Merge pull request #250 from pingcap/siddontang/refactor-builtin

refactor builtin

expression/between_test.go

@@ -18,6 +18,7 @@ import (
 
 	. "github.com/pingcap/check"
 
+	"github.com/pingcap/tidb/expression/builtin"
 	"github.com/pingcap/tidb/util/types"
 )
 
@@ -47,7 +48,7 @@ func (s *testBetweenSuite) TestBetween(c *C) {
 	}
 
 	m := map[interface{}]interface{}{
-		ExprEvalArgAggEmpty: struct{}{},
+		builtin.ExprEvalArgAggEmpty: struct{}{},
 	}
 
 	for _, t := range table {

expression/binop_test.go

@@ -19,6 +19,7 @@ import (
 
 	. "github.com/pingcap/check"
 
+	"github.com/pingcap/tidb/expression/builtin"
 	"github.com/pingcap/tidb/model"
 	mysql "github.com/pingcap/tidb/mysqldef"
 	"github.com/pingcap/tidb/parser/opcode"
@@ -171,7 +172,7 @@ func (s *testBinOpSuite) TestIdentRelOp(c *C) {
 	}
 
 	m := map[interface{}]interface{}{
-		ExprEvalArgAggEmpty: struct{}{},
+		builtin.ExprEvalArgAggEmpty: struct{}{},
 	}
 
 	for _, t := range tbl {

expression/builtin.go → expression/builtin/builtin.go

@@ -15,22 +15,39 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package expression
+package builtin
 
-import (
-	"fmt"
-	"strings"
+import "github.com/juju/errors"
 
-	"github.com/juju/errors"
+const (
+	// ExprEvalFn is the key saving Call expression.
+	ExprEvalFn = "$fn"
+	// ExprEvalArgCtx is the key saving Context for a Call expression.
+	ExprEvalArgCtx = "$ctx"
+	// ExprAggDone is the key indicating that aggregate function is done.
+	ExprAggDone = "$aggDone"
+	// ExprEvalArgAggEmpty is the key to evaluate the aggregate function for empty table.
+	ExprEvalArgAggEmpty = "$agg0"
+	// ExprAggDistinct is the key saving a distinct aggregate.
+	ExprAggDistinct = "$aggDistinct"
 )
 
-var builtin = map[string]struct {
-	f           func([]interface{}, map[interface{}]interface{}) (interface{}, error)
-	minArgs     int
-	maxArgs     int
-	isStatic    bool
-	isAggregate bool
-}{
+// Func is for a builtin function.
+type Func struct {
+	// F is the specific calling function.
+	F func([]interface{}, map[interface{}]interface{}) (interface{}, error)
+	// MinArgs is the minimal arguments needed,
+	MinArgs int
+	// MaxArgs is the maximal arguments needed, -1 for infinity.
+	MaxArgs int
+	// IsStatic shows whether this function can be called statically.
+	IsStatic bool
+	// IsAggregate represents whether this function is an aggregate function or not.
+	IsAggregate bool
+}
+
+// Funcs holds all registered builtin functions.
+var Funcs = map[string]Func{
 	// common functions
 	"coalesce": {builtinCoalesce, 1, -1, true, false},
 
@@ -83,19 +100,6 @@ var builtin = map[string]struct {
 	"user":         {builtinUser, 0, 0, false, false},
 }
 
-func badNArgs(min int, s string, args []interface{}) error {
-	a := []string{}
-	for _, v := range args {
-		a = append(a, fmt.Sprintf("%v", v))
-	}
-	switch len(args) < min {
-	case true:
-		return errors.Errorf("missing argument to %s(%s)", s, strings.Join(a, ", "))
-	default: //case false:
-		return errors.Errorf("too many arguments to %s(%s)", s, strings.Join(a, ", "))
-	}
-}
-
 func invArg(arg interface{}, s string) error {
 	return errors.Errorf("invalid argument %v (type %T) for %s", arg, arg, s)
 }

expression/builtin_test.go → expression/builtin/builtin_test.go

@@ -11,23 +11,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package expression
+package builtin
 
 import (
+	"testing"
+
 	. "github.com/pingcap/check"
 )
 
-var _ = Suite(&testBuiltinSuite{})
-
-type testBuiltinSuite struct {
+func TestT(t *testing.T) {
+	TestingT(t)
 }
 
-func (s *testBuiltinSuite) TestBadNArgs(c *C) {
-	err := badNArgs(1, "", nil)
-	c.Assert(err, NotNil)
+var _ = Suite(&testBuiltinSuite{})
 
-	err = badNArgs(0, "", []interface{}{1})
-	c.Assert(err, NotNil)
+type testBuiltinSuite struct {
 }
 
 func (s *testBuiltinSuite) TestCoalesce(c *C) {

expression/builtin_control.go → expression/builtin/control.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package expression
+package builtin
 
 import "github.com/pingcap/tidb/util/types"
 

expression/builtin/control_test.go

@@ -0,0 +1,82 @@
+// Copyright 2015 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package builtin
+
+import (
+	"errors"
+
+	. "github.com/pingcap/check"
+)
+
+func (s *testBuiltinSuite) TestIf(c *C) {
+	tbl := []struct {
+		Arg1 interface{}
+		Arg2 interface{}
+		Arg3 interface{}
+		Ret  interface{}
+	}{
+		{1, 1, 2, 1},
+		{nil, 1, 2, 2},
+		{0, 1, 2, 2},
+	}
+
+	for _, t := range tbl {
+		v, err := builtinIf([]interface{}{t.Arg1, t.Arg2, t.Arg3}, nil)
+		c.Assert(err, IsNil)
+		c.Assert(v, DeepEquals, t.Ret)
+	}
+
+	_, err := builtinIf([]interface{}{errors.New("must error"), 1, 2}, nil)
+	c.Assert(err, NotNil)
+}
+
+func (s *testBuiltinSuite) TestIfNull(c *C) {
+	tbl := []struct {
+		Arg1 interface{}
+		Arg2 interface{}
+		Ret  interface{}
+	}{
+		{1, 2, 1},
+		{nil, 2, 2},
+		{nil, nil, nil},
+	}
+
+	for _, t := range tbl {
+		v, err := builtinIfNull([]interface{}{t.Arg1, t.Arg2}, nil)
+		c.Assert(err, IsNil)
+		c.Assert(v, DeepEquals, t.Ret)
+	}
+}
+
+func (s *testBuiltinSuite) TestNullIf(c *C) {
+	tbl := []struct {
+		Arg1 interface{}
+		Arg2 interface{}
+		Ret  interface{}
+	}{
+		{1, 1, nil},
+		{nil, 2, nil},
+		{1, nil, 1},
+		{1, 2, 1},
+	}
+
+	for _, t := range tbl {
+		v, err := builtinNullIf([]interface{}{t.Arg1, t.Arg2}, nil)
+		c.Assert(err, IsNil)
+		c.Assert(v, DeepEquals, t.Ret)
+	}
+
+	_, err := builtinNullIf([]interface{}{errors.New("must error"), 1}, nil)
+	c.Assert(err, NotNil)
+}

expression/builtin_groupby.go → expression/builtin/groupby.go

@@ -15,7 +15,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package expression
+package builtin
 
 import (
 	"bytes"
@@ -28,29 +28,32 @@ import (
 	"github.com/pingcap/tidb/util/types"
 )
 
-// see https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html
+// See https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html
 
-type aggregateDistinct struct {
-	// now we have to use memkv Temp, later may be use map directly
+// AggregateDistinct handles distinct data for aggregate function: count, sum, avg, and group_concat.
+type AggregateDistinct struct {
+	// Distinct is a memory key-value map.
+	// Now we have to use memkv Temp, later may be use map directly
 	Distinct memkv.Temp
 }
 
-func (c *Call) createDistinct() *aggregateDistinct {
-	a := new(aggregateDistinct)
+// CreateAggregateDistinct creates a distinct for function f.
+func CreateAggregateDistinct(f string, distinct bool) *AggregateDistinct {
+	a := &AggregateDistinct{}
 
-	switch strings.ToLower(c.F) {
+	switch strings.ToLower(f) {
 	case "count", "sum", "avg", "group_concat":
 		// only these aggregate functions support distinct
-		if c.Distinct {
+		if distinct {
 			a.Distinct, _ = memkv.CreateTemp(true)
 		}
 	}
 
 	return a
 }
 
-// check whether v is distinct or not, return true for distinct
-func (a *aggregateDistinct) isDistinct(v ...interface{}) (bool, error) {
+// Check whether v is distinct or not, return true for distinct
+func (a *AggregateDistinct) isDistinct(v ...interface{}) (bool, error) {
 	// no distinct flag
 	if a.Distinct == nil {
 		return true, nil
@@ -74,7 +77,7 @@ func (a *aggregateDistinct) isDistinct(v ...interface{}) (bool, error) {
 	return true, nil
 }
 
-func (a *aggregateDistinct) clear() {
+func (a *AggregateDistinct) clear() {
 	if a.Distinct == nil {
 		return
 	}
@@ -86,30 +89,15 @@ func (a *aggregateDistinct) clear() {
 	a.Distinct, _ = memkv.CreateTemp(true)
 }
 
-func getDistinct(ctx map[interface{}]interface{}, fn interface{}) *aggregateDistinct {
-	c, ok := fn.(*Call)
+func getDistinct(ctx map[interface{}]interface{}, fn interface{}) *AggregateDistinct {
+	v, ok := ctx[ExprAggDistinct]
 	if !ok {
-		// if fn is not a Call, maybe error
-		// but now we just return a dummpy aggregate distinct
-		return new(aggregateDistinct)
+		// here maybe an error, but now we just return a dummpy aggregate distinct
+		return new(AggregateDistinct)
 	}
 
-	// we may have multi aggregate function in one query
-	// e.g, select sum(c1) + count(*) from t
-	// so here we use a map to keep all aggregate disctinct
-	m := map[interface{}]interface{}{}
-	if v, ok := ctx[ExprAggDistinct]; ok {
-		m = v.(map[interface{}]interface{})
-	}
-
-	if d, ok := m[c]; ok {
-		return d.(*aggregateDistinct)
-	}
-
-	d := c.createDistinct()
-	m[c] = d
-
-	ctx[ExprAggDistinct] = m
+	// must be AggregateDistinct
+	d := v.(*AggregateDistinct)
 	return d
 }