ref: a411870ee4640241e3c494367d922847da84f972
dir: /appl/cmd/sh/expr.b/
implement Shellbuiltin;
include "sys.m";
sys: Sys;
include "draw.m";
include "sh.m";
sh: Sh;
Listnode, Context: import sh;
myself: Shellbuiltin;
initbuiltin(ctxt: ref Context, shmod: Sh): string
{
sys = load Sys Sys->PATH;
sh = shmod;
myself = load Shellbuiltin "$self";
if (myself == nil)
ctxt.fail("bad module", sys->sprint("expr: cannot load self: %r"));
ctxt.addsbuiltin("expr", myself);
ctxt.addbuiltin("ntest", myself);
return nil;
}
whatis(nil: ref Sh->Context, nil: Sh, nil: string, nil: int): string
{
return nil;
}
getself(): Shellbuiltin
{
return myself;
}
EQ, GT, LT, GE, LE, PLUS, MINUS, DIVIDE, AND, TIMES, MOD,
OR, XOR, UMINUS, SHL, SHR, NOT, BNOT, NEQ, REP, SEQ: con iota;
runbuiltin(ctxt: ref Sh->Context, nil: Sh,
cmd: list of ref Sh->Listnode, nil: int): string
{
case (hd cmd).word {
"ntest" =>
if (len cmd != 2)
ctxt.fail("usage", "usage: ntest n");
if (big (hd tl cmd).word == big 0)
return "false";
}
return nil;
}
runsbuiltin(ctxt: ref Sh->Context, nil: Sh,
cmd: list of ref Sh->Listnode): list of ref Listnode
{
# only one sbuiltin: expr.
stk: list of big;
lastop := -1;
lastn := -1;
lastname := "";
radix: int;
(cmd, radix) = opts(ctxt, tl cmd);
for (; cmd != nil; cmd = tl cmd) {
w := (hd cmd).word;
op := -1;
nops := 2;
case w {
"+" =>
op = PLUS;
"-" =>
op = MINUS;
"x" or "*" or "×" =>
op = TIMES;
"/" =>
op = DIVIDE;
"%" =>
op = MOD;
"and" =>
op = AND;
"or" =>
op = OR;
"xor" =>
op = XOR;
"_"=>
(op, nops) = (UMINUS, 1);
"<<" or "shl" =>
op = SHL;
">>" or "shr" =>
op = SHR;
"=" or "==" or "eq" =>
op = EQ;
"!=" or "neq" =>
op = NEQ;
">" or "gt" =>
op = GT;
"<" or "lt" =>
op = LT;
">=" or "ge" =>
op = GE;
"<=" or "le" =>
op = LE;
"!" or "not" =>
(op, nops) = (NOT, 1);
"~" =>
(op, nops) = (BNOT, 1);
"rep" =>
(op, nops) = (REP, 0);
"seq" =>
(op, nops) = (SEQ, 2);
}
if (op == -1)
stk = makenum(ctxt, w) :: stk;
else
stk = operator(ctxt, stk, op, nops, lastop, lastn, w, lastname);
lastop = op;
lastn = nops;
lastname = w;
}
r: list of ref Listnode;
for (; stk != nil; stk = tl stk)
r = ref Listnode(nil, big2string(hd stk, radix)) :: r;
return r;
}
opts(ctxt: ref Context, cmd: list of ref Listnode): (list of ref Listnode, int)
{
radix := 10;
if (cmd == nil)
return (nil, 10);
w := (hd cmd).word;
if (len w < 2)
return (cmd, 10);
if (w[0] != '-' || (w[1] >= '0' && w[1] <= '9'))
return (cmd, 10);
if (w[1] != 'r')
ctxt.fail("usage", "usage: expr [-r radix] [arg...]");
if (len w > 2)
w = w[2:];
else {
if (tl cmd == nil)
ctxt.fail("usage", "usage: expr [-r radix] [arg...]");
cmd = tl cmd;
w = (hd cmd).word;
}
r := int w;
if (r <= 0 || r > 36)
ctxt.fail("usage", "expr: invalid radix " + string r);
return (tl cmd, int w);
}
operator(ctxt: ref Context, stk: list of big, op, nops, lastop, lastn: int,
opname, lastopname: string): list of big
{
al: list of big;
for (i := 0; i < nops; i++) {
if (stk == nil)
ctxt.fail("empty stack",
sys->sprint("expr: empty stack on op '%s'", opname));
al = hd stk :: al;
stk = tl stk;
}
return oper(ctxt, al, op, lastop, lastn, lastopname, stk);
}
# args are in reverse order
oper(ctxt: ref Context, args: list of big, op, lastop, lastn: int,
lastopname: string, stk: list of big): list of big
{
if (op == REP) {
if (lastop == -1 || lastop == SEQ || lastn != 2)
ctxt.fail("usage", "expr: bad operator for rep");
if (stk == nil || tl stk == nil)
return stk;
while (tl stk != nil)
stk = operator(ctxt, stk, lastop, 2, -1, -1, lastopname, nil);
return stk;
}
n2 := big 0;
n1 := hd args;
if (tl args != nil)
n2 = hd tl args;
r := big 0;
case op {
EQ => r = big(n1 == n2);
NEQ => r = big(n1 != n2);
GT => r = big(n1 > n2);
LT => r = big(n1 < n2);
GE => r = big(n1 >= n2);
LE => r = big(n1 <= n2);
PLUS => r = big(n1 + n2);
MINUS => r = big(n1 - n2);
NOT => r = big(n1 != big 0);
DIVIDE =>
if (n2 == big 0)
ctxt.fail("divide by zero", "expr: division by zero");
r = n1 / n2;
MOD =>
if (n2 == big 0)
ctxt.fail("divide by zero", "expr: division by zero");
r = n1 % n2;
TIMES => r = n1 * n2;
AND => r = n1 & n2;
OR => r = n1 | n2;
XOR => r = n1 ^ n2;
UMINUS => r = -n1;
BNOT => r = ~n1;
SHL => r = n1 << int n2;
SHR => r = n1 >> int n2;
SEQ => return seq(n1, n2, stk);
}
return r :: stk;
}
seq(n1, n2: big, stk: list of big): list of big
{
incr := big 1;
if (n2 < n1)
incr = big -1;
for (; n1 != n2; n1 += incr)
stk = n1 :: stk;
return n1 :: stk;
}
makenum(ctxt: ref Context, s: string): big
{
if (s == nil || (s[0] != '-' && (s[0] < '0' || s[0] > '9')))
ctxt.fail("usage", sys->sprint("expr: unknown operator '%s'", s));
t := s;
if (neg := s[0] == '-')
s = s[1:];
radix := 10;
for (i := 0; i < len s && i < 3; i++) {
if (s[i] == 'r') {
radix = int s;
s = s[i+1:];
break;
}
}
if (radix == 10)
return big t;
if (radix == 0 || radix > 36)
ctxt.fail("usage", "expr: bad number " + t);
n := big 0;
for (i = 0; i < len s; i++) {
if ('0' <= s[i] && s[i] <= '9')
n = (n * big radix) + big(s[i] - '0');
else if ('a' <= s[i] && s[i] < 'a' + radix - 10)
n = (n * big radix) + big(s[i] - 'a' + 10);
else if ('A' <= s[i] && s[i] < 'A' + radix - 10)
n = (n * big radix) + big(s[i] - 'A' + 10);
else
break;
}
if (neg)
return -n;
return n;
}
big2string(n: big, radix: int): string
{
if (neg := n < big 0) {
n = -n;
}
s := "";
do {
c: int;
d := int (n % big radix);
if (d < 10)
c = '0' + d;
else
c = 'a' + d - 10;
s[len s] = c;
n /= big radix;
} while (n > big 0);
t := s;
for (i := len s - 1; i >= 0; i--)
t[len s - 1 - i] = s[i];
if (radix != 10)
t = string radix + "r" + t;
if (neg)
return "-" + t;
return t;
}