1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
|
-------------------------------------------------------------------------------
--
-- Copyright (C) 2009 Stephe Leake
-- Copyright (C) 1999,2000 Ted Dennison
--
-- This file is part of the OpenToken package.
--
-- The OpenToken package is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License as published
-- by the Free Software Foundation; either version 3, or (at your option)
-- any later version. The OpenToken package is distributed in the hope that
-- it will be useful, but WITHOUT ANY WARRANTY; without even the implied
-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details. You should have received
-- a copy of the GNU General Public License distributed with the OpenToken
-- package; see file GPL.txt. If not, write to the Free Software Foundation,
-- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
--
-- As a special exception, if other files instantiate generics from
-- this unit, or you link this unit with other files to produce an
-- executable, this unit does not by itself cause the resulting
-- executable to be covered by the GNU General Public License. This
-- exception does not however invalidate any other reasons why the
-- executable file might be covered by the GNU Public License.
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-- This example is an implementation of Example 5.10 from "Compilers
-- Principles, Techniques, and Tools" by Aho, Sethi, and Ullman (aka: "The
-- Dragon Book"). It demonstrates handling of synthesized attributes
-------------------------------------------------------------------------------
with Ada.Command_Line;
with Ada.Text_IO; use Ada.Text_IO;
procedure ASU_Example_5_10_LR.Run is
procedure Put_Usage
is begin
Put_Line ("asu_example_5_10_lr-run [-t] [filename]");
Put_Line (" -t : output trace of parser generation, execution");
Put_Line (" if no filename given, parse standard input");
end Put_Usage;
-- Create a user-settable text feeder, and a string buffer to fill it with
Line : String (1 .. 1024);
Line_Length : Natural;
Test_Parser : LALR_Parser.Instance;
Input_File : File_Type;
procedure Use_File (File_Name : in String)
is begin
Open (Input_File, In_File, File_Name);
Set_Input (Input_File);
end Use_File;
begin
declare
use Ada.Command_Line;
begin
case Argument_Count is
when 0 =>
null;
when 1 =>
if Argument (1) = "-t" then
OpenToken.Trace_Parse := True;
else
Use_File (Argument (1));
end if;
when 2 =>
if Argument (1) = "-t" then
OpenToken.Trace_Parse := True;
else
Set_Exit_Status (Failure);
Put_Usage;
return;
end if;
Use_File (Argument (2));
when others =>
Set_Exit_Status (Failure);
Put_Usage;
return;
end case;
end;
Test_Parser := LALR_Parser.Generate (Grammar, Analyzer, OpenToken.Trace_Parse);
if OpenToken.Trace_Parse then
LALR_Parser.Print_Table (Test_Parser);
end if;
if not Is_Open (Input_File) then
Put_Line ("A simple calculator, as specified in example 5.10 in Aho, Sethi, and Ullman's");
Put_Line ("""Compilers Principles, Techniques and Tools""");
New_Line;
Put_Line ("""+"", ""*"", and ""( num )"" are understood.");
Put_Line ("(Enter a blank line to quit)");
end if;
-- Read and parse lines from the console until an empty line or end of file is read.
loop
Get_Line (Line, Line_Length);
exit when Line_Length = 0;
OpenToken.Text_Feeder.String.Set
(Feeder => Feeder,
Value => Line (1 .. Line_Length));
Put_Line ("Input_String => " & Line (1 .. Line_Length));
LALR_Parser.Parse (Test_Parser);
end loop;
exception
when End_Error =>
null;
end ASU_Example_5_10_LR.Run;
|
