ref: 420aa87291660b3452f42d637227b157dbf86846
dir: /lib/regex/interp.myr/
use std
use "types"
pkg regex =
/* regex execution */
const exec : (re : regex#, str : byte[:] -> std.option(byte[:][:]))
const search : (re : regex#, str : byte[:] -> std.option(byte[:][:]))
/* regex execution returning indexes */
const iexec : (re : regex#, str : byte[:] -> std.option((std.size, std.size)[:]))
const isearch : (re : regex#, str : byte[:] -> std.option((std.size, std.size)[:]))
/* substitution */
const sub : (re : regex#, str : byte[:], subst : byte[:][:] -> std.option(byte[:]))
const sbsub : (sb : std.strbuf#, re : regex#, str : byte[:], subst : byte[:][:] -> bool)
const suball : (re : regex#, str : byte[:], subst : byte[:][:] -> byte[:])
const sbsuball : (sb : std.strbuf#, re : regex#, str : byte[:], subst : byte[:][:] -> void)
const matchfree : (pat : byte[:][:] -> void)
;;
/* Ugly: for performance. std.option() should be used instead when unions get faster. */
const Zthr = (0 : rethread#)
const Maxfree = 128
const matchfree = {m
std.slfree(m)
}
const exec = {re, str
-> getmatches(re, run(re, str, 0, true))
}
const iexec = {re, str
-> getidxmatches(re, run(re, str, 0, true))
}
const search = {re, str
var thr = Zthr
for var i = 0; i < str.len; i++
thr = run(re, str[i:], 0, false)
if thr != Zthr
break
;;
;;
-> getmatches(re, thr)
}
const isearch = {re, str
var thr = Zthr
for var i = 0; i < str.len; i++
thr = run(re, str[i:], 0, false)
if thr != Zthr
break
;;
;;
-> getidxmatches(re, thr)
}
const sub = {re, str, subst
var sb
sb = std.mksb()
if sbsub(sb, re, str, subst)
-> `std.Some std.sbfin(sb)
;;
-> `std.None
}
const sbsub = {sb, re, str, subst
std.assert(re.nmatch == subst.len + 1, "substitution length does not match capture count")
-> dosubst(sb, re, run(re, str, 0, true), str, subst)
}
const suball = {re, str, subst
var sb
sb = std.mksb()
sbsuball(sb, re, str, subst)
-> std.sbfin(sb)
}
const sbsuball = {sb, re, str, subst
var thr, len, i
std.assert(re.nmatch == subst.len + 1, "substitution length does not match capture count")
i = 0
while i < str.len
thr = run(re, str[i:], 0, false)
if thr == Zthr
std.sbputb(sb, str[i])
i++
else
len = thr.mgroup[0][1]
dosubst(sb, re, thr, str[i:len + i], subst)
i += len
;;
cleanup(re, thr)
;;
}
const dosubst = {sb, re, thr, str, subst
var off
if thr == Zthr
-> false
;;
off = 0
for var i = 1; i < re.nmatch; i++
if thr.mgroup[i][0] != -1 && thr.mgroup[i][1] != -1
std.sbputs(sb, str[off:thr.mgroup[i][0]])
std.sbputs(sb, subst[i - 1])
off = thr.mgroup[i][1]
;;
;;
std.sbputs(sb, str[off:])
-> true
}
const cleanup = {re, result
lfree(re.runq)
lfree(re.expired)
lfree(re.free)
std.free(result)
re.runq = Zthr
re.expired = Zthr
re.free = Zthr
re.nfree = 0
re.nthr = 0
}
const lfree = {thr
for var next = thr; thr != Zthr; thr = next
next = thr.next
std.free(thr)
;;
}
const getmatches = {re, thr
var ret, i
if thr == Zthr
-> `std.None
;;
i = 0
ret = std.slalloc(re.nmatch)
for [lo, hi] : thr.mgroup[:re.nmatch]
if lo != -1 && hi != -1
ret[i] = re.str[lo : hi]
;;
i++
;;
cleanup(re, thr)
-> `std.Some ret
}
const getidxmatches = {re, thr
var ret
if thr == Zthr
-> `std.None
;;
ret = std.slalloc(re.nmatch)
for var i = 0; i < re.nmatch; i++
ret[i] = (thr.mgroup[i][0], thr.mgroup[i][1])
;;
cleanup(re, thr)
-> `std.Some ret
}
/*
* Run manages the virtual machine state, and schedules the
* regex threads. Each linear match runs in its own thread.
* When a new thread is created, it is carefully scheduled
* after the current thread, to ensure that match order is
* preserved.
*/
const run = {re, str, idx, wholestr
var bestmatch
var consumed
var states
var thr
var ip
re.str = str
re.strp = 0
re.nexttid = 0
bestmatch = Zthr
states = std.mkbs()
re.runq = mkthread(re, 0)
if re.debug
/*
If we're in debug mode, then we keep
the traces around, so we can show them
to the user. To avoid leaking, we need
to free the traces from the last run
when we start a new one.
*/
for bs : re.traces
std.bsfree(bs)
;;
std.slfree(re.traces)
re.traces = [][:]
std.slpush(&re.traces, std.mkbs())
;;
for var i = 0; i < re.nmatch; i++
re.runq.mgroup[i][0] = -1
re.runq.mgroup[i][1] = -1
;;
while re.nthr > 0
while re.runq != Zthr
if re.trace
std.put("switch\n")
;;
thr = re.runq
re.runq = thr.next
ip = thr.ip
/*
Stepping continues until the first
non-consuming operator is seen. This
keeps all the threads in lockstep,
which means that when a match is
encountered, we know all the other
threads have seen what they need
to, and we can terminate them.
*/
consumed = step(re, thr, -1)
while !consumed
consumed = step(re, thr, ip)
;;
/*
* Because threads have no memory,
* their ip (and current input
* character, which is the same
* thanks to the above mentioned
* lockstep) uniquely identify them.
* As a result, if we have two
* threads with the same ip, one of
* them can be culled.
*/
if std.bshas(states, thr.ip)
die(re, thr)
;;
if thr.dead
thrfree(re, thr)
elif thr.matched
if bestmatch != Zthr
thrfree(re, bestmatch)
;;
if re.strp == re.str.len
bestmatch = thr
goto done
elif !wholestr
bestmatch = thr
else
thrfree(re, thr)
;;
elif !thr.matched
std.bsput(states, thr.ip)
if re.expired == Zthr
re.expired = thr
;;
if re.expiredtail != Zthr
re.expiredtail.next = thr
;;
re.expiredtail = thr
thr.next = Zthr
;;
;;
std.bsclear(states)
re.runq = re.expired
re.expired = Zthr
re.expiredtail = Zthr
re.strp++
;;
:done
std.bsfree(states)
-> bestmatch
}
/*
* Step executes a single step of the compiled regex.
*
* Operations fall into two overall categories. Consuming
* operators advance the match, and nonconsuming operators
* change the state of the regex virtual machine.
*
* Consuming operators are simple: They check if the current
* character matches a criteria, and then advance the regex.
*
* Nonconsuming operators can do one of several things. They
* can fork the vm, record a successful match, or mark a
* thread as a failure.
*
* A thread continues to run forward until a consuming
* opcode is encountered, after which it must switch.
* This is in order to keep all threads in lockstep
* operating over the same characters, and finishing
* at the same time.
*/
const step = {re, thr, curip
var str, nthr, inst
str = re.str
inst = re.code[thr.ip]
if re.trace
itrace(re, thr, re.prog[thr.ip])
;;
if re.debug
std.bsput(re.traces[thr.tid], thr.ip)
;;
match inst & 0xf
/* Consuming opcodes */
| OpRange:
var lo = (inst >> 4 : byte)
var hi = (inst >> 16 : byte)
if !within(re, str) || lo > str[re.strp] || hi < str[re.strp]
die(re, thr)
else
thr.ip++
;;
| OpByte:
var b = (inst >> 4 : byte)
if !within(re, str)
die(re, thr)
elif b != str[re.strp]
die(re, thr)
else
thr.ip++
;;
| OpFork:
var lip = ((inst >> 4) & 0x3fffffff : std.size)
var rip = ((inst >> 34) & 0x3fffffff : std.size)
if rip != curip
nthr = mkthread(re, rip)
nthr.next = re.runq
nthr.mgroup = thr.mgroup
re.runq = nthr
;;
if re.debug
std.slpush(&re.traces, std.bsdup(re.traces[thr.tid]))
;;
thr.ip = lip
-> false
/* Non-consuming opcodes. */
| OpJmp:
var ip = (inst >> 4 : std.size)
thr.ip = ip
-> false
| OpMatch:
var id = (inst >> 4 : std.size)
re.lastthr = thr.tid
finish(re, thr)
-> true
| OpLbra:
var m = (inst >> 4 : std.size)
thr.mgroup[m][0] = re.strp
thr.ip++
-> false
| OpRbra:
var m = (inst >> 4 : std.size)
thr.mgroup[m][1] = re.strp
thr.ip++
-> false
| OpBol:
if re.strp == 0 || str[re.strp - 1] == ('\n' : byte)
thr.ip++
-> false
else
die(re, thr)
;;
| OpEol:
if re.strp == str.len || str[re.strp] == ('\n' : byte)
thr.ip++
-> false
else
die(re, thr)
;;
| OpBow:
if iswordchar(str[re.strp:]) && (re.strp == 0 || !iswordchar(prevchar(str, re.strp)))
thr.ip++
-> false
else
die(re, thr)
;;
| OpEow:
if re.strp == str.len && iswordchar(prevchar(str, re.strp))
thr.ip++
-> false
elif re.strp > 0 && !iswordchar(str[re.strp:]) && iswordchar(prevchar(str, re.strp))
thr.ip++
-> false
else
die(re, thr)
;;
| _:
std.die("corrupt regex bytecode")
;;
-> true
}
const die = {re, thr
/*
we can have die called on a thread
multiple times, eg, if it has a bad
range *and* end in a state that another
thread is in. We should only decrement
the number of threads for that once.
*/
if !thr.dead
re.nthr--
;;
re.lastip = thr.ip
re.lastthr = thr.tid
thr.dead = true
}
const finish = {re, thr
thr.matched = true
re.nthr--
}
const mkthread = {re, ip
var thr : rethread#
if re.free != Zthr
thr = re.free
re.free = thr.next
re.nfree--
else
thr = std.alloc()
;;
thr.next = Zthr
thr.ip = ip
thr.tid = re.nexttid++
thr.dead = false
thr.matched = false
re.nthr++
-> thr
}
const thrfree = {re, thr
if re.nfree >= Maxfree
std.free(thr)
else
thr.next = re.free
re.free = thr
re.nfree++
;;
}
const within = {re, str
-> re.strp < str.len
}
const itrace = {re, thr, inst
match inst
| `Ibyte b: std.put("\t{}.{}:\tByte ({})\n", thr.tid, thr.ip, b)
| `Irange (lo, hi): std.put("\t{}.{}:\tRange {}, {}\n", thr.tid, thr.ip, lo, hi)
| `Ilbra m: std.put("\t{}.{}:\tLbra {}\n", thr.tid, thr.ip, m)
| `Irbra m: std.put("\t{}.{}:\tRbra {}\n", thr.tid, thr.ip, m)
/* anchors */
| `Ibol: std.put("\t{}.{}:\tBol\n", thr.tid, thr.ip)
| `Ieol: std.put("\t{}.{}:\tEol\n", thr.tid, thr.ip)
| `Ibow: std.put("\t{}.{}:\tBow\n", thr.tid, thr.ip)
| `Ieow: std.put("\t{}.{}:\tEow\n", thr.tid, thr.ip)
/* control flow */
| `Ifork (l, r): std.put("\t{}.{}:\tFork {}, {}\n", thr.tid, thr.ip, l, r)
| `Ijmp ip: std.put("\t{}.{}:\tJmp {}\n", thr.tid, thr.ip, ip)
| `Imatch m: std.put("\t{}.{}:\tMatch {}\n", thr.tid, thr.ip, m)
;;
}
const prevchar = {s, i
std.assert(i != 0, "prevchar must be called with i >= 1\n")
i--
while i != 0 && s[i] >= 0x80
i--
;;
-> s[i:]
}
const iswordchar = {s
var c
c = std.decode(s)
-> std.isalpha(c) || std.isdigit(c) || c == '_'
}