Regex help
My Regex-fu has failed me ... I don't do much heavy duty data munging
any more and apparently the skills of The Old Ways[tm] have forsaken me.
Or at least - I'm now lazy. After spending 5 minutes trying to figure it
out I just mailed the list.
Plus my copy of Mr Friedl's book is currently packed up in a box
awaiting lugging to my new place.
Anyway, the problem I have is that I'm trying to parse a line of
DCPU16[*] assembler. It's possible the issue lies in trying to parse
using regexps but that's a debate for another day. Anyway this regex
my ($label, $op, $a, $b) = $line =~ m!
^
(?::(\w+) \s+)? # optional label
([A-Za-z]+)\s+ # opcode
([^,\s]+) (?:, \s+ # operand
([^,\s]+))?\s* # optional second opcode
$
!x;
currently parses lines such as
:label SET A, 2
JSR label
SET [0x1000+I], [PC]
just fine. However I'm trying to add a new opcode DAT which can take any
number of operands
DAT 0x170, "Hello ", 0x2e1 (, )
and it fails there.
Running this
my ($label, $op, @operands) = $line =~ m!
^
(?::(\w+) \s+)? # optional label
([A-Za-z]+)\s+ # opcode
([^,\s]+) (?:, \s+ # operand
([^,\s]+))*\s* # optional second opcode
$
!x;
on
FOO A, B, C
results in @operands being ('A', 'C');
Sp, rather than attempting to actually work this out myself, I'm asking
the lazyweb.
Cheers!
Simon
[*] Notch (Of Minecraft fame)'s virtual CPU for his new game. I've been
noodling with a Assembler/Disassembler/Emulator
Re: Regex help
On 20 Apr 2012, at 16:29, Simon Wistow wrote: >^ >(?::(\w+) \s+)? # optional label >([A-Za-z]+)\s+ # opcode >([^,\s]+) (?:, \s+ # operand >([^,\s]+))*\s* # optional second opcode You don't get a distinct capture for each application of the pattern - so the third operand overwrites the second. Maybe put the * inside the parens and then parse the list of operands in a second step? -- Andy Armstrong, Hexten
Re: Regex help
Simon Wistow writes:
> my ($label, $op, @operands) = $line =~ m!
> ^
> (?::(\w+) \s+)? # optional label
> ([A-Za-z]+)\s+ # opcode
> ([^,\s]+) (?:, \s+ # operand
> ([^,\s]+))*\s* # optional second opcode
> $
> !x;
You could use (?{ push @operands, $^N}) after the operand capture
groups, rather than relying on the returned captures.
--
ilmari
"A disappointingly low fraction of the human race is,
at any given time, on fire." - Stig Sandbeck Mathisen
Re: Regex help
Or use a proper parser? On 20 Apr 2012, at 16:41, Andy Armstrong wrote: > On 20 Apr 2012, at 16:29, Simon Wistow wrote: >> ^ >> (?::(\w+) \s+)? # optional label >> ([A-Za-z]+)\s+ # opcode >> ([^,\s]+) (?:, \s+ # operand >> ([^,\s]+))*\s* # optional second opcode > > You don't get a distinct capture for each application of the pattern - so the > third operand overwrites the second. Maybe put the * inside the parens and > then parse the list of operands in a second step? > > -- > Andy Armstrong, Hexten > > > >
Re: Regex help
How about a parser using Regexp? Parser::MGC? You can implement a proper parser, or just a few staged regexp, or anything in-between. -Original Message- From: Dave Hodgkinson Sender: london.pm-boun...@london.pm.org Date: Fri, 20 Apr 2012 17:15:29 To: London.pm Perl M\[ou\]ngers Reply-To: "London.pm Perl M\[ou\]ngers" Subject: Re: Regex help Or use a proper parser? On 20 Apr 2012, at 16:41, Andy Armstrong wrote: > On 20 Apr 2012, at 16:29, Simon Wistow wrote: >> ^ >> (?::(\w+) \s+)? # optional label >> ([A-Za-z]+)\s+ # opcode >> ([^,\s]+) (?:, \s+ # operand >> ([^,\s]+))*\s* # optional second opcode > > You don't get a distinct capture for each application of the pattern - so the > third operand overwrites the second. Maybe put the * inside the parens and > then parse the list of operands in a second step? > > -- > Andy Armstrong, Hexten > > > >
Re: Regex help
> "Dave" == Dave Hodgkinson writes: Dave> Or use a proper parser? What's the state of "Perl6 grammars in Perl5" at the moment? -- Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095 http://www.stonehenge.com/merlyn/> Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc. See http://methodsandmessages.posterous.com/ for Smalltalk discussion
Re: Regex help
On Fri, Apr 20, 2012 at 08:37:42PM +, Anthony Lucas said: > > How about a parser using Regexp? Parser::MGC? > > You can implement a proper parser, or just a few staged regexp, or anything > in-between. I ended up just doing this my ($label, $op, $operands) = $line =~ m! ^ (?::(\w+) \s+)? # optional label ([A-Za-z]+)\s+ # opcode (.+) \s* # operands $ !x; # TODO this won't cope with commas inside quotes # e.g DAT 0x20, "hello, goodbye", 0x10 my @operands = split /\s*,\s*/, ($operands || ""); at some point I should properly parse the assembler file using a grammar but since the spec is still in flux I'll go with my bodged parser for now. If any of you care you can see the code here http://search.cpan.org/~simonw/CPU-Emulator-DCPU16-0.3/ https://github.com/simonwistow/CPU-Emulator-DCPU16 Simon
Re: Regex help
On 04/20/2012 11:29 AM, Simon Wistow wrote:
just fine. However I'm trying to add a new opcode DAT which can take any
number of operands
DAT 0x170, "Hello ", 0x2e1 (, )
and it fails there.
Running this
my ($label, $op, @operands) = $line =~ m!
^
(?::(\w+) \s+)? # optional label
([A-Za-z]+)\s+ # opcode
([^,\s]+) (?:, \s+ # operand
([^,\s]+))*\s* # optional second opcode
$
!x;
on
FOO A, B, C
results in @operands being ('A', 'C');
i would take a simpler approach. just grab the whole optional string
after the opcode (all the operands) and then split that on comma (and
optional trailing whitespace). why try to do it all in one regex when
that is simpler and should work fine. so your last regex component would
be something like \s*(.+)? or \s*(.*)
uri
Re: Regex help
On 04/20/2012 05:23 PM, Simon Wistow wrote: On Fri, Apr 20, 2012 at 08:37:42PM +, Anthony Lucas said: How about a parser using Regexp? Parser::MGC? You can implement a proper parser, or just a few staged regexp, or anything in-between. I ended up just doing this my ($label, $op, $operands) = $line =~ m! ^ (?::(\w+) \s+)? # optional label ([A-Za-z]+)\s+ # opcode (.+) \s* # operands $ !x; # TODO this won't cope with commas inside quotes # e.g DAT 0x20, "hello, goodbye", 0x10 my @operands = split /\s*,\s*/, ($operands || ""); and that is exactly what i suggested in another post (haven't seen it hit the list yet). :) you can use text::balanced to handle quoted strings. uri
Re: Regex help
On Fri, Apr 20, 2012 at 10:23:36PM +0100, Simon Wistow wrote: > at some point I should properly parse the assembler file using a grammar > but since the spec is still in flux I'll go with my bodged parser for So there's still a chance it will converge onto the VAX instruction set? Nicholas Clark
Re: Regex help
($label, $opcode) = m/^\s*
(?::(\w+)\s+)? # label
([A-Za-z]+)\s+ # opcode
(?:([^,\s]+)(?{push(@operands, $^N)}),?\s*)* # operands
$/x;
Torsten
Re: Regex help
On 21 Apr 2012, at 19:13, Torsten Knorr wrote:
> ($label, $opcode) = m/^\s*
>(?::(\w+)\s+)? # label
>([A-Za-z]+)\s+ # opcode
>(?:([^,\s]+)(?{push(@operands, $^N)}),?\s*)* # operands
>$/x;
~~~NO CARRIER
Your modem cable is loose.
Re: Regex help
On Fri, Apr 20, 2012 at 10:23:36PM +0100, Simon Wistow wrote: > # TODO this won't cope with commas inside quotes > # e.g DAT 0x20, "hello, goodbye", 0x10 > my @operands = split /\s*,\s*/, ($operands || ""); Text::CSV_XS is your special friend, if you can rely on the operand list being reasonably well-formed. Alternatively you might want to take a look at CPU::Z80::Assembler. Paulo Custodio ripped out my crappy regex-based parser and replaced it with one that doesn't suck, so you may be able to re-use bits of that. The DEFM etc pseudo-instructions take arbitrarily long lists of args. -- David Cantrell | top google result for "topless karaoke murders" If you can't imagine how I do something, it's because I have a better imagination than you
