Golang expression.NewFunction函數代碼示例

func (er *expressionRewriter) betweenToScalarFunc(v *ast.BetweenExpr) {
	stkLen := len(er.ctxStack)
	var op string
	var l, r *expression.ScalarFunction
	if v.Not {
		l, er.err = expression.NewFunction(ast.LT, v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-2])
		if er.err == nil {
			r, er.err = expression.NewFunction(ast.GT, v.Type, er.ctxStack[stkLen-3].DeepCopy(), er.ctxStack[stkLen-1])
		}
		op = ast.OrOr
	} else {
		l, er.err = expression.NewFunction(ast.GE, v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-2])
		if er.err == nil {
			r, er.err = expression.NewFunction(ast.LE, v.Type, er.ctxStack[stkLen-3].DeepCopy(), er.ctxStack[stkLen-1])
		}
		op = ast.AndAnd
	}
	if er.err != nil {
		er.err = errors.Trace(er.err)
		return
	}
	function, err := expression.NewFunction(op, v.Type, l, r)
	if err != nil {
		er.err = errors.Trace(err)
		return
	}
	er.ctxStack = er.ctxStack[:stkLen-3]
	er.ctxStack = append(er.ctxStack, function)
}

func (er *expressionRewriter) betweenToExpression(v *ast.BetweenExpr) {
	stkLen := len(er.ctxStack)
	er.checkArgsOneColumn(er.ctxStack[stkLen-3:]...)
	if er.err != nil {
		return
	}
	var op string
	var l, r expression.Expression
	l, er.err = expression.NewFunction(ast.GE, &v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-2])
	if er.err == nil {
		r, er.err = expression.NewFunction(ast.LE, &v.Type, er.ctxStack[stkLen-3].Clone(), er.ctxStack[stkLen-1])
	}
	op = ast.AndAnd
	if er.err != nil {
		er.err = errors.Trace(er.err)
		return
	}
	function, err := expression.NewFunction(op, &v.Type, l, r)
	if err != nil {
		er.err = errors.Trace(err)
		return
	}
	if v.Not {
		function, err = expression.NewFunction(ast.UnaryNot, &v.Type, function)
		if err != nil {
			er.err = errors.Trace(err)
			return
		}
	}
	er.ctxStack = er.ctxStack[:stkLen-3]
	er.ctxStack = append(er.ctxStack, function)
}

func (er *expressionRewriter) notToScalarFunc(b bool, op string, tp *types.FieldType,
	args ...expression.Expression) *expression.ScalarFunction {
	opFunc := expression.NewFunction(op, tp, args...)
	if !b {
		return opFunc
	}
	return expression.NewFunction(ast.UnaryNot, tp, opFunc)
}

func (er *expressionRewriter) handleScalarSubquery(v *ast.SubqueryExpr) (ast.Node, bool) {
	np := er.buildSubquery(v)
	if er.err != nil {
		return v, true
	}
	np = er.b.buildMaxOneRow(np)
	if np.IsCorrelated() {
		er.p = er.b.buildApply(er.p, np, nil)
		if len(np.GetSchema()) > 1 {
			newCols := make([]expression.Expression, 0, len(np.GetSchema()))
			for _, col := range np.GetSchema() {
				newCols = append(newCols, col.Clone())
			}
			expr, err := expression.NewFunction(ast.RowFunc, nil, newCols...)
			if err != nil {
				er.err = errors.Trace(err)
				return v, true
			}
			er.ctxStack = append(er.ctxStack, expr)
		} else {
			er.ctxStack = append(er.ctxStack, er.p.GetSchema()[len(er.p.GetSchema())-1])
		}
		return v, true
	}
	physicalPlan, err := doOptimize(np, er.b.ctx, er.b.allocator)
	if err != nil {
		er.err = errors.Trace(err)
		return v, true
	}
	d, err := EvalSubquery(physicalPlan, er.b.is, er.b.ctx)
	if err != nil {
		er.err = errors.Trace(err)
		return v, true
	}
	if len(np.GetSchema()) > 1 {
		newCols := make([]expression.Expression, 0, len(np.GetSchema()))
		for i, data := range d {
			newCols = append(newCols, &expression.Constant{
				Value:   data,
				RetType: np.GetSchema()[i].GetType()})
		}
		expr, err1 := expression.NewFunction(ast.RowFunc, nil, newCols...)
		if err1 != nil {
			er.err = errors.Trace(err1)
			return v, true
		}
		er.ctxStack = append(er.ctxStack, expr)
	} else {
		er.ctxStack = append(er.ctxStack, &expression.Constant{
			Value:   d[0],
			RetType: np.GetSchema()[0].GetType(),
		})
	}
	return v, true
}

func (er *expressionRewriter) caseToExpression(v *ast.CaseExpr) {
	stkLen := len(er.ctxStack)
	argsLen := 2 * len(v.WhenClauses)
	if v.ElseClause != nil {
		argsLen++
	}
	er.checkArgsOneColumn(er.ctxStack[stkLen-argsLen:]...)
	if er.err != nil {
		return
	}

	// value                          -> ctxStack[stkLen-argsLen-1]
	// when clause(condition, result) -> ctxStack[stkLen-argsLen:stkLen-1];
	// else clause                    -> ctxStack[stkLen-1]
	var args []expression.Expression
	if v.Value != nil {
		// args:  eq scalar func(args: value, condition1), result1,
		//        eq scalar func(args: value, condition2), result2,
		//        ...
		//        else clause
		value := er.ctxStack[stkLen-argsLen-1]
		args = make([]expression.Expression, 0, argsLen)
		for i := stkLen - argsLen; i < stkLen-1; i += 2 {
			arg, err := expression.NewFunction(ast.EQ, types.NewFieldType(mysql.TypeTiny), value.Clone(), er.ctxStack[i])
			if err != nil {
				er.err = errors.Trace(err)
				return
			}
			args = append(args, arg)
			args = append(args, er.ctxStack[i+1])
		}
		if v.ElseClause != nil {
			args = append(args, er.ctxStack[stkLen-1])
		}
		argsLen++ // for trimming the value element later
	} else {
		// args:  condition1, result1,
		//        condition2, result2,
		//        ...
		//        else clause
		args = er.ctxStack[stkLen-argsLen:]
	}
	function, err := expression.NewFunction(ast.Case, &v.Type, args...)
	if err != nil {
		er.err = errors.Trace(err)
		return
	}
	er.ctxStack = er.ctxStack[:stkLen-argsLen]
	er.ctxStack = append(er.ctxStack, function)
}

func (er *expressionRewriter) funcCallToScalarFunc(v *ast.FuncCallExpr) {
	stackLen := len(er.ctxStack)
	var function *expression.ScalarFunction
	function, er.err = expression.NewFunction(v.FnName.L, v.Type, er.ctxStack[stackLen-len(v.Args):]...)
	er.ctxStack = er.ctxStack[:stackLen-len(v.Args)]
	er.ctxStack = append(er.ctxStack, function)
}

func (er *expressionRewriter) binaryOpToExpression(v *ast.BinaryOperationExpr) {
	stkLen := len(er.ctxStack)
	var function expression.Expression
	switch v.Op {
	case opcode.EQ, opcode.NE, opcode.NullEQ:
		function, er.err = er.constructBinaryOpFunction(er.ctxStack[stkLen-2], er.ctxStack[stkLen-1],
			opcode.Ops[v.Op])
	default:
		lLen := getRowLen(er.ctxStack[stkLen-2])
		rLen := getRowLen(er.ctxStack[stkLen-1])
		switch v.Op {
		case opcode.GT, opcode.GE, opcode.LT, opcode.LE:
			if lLen != rLen {
				er.err = ErrOperandColumns.GenByArgs(lLen)
			}
		default:
			if lLen != 1 || rLen != 1 {
				er.err = ErrOperandColumns.GenByArgs(1)
			}
		}
		if er.err != nil {
			return
		}
		function, er.err = expression.NewFunction(opcode.Ops[v.Op], &v.Type, er.ctxStack[stkLen-2:]...)
	}
	if er.err != nil {
		er.err = errors.Trace(er.err)
		return
	}
	er.ctxStack = er.ctxStack[:stkLen-2]
	er.ctxStack = append(er.ctxStack, function)
}

func pushDownNot(expr expression.Expression, not bool) expression.Expression {
	if f, ok := expr.(*expression.ScalarFunction); ok {
		switch f.FuncName.L {
		case ast.UnaryNot:
			return pushDownNot(f.Args[0], !not)
		case ast.LT, ast.GE, ast.GT, ast.LE, ast.EQ, ast.NE:
			if not {
				nf, _ := expression.NewFunction(oppositeOp[f.FuncName.L], f.GetType(), f.Args...)
				return nf
			}
			for i, arg := range f.Args {
				f.Args[i] = pushDownNot(arg, false)
			}
			return f
		case ast.AndAnd:
			if not {
				args := f.Args
				for i, a := range args {
					args[i] = pushDownNot(a, true)
				}
				nf, _ := expression.NewFunction(ast.OrOr, f.GetType(), args...)
				return nf
			}
			for i, arg := range f.Args {
				f.Args[i] = pushDownNot(arg, false)
			}
			return f
		case ast.OrOr:
			if not {
				args := f.Args
				for i, a := range args {
					args[i] = pushDownNot(a, true)
				}
				nf, _ := expression.NewFunction(ast.AndAnd, f.GetType(), args...)
				return nf
			}
			for i, arg := range f.Args {
				f.Args[i] = pushDownNot(arg, false)
			}
			return f
		}
	}
	if not {
		expr, _ = expression.NewFunction(ast.UnaryNot, types.NewFieldType(mysql.TypeTiny), expr)
	}
	return expr
}

func (er *expressionRewriter) betweenToScalarFunc(v *ast.BetweenExpr) {
	stkLen := len(er.ctxStack)
	var op string
	var l, r *expression.ScalarFunction
	if v.Not {
		l = expression.NewFunction(ast.LT, v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-2])
		r = expression.NewFunction(ast.GT, v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-1])
		op = ast.OrOr
	} else {
		l = expression.NewFunction(ast.GE, v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-2])
		r = expression.NewFunction(ast.LE, v.Type, er.ctxStack[stkLen-3], er.ctxStack[stkLen-1])
		op = ast.AndAnd
	}
	function := expression.NewFunction(op, v.Type, l, r)
	er.ctxStack = er.ctxStack[:stkLen-3]
	er.ctxStack = append(er.ctxStack, function)
}

func (er *expressionRewriter) notToScalarFunc(hasNot bool, op string, tp *types.FieldType,
	args ...expression.Expression) *expression.ScalarFunction {
	opFunc, err := expression.NewFunction(op, tp, args...)
	if err != nil {
		er.err = errors.Trace(err)
		return nil
	}
	if !hasNot {
		return opFunc
	}

	opFunc, err = expression.NewFunction(ast.UnaryNot, tp, opFunc)
	if err != nil {
		er.err = errors.Trace(err)
		return nil
	}
	return opFunc
}

func (er *expressionRewriter) funcCallToExpression(v *ast.FuncCallExpr) {
	stackLen := len(er.ctxStack)
	args := er.ctxStack[stackLen-len(v.Args):]
	er.checkArgsOneColumn(args...)
	if er.err != nil {
		return
	}
	var function expression.Expression
	function, er.err = expression.NewFunction(v.FnName.L, &v.Type, args...)
	er.ctxStack = er.ctxStack[:stackLen-len(v.Args)]
	er.ctxStack = append(er.ctxStack, function)
}

// compose CNF items into a balance deep CNF tree, which benefits a lot for pb decoder/encoder.
func composeCondition(conditions []expression.Expression) expression.Expression {
	length := len(conditions)
	if length == 0 {
		return nil
	}
	if length == 1 {
		return conditions[0]
	}
	return expression.NewFunction(model.NewCIStr(ast.AndAnd),
		[]expression.Expression{composeCondition(conditions[0 : length/2]),
			composeCondition(conditions[length/2:])})
}

func (er *expressionRewriter) handleInSubquery(v *ast.PatternInExpr) (ast.Node, bool) {
	v.Expr.Accept(er)
	if er.err != nil {
		return v, true
	}
	lexpr := er.ctxStack[len(er.ctxStack)-1]
	subq, ok := v.Sel.(*ast.SubqueryExpr)
	if !ok {
		er.err = errors.Errorf("Unknown compare type %T.", v.Sel)
		return v, true
	}
	np, outerSchema := er.buildSubquery(subq)
	if er.err != nil {
		return v, true
	}
	if getRowLen(lexpr) != len(np.GetSchema()) {
		er.err = errors.Errorf("Operand should contain %d column(s)", getRowLen(lexpr))
		return v, true
	}
	var rexpr expression.Expression
	if len(np.GetSchema()) == 1 {
		rexpr = np.GetSchema()[0].DeepCopy()
	} else {
		args := make([]expression.Expression, 0, len(np.GetSchema()))
		for _, col := range np.GetSchema() {
			args = append(args, col.DeepCopy())
		}
		rexpr, er.err = expression.NewFunction(ast.RowFunc, nil, args...)
		if er.err != nil {
			er.err = errors.Trace(er.err)
			return v, true
		}
	}
	// a in (subq) will be rewrited as a = any(subq).
	// a not in (subq) will be rewrited as a != all(subq).
	op, all := ast.EQ, false
	if v.Not {
		op, all = ast.NE, true
	}
	checkCondition, err := constructBinaryOpFunction(lexpr, rexpr, op)
	if err != nil {
		er.err = errors.Trace(err)
		return v, true
	}
	er.p = er.b.buildApply(er.p, np, outerSchema, &ApplyConditionChecker{Condition: checkCondition, All: all})
	if er.p.IsCorrelated() {
		er.correlated = true
	}
	// The parent expression only use the last column in schema, which represents whether the condition is matched.
	er.ctxStack[len(er.ctxStack)-1] = er.p.GetSchema()[len(er.p.GetSchema())-1]
	return v, true

}

func (er *expressionRewriter) rowToScalarFunc(v *ast.RowExpr) {
	stkLen := len(er.ctxStack)
	length := len(v.Values)
	rows := make([]expression.Expression, 0, length)
	for i := stkLen - length; i < stkLen; i++ {
		rows = append(rows, er.ctxStack[i])
	}
	er.ctxStack = er.ctxStack[:stkLen-length]
	function, err := expression.NewFunction(ast.RowFunc, nil, rows...)
	if err != nil {
		er.err = errors.Trace(err)
		return
	}
	er.ctxStack = append(er.ctxStack, function)
}

// constructBinaryOpFunctions converts (a0,a1,a2) op (b0,b1,b2) to (a0 op b0) and (a1 op b1) and (a2 op b2).
func constructBinaryOpFunction(l expression.Expression, r expression.Expression, op string) (expression.Expression, error) {
	lLen, rLen := getRowLen(l), getRowLen(r)
	if lLen == 1 && rLen == 1 {
		return expression.NewFunction(op, types.NewFieldType(mysql.TypeTiny), l, r)
	} else if rLen != lLen {
		return nil, errors.Errorf("Operand should contain %d column(s)", lLen)
	}
	funcs := make([]expression.Expression, lLen)
	for i := 0; i < lLen; i++ {
		var err error
		funcs[i], err = constructBinaryOpFunction(getRowArg(l, i), getRowArg(r, i), op)
		if err != nil {
			return nil, err
		}
	}
	return expression.ComposeCNFCondition(funcs), nil
}