s : cmd
| cmd SOMETHING
cmd :WORD
WORD and SOMETHING are non null terminals
it's an LR1 grammar so bison should parse it without problems.
however i faced an unexpected problem in runtime:
the program prompts for input twice, so for example when i enter "qwerty" it prompt for a second input,when i try to debug it i get this:
Starting parse
Entering state 0
Reading a token: qwerty
Next token is token WORD
Shifting token WORD
Entering state 1
Reducing stack by rule 3 (line 20):
$1 = token WORD ()
-> $$ = nterm cmd ()
Stack now 0
Entering state 3
Reading a token:
(asks for input a second time)
How will it know which rule for s to employ until it tries to read SOMETHING and either succeeds (second rule) or fails (first rule)? Which means it HAS to ask for the second input.
Related
Here's my test program:
use Readline;
shell 'clear';
my $r = Readline.new;
loop {
my $a = $r.readline("> ");
{say ''; last} if not defined $a;
$r.add-history( $a );
say $a;
}
After I enter any string, it exits with the following message:
> abc
Internal error: unhandled encoding
in method CALL-ME at /opt/rakudo-pkg/share/perl6/sources/24DD121B5B4774C04A7084827BFAD92199756E03 (NativeCall) line 587
in method readline at /home/evb/.perl6/sources/D8BAC826F02BBAA2CCDEFC8B60D90C2AF8713C3F (Readline) line 1391
in block <unit> at abc.p6 line 7
If I comment the line shell 'clear';, everything is OK.
This is a bit of a guess, but I think when you tell your shell to clear the screen, it's sending a control character or control sequence as input to the terminal emulator. Readline is reading from that same stream, and those characters end up at the beginning of your "line" when you try to read a line. Those characters aren't valid UTF-8 (the default encoding) and so can't be interpreted as a string. You'll know more if you open the text files in the stack trace and look at the relevant line numbers.
You can try calling reset-terminal or reset-line-state to see if you can get rid of that character. What I would do in a low level programming language is to do a nonblocking read of the input (without converting it into a string), but I can't find the API for that in the Perl 6 library.
To test the integrity of PostScript files, I'd like to run Ghostscript in the following way:
Return 1 (or other error code) on error
Return 0 (success) at EOF if stack is empty
Return 1 (or other error code) otherwise
I could run gs in the background, and use a timeout to force termination if gs hangs with items left on the stack. Is there an easier solution?
Ghostscript won't hang if you send files as input (unless you write a program which enters an infinite loop or otherwise fails to reach a halting state). Having items on any of the stacks won't cause it to hang.
On the other hand, it won't give you an error if a PostScript program leaves operands on the operand stack (or dictionaries on the dictionary stack, clips on the clip stack or gstates on the graphics state stack). This is because that's not an error, and since PostScript interpreters normally run in a job server loop its not a problem either. Terminating the job returns control to the job server loop which does a save and restore round the total job, thereby clearing up anything left behind.
I'd suggest that if you really want to do this you need to adopt the same approach, you need to write a PostScript program which executes the PostScript program you want to 'test', then checks the operand stack (and other stacks if required) to see if anything is left. Note that you will want to execute the test program in a stopped context, as an error in the course of the program will clearly potentially leave stuff lying around.
Ghostscript returns 0 on a clean exit and a value less than 0 for errors, if I remember correctly. You would need to use signalerror in your test framework in order to raise an error if items are left at the end of a program.
[EDIT]
Anything supplied to Ghostscript on the command line by either -s or -d is defined in systemdict, so if we do -sInputFileName=/test.pdf then we will find in systemdict a key /InputFileName whose value is a string with the contents (/test.pdf). We can use that to pass the filename to our program.
The stopped operator takes an executable array as an argument, and returns either true or false depending on whether an error occurred while executing the array (3rd Edition PLRM, p 697).
So we need to run the program contained in the filename we've been given, and do it in a 'stopped' context. Something like this:
{InputFileName run} stopped
{
(Error occurred\n) print flush
%% Potentially check $error for more information.
}{
(program terminated normally\n) print flush
%% Here you could check the various stacks
} ifelse
The following, based 90% on KenS's answer, is 99% satisfactory:
Program checkIntegrity.ps:
{Script run} stopped
{
(\n===> Integrity test failed: ) print Script print ( has error\n\n) print
handleerror
(ignore this error which only serves to force a return value of 1) /syntaxerror signalerror
}{
% script passed, now check the stack
count dup 0 eq {
pop (\n===> Integrity test passed: ) print Script print ( terminated normally\n\n) print
} {
(\n===> Integrity test failed: ) print Script print ( left ) print
3 string cvs print ( item(s) on stack\n\n) print
Script /syntaxerror signalerror
} ifelse
} ifelse
quit
Execute with
gs -q -sScript=CodeToBeChecked.ps checkIntegrity.ps ; echo $?
For the last 1% of satisfaction I would need a replacement for
(blabla) /syntaxerror signalerror
It forces exit with return code 1, but is very verbous and distracts from the actual error in the checked script that is reported by handleerror. Therefore a cleaner way to exit(1) would be welcome.
We are currently using sed to filter output of regression runs. Sometimes we have a filter that looks like this:
/copyright/,/end copyright/d
If that end copyright is ever missing, the rest of the file is deleted. I'm wondering if there's some way to generate an error for this? awk would also be okay to use. I don't really want to add code that reads the file line by line and issues an error if it hits EOF.
here's a string
copyright
2016 jan 15
end copyright
date 2016 jan 5 time 15:36
last one
I'd like to get an error if end copyright is missing. The real filter also would replace the date line with DATE, so it's more that just ripping out the copyright.
You can persuade sed to generate an error if you reach end of input (i.e. see address $) between your start and end, but it won't be a very helpful message:
/copyright/,/end copyright/{
$s//\1/ # here
d
}
This will error if end copyright is missing or on the last line, with an exit status of 1 and the helpful message:
sed: -e expression #1, char 0: invalid reference \1 on `s' command's RHS
If you're using this in a makefile, you might want to echo a helpful message first, or (better) to wrap this in something that catches the error and produces a more useful one.
I tested this with GNU sed; though if you are using GNU sed, you could more easily use its useful extension:
q [EXIT-CODE]
This command only accepts a single address.
Exit 'sed' without processing any more commands or input. Note
that the current pattern space is printed if auto-print is not
disabled with the -n options. The ability to return an exit code
from the 'sed' script is a GNU 'sed' extension.
Q [EXIT-CODE]
This command only accepts a single address.
This command is the same as 'q', but will not print the contents of
pattern space. Like 'q', it provides the ability to return an exit
code to the caller.
So you could simply write
/copyright/,/end copyright/{
$Q 42
d
}
Never use range expressions /start/,/end/ as they make trivial code very slightly briefer but require a complete rewrite or duplicate conditions when you have the tiniest requirements change. Always use a flag instead. Note that since sed doesn't support variables, it doesn't support flag variables, and so you shouldn't be using sed you should be using awk instead.
In this case your original code would be:
awk '/copyright/{f=1} !f; /end copyright/{f=0}' file
And your modified code would be:
awk '/copyright/{f=1} !f; /end copyright/{f=0} END{if (f) print "Missing end copyright"}' file
The above is obviously untested since you didn't provide any sample input/output we could test a potential solution against.
With sed you can build a loop:
sed -e '/copyright/{:a;/end copyright/d;N;ba;};' file
:a defines the label "a"
/copyright end/d deletes the pattern space, only when "end copyright" matches
N appends the next line to the pattern space
ba jumps to the label "a"
Note that d ends the loop.
In this way you can avoid to delete the text until the end.
If you don't want the text to be displayed at all and prefer an error message when a "copyright" block stays unclosed, you obviously need to wait the end of the file. You can do it with sed too storing all the lines in the buffer space until the end:
sed -n -e '/copyright/{:a;/end copyright/d;${c\ERROR MESSAGE
;};N;ba;};H;${g;p};' file
H appends the current line to the buffer space
g put the content of the buffer space to the pattern space
The file content is only displayed once the last line reached with ${g;p} otherwise when the closing "end copyright" is missing, the current line is changed in the error message with ${c\ERROR MESSAGE\n;} inside the loop.
This way you can test what returns sed before redirecting it to whatever you want.
I'm currently running a code and I'm always getting to the same end. I am trying to read an input file and it returns the error:
Fortran runtime error: End of file
In an other post they said to put in the iostat specifier so now my code looks like this:
INTEGER :: m
INTEGER :: st
Open(Unit = 13,action='read',file='Data_Inp.dat',status='old')
read (13,*, iostat = st) m
write (*,*) st
write (*,*) m
ALLOCATE(winkel(m),energie(m))
Do i = 1,m
read(13,*),winkel(i),energie(i)
End Do
And the input file looks like this:
12
-17.83 -0.019386527878
-15.83 -0.020125057233
-12.83 -0.020653853148
-11.83 -0.020840036028
-9.83 -0.020974157405
-8.83 -0.021056401707
-6.83 -0.021065517811
-5.83 -0.020992571816
-4.83 -0.020867828448
-1.83 -0.02069158012
Now the terminal prints a -1 for iostat and a constantly changing number for m.
If the first read command is causing an error, check for extraneous characters before or after "12" in your input file, especially if you created it on one platform (Windows?) and using it on another platform (Linux? Mac?)
I am trying to apply multiple SQL scripts to an Ingres database (using a vnode setup). The testing phase will require it done to four databases. Trying to nip this annoyance in the bud I've started a batch file but receive the error above.
Many of the solutions found suggest that the batch file will evaluate everything within a block when it starts but I cannot see the forest for the trees. I have a suspicion that the parts in :1ST and :2ND are causing the problems but they need to be done.
SQL, Batch and command window output are below
UPDATE core SET sysflag='O'
#ECHO off
SET VN1=dave
SET DB1=dbtest1
SET DB2=dbtest2
SET SQL1=open.sql
SET SQL2=open.sql
:MENU
CLS
ECHO 1 - Leave
ECHO 2 - Database1
ECHO 3 - Database2
SET /P M=Choose then press ENTER:
IF "%M%"=="1" GOTO EOF
IF "%M%"=="2" GOTO 1ST
IF "%M%"=="3" GOTO 2ND
GOTO MENU
:1ST
SET DATABASE=%VN1%::%DB1%
GOTO RUNSQL
:2ND
SET DATABASE=%VN1%::%DB2%
GOTO RUNSQL
:RUNSQL
ECHO Applying SQLs to %DATABASE%
SQL %DATABASE% < %SQL1% > log_%SQL1%.txt
PAUSE
SQL %DATABASE% < %SQL2% > log_%SQL2%.txt
PAUSE
GOTO MENU
:EOF
C:\Users\me\BUILD>IF UPDATE core SET sysflag='O'==1 GOTO EOF
You are expecting the value of %M% to have 1, 2, or 3. But somehow the value is UPDATE core. The IF statement fails because there is a space in the middle of the left value. Token delimiters like space must be escaped, or the entire string on each side should be quoted. You could change your statement to IF "%M%"=="1" GOTO EOF to eliminate the error, but it still will not give the results you want.
The SET /P statement reads the value from stdin. I assume you have not typed the value UPDATE core, but instead your input was either redirected or piped. You are feeding your script the wrong value.
You should add error handling so that the code does not fall through to :1ST if the input is not 1, 2, or 3.
You can explicitly redirect input to the console for your SET /P statement. That way it will ignore the redirected input or piped input that was provided for the batch script.
<con: SET /P "M=Choose then press ENTER: "
But something seems wrong with your whole design. If you are piping or redirecting input for the script, then it doesn't make sense to present an interactive menu of choices in a loop. What happens if the user never presses 1 to quit? Eventually the piped or redirected input will be exhausted, and then you have problems.