shithub: mc

ref: a7ba738bca21b54d6cf2bd5cdfe39b00f3d4b350
dir: /interp.myr/

use std

use "types.use"

pkg regex =
	const exec	: (re : regex#, str : byte[:] -> bool)
;;

const exec = {re, str
	var i

	re.str = str
	re.strp = 0
	re.matched = `std.None
	mkthread(re, 0)
	std.put("tid %z, ip %z, strp %z\n", re.thr[0].uid, re.thr[0].ip, re.strp)
	while re.nthr > 0
		for i = 0; i < re.nthr; i++
			std.put("Switch to %i\n", i)
			std.put("tid %z, ip %z, strp %z\n", re.thr[i].uid, re.thr[i].ip, re.strp)
			step(re, i)
		;;
		if re.nthr > 0
			std.put("Step forward\n")
			re.strp++
		;;
	;;
	match re.matched
	`std.Some thr:	-> true;;
	`std.None:	-> false;;
	;;
}

const step = {re, tid
	var thr
	var str

	thr = re.thr[tid]
	str = re.str
	match re.prog[thr.ip]
	/* Char matching. Consume exactly one byte from the string. */
	`Ibyte b:
		if !in(re, str)
			kill(re, tid, "end of string")
		elif b != str[re.strp]
			std.put("re.strp: %i\n", re.strp)
			std.put("\tb: %b (%c), str[re.strp]: %b (%c)\n", b, b castto(char), str[re.strp], str[re.strp] castto(char))
			kill(re, tid, "not right char")
		else
			std.put("matched %b with %b\n", b, str[re.strp])
		;;
		;;
	`Irange (start, end):
		if !in(re, str) || start > str[re.strp] || end < str[re.strp]
			kill(re, tid, "bad range")
		;;
		;;
	`Idot:
		if !in(re, str)
			kill(re, tid, "past end")
		;;
		;;
	/*
	  Control flow. All of these recursively call step() until
	  exactly one byte is consumed from the string.
	 */
	`Ifork	(lip, rip):
		spawn(re, lip)
		jmp(re, tid, rip)
		;;
	`Ijmp ip:
		jmp(re, tid, ip)
		;;
	`Imatch:
		finish(re, tid)
		;;
	;;
	thr.ip++
}

const jmp = {re, tid, ip
	std.put("jmp %z\n", ip)
	re.thr[tid].ip = ip
	step(re, tid)
}

var uid = 0

const mkthread = {re, ip
	var thr : rethread#
	var tid

	std.put("spawn %z\n", re.nthr)
	tid = re.nthr
	if re.nthr >= re.thr.len
		re.thr = std.slgrow(re.thr, std.max(1, re.nthr * 2))
	;;

	thr = std.alloc()
	thr.ip = ip
	thr.uid = uid++

	re.thr[re.nthr] = thr
	re.nthr++
	-> tid
}

const spawn = {re, ip
	step(re, mkthread(re, ip))
}

const kill = {re, tid, msg
	/* 
	   free the dying thread, and shuffle the last
	   thread into the it's place in the thread list
	*/
	std.put("kill %z: %s\n", tid, msg)
	std.free(re.thr[tid])
	re.thr[tid] = re.thr[re.nthr - 1]
	re.nthr--
}

const finish = {re, tid
	std.put("finish\n", tid)
	match re.matched
	`std.Some thr:	std.free(thr);;
	`std.None:	;;
	;;
	re.matched = `std.Some re.thr[tid]
	re.thr[tid] = re.thr[re.nthr - 1]
	re.nthr--
}

const in = {re, str 
	-> re.strp < str.len
}