// VisitBinaryOperation swaps the right side identifier to left side if left side expression is static.
// So it can be used in index plan.
func (iev *IdentEvalVisitor) VisitBinaryOperation(binop *expression.BinaryOperation) (expression.Expression, error) {
var err error
binop.L, err = binop.L.Accept(iev)
if err != nil {
return binop, errors.Trace(err)
}
binop.R, err = binop.R.Accept(iev)
if err != nil {
return binop, errors.Trace(err)
}
if binop.L.IsStatic() {
if _, ok := binop.R.(*expression.Ident); ok {
switch binop.Op {
case opcode.EQ:
case opcode.NE:
case opcode.NullEQ:
case opcode.LT:
binop.Op = opcode.GE
case opcode.LE:
binop.Op = opcode.GT
case opcode.GE:
binop.Op = opcode.LT
case opcode.GT:
binop.Op = opcode.LE
default:
// unsupported opcode
return binop, nil
}
binop.L, binop.R = binop.R, binop.L
}
}
return binop, nil
}
