Elijah Newren <newren@xxxxxxxxx> writes:
> On Mon, Mar 15, 2021 at 7:31 AM Derrick Stolee <stolee@xxxxxxxxx> wrote:
>>
>> On 3/13/2021 5:22 PM, Elijah Newren via GitGitGadget wrote:
>> > From: Elijah Newren <newren@xxxxxxxxx>
>> >
>> > When one side of history renames a directory, and the other side of
>> > history added files to the old directory, directory rename detection is
>> > used to warn about the location of the added files so the user can
>> > move them to the old directory or keep them with the new one.
>> >
>> > This sets up three different types of directories:
>> > * directories that had new files added to them
>> > * directories underneath a directory that had new files added to them
>> > * directories where no new files were added to it or any leading path
>> >
>> > Save this information in dirs_removed; the next several commits will
>> > make use of this information.
>> ...
>> > +/* dir_rename_relevance: the reason we want rename information for a dir */
>> > +enum dir_rename_relevance {
>> > + NOT_RELEVANT = 0,
>> > + RELEVANT_FOR_ANCESTOR = 1,
>> > + RELEVANT_FOR_SELF = 2
>> > +};
>>
>> Is this potentially a flag list? It's hard to tell because we don't
>> have another item (3 or 4?).
>>
>> > unsigned sides = (0x07 - dirmask)/2;
>> > + unsigned relevance = (renames->dir_rename_mask == 0x07) ?
>> > + RELEVANT_FOR_ANCESTOR : NOT_RELEVANT;
>> > + /*
>> > + * Record relevance of this directory. However, note that
>> > + * when collect_merge_info_callback() recurses into this
>> > + * directory and calls collect_rename_info() on paths
>> > + * within that directory, if we find a path that was added
>> > + * to this directory on the other side of history, we will
>> > + * upgrade this value to RELEVANT_FOR_SELF; see below.
>> > + */
>>
>> This comment seems to imply that RELEVANT_FOR_SELF is "more important"
>> than RELEVANT_FOR_ANCESTOR, so the value will just be changed (not a
>> flag).
>
> Yes.
>
>> > + /*
>> > + * Here's the block that potentially upgrades to RELEVANT_FOR_SELF.
>> > + * When we run across a file added to a directory. In such a case,
>> > + * find the directory of the file and upgrade its relevance.
>> > + */
>> > + if (renames->dir_rename_mask == 0x07 &&
>> > + (filemask == 2 || filemask == 4)) {
>> > + /*
>> > + * Need directory rename for parent directory on other side
>> > + * of history from added file. Thus
>> > + * side = (~filemask & 0x06) >> 1
>> > + * or
>> > + * side = 3 - (filemask/2).
>> > + */
>> > + unsigned side = 3 - (filemask >> 1);
>> > + strintmap_set(&renames->dirs_removed[side], dirname,
>> > + RELEVANT_FOR_SELF);
>>
>> Yes, using "RELEVANT_FOR_SELF" here, not "relevance | RELEVANT_FOR_SELF".
>> OK. This should make the later consumers simpler.
>
> Yep, indeed. Would it make it clearer earlier if I were to stop
> assigning the explicit values in the enum? Would adding a comment
> when I introduce the enum be easier? Or was it just "thinking out
> loud"?
You are not asking me, but if you were, I'd say not using enum for
bitmask would be a good discipline to follow, and an enum like this
one that is used only for uniqueness of the values would benefit from
not having explicit value assignments.
