[fpc-pascal] More syntax questions (part 2)

[Michael Van Canneyt]

On Sat, 16 Dec 2023, Adriaan van Os via fpc-pascal wrote:

>
> More questions about the FreePascal Language Reference (version 3.2.0)  part 
> 2
>
> 17. For the following rules, I couldn't find a definition in the Language 
> Reference. Can I assume they can all be defined as <identifier> ?
>
> 	object-type-identifier                 = identifier .
> 	field-identifier                       = identifier .
> 	interface-identifier                   = identifier .
> 	interface-type-identifier              = identifier .
> 	method-identifier                      = identifier .
> 	procedure-identifier                   = identifier .
> 	protocol-identifier                    = identifier .
> 	protocol-type-identifier               = identifier .
> 	qualified-method-identifier            = identifier .
> 	result-identifier                      = identifier .
> 	type-identifier                        = identifier .
> 	function-identifier                    = identifier .
> 	unit-identifier                        = identifier .
> 	variable-identifier                    = identifier .

Yes.

The idea was to use these "dedicated names" to convey that the identifier must be of a certain type.

You cannot express this concept in a formal syntax, but for a formal syntax the above is correct.

>
> 18. Section 14.4.1 defines a rule <value-parameter>
>
> 	value-parameter = identifier-list ":" [ "ARRAY" "OF" ] parameter-type 
> | identifier ":" type-identifier "=" default-parameter-value .
>
> I couldn't find a rule for <parameter-type>. If <parameter-type> equals 
> <type-identifier> then it may be easier to name it <type-identifier> ?

Not quite. it can also be 'const' (the 'array of const' construct).

This diagram needs to be enhanced, I suppose the following is more correct:

(identifier [ "=" constant-expression ] | "array" "of" ("const" | identifier))

>
> 19. Sections 3.6, 14.2 and 15.2 refer to a rule <result-type>.
>
> 	function-header = "FUNCTION" formal-parameter-list ":" result-type .
> 	function-header = "FUNCTION" ( identifier | 
> qualified-method-identifier ) formal-parameter-list ":" result-type [ 
> modifiers ] [ hintdirectives ] .
> 	operator-definition = "operator" ( assignment-operator-definition | 
> arithmetic-operator-definition | comparision-operator-definition ) 
> result-identifier ":" result-type ";" subroutine-block .
>
> I couldn't find a rule for <result-type>. Can I assume ?
>
> 	result-type = type-identifier .

Yes.

>
> 20. For the following rules, I couldn't find a definition in the Language 
> Reference. Can I assume they can all be defined as <single-quoted-string> ?
>
> 	guid = single-quoted-string .
> 	string-constant-declaration = single-quoted-string .
> 	string-literal = single-quoted-string .
> 	stringconstant = single-quoted-string .

Yes.

>
> where <single-quoted-string> is a parser built-in rule that parses two 
> consecutive single-quote chars as a literal single-quote char ? and that may 
> not contain CR and LF characters  ? or any other control characters ?

Yes. 
Following your remarks, I was planning to introduce a list of "parser built-in"
rules, as I need them to define the constants.

>
> 21. Can I assume ?
>
> 	statement-list = statement { ";" statement } .
> 	statementlist = statement-list .

Yes.

>
> 22. Various rules refer to a rule <variable-reference> for which I can't find 
> the rule. What is it ?

identifier.

>
> 23. Section 12.2 defines a rule <function-call> that references rules 
> <qualified-method-designator> and <method-designator>.
>
> 	function-call = ( function-identifier | method-designator | 
> qualified-method-designator | variable-reference ) [ actual-parameter-list ] 
> .
>
> I can't find the rules for <qualified-method-designator> and 
> <method-designator>. What are they ?

With the appearance of nested classes and type definitions, they are actually the same.

method-designator = qualified-method-designator = identifier ({ "." identifier })

So the function-call can be simplified to
   function-call = ( method-designator | variable-reference ) [ actual-parameter-list ]

maybe introducing a

   fully-qualified-identifier = identifier ({ "." identifier })

and using that everywhere instead is a better approach.

>
> 24. Sections 14.4.1 and 14.4.4 define rules that refer to a rule 
> <default-parameter-value>.
>
> 	value-parameter = identifier-list ":" [ "ARRAY" "OF" ] parameter-type 
> | identifier ":" type-identifier "=" default-parameter-value .
> 	constant-parameter = "CONST" ( identifier-list [ ":" [ "ARRAY" "OF" ] 
> type-identifier ] | identifier ":" type-identifier "=" 
> default-parameter-value ) .
>
> I can't find the rule for <default-parameter-value>. What is it ?

default-parameter-value = constant-expression

>
> 25. Section 16.2 defines a  rule <interface-part> that refers to a rule 
> <property-declaration-part>
>
> 	interface-part = "INTERFACE"  [ uses-clause ]  { 
> constant-declaration-part  | type-declaration-part | 
> variable-declaration-part | property-declaration-part | 
> procedure-headers-part } .
>
> I can't find the rule <property-declaration-part>. What is it ?


That should be
    property-declaration-part = property definition { ";" property definition }

("property definition" is defined in the class declaration diagram)

Michael.