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############################################################################
#
# File: expander.icn
#
# Subject: Procedures to convert character pattern expressions
#
# Author: Ralph E. Griswold
#
# Date: May 2, 2001
#
############################################################################
#
# This file is in the public domain.
#
############################################################################
#
# pfl2str(pattern) expands pattern-form expressions, which have the form
#
# [<expr><op><expr>]
#
# to the corresponding string.
#
# The value of <op> determines the operation to be performed.
#
# pfl2gxp(pattern) expands pattern-form expressions into generators
# that, when compiled and evaluated, produce the corresponding
# string.
#
# pfl2pwl(pattern) converts pattern-form expressions to Painter's
# weaving language.
#
###########################################################################n
#
# Links: strings, weaving
#
############################################################################
link strings
link weaving
procedure pfl2str(pattern) #: pattern-form to plain string
local result, expr1, expr2, op
static operator, optbl
initial {
operator := '*-!|+,/~:?%<>#`'
optbl := table()
optbl["*"] := repl
optbl["<"] := Upto
optbl[">"] := Downto
optbl["-"] := UpDown
optbl["|"] := Palindrome
# optbl["!"] := Palindroid
optbl["+"] := Block
optbl["~"] := Interleave
optbl["->"] := Extend
optbl[":"] := Template
optbl["?"] := Permute
optbl["%"] := Pbox
optbl["<>"] := UpDown
optbl["><"] := DownUp
optbl["#"] := rotate
optbl["`"] := reverse
optbl[","] := proc("||", 2)
}
result := ""
pattern ? {
while result ||:= tab(upto('[')) do {
move(1)
# expr1 := pfl2str(tab(bal(operator, '[', ']'))) | return error("1", pattern)
expr1 := pfl2str(tab(bal(operator, '[', ']'))) | {
result ||:= pfl2str(tab(bal(']', '[', ']')))
move(1)
next
}
op := tab(many(operator)) | return error("2", pattern)
expr2 := pfl2str(tab(bal(']', '[', ']'))) | return error("3", pattern)
result ||:= \optbl[op](expr1, expr2) | return error("4", pattern)
move(1)
}
if not pos(0) then result ||:= tab(0)
}
return result
end
procedure pfl2pwl(pattern) #: pattern form to Painter expression
local result, i, j, slist, s, expr1, expr2, op, head
static operator, optbl
initial {
operator := '*-!|+,;/~:?%<>#`'
optbl := table()
optbl["*"] := "*"
optbl["<"] := "<"
optbl[">"] := ">"
optbl["-"] := "-"
optbl["|"] := "|"
optbl["!"] := "!" # not supported in PWL
optbl["+"] := "[]"
optbl["->"] := "->"
optbl["~"] := "~"
optbl[":"] := ":"
optbl["?"] := " perm "
optbl["%"] := " pbox "
optbl["<>"] := "<>"
optbl["><"] := "><"
optbl["#"] := "#"
optbl["`"] := "`"
optbl[","] := ","
}
result := ""
pattern ? {
while head := tab(upto('[')) do {
if *head > 0 then result ||:= "," || head
move(1)
expr1 := pfl2pwl(tab(bal(operator, '[', ']'))) | return error()
op := tab(many(operator)) | return error()
expr2 := pfl2pwl(tab(bal(']', '[', ']'))) | return error()
result ||:= "," || "(" || expr1 || \optbl[op] || expr2 || ")" |
return error()
move(1)
}
if not pos(0) then result ||:= "," || tab(0)
}
return result[2:0]
end
procedure error(expr1, expr2)
write(&errout, "*** error ", expr1, " ", expr2)
fail
end
procedure pfl2gxp(pattern, arg) #: pattern form to generating expression
local result, i, j, slist, s, expr1, expr2, op
static operator, optbl, argtbl
initial {
operator := ',.*-!|+;/~:?%<>#`'
optbl := table()
optbl["*"] := "Repl{"
optbl["<"] := "Upto{"
optbl[">"] := "Downto{"
optbl["-"] := "UpDownto{"
optbl["|"] := "TileMirror{"
optbl["!"] := "Palin{"
optbl["+"] := "Valrpt{"
optbl["~"] := "Inter{"
optbl["->"] := "ExtendSeq{"
optbl["~"] := "Parallel{"
optbl[":"] := "Template{"
optbl["?"] := "Permut{"
optbl["%"] := "Pbox{"
optbl["<>"] := "UpDown{"
optbl["><"] := "DownUp{"
optbl["#"] := "Rotate{"
optbl["`"] := "Reverse{"
optbl["*"] := repl
}
/arg := str
# Handling of literal arguments
argtbl := table(str)
argtbl["*"] := 1
argtbl["#"] := 1
argtbl["->"] := 1
if /pattern | (*pattern = 0) then return image("")
result := ""
pattern ? {
while result ||:= arg(tab(upto('['))) do {
move(1)
expr1 := pfl2gxp(tab(bal(operator, '[', ']')), arg) | {
result ||:= tab(bal(']', '[', ']')) || " | " # no operator
move(1)
next
}
if ="." then result ||:= tab(bal(']', '[', ']')) || " | "
else {
op := tab(many(operator)) | return error()
expr2 := pfl2gxp(tab(bal(']', '[', ']')), argtbl[op]) | return error()
result ||:= \optbl[op] || expr1 || "," || expr2 || ") | " |
return error()
}
move(1)
}
if not pos(0) then result ||:= arg(tab(0))
}
return trim(result, '| ')
end
procedure lit(s)
return "!" || image(s)
end
procedure str(s)
return lit(s) || " | "
end
procedure galt(s)
return "Galt{" || collate(s, repl(",", *s - 1)) || "}"
end
procedure pwl2pfl(wexpr) #: Painter expression to pattern form
return pwlcvt(prepare(wexpr))
end
procedure prepare(wexpr) # preprocess pwl
local inter, result
static names, names1
initial {
names := [
"", # expression placeholder
" block ", "[]",
" repeat ", "*",
" rep ", "*",
" extend ", "==",
" ext ", "==",
" concat ", ",",
" interleave ", "~",
" int ", "~",
" upto ", ">",
" downto ", "<",
" template ", ":",
" temp ", ":",
" palindrome ", "|",
" pal ", "|",
" pal", "|",
" permute ", "?",
" perm ", "?",
" pbox ", "%",
" updown ", "<>",
" downup ", "><",
" rotate ", "#",
" rot ", "#",
" reverse ", "`",
" rev ", "`",
" rev", "`",
]
names1 := [
"", # expression placeholder
"pal", "|",
"rev", "`"
]
}
result := ""
wexpr ? {
while result ||:= tab(upto('[')) do {
move(1)
inter := tab(bal(']'))
if *inter > 0 then result ||:= spray(inter)
else result ||:= "[]"
move(1)
}
result ||:= tab(0)
}
if upto(result, ' ') then {
if upto(result, &letters) then {
names[1] := result
result := (replacem ! names)
}
}
if upto(result, &letters) then {
names1[1] := result
result := (replacem ! names1)
}
return deletec(map(result, "[]", "=="), ' ')
end
procedure pwlcvt(wexpr)
local result, inter
wexpr ?:= {
2(="(", tab(bal(')')), pos(-1))
}
result := ""
wexpr ? {
while result ||:= form1(pwlcvt(tab(bal('|`', '([', ']('))), move(1))
result ||:= tab(0)
}
wexpr := result
result := ""
wexpr ? {
while result ||:= form2(pwlcvt(tab(bal('->:#*=~', '([', ')]'))),
=("#" | "*" | "->" | "~" | ":" | "=="), pwlcvt(tab(0)))
result ||:= tab(0)
}
wexpr := result
result := ""
wexpr ? {
while result ||:= form2(pwlcvt(tab(bal('<>', '([', ')]'))),
=("><" | "<>"), pwlcvt(tab(0)))
result ||:= tab(0)
}
wexpr := result
result := ""
wexpr ? {
while result ||:= form2(pwlcvt(tab(bal('<->,', '([', ')]'))),
=(">" | "<" | "-" | ","), pwlcvt(tab(0)))
result ||:= tab(0)
}
return result
end
procedure form1(wexpr, op)
return "[" || wexpr || op || "]"
end
procedure form2(wexpr1, op, wexpr2)
return "[" || wexpr1 || op || wexpr2 || "]"
end
procedure spray(inter)
local count, s1, s2, s3, colors
s1 := s2 := s3 := ""
inter ?:= { # only palindome and reflection allowed, it seems
1(tab(upto('|`') | 0), s3 := tab(0))
}
inter ? {
while s1 ||:= colors := tab(upto(' ')) do {
tab(many(' '))
count := tab(upto(' ') | 0)
if *count = 1 then s2 ||:= repl(count, *colors)
else s2 ||:= repl("{" || count || "}", *colors)
move(1) | break
}
}
return "((" || s1 || s3 || ")" || "[]" || s2 || ")"
end
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