Golang evaluator.Eval函数代码示例

func (e *InsertExec) onDuplicateUpdate(row []types.Datum, h int64, cols map[int]*ast.Assignment) error {
	// On duplicate key update the duplicate row.
	// Evaluate the updated value.
	// TODO: report rows affected and last insert id.
	data, err := e.Table.Row(e.ctx, h)
	if err != nil {
		return errors.Trace(err)
	}
	// For evaluate ValuesExpr
	// http://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_values
	for i, rf := range e.fields {
		rf.Expr.SetValue(row[i].GetValue())
	}
	// Evaluate assignment
	newData := make([]types.Datum, len(data))
	for i, c := range row {
		asgn, ok := cols[i]
		if !ok {
			newData[i] = c
			continue
		}
		val, err1 := evaluator.Eval(e.ctx, asgn.Expr)
		if err1 != nil {
			return errors.Trace(err1)
		}
		newData[i] = val
	}
	if err = updateRecord(e.ctx, h, data, newData, cols, e.Table, 0, true); err != nil {
		return errors.Trace(err)
	}
	return nil
}

// Next implements Executor Next interface.
func (e *SelectFieldsExec) Next() (*Row, error) {
	var rowKeys []*RowKeyEntry
	if e.Src != nil {
		srcRow, err := e.Src.Next()
		if err != nil {
			return nil, errors.Trace(err)
		}
		if srcRow == nil {
			return nil, nil
		}
		rowKeys = srcRow.RowKeys
	} else {
		// If Src is nil, only one row should be returned.
		if e.executed {
			return nil, nil
		}
	}
	e.executed = true
	row := &Row{
		RowKeys: rowKeys,
		Data:    make([]types.Datum, len(e.ResultFields)),
	}
	for i, field := range e.ResultFields {
		val, err := evaluator.Eval(e.ctx, field.Expr)
		if err != nil {
			return nil, errors.Trace(err)
		}
		row.Data[i] = val
	}
	return row, nil
}

func getDefaultValue(ctx context.Context, c *ast.ColumnOption, tp byte, fsp int) (interface{}, error) {
	if tp == mysql.TypeTimestamp || tp == mysql.TypeDatetime {
		vd, err := evaluator.GetTimeValue(ctx, c.Expr, tp, fsp)
		value := vd.GetValue()
		if err != nil {
			return nil, errors.Trace(err)
		}

		// Value is nil means `default null`.
		if value == nil {
			return nil, nil
		}

		// If value is types.Time, convert it to string.
		if vv, ok := value.(types.Time); ok {
			return vv.String(), nil
		}

		return value, nil
	}
	v, err := evaluator.Eval(ctx, c.Expr)
	if err != nil {
		return nil, errors.Trace(err)
	}
	if v.IsNull() {
		return nil, nil
	}
	return v.ToString()
}

// Next implements Executor Next interface.
func (e *SortExec) Next() (*Row, error) {
	if !e.fetched {
		for {
			srcRow, err := e.Src.Next()
			if err != nil {
				return nil, errors.Trace(err)
			}
			if srcRow == nil {
				break
			}
			orderRow := &orderByRow{
				row: srcRow,
				key: make([]interface{}, len(e.ByItems)),
			}
			for i, byItem := range e.ByItems {
				orderRow.key[i], err = evaluator.Eval(e.ctx, byItem.Expr)
				if err != nil {
					return nil, errors.Trace(err)
				}
			}
			e.Rows = append(e.Rows, orderRow)
		}
		sort.Sort(e)
		e.fetched = true
	}
	if e.err != nil {
		return nil, errors.Trace(e.err)
	}
	if e.Idx >= len(e.Rows) {
		return nil, nil
	}
	row := e.Rows[e.Idx].row
	e.Idx++
	return row, nil
}

func (e *InsertValues) getRow(cols []*table.Column, list []ast.ExprNode, defaultVals map[string]types.Datum) ([]types.Datum, error) {
	vals := make([]types.Datum, len(list))
	var err error
	for i, expr := range list {
		if d, ok := expr.(*ast.DefaultExpr); ok {
			cn := d.Name
			if cn == nil {
				vals[i] = defaultVals[cols[i].Name.L]
				continue
			}
			var found bool
			vals[i], found = defaultVals[cn.Name.L]
			if !found {
				return nil, errors.Errorf("default column not found - %s", cn.Name.O)
			}
		} else {
			var val types.Datum
			val, err = evaluator.Eval(e.ctx, expr)
			vals[i] = val
			if err != nil {
				return nil, errors.Trace(err)
			}
		}
	}
	return e.fillRowData(cols, vals, false)
}

func (e *UpdateExec) fetchRows() error {
	for {
		row, err := e.SelectExec.Next()
		if err != nil {
			return errors.Trace(err)
		}
		if row == nil {
			return nil
		}
		data := make([]types.Datum, len(e.SelectExec.Fields()))
		newData := make([]types.Datum, len(e.SelectExec.Fields()))
		for i, f := range e.SelectExec.Fields() {
			data[i] = types.NewDatum(f.Expr.GetValue())
			newData[i] = data[i]
			if e.OrderedList[i] != nil {
				val, err := evaluator.Eval(e.ctx, e.OrderedList[i].Expr)
				if err != nil {
					return errors.Trace(err)
				}
				newData[i] = val
			}
		}
		row.Data = data
		e.rows = append(e.rows, row)
		e.newRowsData = append(e.newRowsData, newData)
	}
}

func (e *SimpleExec) executeDo(s *ast.DoStmt) error {
	for _, expr := range s.Exprs {
		_, err := evaluator.Eval(e.ctx, expr)
		if err != nil {
			return errors.Trace(err)
		}
	}
	return nil
}

// Build builds a prepared statement into an executor.
func (e *ExecuteExec) Build() error {
	vars := variable.GetSessionVars(e.Ctx)
	if e.Name != "" {
		e.ID = vars.PreparedStmtNameToID[e.Name]
	}
	v := vars.PreparedStmts[e.ID]
	if v == nil {
		return ErrStmtNotFound
	}
	prepared := v.(*Prepared)

	if len(prepared.Params) != len(e.UsingVars) {
		return ErrWrongParamCount
	}

	for i, usingVar := range e.UsingVars {
		val, err := evaluator.Eval(e.Ctx, usingVar)
		if err != nil {
			return errors.Trace(err)
		}
		prepared.Params[i].SetDatum(val)
	}

	ast.ResetEvaluatedFlag(prepared.Stmt)
	if prepared.SchemaVersion != e.IS.SchemaMetaVersion() {
		// If the schema version has changed we need to prepare it again,
		// if this time it failed, the real reason for the error is schema changed.
		err := plan.PrepareStmt(e.IS, e.Ctx, prepared.Stmt)
		if err != nil {
			return ErrSchemaChanged.Gen("Schema change casued error: %s", err.Error())
		}
		prepared.SchemaVersion = e.IS.SchemaMetaVersion()
	}
	sb := &subqueryBuilder{is: e.IS}
	p, err := plan.Optimize(e.Ctx, prepared.Stmt, sb, e.IS)
	if err != nil {
		return errors.Trace(err)
	}
	b := newExecutorBuilder(e.Ctx, e.IS)
	stmtExec := b.build(p)
	if b.err != nil {
		return errors.Trace(b.err)
	}
	e.StmtExec = stmtExec
	e.Stmt = prepared.Stmt
	return nil
}

func (e *AggregateExec) getGroupKey() ([]byte, error) {
	if len(e.GroupByItems) == 0 {
		return singleGroup, nil
	}
	vals := make([]types.Datum, 0, len(e.GroupByItems))
	for _, item := range e.GroupByItems {
		v, err := evaluator.Eval(e.ctx, item.Expr)
		if err != nil {
			return nil, errors.Trace(err)
		}
		vals = append(vals, v)
	}
	bs, err := codec.EncodeValue([]byte{}, vals...)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return bs, nil
}

func (e *SimpleExec) getVarValue(v *ast.VariableAssignment, sysVar *variable.SysVar, globalVars variable.GlobalVarAccessor) (value types.Datum, err error) {
	switch v.Value.(type) {
	case *ast.DefaultExpr:
		// To set a SESSION variable to the GLOBAL value or a GLOBAL value
		// to the compiled-in MySQL default value, use the DEFAULT keyword.
		// See http://dev.mysql.com/doc/refman/5.7/en/set-statement.html
		if sysVar != nil {
			value = types.NewStringDatum(sysVar.Value)
		} else {
			s, err1 := globalVars.GetGlobalSysVar(e.ctx, strings.ToLower(v.Name))
			if err1 != nil {
				return value, errors.Trace(err1)
			}
			value = types.NewStringDatum(s)
		}
	default:
		value, err = evaluator.Eval(e.ctx, v.Value)
	}
	return value, errors.Trace(err)
}

// onDuplicateUpdate updates the duplicate row.
// TODO: Report rows affected and last insert id.
func (e *InsertExec) onDuplicateUpdate(row []types.Datum, h int64, cols map[int]*ast.Assignment) error {
	data, err := e.Table.Row(e.ctx, h)
	if err != nil {
		return errors.Trace(err)
	}

	// for evaluating ColumnNameExpr
	for i, rf := range e.fields {
		rf.Expr.SetValue(data[i].GetValue())
	}
	// for evaluating ValuesExpr
	// See http://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_values
	e.ctx.GetSessionVars().CurrInsertValues = row
	// evaluate assignment
	newData := make([]types.Datum, len(data))
	for i, c := range row {
		asgn, ok := cols[i]
		if !ok {
			newData[i] = c
			continue
		}
		val, err1 := evaluator.Eval(e.ctx, asgn.Expr)
		if err1 != nil {
			return errors.Trace(err1)
		}
		newData[i] = val
	}

	assignFlag := make([]bool, len(e.Table.Cols()))
	for i, asgn := range cols {
		if asgn != nil {
			assignFlag[i] = true
		} else {
			assignFlag[i] = false
		}
	}
	if err = updateRecord(e.ctx, h, data, newData, assignFlag, e.Table, 0, true); err != nil {
		return errors.Trace(err)
	}
	return nil
}

func (r *preEvaluator) Leave(in ast.Node) (ast.Node, bool) {
	if expr, ok := in.(ast.ExprNode); ok {
		if _, ok = expr.(*ast.ValueExpr); ok {
			return in, true
		} else if ast.IsPreEvaluable(expr) {
			val, err := evaluator.Eval(r.ctx, expr)
			if err != nil {
				r.err = err
				return in, false
			}
			if ast.IsConstant(expr) {
				// The expression is constant, rewrite the expression to value expression.
				valExpr := &ast.ValueExpr{}
				valExpr.SetText(expr.Text())
				valExpr.SetType(expr.GetType())
				valExpr.SetDatum(val)
				return valExpr, true
			}
			expr.SetDatum(val)
		}
	}
	return in, true
}

// Fetch a single row from src and update each aggregate function.
// If the first return value is false, it means there is no more data from src.
func (e *AggregateExec) innerNext() (bool, error) {
	if e.Src != nil {
		srcRow, err := e.Src.Next()
		if err != nil {
			return false, errors.Trace(err)
		}
		if srcRow == nil {
			return false, nil
		}
	} else {
		// If Src is nil, only one row should be returned.
		if e.executed {
			return false, nil
		}
	}
	e.executed = true
	groupKey, err := e.getGroupKey()
	if err != nil {
		return false, errors.Trace(err)
	}
	if _, ok := e.groupMap[string(groupKey)]; !ok {
		e.groupMap[string(groupKey)] = true
		e.groups = append(e.groups, groupKey)
	}
	for _, af := range e.AggFuncs {
		for _, arg := range af.Args {
			_, err := evaluator.Eval(e.ctx, arg)
			if err != nil {
				return false, errors.Trace(err)
			}
		}
		af.CurrentGroup = groupKey
		af.Update()
	}
	return true, nil
}

func (s *testAggFuncSuite) TestCount(c *C) {
	// Compose aggregate exec for "select c1, count(c2) from t";
	// c1  c2
	// 1	1
	// 2	1
	// 3    nil
	c1 := ast.NewValueExpr(0)
	rf1 := &ast.ResultField{Expr: c1}
	col1 := &ast.ColumnNameExpr{Refer: rf1}
	fc1 := &ast.AggregateFuncExpr{
		F:    ast.AggFuncFirstRow,
		Args: []ast.ExprNode{col1},
	}
	c2 := ast.NewValueExpr(0)
	rf2 := &ast.ResultField{Expr: c2}
	col2 := &ast.ColumnNameExpr{Refer: rf2}
	fc2 := &ast.AggregateFuncExpr{
		F:    ast.AggFuncCount,
		Args: []ast.ExprNode{col2},
	}
	row1 := types.MakeDatums(1, 1)
	row2 := types.MakeDatums(2, 1)
	row3 := types.MakeDatums(3, nil)
	data := []([]types.Datum){row1, row2, row3}

	rows := make([]*Row, 0, 3)
	for _, d := range data {
		rows = append(rows, &Row{Data: d})
	}
	src := &mockExec{
		rows:   rows,
		fields: []*ast.ResultField{rf1, rf2},
	}
	agg := &AggregateExec{
		AggFuncs: []*ast.AggregateFuncExpr{fc1, fc2},
		Src:      src,
	}
	var (
		row *Row
		cnt int
	)
	for {
		r, err := agg.Next()
		c.Assert(err, IsNil)
		if r == nil {
			break
		}
		row = r
		cnt++
	}
	c.Assert(cnt, Equals, 1)
	c.Assert(row, NotNil)
	ctx := mock.NewContext()
	val, err := evaluator.Eval(ctx, fc1)
	c.Assert(err, IsNil)
	c.Assert(val, Equals, int64(1))
	val, err = evaluator.Eval(ctx, fc2)
	c.Assert(err, IsNil)
	c.Assert(val, Equals, int64(2))

	agg.Close()
	val, err = evaluator.Eval(ctx, fc1)
	c.Assert(err, IsNil)
	c.Assert(val, IsNil)
	val, err = evaluator.Eval(ctx, fc2)
	c.Assert(err, IsNil)
	c.Assert(val, Equals, int64(0))
}

// columnDefToCol converts ColumnDef to Col and TableConstraints.
func columnDefToCol(ctx context.Context, offset int, colDef *ast.ColumnDef) (*table.Column, []*ast.Constraint, error) {
	constraints := []*ast.Constraint{}
	col := &table.Column{
		Offset:    offset,
		Name:      colDef.Name.Name,
		FieldType: *colDef.Tp,
	}

	// Check and set TimestampFlag and OnUpdateNowFlag.
	if col.Tp == mysql.TypeTimestamp {
		col.Flag |= mysql.TimestampFlag
		col.Flag |= mysql.OnUpdateNowFlag
		col.Flag |= mysql.NotNullFlag
	}

	setOnUpdateNow := false
	hasDefaultValue := false
	if colDef.Options != nil {
		keys := []*ast.IndexColName{
			{
				Column: colDef.Name,
				Length: colDef.Tp.Flen,
			},
		}
		for _, v := range colDef.Options {
			switch v.Tp {
			case ast.ColumnOptionNotNull:
				col.Flag |= mysql.NotNullFlag
			case ast.ColumnOptionNull:
				col.Flag &= ^uint(mysql.NotNullFlag)
				removeOnUpdateNowFlag(col)
			case ast.ColumnOptionAutoIncrement:
				col.Flag |= mysql.AutoIncrementFlag
			case ast.ColumnOptionPrimaryKey:
				constraint := &ast.Constraint{Tp: ast.ConstraintPrimaryKey, Keys: keys}
				constraints = append(constraints, constraint)
				col.Flag |= mysql.PriKeyFlag
			case ast.ColumnOptionUniq:
				constraint := &ast.Constraint{Tp: ast.ConstraintUniq, Name: colDef.Name.Name.O, Keys: keys}
				constraints = append(constraints, constraint)
				col.Flag |= mysql.UniqueKeyFlag
			case ast.ColumnOptionIndex:
				constraint := &ast.Constraint{Tp: ast.ConstraintIndex, Name: colDef.Name.Name.O, Keys: keys}
				constraints = append(constraints, constraint)
			case ast.ColumnOptionUniqIndex:
				constraint := &ast.Constraint{Tp: ast.ConstraintUniqIndex, Name: colDef.Name.Name.O, Keys: keys}
				constraints = append(constraints, constraint)
				col.Flag |= mysql.UniqueKeyFlag
			case ast.ColumnOptionKey:
				constraint := &ast.Constraint{Tp: ast.ConstraintKey, Name: colDef.Name.Name.O, Keys: keys}
				constraints = append(constraints, constraint)
			case ast.ColumnOptionUniqKey:
				constraint := &ast.Constraint{Tp: ast.ConstraintUniqKey, Name: colDef.Name.Name.O, Keys: keys}
				constraints = append(constraints, constraint)
				col.Flag |= mysql.UniqueKeyFlag
			case ast.ColumnOptionDefaultValue:
				value, err := getDefaultValue(ctx, v, colDef.Tp.Tp, colDef.Tp.Decimal)
				if err != nil {
					return nil, nil, ErrColumnBadNull.Gen("invalid default value - %s", err)
				}
				col.DefaultValue = value
				hasDefaultValue = true
				removeOnUpdateNowFlag(col)
			case ast.ColumnOptionOnUpdate:
				if !evaluator.IsCurrentTimeExpr(v.Expr) {
					return nil, nil, ErrInvalidOnUpdate.Gen("invalid ON UPDATE for - %s", col.Name)
				}

				col.Flag |= mysql.OnUpdateNowFlag
				setOnUpdateNow = true
			case ast.ColumnOptionComment:
				value, err := evaluator.Eval(ctx, v.Expr)
				if err != nil {
					return nil, nil, errors.Trace(err)
				}
				col.Comment, err = value.ToString()
				if err != nil {
					return nil, nil, errors.Trace(err)
				}
			case ast.ColumnOptionFulltext:
				// Do nothing.
			}
		}
	}

	setTimestampDefaultValue(col, hasDefaultValue, setOnUpdateNow)

	// Set `NoDefaultValueFlag` if this field doesn't have a default value and
	// it is `not null` and not an `AUTO_INCREMENT` field or `TIMESTAMP` field.
	setNoDefaultValueFlag(col, hasDefaultValue)

	err := checkDefaultValue(col, hasDefaultValue)
	if err != nil {
		return nil, nil, errors.Trace(err)
	}
	if col.Charset == charset.CharsetBin {
		col.Flag |= mysql.BinaryFlag
	}
	return col, constraints, nil
//.........这里部分代码省略.........