sets.at   [plain text]


# Exercising Bison Grammar Sets.                      -*- Autotest -*-
# Copyright (C) 2001, 2002, 2005 Free Software Foundation, Inc.

# This program 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 2, or (at your option)
# any later version.

# This program 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
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


# AT_EXTRACT_SETS(INPUT, OUTPUT)
# ------------------------------
# Extract the information about the grammar sets from a bison
# trace output (INPUT), and save it in OUTPUT.
# And remember, there is no alternation in portable sed.
m4_define([AT_EXTRACT_SETS],
[AT_DATA([extract.sed],
[[#n
/^NULLABLE$/ {
   :null
   p
   n
   /^[	 ]*$/ !b null
}
/^FIRSTS$/ {
   :firsts
   p
   n
   /^[	 ]*$/ !b firsts
}
/^FDERIVES$/ {
   :fderiv
   p
   n
   /^[	 ]*$/ !b fderiv
}
/^DERIVES$/ {
   :deriv
   p
   n
   /^[	 ]*$/ !b deriv
}
]])
AT_CHECK([sed -f extract.sed $1], 0, [stdout])
AT_CHECK([mv stdout $2])
])



AT_BANNER([[Grammar Sets (Firsts etc.).]])


## ---------- ##
## Nullable.  ##
## ---------- ##

AT_SETUP([Nullable])

# At some point, nullable had been smoking grass, and managed to say:
#
# Entering set_nullable
# NULLABLE
#         'e': yes
#         (null): no
# ...

AT_DATA([[input.y]],
[[%%
e: 'e' | /* Nothing */;
]])

AT_CHECK([[bison --trace=sets input.y]], [], [], [stderr])
AT_EXTRACT_SETS([stderr], [sets])
AT_CHECK([[cat sets]], [],
[[DERIVES
	$accept derives
		  0  e $end
	e derives
		  1  'e'
		  2  /* empty */
NULLABLE
	$accept: no
	e: yes
FIRSTS
	$accept firsts
		$accept
		e
	e firsts
		e
FDERIVES
	$accept derives
		  0  e $end
		  1  'e'
		  2  /* empty */
	e derives
		  1  'e'
		  2  /* empty */
]])

AT_CLEANUP


## ---------------- ##
## Broken Closure.  ##
## ---------------- ##

# TC was once broken during a massive `simplification' of the code.
# It resulted in bison dumping core on the following grammar (the
# computation of FIRSTS uses TC).  It managed to produce a pretty
# exotic closure:
#
# TC: Input
#
#    01234567
#   +--------+
#  0| 1      |
#  1|  1     |
#  2|   1    |
#  3|    1   |
#  4|     1  |
#  5|      1 |
#  6|       1|
#  7|        |
#   +--------+
#
# TC: Output
#
#    01234567
#   +--------+
#  0| 1      |
#  1| 111    |
#  2| 111    |
#  3| 1111   |
#  4| 111 1  |
#  5| 111  1 |
#  6| 111   1|
#  7| 111    |
#   +--------+
#
# instead of that below.

AT_SETUP([Broken Closure])

AT_DATA([input.y],
[[%%
a: b;
b: c;
c: d;
d: e;
e: f;
f: g;
g: h;
h: 'h';
]])

AT_CHECK([[bison --trace=sets input.y]], [], [], [stderr])

AT_CHECK([[sed -n 's/[	 ]*$//;/^RTC: Firsts Output BEGIN/,/^RTC: Firsts Output END/p' stderr]], [],
[[RTC: Firsts Output BEGIN

   012345678
  .---------.
 0|111111111|
 1| 11111111|
 2|  1111111|
 3|   111111|
 4|    11111|
 5|     1111|
 6|      111|
 7|       11|
 8|        1|
  `---------'
RTC: Firsts Output END
]])

AT_CLEANUP



## -------- ##
## Firsts.  ##
## -------- ##

AT_SETUP([Firsts])

AT_DATA([input.y],
[[%nonassoc '<' '>'
%left '+' '-'
%right '^' '='
%%
exp:
   exp '<' exp
 | exp '>' exp
 | exp '+' exp
 | exp '-' exp
 | exp '^' exp
 | exp '=' exp
 | "exp"
 ;
]])

AT_CHECK([[bison --trace=sets input.y]], [], [], [stderr])
AT_EXTRACT_SETS([stderr], [sets])
AT_CHECK([[cat sets]], [],
[[DERIVES
	$accept derives
		  0  exp $end
	exp derives
		  1  exp '<' exp
		  2  exp '>' exp
		  3  exp '+' exp
		  4  exp '-' exp
		  5  exp '^' exp
		  6  exp '=' exp
		  7  "exp"
NULLABLE
	$accept: no
	exp: no
FIRSTS
	$accept firsts
		$accept
		exp
	exp firsts
		exp
FDERIVES
	$accept derives
		  0  exp $end
		  1  exp '<' exp
		  2  exp '>' exp
		  3  exp '+' exp
		  4  exp '-' exp
		  5  exp '^' exp
		  6  exp '=' exp
		  7  "exp"
	exp derives
		  1  exp '<' exp
		  2  exp '>' exp
		  3  exp '+' exp
		  4  exp '-' exp
		  5  exp '^' exp
		  6  exp '=' exp
		  7  "exp"
]])

AT_CLEANUP




## -------- ##
## Accept.  ##
## -------- ##

# In some weird cases Bison could compute an incorrect final state
# number.  This happens only if the $end token is used in the user
# grammar, which is a very suspicious accidental feature introduced as
# a side effect of allowing the user to name $end using `%token END 0
# "end of file"'.

AT_SETUP([Accept])

AT_DATA([input.y],
[[%token END 0
%%
input:
  'a'
| '(' input ')'
| '(' error END
;
]])

AT_CHECK([[bison -v -o input.c input.y]])

# Get the final state in the parser.
AT_CHECK([[sed -n 's/.*define YYFINAL *\([0-9][0-9]*\)/final state \1/p' input.c]],
         0, [stdout])
mv stdout expout

# Get the final state in the report, from the "accept" action..
AT_CHECK([sed -n '
           /^state \(.*\)/{
	     s//final state \1/
	     x
	   }
	   / accept/{
	     x
	     p
	     q
	   }
	' input.output],
	0, [expout])

AT_CLEANUP