Subversion Repositories tendra.SVN

/*

    		 Crown Copyright (c) 1997

    This TenDRA(r) Computer Program is subject to Copyright

    owned by the United Kingdom Secretary of State for Defence

    acting through the Defence Evaluation and Research Agency

    (DERA).  It is made available to Recipients with a

    royalty-free licence for its use, reproduction, transfer

    to other parties and amendment for any purpose not excluding

    product development provided that any such use et cetera

    shall be deemed to be acceptance of the following conditions:-

        (1) Its Recipients shall ensure that this Notice is

        reproduced upon any copies or amended versions of it;

        (2) Any amended version of it shall be clearly marked to

        show both the nature of and the organisation responsible

        for the relevant amendment or amendments;

        (3) Its onward transfer from a recipient to another

        party shall be deemed to be that party's acceptance of

        these conditions;

        (4) DERA gives no warranty or assurance as to its

        quality or suitability for any purpose and DERA accepts

        no liability whatsoever in relation to any use to which

        it may be put.

*/

%types%

/*

    TYPES

    There are four types, representing booleans, identifiers, input strings

    and strings of character codes.

*/

BOOL ;

CHARACTERS ;

IDENTIFIER ;

STRING ;

%terminals%

/*

    TERMINALS

    These terminals give the various terminals identified by the lexical

    analysis routines.

*/

identifier : () -> ( :IDENTIFIER ) ;

sid-identifier : () -> ( :IDENTIFIER ) ;

string : () -> ( :STRING ) ;

upper : () -> ( :STRING ) ;

lower : () -> ( :STRING ) ;

digit : () -> ( :STRING ) ;

group ;

keyword ;

mapping ;

token ;

white ;

if ;

else ;

open ;

close ;

open-brace ;

close-brace ;

arrow ;

eof ;

equal ;

plus ;

semicolon ;

!unknown ;

%productions%

/*

    ACTION DECLARATIONS

    The actions are described in more detail in the action definition

    file.

*/

<string-concat> : ( :STRING, :STRING ) -> ( :STRING ) ;

<make-chars> : ( :STRING ) -> ( :CHARACTERS ) ;

<make-white> : ( :CHARACTERS ) -> () ;

<make-group> : ( :IDENTIFIER, :CHARACTERS ) -> () ;

<make-trigraph> : ( :CHARACTERS, :STRING ) -> () ;

<make-token> : ( :CHARACTERS, :IDENTIFIER, :BOOL ) -> () ;

<make-keyword> : ( :STRING, :IDENTIFIER, :BOOL ) -> () ;

<add-condition> : ( :IDENTIFIER ) -> () ;

<compl-condition> : () -> () ;

<get-condition> : () -> ( :IDENTIFIER ) ;

<set-condition> : ( :IDENTIFIER ) -> () ;

<true> : () -> ( :BOOL ) ;

<false> : () -> ( :BOOL ) ;

<syntax-error> : () -> () ;

/*

    STRINGS

    This action gives the full definition of a string, including special

    strings and string concatenation.

*/

string-plus : () -> ( s : STRING ) = {

	{

		a = string ;

	    ||	a = upper ;

	    ||	a = lower ;

	    ||	a = digit ;

	} ;

	{

		s = a ;

	    ||	plus ; b = string-plus ; s = <string-concat> ( a, b ) ;

	} ;

} ;

/*

    CHARACTER STRING

    This action transforms an input string into the internal representation

    of arrays of character codes.

*/

chars : () -> ( c : CHARACTERS ) = {

	s = string-plus ;

	c = <make-chars> ( s ) ;

} ;

/*

    WHITE SPACE DEFINITION

    This action defines the set of white space characters.

*/

white-defn : () -> () = {

	group ; white ; equal ; s = chars ;

	<make-white> ( s ) ;

} ;

/*

    CHARACTER GROUP DEFINITION

    This action assigns a name to a group of characters.

*/

group-defn : () -> () = {

	group ; i = identifier ; equal ; s = chars ;

	<make-group> ( i, s ) ;

} ;

/*

    RETURN ARGUMENTS

    This action deals with the optional arguments which may be used in

    a token definition.

*/

args : () -> ( a : BOOL ) = {

	a = <false> ;

    ||	open ; close ; a = <true> ;

} ;

/*

    TRIGRAPH DEFINITION

    This action defines a lexical pre-pass mapping (for example, trigraphs

    in ANSI C).

*/

trigraph-defn : () -> () = {

	mapping ; s = chars ; arrow ; t = string-plus ;

	<make-trigraph> ( s, t ) ;

} ;

/*

    TOKEN DEFINITION

    This action defines a lexical main-pass mapping (for example, operators

    and keywords).

*/

token-defn : () -> () = {

	token ; s = chars ; arrow ;

	{

		i = identifier ; a = args ;

	    ||	i = sid-identifier ; a = <false> ;

	} ;

	<make-token> ( s, i, a ) ;

} ;

/*

    KEYWORD DEFINITION

    This action defines a keyword.

*/

keyword-defn : () -> () = {

	keyword ; s = string ; arrow ;

	{

		i = identifier ; a = args ;

	    ||	i = sid-identifier ; a = <false> ;

	} ;

	<make-keyword> ( s, i, a ) ;

} ;

/*

    COMMANDS

    These actions define the composite commands derived from the basic

    commands above.

*/

command : () -> () ;

command-list : () -> () = {

	$ ;

    ||	command ; command-list ;

    ##	<syntax-error> ;

} ;

if-command : () -> () = {

	if ; open ; i = identifier ; close ;

	j = <get-condition> ;

	<add-condition> ( i ) ;

	command ;

	{

		else ; <compl-condition> ; command ; <set-condition> ( j ) ;

	    ##	<set-condition> ( j ) ;

	} ;

} ;

command : () -> () = {

	semicolon ;

    ||	white-defn ; semicolon ;

    ||	group-defn ; semicolon ;

    ||	trigraph-defn ; semicolon ;

    ||	token-defn ; semicolon ;

    ||	keyword-defn ; semicolon ;

    ||	open-brace ; command-list ; close-brace ;

    ||	if-command ;

} ;

/*

    COMPLETE UNIT

    This action gives the main entry point for the syntax.  A complete

    unit just consists of a list of commands.

*/

unit : () -> () = {

	command-list ;

	{

		eof ;

	    ##	<syntax-error> ;

	} ;

}  ;

%entry% unit ;