/* walk -- walk through a tree, evaluating nodes */
extern List *walk(Tree *tree0, Binding *binding0, int flags) {
Tree *volatile tree = tree0;
Binding *volatile binding = binding0;
SIGCHK();
top:
if (tree == NULL)
return true;
switch (tree->kind) {
case nConcat: case nList: case nQword: case nVar: case nVarsub:
case nWord: case nThunk: case nLambda: case nCall: case nPrim: {
List *list;
Ref(Binding *, bp, binding);
list = glom(tree, binding, TRUE);
binding = bp;
RefEnd(bp);
return eval(list, binding, flags);
}
case nAssign:
return assign(tree->u[0].p, tree->u[1].p, binding);
case nLet: case nClosure:
Ref(Tree *, body, tree->u[1].p);
binding = letbindings(tree->u[0].p, binding, binding, flags);
tree = body;
RefEnd(body);
goto top;
case nLocal:
return local(tree->u[0].p, tree->u[1].p, binding, flags);
case nFor:
return forloop(tree->u[0].p, tree->u[1].p, binding, flags);
case nMatch:
return matchpattern(tree->u[0].p, tree->u[1].p, binding);
case nExtract:
return extractpattern(tree->u[0].p, tree->u[1].p, binding);
default:
panic("walk: bad node kind %d", tree->kind);
}
NOTREACHED;
}
ex_take()
{
int takezr();
int i, k, o, fill[MRANK], fflg;
/* While TANSTAAFL, in APL there is a close approximation. It
* is possible to perform a "take" of more elements than an
* array actually contains (to be padded with zeros or blanks).
* If "td1()" detects that a dimension exceeds what the array
* actually contains it will return 1. Special code is then
* required to force the extra elements in the new array to
* zero or blank. This code is supposed to work for null items
* also, but it doesn't.
*/
o = 0;
fflg = td1(0);
for(i=0; i<idx.rank; i++) {
fill[i] = 0;
k = idx.idx[i];
if(k < 0) {
k = -k;
if (k > idx.dim[i]) fill[i] = idx.dim[i] - k;
o += idx.del[i] * (idx.dim[i] - k);
}
else {
if (k > idx.dim[i]) fill[i] = idx.dim[i];
}
idx.dim[i] = k;
}
map(o);
if (fflg){
bidx(sp[-1]);
forloop(takezr, fill);
}
}
void op_forloops()
{
forloop(TRUE);
}
void op_forloop()
{
forloop(FALSE);
}
static void udelay(unsigned us)
{
while (us--)
forloop(100);
}
