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validate_arglist(): Re-written to reflect extended call syntax.

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validate_numnodes():  Added comment to explain the sometimes idiomatic
        usage pattern.
This commit is contained in:
Fred Drake 2000-04-25 04:14:46 +00:00
parent c35a20ed1e
commit e7ab64e070
1 changed files with 80 additions and 3 deletions
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83
Modules/parsermodule.c
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@ -954,6 +954,13 @@ validate_ntype(node *n, int t)
}
/* Verifies that the number of child nodes is exactly 'num', raising
* an exception if it isn't. The exception message does not indicate
* the exact number of nodes, allowing this to be used to raise the
* "right" exception when the wrong number of nodes is present in a
* specific variant of a statement's syntax. This is commonly used
* in that fashion.
*/
static int
validate_numnodes(node *n, int num, const char *const name)
{
@ -2094,13 +2101,83 @@ validate_lambdef(node *tree)
/* arglist:
*
* argument (',' argument)* [',']
* (argument ',')* (argument* [','] | '*' test [',' '**' test] | '**' test)
*/
static int
validate_arglist(node *tree)
{
return (validate_repeating_list(tree, arglist,
validate_argument, "arglist"));
int nch = NCH(tree);
int i, ok;
node *last;
if (nch <= 0)
/* raise the right error from having an invalid number of children */
return validate_numnodes(tree, nch + 1, "arglist");
last = CHILD(tree, nch - 1);
if (TYPE(last) == test) {
/* Extended call syntax introduced in Python 1.6 has been used;
* validate and strip that off and continue;
* adjust nch to perform the cut, and ensure resulting nch is even
* (validation of the first part doesn't require that).
*/
if (nch < 2) {
validate_numnodes(tree, nch + 1, "arglist");
return 0;
}
ok = validate_test(last);
if (ok) {
node *prev = CHILD(tree, nch - 2);
/* next must be '*' or '**' */
if (validate_doublestar(prev)) {
nch -= 2;
if (nch >= 3) {
/* may include: '*' test ',' */
last = CHILD(tree, nch - 1);
prev = CHILD(tree, nch - 2);
if (TYPE(prev) == test) {
ok = validate_comma(last)
&& validate_test(prev)
&& validate_star(CHILD(tree, nch - 3));
if (ok)
nch -= 3;
}
/* otherwise, nothing special */
}
}
else {
/* must be only: '*' test */
PyErr_Clear();
ok = validate_star(prev);
nch -= 2;
}
if (ok && is_odd(nch)) {
/* Illegal number of nodes before extended call syntax;
* validation of the "normal" arguments does not require
* a trailing comma, but requiring an even number of
* children will effect the same requirement.
*/
return validate_numnodes(tree, nch + 1, "arglist");
}
}
}
/* what remains must be: (argument ",")* [argument [","]] */
i = 0;
while (ok && nch - i >= 2) {
ok = validate_argument(CHILD(tree, i))
&& validate_comma(CHILD(tree, i + 1));
i += 2;
}
if (ok && i < nch) {
ok = validate_comma(CHILD(tree, i));
++i;
}
if (i != nch) {
/* internal error! */
ok = 0;
err_string("arglist: internal error; nch != i");
}
return (ok);
}