func (this *JSConverter) Visit(expr expression.Expression) string {
var buf bytes.Buffer
s, err := expr.Accept(this)
if err != nil {
logging.Errorf("Unexpected error in JSConverter: %v", err)
return ""
}
switch s := s.(type) {
case string:
buf.WriteString(s)
for this.stack.Size() != 0 {
funcExpr := this.stack.Pop().(*funcExpr)
buf.WriteString(funcExpr.name)
if funcExpr.operands.Front() != nil {
buf.WriteString(writeOperands(funcExpr.operands))
}
}
case []byte:
buf.WriteString(string(s))
for this.stack.Size() != 0 {
funcExpr := this.stack.Pop().(*funcExpr)
buf.WriteString(funcExpr.name)
if funcExpr.operands.Front() != nil {
buf.WriteString(writeOperands(funcExpr.operands))
}
}
default:
buf.WriteString(s.(string))
}
return buf.String()
}
func SubsetOf(expr1, expr2 expression.Expression) bool {
v2 := expr2.Value()
if v2 != nil {
return v2.Truth()
}
s := newSubset(expr1)
result, _ := expr2.Accept(s)
return result.(bool)
}
func sargFor(pred, expr expression.Expression, missingHigh bool) (plan.Spans, error) {
s := newSarg(pred)
s.SetMissingHigh(missingHigh)
r, err := expr.Accept(s)
if err != nil || r == nil {
return nil, err
}
rs := r.(plan.Spans)
return rs, nil
}
func newSargable(pred expression.Expression) expression.Visitor {
s, _ := pred.Accept(_SARGABLE_FACTORY)
return s.(expression.Visitor)
}
func newSarg(pred expression.Expression) sarg {
s, _ := pred.Accept(_SARG_FACTORY)
return s.(sarg)
}
func newSubset(expr expression.Expression) expression.Visitor {
s, _ := expr.Accept(_SUBSET_FACTORY)
return s.(expression.Visitor)
}