ref: d916a4c3823f55227ffae35738c2497256e307b5
dir: /appl/cmd/mash/xeq.b/
#
# Command execution.
#
#
# Entry from parser.
#
Cmd.xeq(c: self ref Cmd, e: ref Env)
{
if (e.flags & EDumping) {
s := c.text();
f := e.outfile();
f.puts(s);
if (s != nil && s[len s - 1] != '&')
f.putc(';');
f.putc('\n');
f.close();
f = nil;
}
if ((e.flags & ENoxeq) == 0)
c.xeqit(e, 1);
}
#
# Execute a command. Tail recursion.
#
Cmd.xeqit(c: self ref Cmd, e: ref Env, wait: int)
{
tail: for (;;) {
if (c == nil)
return;
case c.op {
Csimple =>
c.simple(e, wait);
Casync =>
e = e.clone();
e.in = e.devnull();
e.wait = nil;
spawn c.left.xeqit(e, 1);
Cgroup =>
if (c.redirs != nil) {
(ok, in, out) := mkredirs(e, c.redirs);
if (!ok)
return;
e = e.copy();
e.in = in;
e.out = out;
c.left.xeqit(e, 1);
} else {
c = c.left;
continue tail;
}
Csubgroup =>
e = e.clone();
if (c.redirs != nil) {
(ok, in, out) := mkredirs(e, c.redirs);
if (!ok)
return;
e.in = in;
e.out = out;
}
c = c.left;
continue tail;
Cseq =>
c.left.xeqit(e, 1);
c = c.right;
continue tail;
Cpipe =>
do {
fds := e.pipe();
if (fds == nil)
return;
n := e.clone();
n.out = fds[0];
c.left.xeqit(n, 0);
n = nil;
e = e.clone();
e.in = fds[1];
fds = nil;
c = c.right;
} while (c.op == Cpipe);
continue tail;
Cif =>
t := c.left.truth(e);
if (c.right.op == Celse) {
if (t)
c.right.left.xeqit(e, wait);
else
c.right.right.xeqit(e, wait);
} else if (t)
c.right.xeqit(e, wait);
Celse =>
panic("unexpected else");
Cwhile =>
while (c.left.truth(e))
c.right.xeqit(e, wait);
Cfor =>
(ok, l) := evalw(c.words, e);
if (!ok)
return;
s := c.item.word.text;
c = c.left;
while (l != nil) {
e.let(s, (hd l) :: nil);
c.xeqit(e, 1);
l = tl l;
}
Ccase =>
(s1, l1) := c.left.eeval(e);
r := c.right;
while (r != nil) {
l := r.left;
(s2, l2) := l.left.eeval(e);
if (match2(e, s1, l1, s2, l2)) {
c = l.right;
continue tail;
}
r = r.right;
}
Ceq =>
c.assign(e, 0);
Cdefeq =>
c.assign(e, 1);
Cfn =>
(s, nil, nil) := c.item.ieval(e);
if (!ident(s)) {
e.report("bad function name");
return;
}
e.define(s, c.left);
Crescue =>
e.report("rescue not implemented");
Cdepend =>
c.depend(e);
Crule =>
c.rule(e);
* =>
sys->print("number %d\n", c.op);
} return; } # tail recursion
}
#
# Execute quote or backquote generator. Return generated item.
#
Cmd.quote(c: self ref Cmd, e: ref Env, back: int): ref Item
{
e = e.copy();
fds := e.pipe();
if (fds == nil)
return nil;
e.out = fds[0];
in := bufio->fopen(fds[1], Bufio->OREAD);
if (in == nil)
e.couldnot("fopen", "pipe");
c.xeqit(e, 0);
fds = nil;
e = nil;
if (back) {
l: list of string;
while ((s := in.gets('\n')) != nil) {
(nil, r) := sys->tokenize(s, " \t\r\n");
l = prepend(l, r);
}
return Item.iteml(revstrs(l));
} else {
s := in.gets('\n');
if (s != nil && s[len s - 1] == '\n')
s = s[:len s - 1];
return Item.itemw(s);
}
}
#
# Execute serve generator.
#
Cmd.serve(c: self ref Cmd, e: ref Env, write: int): ref Item
{
e = e.clone();
fds := e.pipe();
if (fds == nil)
return nil;
if (write)
e.in = fds[0];
else
e.out = fds[0];
s := e.servefd(fds[1], write);
if (s == nil)
return nil;
c.xeqit(e, 0);
return Item.itemw(s);
}
#
# Expression evaluation, first pass.
# Parse tree is copied and word items are evaluated.
# nil return for error is propagated.
#
Cmd.eeval1(c: self ref Cmd, e: ref Env): ref Cmd
{
case c.op {
Cword =>
l := c.item.ieval1(e);
if (l == nil)
return nil;
return Cmd.cmd1i(Cword, nil, l);
Chd or Ctl or Clen or Cnot =>
l := c.left.eeval1(e);
if (l == nil)
return nil;
return Cmd.cmd1(c.op, l);
Ccaret or Ccons or Ceqeq or Cnoteq or Cmatch =>
l := c.left.eeval1(e);
r := c.right.eeval1(e);
if (l == nil || r == nil)
return nil;
return Cmd.cmd2(c.op, l, r);
}
panic("expr1: bad op");
return nil;
}
#
# Expression evaluation, second pass.
# Returns a tuple (singleton, list, expand flag).
#
Cmd.eeval2(c: self ref Cmd, e: ref Env): (string, list of string, int)
{
case c.op {
Cword =>
return c.item.ieval2(e);
Clist =>
return (nil, c.value, 0);
Ccaret =>
(s1, l1, x1) := c.left.eeval2(e);
(s2, l2, x2) := c.right.eeval2(e);
return caret(s1, l1, x1, s2, l2, x2);
Chd =>
(s, l, x) := c.left.eeval2(e);
if (s != nil)
return (s, nil, x);
if (l != nil)
return (hd l, nil, 0);
Ctl =>
(s, l, nil) := c.left.eeval2(e);
if (s != nil)
break;
if (l != nil)
return (nil, tl l, 0);
Clen =>
(s, l, nil) := c.left.eeval2(e);
if (s != nil)
return ("1", nil, 0);
return (string len l, nil, 0);
Cnot =>
(s, l, nil) := c.left.eeval2(e);
if (s == nil && l == nil)
return (TRUE, nil, 0);
Ccons =>
(s1, l1, nil) := c.left.eeval2(e);
(s2, l2, nil) := c.right.eeval2(e);
if (s1 != nil) {
if (s2 != nil)
return (nil, s1 :: s2 :: nil, 0);
if (l2 != nil)
return (nil, s1 :: l2, 0);
return (s1, nil, 0);
} else if (l1 != nil) {
if (s2 != nil)
return (nil, prepend(s2 :: nil, revstrs(l1)), 0);
if (l2 != nil)
return (nil, prepend(l2, revstrs(l1)), 0);
return (nil, l1, 0);
} else
return (s2, l2, 0);
Ceqeq =>
if (c.evaleq(e))
return (TRUE, nil, 0);
Cnoteq =>
if (!c.evaleq(e))
return (TRUE, nil, 0);
Cmatch =>
if (c.evalmatch(e))
return (TRUE, nil, 0);
* =>
panic("expr2: bad op");
}
return (nil, nil, 0);
}
#
# Evaluate expression. 1st pass, 2nd pass, maybe glob.
#
Cmd.eeval(c: self ref Cmd, e: ref Env): (string, list of string)
{
c = c.eeval1(e);
if (c == nil)
return (nil, nil);
(s, l, x) := c.eeval2(e);
if (x && s != nil)
(s, l) = glob(e, s);
return (s, l);
}
#
# Assignment - let or set.
#
Cmd.assign(c: self ref Cmd, e: ref Env, def: int)
{
i := c.item;
if (i == nil)
return;
(ok, v) := evalw(c.words, e);
if (!ok)
return;
s := c.item.word.text;
if (def)
e.let(s, v);
else
e.set(s, v);
}
#
# Evaluate command and test for non-empty.
#
Cmd.truth(c: self ref Cmd, e: ref Env): int
{
(s, l) := c.eeval(e);
return s != nil || l != nil;
}
#
# Evaluate word.
#
evalw(l: list of ref Item, e: ref Env): (int, list of string)
{
if (l == nil)
return (1, nil);
w := pass1(e, l);
if (w == nil)
return (0, nil);
return (1, pass2(e, w));
}
#
# Evaluate list of items, pass 1 - reverses.
#
pass1(e: ref Env, l: list of ref Item): list of ref Item
{
r: list of ref Item;
while (l != nil) {
i := (hd l).ieval1(e);
if (i == nil)
return nil;
r = i :: r;
l = tl l;
}
return r;
}
#
# Evaluate list of items, pass 2 with globbing - reverses (restores order).
#
pass2(e: ref Env, l: list of ref Item): list of string
{
r: list of string;
while (l != nil) {
(s, t, x) := (hd l).ieval2(e);
if (x && s != nil)
(s, t) = glob(e, s);
if (s != nil)
r = s :: r;
else if (t != nil)
r = prepend(r, revstrs(t));
l = tl l;
}
return r;
}
#
# Simple command. Maybe a function.
#
Cmd.simple(c: self ref Cmd, e: ref Env, wait: int)
{
w := pass1(e, c.words);
if (w == nil)
return;
s := pass2(e, w);
if (s == nil)
return;
if (e.flags & EEcho)
echo(e, s);
(ok, in, out) := mkredirs(e, c.redirs);
if (ok)
e.runit(s, in, out, wait);
}
#
# Cmd name and arglist. Maybe a function.
#
Env.runit(e: self ref Env, s: list of string, in, out: ref Sys->FD, wait: int)
{
d := e.func(hd s);
if (d != nil) {
if (e.level >= MAXELEV) {
e.report(hd s + ": function nesting too deep");
return;
}
e = e.copy();
e.level++;
e.in = in;
e.out = out;
e.local = Stab.new();
e.local.assign(ARGS, tl s);
d.xeqit(e, wait);
} else
exec(s, e, in, out, wait);
}
#
# Item evaluation, first pass. Copy parse tree. Expand variables.
# Call first pass of expression evaluation. Execute generators.
#
Item.ieval1(i: self ref Item, e: ref Env): ref Item
{
if (i == nil)
return nil;
case i.op {
Icaret or Iicaret =>
l := i.left.ieval1(e);
r := i.right.ieval1(e);
if (l == nil || r == nil)
return nil;
return Item.item2(i.op, l, r);
Idollar or Idollarq=>
s := e.dollar(i.word.text);
if (s == nil) {
e.undefined(i.word.text);
return nil;
}
if (s.value == empty)
return Item.itemw(nil);
if (i.op == Idollar)
return Item.iteml(s.value);
else
return Item.itemw(concat(s.value));
Iword or Imatch =>
return i;
Iexpr =>
l := i.cmd.eeval1(e);
if (l == nil)
return nil;
return Item.itemc(Iexpr, l);
Ibackq =>
return i.cmd.quote(e, 1);
Iquote =>
return i.cmd.quote(e, 0);
Iinpipe =>
return i.cmd.serve(e, 0);
Ioutpipe =>
return i.cmd.serve(e, 1);
}
panic("ieval1: bad op");
return nil;
}
#
# Item evaluation, second pass. Outer level carets. Expand matches.
# Call second pass of expression evaluation.
#
Item.ieval2(i: self ref Item, e: ref Env): (string, list of string, int)
{
case i.op {
Icaret or Iicaret =>
return i.caret(e);
Imatch =>
return (e.arg(i.word.text), nil, 0);
Idollar or Idollarq =>
panic("ieval2: unexpected $");
Iword =>
return (i.word.text, nil, i.word.flags & Wexpand);
Iexpr =>
return i.cmd.eeval2(e);
Ibackq or Iinpipe or Ioutpipe =>
panic("ieval2: unexpected generator");
}
panic("ieval2: bad op");
return (nil, nil, 0);
}
#
# Item evaluation.
#
Item.ieval(i: self ref Item, e: ref Env): (string, list of string, int)
{
i = i.ieval1(e);
if (i == nil)
return (nil, nil, 0);
return i.ieval2(e);
}
#
# Redirection item evaluation.
#
Item.reval(i: self ref Item, e: ref Env): (int, string)
{
(s, l, nil) := i.ieval(e);
if (s == nil) {
if (l == nil)
e.report("null redirect");
else
e.report("list for redirect");
return (0, nil);
}
return (1, s);
}
#
# Make redirection names.
#
mkrdnames(e: ref Env, l: list of ref Redir): (int, array of string)
{
f := array[Rcount] of string;
while (l != nil) {
r := hd l;
(ok, s) := r.word.reval(e);
if (!ok)
return (0, nil);
f[r.op] = s;
l = tl l;
}
return (1, f);
}
#
# Perform redirections.
#
mkredirs(e: ref Env, l: list of ref Redir): (int, ref Sys->FD, ref Sys->FD)
{
(ok, f) := mkrdnames(e, l);
if (!ok)
return (0, nil, nil);
return redirect(e, f, e.in, e.out);
}