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Compiler-Regex.pir
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Compiler-Regex.pir
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# $Id$
=head1 NAME
PAST::Compiler-Regex - Compiler for PAST::Regex nodes
=head1 DESCRIPTION
PAST::Compiler-Regex implements the transformations to convert
PAST::Regex nodes into POST. It's still a part of PAST::Compiler;
we've separated out the regex-specific transformations here for
better code management and debugging.
=head2 Compiler methods
=head3 C<PAST::Regex>
=over 4
=item as_post(PAST::Regex node)
Return the POST representation of the regex AST rooted by C<node>.
=cut
.include 'cclass.pasm'
.namespace ['PAST';'Compiler']
.sub 'as_post' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.param pmc options :slurpy :named
.local pmc ops
ops = self.'post_new'('Ops', 'node'=>node)
.local pmc reghash
reghash = new ['Hash']
.lex '$*REG', reghash
.local string prefix, rname, rtype
prefix = self.'unique'('rx')
concat prefix, '_'
$P0 = split ' ', 'tgt string pos int off int eos int rep int cur pmc act pmc'
$P1 = iter $P0
iter_loop:
unless $P1 goto iter_done
rname = shift $P1
rtype = shift $P1
$S1 = concat prefix, rname
reghash[rname] = $S1
$S2 = concat '.local ', rtype
ops.'push_pirop'($S2, $S1)
goto iter_loop
iter_done:
.local pmc faillabel
$S0 = concat prefix, 'fail'
faillabel = self.'post_new'('Label', 'result'=>$S0)
reghash['fail'] = faillabel
.local string cur, rep, pos, tgt, off, eos
(cur, rep, pos, tgt, off, eos) = self.'!rxregs'('cur rep pos tgt off eos')
.local pmc startlabel, donelabel
$S0 = concat prefix, 'start'
startlabel = self.'post_new'('Label', 'result'=>$S0)
$S0 = concat prefix, 'done'
donelabel = self.'post_new'('Label', 'result'=>$S0)
$S0 = concat '(', cur
concat $S0, ', '
concat $S0, pos
concat $S0, ', '
concat $S0, tgt
concat $S0, ')'
ops.'push_pirop'('callmethod', '"!cursor_start"', 'self', 'result'=>$S0)
ops.'push_pirop'('length', eos, tgt, 'result'=>eos)
# On Parrot, indexing into variable-width encoded strings
# (such as utf8) becomes much more expensive as we move
# farther away from the beginning of the string (via calls
# to utf8_skip_forward). For regexes that are starting a match
# at a position other than the beginning of the string (e.g.,
# a subrule call), we can save a lot of useless scanning work
# in utf8_skip_forward by removing the first C<off = pos-1>
# characters from the target and then performing all indexed
# operations on the resulting target relative to C<off>.
ops.'push_pirop'('set', off, 0)
ops.'push_pirop'('lt', pos, 2, startlabel)
ops.'push_pirop'('sub', off, pos, 1, 'result'=>off)
ops.'push_pirop'('substr', tgt, tgt, off, 'result'=>tgt)
ops.'push'(startlabel)
$P0 = self.'post_regex'(node)
ops.'push'($P0)
ops.'push'(faillabel)
self.'!cursorop'(ops, '!mark_fail', 3, rep, pos, '$I10', 0)
ops.'push_pirop'('lt', pos, -1, donelabel)
ops.'push_pirop'('eq', pos, -1, faillabel)
ops.'push_pirop'('jump', '$I10')
ops.'push'(donelabel)
ops.'push_pirop'('return', cur)
ops.'push_pirop'('goto', donelabel)
.return (ops)
.end
=item !cursorop(ops, func, retelems, arg :slurpy)
Helper function to push POST nodes onto C<ops> that perform C<func>
on the regex's current cursor. By default this ends up being a method
call on the cursor, but some values of C<func> can result in inlined
code to perform the equivalent operation without using the method call.
The C<retelems> argument is the number of elements in C<arg> that
represent return values from the function; any remaining elements in arg
are passed to the function as input arguments.
=cut
.sub '!cursorop' :method
.param pmc ops
.param string func
.param int retelems
.param pmc args :slurpy
if retelems < 1 goto result_done
.local pmc retargs
retargs = new ['ResizableStringArray']
$I0 = retelems
retargs_loop:
unless $I0 > 0 goto retargs_done
$S0 = shift args
push retargs, $S0
dec $I0
goto retargs_loop
retargs_done:
.local string result
result = join ', ', retargs
result = concat '(', result
concat result, ')'
result_done:
.local pmc cur
cur = self.'!rxregs'('cur')
$S0 = self.'escape'(func)
$P0 = ops.'push_pirop'('callmethod', $S0, cur, args :flat)
if retelems < 1 goto done
$P0.'result'(result)
done:
.return (ops)
.end
=item !rxregs(keystr)
Helper function -- looks up the current regex register table
in the dynamic scope and returns a slice based on the keys
given in C<keystr>.
=cut
.sub '!rxregs' :method
.param string keystr
.local pmc keys, reghash, vals
keys = split ' ', keystr
reghash = find_dynamic_lex '$*REG'
vals = new ['ResizablePMCArray']
keys_loop:
unless keys goto keys_done
$S0 = shift keys
$P0 = reghash[$S0]
push vals, $P0
goto keys_loop
keys_done:
.return (vals :flat)
.end
=item post_regex(PAST::Regex node)
Return the POST representation of the regex component given by C<node>.
Normally this is handled by redispatching to a method corresponding to
the node's "pasttype" and "backtrack" attributes. If no "pasttype" is
given, then "concat" is assumed.
=cut
.sub 'post_regex' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.param string cur :optional
.param int have_cur :opt_flag
.local string pasttype
pasttype = node.'pasttype'()
if pasttype goto have_pasttype
pasttype = 'concat'
have_pasttype:
$P0 = find_method self, pasttype
$P1 = self.$P0(node)
unless have_cur goto done
$S0 = $P1.'result'()
if $S0 == cur goto done
$P1 = self.'coerce'($P1, cur)
done:
.return ($P1)
.end
.sub 'post_regex' :method :multi(_, _)
.param pmc node
.param string cur :optional
.param int have_cur :opt_flag
$P0 = self.'as_post'(node)
unless have_cur goto done
$P0 = self.'coerce'($P0, cur)
done:
.return ($P0)
.end
=item alt(PAST::Regex node)
=cut
.sub 'alt' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.local pmc cur, pos
(cur, pos) = self.'!rxregs'('cur pos')
.local string name
name = self.'unique'('alt')
concat name, '_'
.local pmc ops, iter
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
iter = node.'iterator'()
unless iter goto done
.local int acount
.local pmc alabel, endlabel
acount = 0
$S0 = acount
$S0 = concat name, $S0
alabel = self.'post_new'('Label', 'result'=>$S0)
$S0 = concat name, 'end'
endlabel = self.'post_new'('Label', 'result'=>$S0)
iter_loop:
ops.'push'(alabel)
.local pmc apast, apost
apast = shift iter
apost = self.'post_regex'(apast, cur)
unless iter goto iter_done
inc acount
$S0 = acount
$S0 = concat name, $S0
alabel = self.'post_new'('Label', 'result'=>$S0)
ops.'push_pirop'('set_addr', '$I10', alabel)
self.'!cursorop'(ops, '!mark_push', 0, 0, pos, '$I10')
ops.'push'(apost)
ops.'push_pirop'('goto', endlabel)
goto iter_loop
iter_done:
ops.'push'(apost)
ops.'push'(endlabel)
done:
.return (ops)
.end
=item alt_longest(PAST::Regex node)
Same as 'alt' above, but use declarative/LTM semantics.
(Currently we cheat and just use 'alt' above.)
=cut
.sub 'alt_longest' :method
.param pmc node
.tailcall self.'alt'(node)
.end
=item anchor(PAST::Regex node)
Match various anchor points, including ^, ^^, $, $$.
=cut
.sub 'anchor' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.local pmc cur, tgt, pos, off, eos, fail, ops
(cur, tgt, pos, off, eos, fail) = self.'!rxregs'('cur tgt pos off eos fail')
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
.local string subtype
subtype = node.'subtype'()
ops.'push_pirop'('inline', subtype, 'inline'=>' # rxanchor %0')
if subtype == 'bos' goto anchor_bos
if subtype == 'eos' goto anchor_eos
if subtype == 'lwb' goto anchor_lwb
if subtype == 'rwb' goto anchor_rwb
.local pmc donelabel
$S0 = self.'unique'('rxanchor')
concat $S0, '_done'
donelabel = self.'post_new'('Label', 'result'=>$S0)
if subtype == 'bol' goto anchor_bol
if subtype == 'eol' goto anchor_eol
self.'panic'('Unrecognized subtype "', subtype, '" in PAST::Regex anchor node')
anchor_bos:
ops.'push_pirop'('ne', pos, 0, fail)
goto done
anchor_eos:
ops.'push_pirop'('ne', pos, eos, fail)
goto done
anchor_bol:
ops.'push_pirop'('eq', pos, 0, donelabel)
ops.'push_pirop'('ge', pos, eos, fail)
ops.'push_pirop'('sub', '$I10', pos, off)
ops.'push_pirop'('dec', '$I10')
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_NEWLINE, tgt, '$I10')
ops.'push_pirop'('eq', '$I11', 0, fail)
ops.'push'(donelabel)
goto done
anchor_eol:
ops.'push_pirop'('sub', '$I10', pos, off)
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_NEWLINE, tgt, '$I10')
ops.'push_pirop'('ne', '$I11', 0, donelabel)
ops.'push_pirop'('ne', pos, eos, fail)
ops.'push_pirop'('eq', pos, 0, donelabel)
ops.'push_pirop'('dec', '$I10')
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_NEWLINE, tgt, '$I10')
ops.'push_pirop'('ne', '$I11', 0, fail)
ops.'push'(donelabel)
goto done
anchor_lwb:
ops.'push_pirop'('ge', pos, eos, fail)
ops.'push_pirop'('sub', '$I10', pos, off)
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_WORD, tgt, '$I10')
ops.'push_pirop'('eq', '$I11', 0, fail)
ops.'push_pirop'('dec', '$I10')
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_WORD, tgt, '$I10')
ops.'push_pirop'('ne', '$I11', 0, fail)
goto done
anchor_rwb:
ops.'push_pirop'('le', pos, 0, fail)
ops.'push_pirop'('sub', '$I10', pos, off)
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_WORD, tgt, '$I10')
ops.'push_pirop'('ne', '$I11', 0, fail)
ops.'push_pirop'('dec', '$I10')
ops.'push_pirop'('is_cclass', '$I11', .CCLASS_WORD, tgt, '$I10')
ops.'push_pirop'('eq', '$I11', 0, fail)
goto done
done:
.return (ops)
.end
=item charclass(PAST::Regex node)
Match something in a character class, such as \w, \d, \s, dot, etc.
=cut
.sub 'charclass' :method
.param pmc node
.local pmc cur, tgt, pos, off, eos, fail, ops
(cur, tgt, pos, off, eos, fail) = self.'!rxregs'('cur tgt pos off eos fail')
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
.local string subtype
subtype = node.'subtype'()
ops.'push_pirop'('inline', subtype, 'inline'=>' # rx charclass %0')
ops.'push_pirop'('ge', pos, eos, fail)
if subtype == '.' goto charclass_done
.local pmc cctest
$S0 = downcase subtype
$I0 = iseq subtype, $S0
cctest = self.'??!!'($I0, 'eq', 'ne')
if $S0 == 'd' goto cclass_digit
if $S0 == 's' goto cclass_space
if $S0 == 'w' goto cclass_word
if $S0 == 'n' goto cclass_newline
if $S0 == 'nl' goto cclass_newline
self.'panic'('Unrecognized subtype "', subtype, '" in PAST::Regex charclass node')
cclass_digit:
.local int cclass
cclass = .CCLASS_NUMERIC
goto cclass_done
cclass_space:
cclass = .CCLASS_WHITESPACE
goto cclass_done
cclass_word:
cclass = .CCLASS_WORD
goto cclass_done
cclass_newline:
cclass = .CCLASS_NEWLINE
cclass_done:
ops.'push_pirop'('sub', '$I10', pos, off)
ops.'push_pirop'('is_cclass', '$I11', cclass, tgt, '$I10')
ops.'push_pirop'(cctest, '$I11', 0, fail)
unless $S0 == 'nl' goto charclass_done
# handle logical newline here
ops.'push_pirop'('substr', '$S10', tgt, '$I10', 2)
ops.'push_pirop'('iseq', '$I11', '$S10', '"\r\n"')
ops.'push_pirop'('add', pos, '$I11')
charclass_done:
ops.'push_pirop'('inc', pos)
.return (ops)
.end
=item concat(PAST::Regex node)
Handle a concatenation of regexes.
=cut
.sub 'concat' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.local pmc cur, ops, iter
(cur) = self.'!rxregs'('cur')
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
iter = node.'iterator'()
iter_loop:
unless iter goto iter_done
.local pmc cpast, cpost
cpast = shift iter
cpost = self.'post_regex'(cpast, cur)
ops.'push'(cpost)
goto iter_loop
iter_done:
.return (ops)
.end
=item enumcharlist(PAST::Regex node)
Generate POST for matching a character from an enumerated
character list.
=cut
.sub 'enumcharlist' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.local pmc cur, tgt, pos, off, eos, fail, ops
(cur, tgt, pos, off, eos, fail) = self.'!rxregs'('cur tgt pos off eos fail')
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
.local string charlist
charlist = node[0]
charlist = self.'escape'(charlist)
.local pmc negate, testop
negate = node.'negate'()
testop = self.'??!!'(negate, 'ge', 'lt')
ops.'push_pirop'('inline', negate, 'inline'=>' # rx enumcharlist negate=%0')
ops.'push_pirop'('ge', pos, eos, fail)
ops.'push_pirop'('sub', '$I10', pos, off)
ops.'push_pirop'('substr', '$S10', tgt, '$I10', 1)
ops.'push_pirop'('index', '$I11', charlist, '$S10')
ops.'push_pirop'(testop, '$I11', 0, fail)
ops.'push_pirop'('inc', pos)
.return (ops)
.end
=item literal(PAST::Regex node)
Generate POST for matching a literal string provided as the
second child of this node.
=cut
.sub 'literal' :method :multi(_,['PAST';'Regex'])
.param pmc node
.local pmc cur, pos, eos, tgt, fail, off
(cur, pos, eos, tgt, fail, off) = self.'!rxregs'('cur pos eos tgt fail off')
.local pmc ops, cpast, cpost, lpast, lpost
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
# literal to be matched is our first child
lpast = node[0]
lpost = self.'as_post'(lpast, 'rtype'=>'~')
$S0 = lpost.'result'()
ops.'push_pirop'('inline', $S0, 'inline'=>' # rx literal %0')
ops.'push'(lpost)
# compute constant literal length at compile time
.local string litlen
$I0 = isa lpast, ['String']
if $I0 goto literal_string
litlen = '$I10'
ops.'push_pirop'('length', '$I10', lpost)
goto have_litlen
literal_string:
$S0 = lpast
$I0 = length $S0
litlen = $I0
if $I0 > 0 goto have_litlen
.return (cpost)
have_litlen:
# fail if there aren't enough characters left in string
ops.'push_pirop'('add', '$I11', pos, litlen)
ops.'push_pirop'('gt', '$I11', eos, fail)
# compute string to be matched and fail if mismatch
ops.'push_pirop'('sub', '$I11', pos, off)
ops.'push_pirop'('substr', '$S10', tgt, '$I11', litlen)
ops.'push_pirop'('ne', '$S10', lpost, fail)
# increase position by literal length and move on
ops.'push_pirop'('add', pos, litlen)
.return (ops)
.end
=item pass(PAST::Regex node)
=cut
.sub 'pass' :method :multi(_,['PAST';'Regex'])
.param pmc node
.local pmc ops
ops = self.'reduce'(node)
ops.'push_pirop'('inline', 'inline'=>' # rx pass')
.local string cur, pos
cur = ops.'result'()
pos = self.'!rxregs'('pos')
$S0 = concat pos, " :named('pos')"
self.'!cursorop'(ops, '!matchify', 0, $S0)
ops.'push_pirop'('yield', cur)
.return (ops)
.end
=item reduce
=cut
.sub 'reduce' :method :multi(_,['PAST';'Regex'])
.param pmc node
.local pmc cur, act
(cur, act) = self.'!rxregs'('cur act')
.local pmc ops, name, redlabel
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
$P0 = node.'name'()
unless $P0 goto done
name = self.'as_post'($P0, 'rtype'=>'~')
redlabel = self.'post_new'('Label', 'name'=>'rxreduce_')
ops.'push_pirop'('inline', name, 'inline'=>' # rx reduce %0')
ops.'push'(name)
ops.'push_pirop'('if_null', act, redlabel)
ops.'push_pirop'('find_method', '$P10', act, name)
ops.'push_pirop'('if_null', '$P10', redlabel)
self.'!cursorop'(ops, '!MATCH', 1, '$P11')
ops.'push_pirop'('callmethod', '$P10', act, '$P11')
ops.'push'(redlabel)
done:
.return (ops)
.end
=item quant(PAST::Regex node)
=cut
.sub 'quant' :method :multi(_,['PAST';'Regex'])
.param pmc node
.local string backtrack
backtrack = node.'backtrack'()
if backtrack goto have_backtrack
backtrack = 'g'
have_backtrack:
.local int min, max
min = node.'min'()
$P0 = node.'max'()
max = $P0
$I0 = defined $P0
if $I0 goto have_max
max = -1 # -1 represents Inf
have_max:
.local pmc cur, pos, rep, fail
(cur, pos, rep, fail) = self.'!rxregs'('cur pos rep fail')
.local string qname
.local pmc ops, q1label, q2label, btreg, cpost
$S0 = concat 'rxquant', backtrack
qname = self.'unique'($S0)
ops = self.'post_new'('Ops', 'node'=>node)
$S0 = concat qname, '_loop'
q1label = self.'post_new'('Label', 'result'=>$S0)
$S0 = concat qname, '_done'
q2label = self.'post_new'('Label', 'result'=>$S0)
cpost = self.'concat'(node)
.local pmc seppast, seppost
null seppost
seppast = node.'sep'()
unless seppast goto have_seppost
seppost = self.'post_regex'(seppast)
have_seppost:
$S0 = max
.local int needrep
$I0 = isgt min, 1
$I1 = isgt max, 1
needrep = or $I0, $I1
unless max < 0 goto have_s0
$S0 = '*'
have_s0:
ops.'push_pirop'('inline', qname, min, $S0, 'inline'=>' # rx %0 ** %1..%2')
if backtrack == 'f' goto frugal
greedy:
btreg = self.'uniquereg'('I')
ops.'push_pirop'('set_addr', btreg, q2label)
.local int needmark
.local string peekcut
needmark = needrep
peekcut = '!mark_peek'
if backtrack != 'r' goto greedy_1
needmark = 1
peekcut = '!mark_commit'
greedy_1:
if min == 0 goto greedy_2
unless needmark goto greedy_loop
self.'!cursorop'(ops, '!mark_push', 0, 0, -1, btreg)
goto greedy_loop
greedy_2:
self.'!cursorop'(ops, '!mark_push', 0, 0, pos, btreg)
greedy_loop:
ops.'push'(q1label)
ops.'push'(cpost)
unless needmark goto greedy_3
self.'!cursorop'(ops, peekcut, 1, rep, btreg)
unless needrep goto greedy_3
ops.'push_pirop'('inc', rep)
greedy_3:
unless max > 1 goto greedy_4
ops.'push_pirop'('ge', rep, max, q2label)
greedy_4:
unless max != 1 goto greedy_5
self.'!cursorop'(ops, '!mark_push', 0, rep, pos, btreg)
if null seppost goto greedy_4a
ops.'push'(seppost)
greedy_4a:
ops.'push_pirop'('goto', q1label)
greedy_5:
ops.'push'(q2label)
unless min > 1 goto greedy_6
ops.'push_pirop'('lt', rep, min, fail)
greedy_6:
.return (ops)
frugal:
.local pmc ireg
ireg = self.'uniquereg'('I')
if min == 0 goto frugal_1
unless needrep goto frugal_0
ops.'push_pirop'('set', rep, 0)
frugal_0:
if null seppost goto frugal_2
.local pmc seplabel
$S0 = concat qname, '_sep'
seplabel = self.'post_new'('Label', 'result'=>$S0)
ops.'push_pirop'('goto', seplabel)
goto frugal_2
frugal_1:
ops.'push_pirop'('set_addr', '$I10', q1label)
self.'!cursorop'(ops, '!mark_push', 0, 0, pos, '$I10')
ops.'push_pirop'('goto', q2label)
frugal_2:
ops.'push'(q1label)
if null seppost goto frugal_2a
ops.'push'(seppost)
ops.'push'(seplabel)
frugal_2a:
unless needrep goto frugal_3
ops.'push_pirop'('set', ireg, rep)
frugal_3:
ops.'push'(cpost)
unless needrep goto frugal_4
ops.'push_pirop'('add', rep, ireg, 1)
frugal_4:
unless min > 1 goto frugal_5
ops.'push_pirop'('lt', rep, min, q1label)
frugal_5:
unless max > 1 goto frugal_6
ops.'push_pirop'('ge', rep, max, q2label)
frugal_6:
unless max != 1 goto frugal_7
ops.'push_pirop'('set_addr', '$I10', q1label)
self.'!cursorop'(ops, '!mark_push', 0, ireg, pos, '$I10')
frugal_7:
ops.'push'(q2label)
.return (ops)
.end
=item scan(POST::Regex)
Code for initial regex scan.
=cut
.sub 'scan' :method :multi(_, ['PAST';'Regex'])
.param pmc node
.local pmc cur, pos, eos, ops
(cur, pos, eos) = self.'!rxregs'('cur pos eos')
ops = self.'post_new'('Ops', 'node'=>node, 'result'=>cur)
.local pmc looplabel, donelabel
$S0 = self.'unique'('rxscan')
$S1 = concat $S0, '_loop'
looplabel = self.'post_new'('Label', 'result'=>$S1)
$S1 = concat $S0, '_done'
donelabel = self.'post_new'('Label', 'result'=>$S1)
ops.'push_pirop'('ge', pos, 0, donelabel)
ops.'push'(looplabel)
self.'!cursorop'(ops, 'from', 1, '$P10')
ops.'push_pirop'('inc', '$P10')
ops.'push_pirop'('set', pos, '$P10')
ops.'push_pirop'('ge', pos, eos, donelabel)
ops.'push_pirop'('set_addr', '$I10', looplabel)
self.'!cursorop'(ops, '!mark_push', 0, 0, pos, '$I10')
ops.'push'(donelabel)
.return (ops)
.end
=item post_new(type, args :slurpy, options :slurpy :named)
Helper method to create a new POST node of C<type>.
=cut
.sub 'post_new' :method
.param string type
.param pmc args :slurpy
.param pmc options :slurpy :named
$P0 = get_hll_global ['POST'], type
.tailcall $P0.'new'(args :flat, options :flat :named)
.end
=item ??!!(test, trueval, falseval)
Helper method to perform ternary operation -- returns C<trueval>
if C<test> is true, C<falseval> otherwise.
=cut
.sub '??!!' :method
.param pmc test
.param pmc trueval
.param pmc falseval
if test goto true
.return (falseval)
true:
.return (trueval)
.end
=back
=head1 AUTHOR
Patrick Michaud <pmichaud@pobox.com> is the author and maintainer.
=head1 COPYRIGHT
Copyright (C) 2009, Patrick R. Michaud.
=cut
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