More questions about the FreePascal Language Reference (version 3.2.0)

1. Section 17.1 defines a rule <raise-statement> and <exception-address>

raise-statement = "raise" [ exception-instance [ exception-address ] ] . exception-address = "at" exception-address [ "," address-expression ] .

a) Is it correct that <exception-address> defines itself recursively ?

b) I can't find the rule that defines <address-expression>. What is it ?

c) I can't find the rule that defines <exception-instance>. What is it ?

2. Section 12.1 refers to a rule <address-factor>

factor = "(" expression ")" | variable-reference | function-call | unsigned-constant| "NOT" factor | "sign" factor | set-constructor | value-typecast | address-factor .

I can't find the rule <address-factor> but it may be the same as the rule <addressfactor> given in section 12.7 ?

addressfactor = "@" ( variable-reference | procedure-identifier | function-identifier | qualified-method-identifier ) .

3. Section 2.2 refers to a rule <address-constant>

typed-constant = constant | address-constant | array-constant | record-constant | procedural-constant .

I can't find the rule <address-constant>. What is it ?

4. Section 2.2 also refers to a rule <array-constant>

typed-constant = constant | address-constant | array-constant | record-constant | procedural-constant .

I can't find the rule <array-constant>. What is it ?

5. Section 2.2 also refers to a rule <record-constant>

typed-constant = constant | address-constant | array-constant | record-constant | procedural-constant .

I can't find the rule <record-constant>. What is it ?

6. Section 2.2 also refers to a rule <procedural-constant>

typed-constant = constant | address-constant | array-constant | record-constant | procedural-constant .

I can't find the rule <procedural-constant>. What is it ?

7. Section 13.3 refers to a rule <assembler code>

asm-statement = "asm" assembler-code "END" [ registerlist ] .

I can't find a rule for <assembler code> What is it, from the point of view of parsing Pascal ?

8. Section 10.1 refers to a rule <basehelper>

helper-type = ( "CLASS" | "RECORD" | "TYPE" ) "helper" [ "(" basehelper ")" ] "FOR" identifier { helper-component-list } "END" hint-modifiers .

I can't find a rule for <basehelper>. What is it ?

9. Sections 17.2 and 6.1 refer to a rule <class-type-identifier>

exception-handler = "ON" [ identifier ":" ] class-type-identifier "DO" statement . class-heritage = "(" class-type-identifier [ class-implemented-interfaces ] ")" .

I can assume ?

class-type-identifier = identifier .

10. Section 11.2 refers to a rule <objective-Cclass-type-identifier>

objc-class-heritage = "(" [ objective-Cclass-type-identifier ] [ objc-implemented-protocols ] ")" .

I can assume ?

objective-Cclass-type-identifier = identifier .

11. Section 6.1 refers to a rule <classtype>

class-reference-type = "CLASS" "OF" classtype .

I can't find a rule for <classtype>. What is it ?

12. Section 13.2 refers to a rule <conditional-statement>

structured-statement = compound-statement | conditional-statement | repetitive-statement | with-statement | exception-statement .

I can't find a rule for <conditional-statement>. What is it ?

13. Section 6.1 referes to a rule <const-declaration-part>

component-list = [ visibility-specifier ] { field-definition } { const-declaration-part | type-declaration-part | variable-declaration-part | class-variable-declaration-part | method-definition | property-definition } .

I can assume ?

const-declaration-part = constant-declaration-part .

14. Sections 2.2, 3.1.1, 3.3.2, 4.7 and 13.2.2 refer to a rule <constant>

typed-constant = constant | address-constant | array-constant | record-constant | procedural-constant .
subrange-type = constant ".." constant .
variant = constant { "," constant } ":" "(" [ field-list ] ")" . default-specifier = "default" [ constant ] | "nodefault" . stored-specifier = "stored" ( constant | identifier ) . case = constant [ ".." constant ] { "," constant [ ".." constant ] } ":" statement .

I can't find a rule for <constant>. What is it ?

15. Sections 5.1 and 6.6.1 refer to a rule <constant-expression>

const-definition = "CONST" identifier "=" constant-expression ";" . class-method-directives = ( ( "virtual" | "dynamic" ) [ ";" "abstract" ] | "reintroduce" ";" | "override" ";" | "message" constant-expression ) [ call-modifiers ";" ] .

I can assume ?

constant-expression = expression .

16. Section 12.1 refers to a rule <constant-identifier>

unsigned-constant = unsigned-number | character-string | constant-identifier | "NIL" .

I can assume ?

constant-identifier = identifier .

(more to follow)

Regards,

Adriaan van Os

No.

That should be exception-address = "at" address-factor

Corrected.

b) I can't find the rule that defines <address-expression>. What is it ?

Typo, should be address-factor.

Corrected.

c) I can't find the rule that defines <exception-instance>. What is it ?

An expression of type exception.

Added.

Yes. Corrected.

A constant of type address. So either Nil or @identifier.

A constant of type array, obviously.

Needs to be added.

A constant of type record.

Needs to be added.

Address-factor of procedural type.

Needs to be added.

Undefined. Skip all tokens till you meet END.

An identifier.

Corrected.

Yes.

Added.

Yes.

Added.

class-type-identifier (or identifier)

Added.

You missed it. It is defined under 'Structured statements'.

Yes. Corrected.

A simple constant. ordinal, string or float.

Needs to be added.

As far as parsing is concerned, yes.

Yes. Added.

Thanks for the questions. They showed me deficiencies of the text. I have corrected what could be done quickly.

For the typed constants I need some time to correct/add them, since I need to provide some explanatory text.

Please note that the syntax diagrams are NOT meant to be exhaustive. They are an aid to explain the syntax. I strive to make them as correct as possible, but they make no pretense to being complete.

Furthermore, recent changes in Delphi syntax unfortunately require that the parser is aware of the types of some of the elements, something which cannot be expressed in a formal syntax :/

As far as I know, Delphi no longer provides an up-to-date grammar. The last one I saw came with Delphi 7.

Michael.

Michael Van Canneyt via fpc-pascal wrote:

Thanks for the replies.

Please note that the syntax diagrams are NOT meant to be exhaustive. They are an aid to explain the syntax. I strive to make them as correct as possible, but they make no pretense to being complete.

Anyway, I strive to make the syntax complete and correct. When it is ready, I can send it in to be added as an Appendix to the Language Reference manual. I have an ebfn-driven general (back-parsing) parser, that already works for Oberon-0 end UCSD-Pascal. So, the ebnf can be tested.

Regards,

Adriaan van Os

There are several typesetting systems that can convert EBNF to a nice diagram, so it can be nicely typeset too.

I have long been looking for an EBNF, and only found several syntaxes for other systems, so that would be really good if you could make one. I would include it at once :-)

Michael.