Esempio n. 1
0
func newSubsetLike(expr expression.BinaryFunction, re *regexp.Regexp) expression.Visitor {
	if re == nil {
		// Pattern is not a constant
		return newSubsetDefault(expr)
	}

	prefix, complete := re.LiteralPrefix()
	if complete {
		eq := expression.NewEq(expr.First(), expression.NewConstant(prefix))
		return newSubsetEq(eq.(*expression.Eq))
	}

	if prefix == "" {
		return newSubsetDefault(expr)
	}

	var and expression.Expression
	le := expression.NewLE(expression.NewConstant(prefix), expr.First())
	last := len(prefix) - 1
	if prefix[last] < math.MaxUint8 {
		bytes := []byte(prefix)
		bytes[last]++
		and = expression.NewAnd(le, expression.NewLT(
			expr.First(),
			expression.NewConstant(string(bytes))))
	} else {
		and = expression.NewAnd(le, expression.NewLT(
			expr.First(),
			expression.EMPTY_ARRAY_EXPR))
	}

	return newSubsetAnd(and.(*expression.And))
}
Esempio n. 2
0
func (this *NNF) VisitFunction(expr expression.Function) (interface{}, error) {
	var exp expression.Expression = expr

	switch expr := expr.(type) {
	case *expression.IsBoolean:
		exp = expression.NewLE(expr.Operand(), expression.TRUE_EXPR)
	case *expression.IsNumber:
		exp = expression.NewAnd(
			expression.NewGT(expr.Operand(), expression.TRUE_EXPR),
			expression.NewLT(expr.Operand(), expression.EMPTY_STRING_EXPR))
	case *expression.IsString:
		exp = expression.NewAnd(
			expression.NewGE(expr.Operand(), expression.EMPTY_STRING_EXPR),
			expression.NewLT(expr.Operand(), expression.EMPTY_ARRAY_EXPR))
	case *expression.IsArray:
		exp = expression.NewAnd(
			expression.NewGE(expr.Operand(), expression.EMPTY_ARRAY_EXPR),
			expression.NewLT(expr.Operand(), _EMPTY_OBJECT_EXPR))
	case *expression.IsObject:
		// Not equivalent to IS OBJECT. Includes BINARY values.
		exp = expression.NewGE(expr.Operand(), _EMPTY_OBJECT_EXPR)
	}

	return exp, exp.MapChildren(this)
}
Esempio n. 3
0
func (this *NNF) VisitBetween(expr *expression.Between) (interface{}, error) {
	err := expr.MapChildren(this)
	if err != nil {
		return nil, err
	}

	return expression.NewAnd(expression.NewGE(expr.First(), expr.Second()),
		expression.NewLE(expr.First(), expr.Third())), nil
}
Esempio n. 4
0
func (this *NNF) VisitNot(expr *expression.Not) (interface{}, error) {
	err := expr.MapChildren(this)
	if err != nil {
		return nil, err
	}

	var exp expression.Expression = expr

	switch operand := expr.Operand().(type) {
	case *expression.Not:
		exp = operand.Operand()
	case *expression.And:
		operands := make(expression.Expressions, len(operand.Operands()))
		for i, op := range operand.Operands() {
			operands[i] = expression.NewNot(op)
		}

		exp = expression.NewOr(operands...)
	case *expression.Or:
		operands := make(expression.Expressions, len(operand.Operands()))
		for i, op := range operand.Operands() {
			operands[i] = expression.NewNot(op)
		}

		exp = expression.NewAnd(operands...)
	case *expression.Eq:
		exp = expression.NewOr(expression.NewLT(operand.First(), operand.Second()),
			expression.NewLT(operand.Second(), operand.First()))
	case *expression.LT:
		exp = expression.NewLE(operand.Second(), operand.First())
	case *expression.LE:
		exp = expression.NewLT(operand.Second(), operand.First())
	}

	return exp, exp.MapChildren(this)
}