annotate mercurial/mpatch.h @ 37210:2a2ce93e12f4

templatefuncs: add mailmap template function

This commit adds a template function to support the .mailmap file
in Mercurial repositories. The .mailmap file comes from git, and
can be used to map new emails and names for old commits. The general
use case is that someone may change their name or author commits
under different emails and aliases, which would make these
commits appear as though they came from different persons. The
file allows you to specify the correct name that should be used
in place of the author field specified in the commit.

The mailmap file has 4 possible formats used to map old "commit"
names to new "proper" names:

1. <[e-mail]> <[e-mail]>
2. Proper Name <[e-mail]>
3. Proper Name <[e-mail]> <[e-mail]>
4. Proper Name <[e-mail]> Commit Name <[e-mail]>

Essentially there is a commit email present in each mailmap entry,
that maps to either an updated name, email, or both. The final
possible format allows commits authored by a person who used
both an old name and an old email to map to a new name and email.

To parse the file, we split by spaces and build a name out
of every element that does not start with "<". Once we find an element
that does start with "<" we concatenate all the name elements that preceded
and add that as a parsed name. We then add the email as the first
parsed email. We repeat the process until the end of the line, or
a comment is found. We will be left with all parsed names in a list,
and all parsed emails in a list, with the 0 index being the proper
values and the 1 index being the commit values (if they were specified
in the entry).

The commit values are added as the keys to a dict, and with the proper
fields as the values. The mapname function takes the mapping object and
the commit author field and attempts to look for a corresponding entry.
To do so we try (commit name, commit email) first, and if no results are
returned then (None, commit email) is also looked up. This is due to
format 4 from above, where someone may have a mailmap entry with both
name and email, and if they don't it is possible they have an entry that
uses only the commit email.

Differential Revision: https://phab.mercurial-scm.org/D2904

#ifndef _HG_MPATCH_H_
#define _HG_MPATCH_H_

#define MPATCH_ERR_NO_MEM -3
#define MPATCH_ERR_CANNOT_BE_DECODED -2
#define MPATCH_ERR_INVALID_PATCH -1

struct mpatch_frag {
	int start, end, len;
	const char *data;
};

struct mpatch_flist {
	struct mpatch_frag *base, *head, *tail;
};

int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res);
ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l);
void mpatch_lfree(struct mpatch_flist *a);
int mpatch_apply(char *buf, const char *orig, ssize_t len,
                 struct mpatch_flist *l);
struct mpatch_flist *
mpatch_fold(void *bins, struct mpatch_flist *(*get_next_item)(void *, ssize_t),
            ssize_t start, ssize_t end);

#endif