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############################################################################
#
# Name: skin.icn
#
# Title: Scheme in Icon
#
# Author: Bob Alexander
#
# Date: February 19, 1995
#
# Description: see skeem.icn
#
############################################################################
#
# skeem -- Scheme in Icon
#
# Input utility procedures
#
global BackToken
#
# ReadAllExprs() - Generate expressions from file f
#
procedure ReadAllExprs(f)
"" ? (suspend |ScanExpr(FileRec(f)))
end
#
# ReadOneExpr() - Read one expression from f.
#
procedure ReadOneExpr(f)
local result,fRec
"" ? {
result := ScanExpr(fRec := FileRec(f))
seek(f,fRec.where + &pos - 1)
}
return result
end
#
# StringToExpr() - Generate expressions from string s
#
procedure StringToExpr(s)
s ? (suspend |ScanExpr())
end
procedure ScanExpr(f)
local token
return case token := ScanToken(f) | fail of {
"(": ScanList(f)
"#(": ScanVector(f)
!"'`," | ",@": ScanQuote(f,token)
default:
if type(token) == "Symbol" then token.string
else token
}
end
procedure ScanList(f)
local result,token,dot
result := LLNull
while (token := ScanToken(f)) ~=== ")" do {
if token === "." then {
dot := ScanExpr(f)
}
else {
BackToken := token
result := LLPair(ScanExpr(f),result)
}
}
return LLInvert(result,dot)
end
procedure ScanVector(f)
local result,token
result := []
while (token := ScanToken(f)) ~=== ")" do {
BackToken := token
put(result,ScanExpr(f))
}
return result
end
procedure ScanQuote(f,token)
return LList(
case token of {
"'": "QUOTE"
"`": "QUASIQUOTE"
",": "UNQUOTE"
",@": "UNQUOTE-SPLICING"
},
ScanExpr(f))
end
procedure ScanToken(f)
return 1(\.BackToken,BackToken := &null) | {
#
# Skip over leading white space (including comments, possibly
# spanning lines).
#
#showscan("before space")
while {
tab(many(Space)) |
(if pos(0) then &subject := ReadFileRec(\f)) |
(if =";" then tab(0)) |
(if ="#|" then {
until tab(find("|#") + 2) do &subject := ReadFileRec(\f) | fail
&null
})
}
#showscan("after space")
#
# Scan then token.
#
ScanSymbol() | ScanNumber() | ScanSpecial() | ScanString() |
ScanChar() | ScanBoolean() | move(1)
}
end
procedure ScanSymbol()
static symFirst,symRest,nonSym
initial {
symFirst := &letters ++ '!$%&*/:<=>?~_^'
symRest := symFirst ++ &digits ++ '.+-'
nonSym := ~symRest
}
return Symbol(
(match("|"),escape(quotedstring("|")[2:-1])) |
map(1((tab(any(symFirst)) || (tab(many(symRest)) | "") |
=("+" | "-" | "...")),
(any(nonSym) | pos(0))),&lcase,&ucase))
end
procedure ScanNumber()
local nbr
static nbrFirst,nbrRest
initial {
nbrFirst := &digits ++ 'eE.'
nbrRest := nbrFirst ++ &letters ++ '#+-'
}
(nbr := ((tab(any('+-')) | "") || tab(any(nbrFirst)) |
="#" || tab(any('bodxeiBODXEI'))) || (tab(many(nbrRest)) | "") &
nbr ~== ".") | fail
return StringToNumber(nbr) |
Error("READER","bad number: ",image(nbr))
end
procedure StringToNumber(nbr,radix)
local exact,sign,number,c
radix := if \radix ~= 10 then radix || "r" else ""
sign := ""
exact := 1
map(nbr) ? return {
while ="#" do case move(1) of {
"b": radix := "2r"
"o": radix := "8r"
"d": radix := ""
"x": radix := "16r"
"e": exact := Round
"i": exact := real
default: &null # this case prevents the expression from failing
}
sign := tab(any('+-'))
number := ""
while number ||:= tab(upto('#sfdl')) do {
c := move(1)
number ||:=
if c == "#" then {
if exact === 1 then exact := real
"0"
}
else "e"
}
number ||:= tab(0)
#write(&errout,"+++++ exact = ",image(exact),
# "; radix = ",image(radix),"; sign = ",image(sign),
# "; number = ",image(number))
exact(numeric(sign || radix || number))
}
end
procedure ScanSpecial()
return =("#(" | ",@" | !"()'`,") |
(="#<",Error("READER","unreadable object #<",tab(find(">") + 1 | 0)),F)
end
procedure ScanBoolean()
return (="#",(=!"fF",F) | (=!"tT",T))
end
procedure ScanString()
return String((match("\""),escape(quotedstring()[2:-1])))
end
procedure ScanChar()
local chName
return Char((="#\\",
(case map(1(chName := tab(many(&letters)),*chName > 1)) of {
"space": " "
"tab": "\t"
"newline": "\n"
"backspace": "\b"
"delete": "\d"
"escape": "\e"
"formfeed": "\f"
"return": "\r"
"verticaltab": "\v"
default: Error("READER","unknown character name")
}) | move(1)))
end
record FileRec(file,where)
procedure ReadFileRec(f)
local line
static doPrompt
initial doPrompt := if find("MPW",&host) then &null else "true"
f.where := where(f.file)
if f.file === &input then {
if \doPrompt then
writes(if BreakLevel = 0 then "> " else "[" || BreakLevel || "] ")
line := read() | fail
## line ? {
## if =">" | (="[" || tab(find("]") + 1)) then
## \f.where +:= &pos - 1
## line := tab(0)
## }
return line
}
else return read(f.file)
end
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