Constant_BoolValue never appears in has statement

[moxianfeng]

When i try to use bool variable in has statement,
filter like bottom, and i always got Constant_StringValue type

a.c:true
a.c:True
a.c:TRUE

so, I try to strings.ParseBool to get bool variable，but how can'i check explicit string declaration between a.c:"true" and a.c:true

[jsocol]

There's a missing piece in the filtering.Declarations type, which doesn't include the constants true and false, or a way to declare those constants. There is a function NewConstantDeclaration(), which is used internally, but there's no public API to use the output as a declaration.

I had to add two new "ident" declarations to work around this:

// var parsedExp *expr.ParsedExpr

declOpts := []filtering.DeclarationOptions{
  filtering.DeclareStandardFunctions(),
  filtering.DeclareIdent("true", filtering.TypeBool),
  filtering.DeclareIdent("false", filtering.TypeBool),
}

decl := filtering.NewDeclarations(declOpts...)

checker := &filtering.Checker{}
checker.Init(parsedExp.Expr, parsedExp.SourceInfo, decl)

And then while walking over the parsed expression tree, where I pull out the constants like int64s, strings, etc, I do a check first, to see if it's an ident:

// var curr *expr.Expr
ident := curr.GetIdentExpr()
if ident != nil {
  if ident.Name == "true" {
    // treat as a `true` constant
  } else if ident.Name == "false" {
    // treat as a `false` constant
  }
}

constant := curr.GetConstExpr()
if constant != nil {
  switch kind := constant.Kind.(type) {
    // etc

It would be nice if true and false were part of the standard declarations, but I get why they aren't.

As an alternative, it would be great if filtering.Declarations.declare(*expr.Decl) were exported as an escape hatch for more advanced uses, or possibly a function like

func DeclareConstant(name string, t *expr.Type, value *expr.Constant) DeclarationOption {
  return func(d *Declarations) error {
    return d.declareConstant(name, t, value)
  }
}

[github-actions]

This issue has been open for 365 days with no activity. Marking as stale.