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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.
*/


/*** c-lexer.c --- SID C lexical analyser.
 *
 ** Author: Steve Folkes <smf@hermes.mod.uk>
 *
 *** Commentary:
 *
 * This file implements the SID C lexical analyser.  Any changes to the syntax
 * of SID identifiers should be made both here and in the file
 * "../parser/lexer.c".
 *
 *** Change Log:
 * $Log: c-lexer.c,v $
 * Revision 1.1.1.1  1998/01/17  15:57:42  release
 * First version to be checked into rolling release.
 *
 * Revision 1.2  1994/12/15  09:55:56  smf
 * Brought into line with OSSG C Coding Standards Document, as per
 * "CR94_178.sid+tld-update".
 *
 * Revision 1.1.1.1  1994/07/25  16:04:13  smf
 * Initial import of SID 1.8 non shared files.
 *
**/

/****************************************************************************/

#include "c-lexer.h"
#include "gen-errors.h"
#include "syntax.h"

/*--------------------------------------------------------------------------*/

#define LEXER_READ_ONE_CHAR(istream, redo, eof, id) \
    switch ((id) = ISTREAM_READ_CHAR (istream)) { \
      case '\0': \
        ISTREAM_HANDLE_NULL ((istream), redo, eof); \
        break; \
      case '\n': \
        istream_inc_line (istream); \
        break; \
      default: \
        break; \
    }

/*--------------------------------------------------------------------------*/

static BoolT
c_lexer_skip_bracketed_comment PROTO_N ((istream))
                               PROTO_T (IStreamP istream)
{
    char c1;
    char c2;

  redo1:
    LEXER_READ_ONE_CHAR (istream, redo1, eof, c1);
  redo2:
    LEXER_READ_ONE_CHAR (istream, redo2, eof, c2);
    for (;;) {
        if ((c1 == '/') && (c2 == '*')) {
            if (!c_lexer_skip_bracketed_comment (istream)) {
                goto eof;
            }
          redo3:
            LEXER_READ_ONE_CHAR (istream, redo3, eof, c2);
        } else if ((c1 == '*') && (c2 == '/')) {
            return (TRUE);
        }
        c1 = c2;
      redo4:
        LEXER_READ_ONE_CHAR (istream, redo4, eof, c2);
    }
  eof:
    return (FALSE);
}

static char
c_lexer_skip_white_space PROTO_N ((istream))
                         PROTO_T (IStreamP istream)
{
    for (;;) {
        char c;

      redo1:
        switch (c = ISTREAM_READ_CHAR (istream)) {
          case '\0':
            ISTREAM_HANDLE_NULL (istream, redo1, eof);
            break;
          case '\n':
            istream_inc_line (istream);
            break;
          case '/':
          redo2:
            switch (c = ISTREAM_READ_CHAR (istream)) {
              case '\0':
                ISTREAM_HANDLE_NULL (istream, redo2, eof_in_comment);
                goto illegal_in_comment;
              case '\n':
                istream_inc_line (istream);
                goto illegal_in_comment;
              case '*':
                if (!c_lexer_skip_bracketed_comment (istream)) {
                  eof_in_comment:
                    E_c_eof_in_comment (istream);
                    return ('\0'); /*FOR EOF*/
                }
                break;
              case '/':
                do {
                  redo3:
                    LEXER_READ_ONE_CHAR (istream, redo3, eof, c);
                } while (c != '\n');
                break;
              default:
              illegal_in_comment:
                E_c_illegal_comment_character (istream, c);
                break;
            }
            break;
          default:
            if (!syntax_is_white_space (c)) {
                return (c);
            }
            break;
        }
    }
  eof:
    return ('\0'); /*FOR EOF*/
}

static void
c_lexer_read_builtin PROTO_N ((istream, token))
                     PROTO_T (IStreamP istream X
                              CLexP    token)
{
    DStringT dstring;
    CStringP cstring;

    dstring_init (&dstring);
    for (;;) {
        char c;

      redo:
        switch (c = ISTREAM_READ_CHAR (istream)) {
          case '\0':
            ISTREAM_HANDLE_NULL (istream, redo, eof);
            E_c_null_character_in_builtin (istream);
            break;
          case '\n':
            istream_inc_line (istream);
            E_c_newline_in_builtin (istream);
            goto done;
          case '%':
            goto done;
          default:
            dstring_append_char (&dstring, c);
            break;
        }
    }
  eof:
    E_c_eof_in_builtin (istream);
  done:
    cstring = dstring_destroy_to_cstring (&dstring);
    if (cstring_ci_equal (cstring, "prefixes")) {
        token->t = C_TOK_BLT_PREFIXES;
    } else if (cstring_ci_equal (cstring, "maps")) {
        token->t = C_TOK_BLT_MAPS;
    } else if (cstring_ci_equal (cstring, "assignments")) {
        token->t = C_TOK_BLT_ASSIGNMENTS;
    } else if (cstring_ci_equal (cstring, "assign")) {
        token->t = C_TOK_BLT_ASSIGNMENTS;
    } else if (cstring_ci_equal (cstring, "terminals")) {
        token->t = C_TOK_BLT_TERMINALS;
    } else if (cstring_ci_equal (cstring, "header")) {
        token->t = C_TOK_BLT_HEADER;
    } else if (cstring_ci_equal (cstring, "actions")) {
        token->t = C_TOK_BLT_ACTIONS;
    } else if (cstring_ci_equal (cstring, "trailer")) {
        token->t = C_TOK_BLT_TRAILER;
    } else if (cstring_ci_equal (cstring, "result-assignments")) {
        token->t = C_TOK_BLT_RESULT_ASSIGN;
    } else if (cstring_ci_equal (cstring, "result-assign")) {
        token->t = C_TOK_BLT_RESULT_ASSIGN;
    } else if (cstring_ci_equal (cstring, "parameter-assignments")) {
        token->t = C_TOK_BLT_PARAM_ASSIGN;
    } else if (cstring_ci_equal (cstring, "parameter-assign")) {
        token->t = C_TOK_BLT_PARAM_ASSIGN;
    } else if (cstring_ci_equal (cstring, "param-assignments")) {
        token->t = C_TOK_BLT_PARAM_ASSIGN;
    } else if (cstring_ci_equal (cstring, "param-assign")) {
        token->t = C_TOK_BLT_PARAM_ASSIGN;
    } else {
        E_c_unknown_builtin (istream, cstring);
        UNREACHED;
    }
    DEALLOCATE (cstring);
}

static void
c_lexer_read_identifier PROTO_N ((istream, c, token))
                        PROTO_T (IStreamP istream X
                                 char     c X
                                 CLexP    token)
{
    BoolT    c_ident = (c != '-');
    DStringT dstring;

    dstring_init (&dstring);
    dstring_append_char (&dstring, c);
    for (;;) {
      redo1:
        switch (c = ISTREAM_PEEK_CHAR (istream)) {
          case '\0':
            ISTREAM_HANDLE_NULL (istream, redo1, done);
            goto done;
          default:
            if ((syntax_is_letter (c)) || (syntax_is_digit (c)) ||
                (c == '_') || (c == '-')) {
              redo2:
                LEXER_READ_ONE_CHAR (istream, redo2, done, c);
                dstring_append_char (&dstring, c);
                if (c == '-') {
                    c_ident = FALSE;
                }
            } else {
                goto done;
            }
            break;
        }
    }
  done:
    if (c_ident) {
        token->t = C_TOK_C_IDENTIFIER;
    } else {
        token->t = C_TOK_SID_IDENTIFIER;
    }
    dstring_to_nstring (&dstring, &(token->u.string));
    dstring_destroy (&dstring);
}

static void
c_lexer_read_code_id PROTO_N ((istream, c, nstring))
                     PROTO_T (IStreamP istream X
                              char     c X
                              NStringP nstring)
{
    BoolT    numbers_ok = (syntax_is_letter (c) || (c == '_'));
    DStringT dstring;
    char     c1;

    dstring_init (&dstring);
    if (numbers_ok) {
        dstring_append_char (&dstring, c);
    }
    for (;;) {
      redo1:
        switch (c1 = ISTREAM_PEEK_CHAR (istream)) {
          case '\0':
            ISTREAM_HANDLE_NULL (istream, redo1, done);
            goto done;
          default:
            if (syntax_is_letter (c1) || (c1 == '_') ||
                (numbers_ok && syntax_is_digit (c1))) {
              redo2:
                LEXER_READ_ONE_CHAR (istream, redo2, done, c1);
                dstring_append_char (&dstring, c1);
                numbers_ok = TRUE;
            } else {
                goto done;
            }
            break;
        }
    }
  done:
    if (!numbers_ok) {
        E_c_expected_at_id (istream, c);
    }
    dstring_to_nstring (&dstring, nstring);
    dstring_destroy (&dstring);
}

static void
c_lexer_flush_string PROTO_N ((dstring, code, force_nl))
                     PROTO_T (DStringP dstring X
                              CCodeP   code X
                              BoolT    force_nl)
{
    NStringT nstring;

    if (dstring_length (dstring) > 0) {
        if (force_nl && (!dstring_last_char_equal (dstring, '\n'))) {
            dstring_append_char (dstring, '\n');
        }
        dstring_to_nstring (dstring, &nstring);
        c_code_append_string (code, &nstring);
        dstring_destroy (dstring);
        dstring_init (dstring);
    } else if (force_nl) {
        nstring_copy_cstring (&nstring, "\n");
        c_code_append_string (code, &nstring);
    }
}

static BoolT
c_lexer_read_at PROTO_N ((istream, dstring, code))
                PROTO_T (IStreamP istream X
                         DStringP dstring X
                         CCodeP   code)
{
    char     c;
    NStringT nstring;

  redo:
    switch (c = ISTREAM_READ_CHAR (istream)) {
      case '\0':
        ISTREAM_HANDLE_NULL (istream, redo, error);
        goto error;
      case '\n':
        istream_inc_line (istream);
        goto error;
      case '@':
        dstring_append_char (dstring, c);
        break;
      case '}':
        return (TRUE);
      case '!':
        c_lexer_flush_string (dstring, code, FALSE);
        c_code_append_exception (code);
        break;
      case '.':
        c_lexer_flush_string (dstring, code, FALSE);
        c_code_append_terminal (code);
        break;
      case '>':
        c_lexer_flush_string (dstring, code, FALSE);
        c_code_append_advance (code);
        break;
      case ':':
        c_lexer_flush_string (dstring, code, FALSE);
        c_lexer_read_code_id (istream, ':', &nstring);
        c_code_append_label (code, &nstring);
        break;
      case '&':
        c_lexer_flush_string (dstring, code, FALSE);
        c_lexer_read_code_id (istream, '&', &nstring);
        c_code_append_reference (code, &nstring);
        break;
      case '=':
        c_lexer_flush_string (dstring, code, FALSE);
        c_lexer_read_code_id (istream, '=', &nstring);
        c_code_append_modifiable (code, &nstring);
        break;
      default:
        if (syntax_is_letter (c) || (c == '_')) {
            c_lexer_flush_string (dstring, code, FALSE);
            c_lexer_read_code_id (istream, c, &nstring);
            c_code_append_identifier (code, &nstring);
        } else {
          error:
            E_c_illegal_at_char (istream, c);
        }
        break;
    }
    return (FALSE);
}
    
static void
c_lexer_read_code PROTO_N ((istream, token))
                  PROTO_T (IStreamP istream X
                           CLexP    token)
{
    CCodeP   code = c_code_create (istream_name (istream),
                                   istream_line (istream));
    DStringT dstring;
    char     c;

  redo1:
    switch (ISTREAM_PEEK_CHAR (istream)) {
      case '\0':
        ISTREAM_HANDLE_NULL (istream, redo1, error);
        goto error;
      case '{':
      redo2:
        LEXER_READ_ONE_CHAR (istream, redo2, error, c);
        UNUSED (c);
        break;
      default:
      error:
        E_c_code_block_syntax (istream);
        break;
    }
    dstring_init (&dstring);
    for (;;) {
      redo3:
        switch (c = ISTREAM_READ_CHAR (istream)) {
          case '\0':
            ISTREAM_HANDLE_NULL (istream, redo3, eof);
            dstring_append_char (&dstring, c);
            break;
          case '\n':
            istream_inc_line (istream);
            dstring_append_char (&dstring, c);
            break;
          case '@':
            if (c_lexer_read_at (istream, &dstring, code)) {
                goto done;
            }
            break;
          default:
            dstring_append_char (&dstring, c);
            break;
        }
    }
  eof:
    E_c_eof_in_code (istream);
  done:
    token->t = C_TOK_CODE;
    c_lexer_flush_string (&dstring, code, TRUE);
    dstring_destroy (&dstring);
    token->u.code = code;
}

/*--------------------------------------------------------------------------*/

void
c_lexer_init PROTO_N ((stream, istream))
             PROTO_T (CLexerStreamP stream X
                      IStreamP      istream)
{
    istream_assign (&(stream->istream), istream);
    c_lexer_next_token (stream);
}

#ifdef FS_FAST
#undef c_lexer_close
#endif /* defined (FS_FAST) */
void
c_lexer_close PROTO_N ((stream))
              PROTO_T (CLexerStreamP stream)
{
    istream_close (&(stream->istream));
}
#ifdef FS_FAST
#define c_lexer_close(s) (istream_close (&((s)->istream)))
#endif /* defined (FS_FAST) */

#ifdef FS_FAST
#undef c_lexer_stream_name
#endif /* defined (FS_FAST) */
CStringP
c_lexer_stream_name PROTO_N ((stream))
                    PROTO_T (CLexerStreamP stream)
{
    return (istream_name (&(stream->istream)));
}
#ifdef FS_FAST
#define c_lexer_stream_name(s) (istream_name (&((s)->istream)))
#endif /* defined (FS_FAST) */

#ifdef FS_FAST
#undef c_lexer_stream_line
#endif /* defined (FS_FAST) */
unsigned
c_lexer_stream_line PROTO_N ((stream))
                    PROTO_T (CLexerStreamP stream)
{
    return (istream_line (&(stream->istream)));
}
#ifdef FS_FAST
#define c_lexer_stream_line(s) (istream_line (&((s)->istream)))
#endif /* defined (FS_FAST) */

#ifdef FS_FAST
#undef c_lexer_get_terminal
#endif /* defined (FS_FAST) */
CTokenT
c_lexer_get_terminal PROTO_N ((stream))
                     PROTO_T (CLexerStreamP stream)
{
    return (stream->token.t);
}
#ifdef FS_FAST
#define c_lexer_get_terminal(s) ((s)->token.t)
#endif /* defined (FS_FAST) */

void
c_lexer_next_token PROTO_N ((stream))
                   PROTO_T (CLexerStreamP stream)
{
    IStreamP istream = &(stream->istream);
    CLexT    token;
    char     c;

  retry:
    switch (c = c_lexer_skip_white_space (istream)) {
      case '\0': /*FOR EOF*/
        token.t = C_TOK_EOF;
        break;
      case '%':
        c_lexer_read_builtin (istream, &token);
        break;
      case ',':
        token.t = C_TOK_SEPARATOR;
        break;
      case ':':
        token.t = C_TOK_TYPEMARK;
        break;
      case ';':
        token.t = C_TOK_TERMINATOR;
        break;
      case '<':
        token.t = C_TOK_BEGIN_ACTION;
        break;
      case '=':
        token.t = C_TOK_DEFINE;
        break;
      case '>':
        token.t = C_TOK_END_ACTION;
        break;
      case '(':
        token.t = C_TOK_OPEN_TUPLE;
        break;
      case ')':
        token.t = C_TOK_CLOSE_TUPLE;
        break;
      case '&':
        token.t = C_TOK_REFERENCE;
        break;
      case '@':
        c_lexer_read_code (istream, &token);
        break;
      case '-':
        if ((istream_peek_char (istream, &c)) && (c == '>')) {
            (void) istream_read_char (istream, &c);
            token.t = C_TOK_ARROW;
            break;
        }
        c_lexer_read_identifier (istream, '-', &token);
        break;
      default:
        if ((syntax_is_letter (c)) || (c == '_')) {
            c_lexer_read_identifier (istream, c, &token);
        } else {
            E_c_illegal_character (istream, c);
            goto retry;
        }
        break;
    }
    stream->token = token;
}

#ifdef FS_FAST
#undef c_lexer_string_value
#endif /* defined (FS_FAST) */
NStringP
c_lexer_string_value PROTO_N ((stream))
                     PROTO_T (CLexerStreamP stream)
{
    ASSERT ((stream->token.t == C_TOK_C_IDENTIFIER) ||
            (stream->token.t == C_TOK_SID_IDENTIFIER));
    return (&(stream->token.u.string));
}
#ifdef FS_FAST
#define c_lexer_string_value(s) (&((s)->token.u.string))
#endif /* defined (FS_FAST) */

#ifdef FS_FAST
#undef c_lexer_code_value
#endif /* defined (FS_FAST) */
CCodeP
c_lexer_code_value PROTO_N ((stream))
                   PROTO_T (CLexerStreamP stream)
{
    ASSERT (stream->token.t == C_TOK_CODE);
    return (stream->token.u.code);
}
#ifdef FS_FAST
#define c_lexer_code_value(s) ((s)->token.u.code)
#endif /* defined (FS_FAST) */

void
c_lexer_save_terminal PROTO_N ((stream, error_terminal))
                      PROTO_T (CLexerStreamP stream X
                               CTokenT       error_terminal)
{
    ASSERT (stream->token.t != error_terminal);
    stream->saved_terminal = stream->token.t;
    stream->token.t        = error_terminal;
}

void
c_lexer_restore_terminal PROTO_N ((stream))
                         PROTO_T (CLexerStreamP stream)
{
    stream->token.t = stream->saved_terminal;
}

/*
 * Local variables(smf):
 * eval: (include::add-path-entry "../os-interface" "../library")
 * eval: (include::add-path-entry "../transforms" "../output")
 * eval: (include::add-path-entry "../c-output" "../generated")
 * end:
**/