############################################################################
#
#	File:     interpp.icn
#
#	Subject:  Program to interpret Icon programs
#
#	Author:   Jerry Nowlin
#
#	Date:     December 30, 1991
#
############################################################################
#
#   This file is in the public domain.
#
############################################################################
#  
#    This program is kind of like an interactive version of BASIC in that Icon
#  expressions are entered with line numbers and you can resequence them list
#  them etc. and execute all the lines entered.  There is no editor built
#  in.  You have to retype a line to change it.
#
#    Documentation is lacking but there is a "?" help command that lists all
#  the other commands.
#
############################################################################
#
#  See also:  interpe.icn
#
############################################################################

global	WHITE,	# the white space cset
	MFLAG,	# the modified flag
	PRTBL	# the program table

procedure main(arg)
   local line, lno, pline

#	define the needed cset
	WHITE := ' \t\n\f'

#	initialize the program table
	PRTBL := table()

#	initialize the modified flag
	MFLAG := 0

#	get all the input
	writes("Icon> ")
	while line := read() do {

#		scan the input line
		line ? {

#			skip any initial white space
			tab(many(WHITE))

#			check for program lines (they have line numbers)
			if lno := tab(many(&digits)) & tab(many(WHITE)) then {

#				get the program line
				pline := tab(0)

#				store the line in the program table
				PRTBL[numeric(lno)] := pline

#				set the modified flag
				MFLAG +:= 1
			}

#			read command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("read" | "r") then {
				readprog()

#				clear the modified flag
				MFLAG := 0
			}

#			write command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("write" | "w") then {
				writeprog()

#				clear the modified flag
				MFLAG := 0
			}

#			delete command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("delete" | "d") then {
				delprog()

#				set the modified flag
				MFLAG +:= 1
			}

#			sequence command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("sequence" | "s") then {
				seqprog()
			}

#			list command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("list" | "l") then {
				listprog()
			}

#			execute command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("execute" | "e") then {
				execprog()
			}

#			help command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("help" | "h" | "?") then {
				helpprog()
			}

#			quit command
			else if (tab(upto(WHITE)) | tab(0)) ==
				("quit" | "q") then {
				quitprog()
			}

#			invalid syntax input
			else {
				write("Syntax Error: ",line)
				helpprog()
			}
		}
		writes("Icon> ")
	}

end

procedure execprog()
   local runargs, out, prog, line, command

	static	tmpfile

	initial tmpfile := "TMPFILE.icn"

#	get any runtime arguments
	runargs := tab(0)

#	create the temporary Icon file
	(out := open(tmpfile,"w")) |

#	or mention the problem and fail
	(write("I can't open '",tmpfile,"' for writing") & fail)

#	sort the program table
	prog := sort(PRTBL)

#	put the program in the file
	every line := !prog do {
		write(out,line[2])
	}
	close(out)

#	format the command to execute the program
	command := "icont -s " || tmpfile || " -x " || runargs

#	add the command to remove the temporary file
	command ||:= " ; rm -f " || tmpfile

#	execute the command
	system(command)

end

procedure seqprog()
   local begno, incno, prog, lno, l

#	initialize the sequencing numbers
	begno := incno := 10

#	skip any white space
	tab(many(WHITE))

#	get an initial line number
	begno := numeric(tab(many(&digits)))

#	skip any white space
	tab(many(WHITE))

#	get a increment number
	incno := numeric(tab(many(&digits)))

#	sort the program table
	prog := sort(PRTBL)

#	reinitialize it
	PRTBL := table()

#	sequence the program lines starting with begno by incno
	lno := begno
	every l := !prog do {
		PRTBL[lno] := l[2]
		lno +:= incno
	}

end

procedure readprog()
   local readfile, response, in, lno, line

#	get a possible command line file name
	tab(many(WHITE))
	readfile := tab(upto(WHITE) | 0)

#	if there was no file with the command get one
	if /readfile | *readfile = 0 then {
		writes("Read file name: ")
		readfile := read()
	}

#	make sure a modified file has been written
	if MFLAG > 0 then {
		writes("Write before reading over current program? ")
		response := read()
		if any('yY',response) then
			writeprog()
	}

#	initialize the program table
	PRTBL := table()

#	read the program from the read file
	in := open(readfile,"r")
	lno := 10
	every line := !in do {
		PRTBL[lno] := line
		lno +:= 10
	}
	close(in)

#	tell them what you did
	write("Read '",readfile,"'...",*PRTBL," lines")

end

procedure writeprog()
   local writefile, prog, out, l

#	get a possible command line file name
	tab(many(WHITE))
	writefile := tab(upto(WHITE) | 0)

#	if there was no file with the command get one
	if /writefile | *writefile = 0 then {
		writes("Write file name: ")
		writefile := read()
	}

#	sort the program table
	prog := sort(PRTBL)

#	write the program to the write file
	out := open(writefile,"w")
	every l := !prog do {
		write(out,l[2])
	}
	close(out)

#	tell them what you did
	write("Write '",writefile,"'...",*PRTBL," lines")

end

procedure delprog()
   local begno, endno, prog, l, lno

#	initialize the line numbers
	begno := 0
	endno := 99999

#	skip any white space
	tab(many(WHITE))

#	get an initial line number
	begno := endno := numeric(tab(many(&digits)))

#	skip any white space
	tab(many(WHITE))

#	get a final line number
	endno := numeric(tab(many(&digits)))

#	sort the program table
	prog := sort(PRTBL)

#	reinitialize it
	PRTBL := table()

#	delete the program lines between the optional numbers
	every l := !prog do {
		lno := numeric(l[1])
		if (lno < begno) | (lno > endno) then PRTBL[lno] := l[2]
	}

end

procedure listprog()
   local begno, endno, prog, l, lno

#	initialize the line numbers
	begno := 0
	endno := 99999

#	skip any white space
	tab(many(WHITE))

#	get an initial line number
	begno := endno := numeric(tab(many(&digits)))

#	skip any white space
	tab(many(WHITE))

#	get a final line number
	endno := numeric(tab(many(&digits)))

#	sort the program table
	prog := sort(PRTBL)

#	list the program lines between the optional numbers
	every l := !prog do {
		lno := numeric(l[1])
		if (lno >= begno) & (lno <= endno) then
			write(right(lno,5),": ",l[2])
		if lno > endno then break
	}

end

procedure helpprog()

	static helpmsg

#	define the help message
	initial {
		helpmsg := [
		"<<< Icon Expression Syntax >>>",
		"",
		"lineno expression",
		"",
		"<<< Command Summary >>>",
		" (1st character works)",
		"",
		"read [ file ]",
		"write [ file ]",
		"list [ begno [ endno ] ]",
		"delete [ begno [ endno ] ]",
		"sequence [ begno [ increment ] ]",
		"execute [ args ]",
		"quit",
		"help"
		]
	}

#	print it
	every write(!helpmsg)

end

procedure quitprog()
   local response

#	make sure a modified file has been written
	if MFLAG > 0 then {
		writes("Write before quitting? ")
		response := read()
		if any('yY',response) then
			writeprog()
	}

	stop("Goodbye.")

end