Status of this document

This is just a sketch of the final XPIDL Syntax Documentation. I'm working on gathering all of the BNF and organizing the TOC of this document.

Purpose of this document

This document is not an introduction to XPIDL or IDL in general. It is more focused on XPIDL syntax and grammar. However, I plan to link all of the material to relevant introductory contents.

Some simplifications

In order to simplify the BNF, I will not include XPIDL comments in every place where they can be found. I rather describe them separately and explain how they can be used elsewhere outside the BNF. Otherwise, the BNF itself would get very mangled.

Common BNF

any-char :=any unicode char
any-char-but-LF :=any unicode char excluding linefeed char code

any-char and any-char-but-LF are used in a context-dependant manner as will be explained where appropiate.

XPIDL Syntax (BNF)

XPIDL Comments

xpidl-comment := '/*' any-char* '*/'

Comments are blocks of text which are not parsed by XPIDL interpreters. They are used as a form of documentation. A comment begins with an '/*' and ends with a '*/'. Valid XPIDL declarations inside comments are ignored.

In the context of a xpidl-comment, any-char actually means any char excluding */ if they happen to be together and in that order , which represents the end of the comment itself.


/* Valid char for identifiers */
xpidl-id-char := [a-zA-Z_0-9]

/* Valid char for the beginning of identifiers */
xpidl-id-char-valid-begin := [a-zA-Z]

xpidl-valid-id := xpidl-id-char-valid-begin xpidl-id-char*

xpidl-valid-id-list :=
       xpidl-valid-id |
       xpidl-valid-id ',' xpidl-valid-id-list

Inline C headers

inline-c-header := '{%C++ ' any-char* '%}'

In the context of a inline-c-header, any-char actually means any char excluding %} if they happen to be together and in that order , which represent the end of the inline c headers section.

Including other XPIDL

 xpidl-include := '#include "' any-char* '"\n'

In the context of xpidl-include, any-char actually means any char but the quotation mark (").


xpidl-type := 
       'boolean' |
       'void' |
       'string' |


xpidl-HEX := [a-fA-F0-9]

xpidl-UUID := xpidl-HEX{8}'-'xpidl-HEX{4}'-'xpidl-HEX{4}'-'xpidl-HEX{4}'-'xpidl-HEX{12}


xpidl-ARRAY-param-modifier := 'array'
xpidl-SIZE_IS-param-modifier := 'size_is('xpidl-valid-id')'
xpidl-RETVAL-param-modifier := 'retval'

xpidl-param-modifier :=
      xpidl-ARRAY-param-modifier |
      xpidl-SIZE_IS-param-modifier |

xpidl-param-modifier-list := 
       xpidl-param-modifier |
       xpidl-param-modifier ',' xpidl-param-modifier-list

xpidl-param-modifier-list-decl := '[' xpidl-param-modifier-list ']'

xpidl-param-type := 'in' | 'out' | 'inout'
xpidl-param-decl := [ xpidl-param-modifier-list-decl ] xpidl-param-type xpidl-type xpidl-valid-id

xpidl-param-list := 
       xpidl-param-decl |
       xpidl-param-decl ',' xpidl-param-list

Attributes and Methods

xpidl-attribute := 'attribute' xpidl-type xpidl-valid-id ';'

xpidl-method := xpidl-type xpidl-valid-id '('[ xpidl-param-list ]');'

xpidl-attr-or-method :=
       xpidl-attribute |


xpidl-interface-body := xpidl-attr-or-method*

xpidl-scriptable-interface := 'scriptable'
xpidl-interface-uuid := 'uuid('xpidl-UUID')'

xpidl-interface-header := '['[ xpidl-scriptable-interface ','] xpidl-interface-uuid ']'

xpidl-interface := 
       'interface ' xpidl-valid-id [ ':' xpidl-valid-id-list ]


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