Thread (34 messages) flat view 34 messages, 2 authors, 2016-06-15

Re: [PATCH v2 11/11] ref-filter: introduce objectname_atom_parser()

From: Eric Sunshine <hidden>
Date: 2016-06-15 23:07:30

On Wed, Dec 16, 2015 at 10:30 AM, Karthik Nayak [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Introduce objectname_atom_parser() which will parse the
'%(objectname)' atom and store information into the 'used_atom'
structure based on the modifiers used along with the atom.

Helped-by: Ramsay Jones [off-list ref]
Signed-off-by: Karthik Nayak <redacted>
---
diff --git a/ref-filter.c b/ref-filter.c
@@ -43,6 +43,7 @@ static struct used_atom {
                        enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB } option;
                        unsigned int no_lines;
                } contents;
+               enum { O_FULL, O_SHORT } objectname;
        } u;
 } *used_atom;
@@ -124,6 +125,21 @@ static void contents_atom_parser(struct used_atom *atom)
+static void objectname_atom_parser(struct used_atom *atom)
+{
+       const char * buf;
+
+       if (match_atom_name(atom->str, "objectname", &buf))
+               atom->u.objectname = O_FULL;
+       if (!buf)
+               return;
Let me make sure that I understand this correctly.

make_atom_name("objectname") will return true only for "objectname" or
"objectname:", and will return false for anything else, such as
"objectnamely" or "schmorf". Furthermore, the only way
objectname_atom_parser() can be called is when %(objectname) or
%(objectname:...) is seen, thus match_atom_name() *must* return true
here, which means the above conditional is misleading, suggesting that
it could somehow return false.

And, if match_atom_name() did return false here, then that indicates a
programming error: objectname_atom_parser() somehow got called for
something other than %(objectname) or %(objectname:...). This implies
that the code should instead be structured like this:

    if (!match_atom_name(..., "objectname", &buf)
        die("BUG: parsing non-'objectname'")
    if (!buf)
        atom->u.objectname = O_FULL;
    else if (!strcmp(buf, "short"))
        atom->u.objectname = O_SHORT;
    else
        die(_("unrecognized %%(objectname) argument: %s"), buf);

However, this can be simplified further by recognizing that, following
this patch series, match_atom_name() is *only* called by these new
parse functions[1], which means that, as a convenience,
match_atom_name() itself could become a void rather than boolean
function and die() if the expected atom name is not found. Thus, the
code would become:

    match_atom_name(...);
    if (!buf)
        ...
    else if (!strcmp(...))
        ...
    ...

By the way, the above commentary isn't specific to this patch and
%(objectname), but is in fact also relevant for all of the preceding
patches which introduce parse functions calling match_atom_name().

More below...

[1]: ...assuming you replace the unnecessary match_atom_name() in
populate_value() with starts_with() as suggested in my patch 7/11
review addendum[2].

[2]: http://article.gmane.org/gmane.comp.version-control.git/282700
quoted hunk ↗ jump to hunk
+
+       if (!strcmp(buf, "short"))
+               atom->u.objectname = O_SHORT;
+       else
+               die(_("unrecognized %%(objectname) argument: %s"), buf);
+}
+
@@ -461,15 +477,16 @@ static void *get_obj(const unsigned char *sha1, struct object **obj, unsigned lo
 static int grab_objectname(const char *name, const unsigned char *sha1,
-                           struct atom_value *v)
+                          struct atom_value *v, struct used_atom *atom)
 {
-       if (!strcmp(name, "objectname")) {
-               v->s = xstrdup(sha1_to_hex(sha1));
-               return 1;
-       }
-       if (!strcmp(name, "objectname:short")) {
-               v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
-               return 1;
+       if (starts_with(name, "objectname")) {
+               if (atom->u.objectname == O_SHORT) {
+                       v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
+                       return 1;
+               } else if (atom->u.objectname == O_FULL) {
+                       v->s = xstrdup(sha1_to_hex(sha1));
+                       return 1;
+               }
Since 'objectname' can only ever be O_SHORT or O_FULL wouldn't it be a
programming error if it ever falls through to this point after the
closing brace? Perhaps a die("BUG:...") would be appropriate?
quoted hunk ↗ jump to hunk
        }
        return 0;
 }
@@ -493,7 +510,7 @@ static void grab_common_values(struct atom_value *val, int deref, struct object
                        v->s = xstrfmt("%lu", sz);
                }
                else if (deref)
-                       grab_objectname(name, obj->sha1, v);
+                       grab_objectname(name, obj->sha1, v, &used_atom[i]);
This patch hunk is somehow corrupt and doesn't apply. Was there some
hand-editing involved, or were some earlier patches regenerated after
this patch was made or something?
quoted hunk ↗ jump to hunk
        }
 }
@@ -999,7 +1016,7 @@ static void populate_value(struct ref_array_item *ref)
                                v->s = xstrdup(buf + 1);
                        }
                        continue;
-               } else if (!deref && grab_objectname(name, ref->objectname, v)) {
+               } else if (!deref && grab_objectname(name, ref->objectname, v, atom)) {
                        continue;
                } else if (!strcmp(name, "HEAD")) {
                        const char *head;
--
2.6.4
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