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/*

    		 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.

*/

#include "config.h"

#include "error.h"

#include "lex.h"

#include "syntax.h"

#include "xalloc.h"

/*

    INPUT FILE

    This is the file from which the lexical routine read their input.

*/

static FILE *lex_input ;

/*

    PENDING BUFFER

    Pending characters are dealt with by means of this buffer.  pending

    is set to the start of the buffer to indicate that there are no

    characters pending, otherwise the pending characters are stored in

    the buffer.  The buffer may need increasing in size if the look-ahead

    required by the lexical analyser increases.

*/

static int pending_buff [12] = { '?' } ;

static int *pending = pending_buff ;

/*

    MAPPINGS AND DECLARATIONS FOR AUTOMATICALLY GENERATED SECTION

    These macros give the mappings between the actions used in the

    automatically generated lexical analyser and the routines defined

    in this file.

*/

static int read_char PROTO_S ( ( void ) ) ;

static int read_comment PROTO_S ( ( void ) ) ;

static int read_identifier PROTO_S ( ( int, int ) ) ;

static int read_string PROTO_S ( ( void ) ) ;

#define get_comment( A, B )	read_comment ()

#define get_identifier( A )	read_identifier ( ( A ), 0 )

#define get_sid_ident( A, B )	read_identifier ( ( B ), 1 )

#define get_string( A )		read_string ()

#define unknown_token( A )	lex_unknown

#define unread_char( A )	*( ++pending ) = ( A )

/*

    AUTOMATICALLY GENERATED SECTION

    The main body of the lexical analyser is automatically generated.

*/

#include "lexer.h"

/*

    GET THE NEXT CHARACTER

    This routine reads the next character, either from the pending buffer

    or from the input file.

*/

static int read_char

    PROTO_Z ()

{

    int c ;

    if ( pending != pending_buff ) {

	c = *( pending-- ) ;

    } else {

	c = fgetc ( lex_input ) ;

	if ( c == '\n' ) crt_line_no++ ;

	if ( c == EOF ) return ( LEX_EOF ) ;

	c &= 0xff ;

    }

    return ( c ) ;

}

/*

    TOKEN BUFFER

    This buffer is used by read_token to hold the values of identifiers

    and strings.

*/

char token_buff [2000] ;

static char *token_end = token_buff + sizeof ( token_buff ) ;

char *first_comment = NULL ;

/*

    READ AN IDENTIFIER

    This routine reads an identifier beginning with a, returning the

    corresponding lexical token.  Keywords are dealt with locally.

    The sid flag indicates whether a sid-style identifier is expected.

*/

static int read_identifier

    PROTO_N ( ( a, sid ) )

    PROTO_T ( int a X int sid )

{

    int c = a, cl ;

    int e = ( sid ? '-' : 'x' ) ;

    char *t = token_buff ;

    do {

	*( t++ ) = ( char ) c ;

	if ( t == token_end ) error ( ERROR_FATAL, "Buffer overflow" ) ;

	c = read_char () ;

	cl = lookup_char ( c ) ;

    } while ( is_alphanum ( cl ) || c == e ) ;

    *t = 0 ;

    unread_char ( c ) ;

    /* Deal with keywords */

    if ( sid ) return ( lex_sid_Hidentifier ) ;

    t = token_buff ;

#define MAKE_KEYWORD( A, B )\

    if ( streq ( t, ( A ) ) ) return ( B ) ;

#include "keyword.h"

    return ( lex_identifier ) ;

}

/*

    READ A STRING

    This routine reads a string.  It is entered after the initial

    quote has been read.

*/

static int read_string

    PROTO_Z ()

{

    int c ;

    int escaped = 0 ;

    char *t = token_buff ;

    while ( c = read_char (), ( c != '"' || escaped ) ) {

	if ( c == '\n' || c == LEX_EOF ) {

	    error ( ERROR_SERIOUS, "Unexpected end of string" ) ;

	    break ;

	}

	*( t++ ) = ( char ) c ;

	if ( t == token_end ) error ( ERROR_FATAL, "Buffer overflow" ) ;

	if ( escaped ) {

	    escaped = 0 ;

	} else {

	    if ( c == '\\' ) escaped = 1 ;

	}

    }

    *t = 0 ;

    return ( lex_string ) ;

}

/*

    READ A COMMENT

    This routine reads a C style comment, returning the lexical token

    immediately following.  It is entered after the first two characters

    have been read.

*/

static int read_comment

    PROTO_Z ()

{

    int state = 0 ;

    char *t = token_buff ;

    *( t++ ) = '/' ;

    *( t++ ) = '*' ;

    while ( state != 2 ) {

	int c = read_char () ;

	if ( c == LEX_EOF ) {

	    error ( ERROR_SERIOUS, "End of file in comment" ) ;

	    return ( lex_eof ) ;

	}

	if ( c == '*' ) {

	    state = 1 ;

	} else if ( state == 1 && c == '/' ) {

	    state = 2 ;

	} else {

	    state = 0 ;

	}

	*( t++ ) = ( char ) c ;

	if ( t == token_end ) t = token_buff + 2 ;

    }

    *t = 0 ;

    if ( first_comment == NULL ) first_comment = xstrcpy ( token_buff ) ;

    return ( read_token () ) ;

}

/*

    CURRENT TOKEN

    These variables are used by the parser to hold the current and former

    lexical tokens.

*/

int crt_lex_token ;

int saved_lex_token ;

/*

    PROCESS FILE

    This routine processes the input file nm.

*/

void process_file

    PROTO_N ( ( nm ) )

    PROTO_T ( char *nm )

{

    crt_line_no = 1 ;

    if ( nm == NULL || streq ( nm, "-" ) ) {

	crt_file_name = "<stdin>" ;

	lex_input = stdin ;

	nm = NULL ;

    } else {

	crt_file_name = nm ;

	lex_input = fopen ( nm, "r" ) ;

	if ( lex_input == NULL ) {

	    error ( ERROR_SERIOUS, "Can't open input file, '%s'", nm ) ;

	    return ;

	}

    }

    ADVANCE_LEXER ;

    read_lex () ;

    if ( nm ) fclose_v ( lex_input ) ;

    return ;

}