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87 lines
2.6 KiB
ObjectPascal
87 lines
2.6 KiB
ObjectPascal
{
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DFA table construction. This code, admittedly, is not the most aesthetic,
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but it's quite efficient (and that's the main goal). For further
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explanation, refer to Aho/Sethi/Ullman 1986, Section 3.9.
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Copyright (c) 1990-92 Albert Graef <ag@muwiinfa.geschichte.uni-mainz.de>
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Copyright (C) 1996 Berend de Boer <berend@pobox.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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$Revision: 1.2 $
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$Modtime: 96-08-01 6:13 $
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$History: LEXDFA.PAS $
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*
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* ***************** Version 2 *****************
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* User: Berend Date: 96-10-10 Time: 21:16
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* Updated in $/Lex and Yacc/tply
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* Updated for protected mode, windows and Delphi 1.X and 2.X.
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}
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unit LexDFA;
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interface
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procedure makeDFATable;
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(* construct DFA from position table *)
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implementation
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uses LexBase, LexTable;
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procedure makeDFATable;
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var i : Integer;
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begin
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(* initialize start states: *)
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for i := 2 to 2*n_start_states+1 do
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if not start_excl^[i div 2] then
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setunion(first_pos_table^[i]^, first_pos_table^[i mod 2]^);
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for i := 0 to 2*n_start_states+1 do
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act_state := newState(first_pos_table^[i]);
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act_state := -1;
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while succ(act_state)<n_states do
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begin
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inc(act_state);
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(* add transitions for active state: *)
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startStateTrans;
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for i := 1 to size(state_table^[act_state].state_pos^) do
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with pos_table^[state_table^[act_state].state_pos^[i]] do
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if pos_type=char_pos then
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addTrans([c], follow_pos)
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else if pos_type=cclass_pos then
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addTrans(cc^, follow_pos)
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else if pos=0 then
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state_table^[act_state].final := true;
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(* assign next states: *)
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for i := state_table^[act_state].trans_lo to n_trans do
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with trans_table^[i] do
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next_state := addState(follow_pos);
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(* merge transitions for the same next state: *)
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mergeTrans;
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(* sort transitions: *)
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sortTrans;
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endStateTrans;
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end;
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end(*makeDFATable*);
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end(*LexDFA*).
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