (i *FilterIter) Next(ctx *sql.Context) (sql.Row, error) {
 }
 
 func (i *FilterIter) Next2(ctx *sql.Context) (sql.Row2, error) {
-	ri2, ok := i.childIter.(sql.RowIter2)
-	if !ok {
-		panic(fmt.Sprintf("%T is not a sql.RowIter2", i.childIter))
-	}
-
 	for {
-		row, err := ri2.Next2(ctx)
+		row, err := i.childIter2.Next2(ctx)
 		if err != nil {
 			return nil, err
 		}
-
-		// TODO: write EvaluateCondition2?
-		cond, isCond2 := i.cond.(sql.Expression2)
-		if !isCond2 {
-			panic(fmt.Sprintf("%T does not implement sql.Expression2 interface", i.cond))
-		}
-		res, err := cond.Eval2(ctx, row)
+		res, err := i.cond2.Eval2(ctx, row)
 		if err != nil {
 			return nil, err
 		}
@@ -163,15 +153,17 @@ func (i *FilterIter) Next2(ctx *sql.Context) (sql.Row2, error) {
 }
 
 func (i *FilterIter) IsRowIter2(ctx *sql.Context) bool {
-	if cond, isExpr2 := i.cond.(sql.Expression2); isExpr2 {
-		if !cond.IsExpr2() {
-			return false
-		}
+	cond, ok := i.cond.(sql.Expression2)
+	if !ok || !cond.IsExpr2() {
+		return false
 	}
-	if ri2, ok := i.childIter.(sql.RowIter2); ok {
-		return ri2.IsRowIter2(ctx)
+	childIter, ok := i.childIter.(sql.RowIter2)
+	if !ok || !childIter.IsRowIter2(ctx) {
+		return false
 	}
-	return false
+	i.cond2 = cond
+	i.childIter2 = childIter
+	return true
 }
 
 // Close implements the RowIter interface.

sql/plan/process.go

@@ -226,6 +226,7 @@ const (
 type TrackedRowIter struct {
 	node               sql.Node
 	iter               sql.RowIter
+	iter2              sql.RowIter2
 	onDone             NotifyFunc
 	onNext             NotifyFunc
 	numRows            int64
@@ -318,11 +319,7 @@ func (i *TrackedRowIter) Next(ctx *sql.Context) (sql.Row, error) {
 }
 
 func (i *TrackedRowIter) Next2(ctx *sql.Context) (sql.Row2, error) {
-	ri2, ok := i.iter.(sql.RowIter2)
-	if !ok {
-		panic(fmt.Sprintf("%T does not implement sql.RowIter2 interface", i.iter))
-	}
-	row, err := ri2.Next2(ctx)
+	row, err := i.iter2.Next2(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -334,10 +331,12 @@ func (i *TrackedRowIter) Next2(ctx *sql.Context) (sql.Row2, error) {
 }
 
 func (i *TrackedRowIter) IsRowIter2(ctx *sql.Context) bool {
-	if ri2, ok := i.iter.(sql.RowIter2); ok {
-		return ri2.IsRowIter2(ctx)
+	iter, ok := i.iter.(sql.RowIter2)
+	if !ok || !iter.IsRowIter2(ctx) {
+		return false
 	}
-	return false
+	i.iter2 = iter
+	return true
 }
 
 func (i *TrackedRowIter) Close(ctx *sql.Context) error {

sql/rowexec/transaction_iters.go

@@ -15,7 +15,6 @@
 package rowexec
 
 import (
-	"fmt"
 	"io"
 
 	"gopkg.in/src-d/go-errors.v1"
@@ -72,6 +71,7 @@ func getLockableTable(table sql.Table) (sql.Lockable, error) {
 // during the Close() operation
 type TransactionCommittingIter struct {
 	childIter           sql.RowIter
+	childIter2          sql.RowIter2
 	transactionDatabase string
 	autoCommit          bool
 	implicitCommit      bool
@@ -101,18 +101,16 @@ func (t *TransactionCommittingIter) Next(ctx *sql.Context) (sql.Row, error) {
 }
 
 func (t *TransactionCommittingIter) Next2(ctx *sql.Context) (sql.Row2, error) {
-	ri2, ok := t.childIter.(sql.RowIter2)
-	if !ok {
-		panic(fmt.Sprintf("%T does not implement sql.RowIter2 interface", t.childIter))
-	}
-	return ri2.Next2(ctx)
+	return t.childIter2.Next2(ctx)
 }
 
 func (t *TransactionCommittingIter) IsRowIter2(ctx *sql.Context) bool {
-	if ri2, ok := t.childIter.(sql.RowIter2); ok {
-		return ri2.IsRowIter2(ctx)
+	childIter, ok := t.childIter.(sql.RowIter2)
+	if !ok || !childIter.IsRowIter2(ctx) {
+		return false
 	}
-	return false
+	t.childIter2 = childIter
+	return true
 }
 
 func (t *TransactionCommittingIter) Close(ctx *sql.Context) error {

sql/table_iter.go

@@ -106,7 +106,7 @@ func (i *TableRowIter) Next2(ctx *Context) (Row2, error) {
 			return nil, err
 		}
 		ri2, ok := rows.(RowIter2)
-		if !ok {
+		if !ok || !ri2.IsRowIter2(ctx) {
 			panic(fmt.Sprintf("%T does not implement RowIter2", rows))
 		}
 		i.rows2 = ri2