git/xdiff-interface.h
Glen Choo a4e7e317f8 config: add ctx arg to config_fn_t
Add a new "const struct config_context *ctx" arg to config_fn_t to hold
additional information about the config iteration operation.
config_context has a "struct key_value_info kvi" member that holds
metadata about the config source being read (e.g. what kind of config
source it is, the filename, etc). In this series, we're only interested
in .kvi, so we could have just used "struct key_value_info" as an arg,
but config_context makes it possible to add/adjust members in the future
without changing the config_fn_t signature. We could also consider other
ways of organizing the args (e.g. moving the config name and value into
config_context or key_value_info), but in my experiments, the
incremental benefit doesn't justify the added complexity (e.g. a
config_fn_t will sometimes invoke another config_fn_t but with a
different config value).

In subsequent commits, the .kvi member will replace the global "struct
config_reader" in config.c, making config iteration a global-free
operation. It requires much more work for the machinery to provide
meaningful values of .kvi, so for now, merely change the signature and
call sites, pass NULL as a placeholder value, and don't rely on the arg
in any meaningful way.

Most of the changes are performed by
contrib/coccinelle/config_fn_ctx.pending.cocci, which, for every
config_fn_t:

- Modifies the signature to accept "const struct config_context *ctx"
- Passes "ctx" to any inner config_fn_t, if needed
- Adds UNUSED attributes to "ctx", if needed

Most config_fn_t instances are easily identified by seeing if they are
called by the various config functions. Most of the remaining ones are
manually named in the .cocci patch. Manual cleanups are still needed,
but the majority of it is trivial; it's either adjusting config_fn_t
that the .cocci patch didn't catch, or adding forward declarations of
"struct config_context ctx" to make the signatures make sense.

The non-trivial changes are in cases where we are invoking a config_fn_t
outside of config machinery, and we now need to decide what value of
"ctx" to pass. These cases are:

- trace2/tr2_cfg.c:tr2_cfg_set_fl()

  This is indirectly called by git_config_set() so that the trace2
  machinery can notice the new config values and update its settings
  using the tr2 config parsing function, i.e. tr2_cfg_cb().

- builtin/checkout.c:checkout_main()

  This calls git_xmerge_config() as a shorthand for parsing a CLI arg.
  This might be worth refactoring away in the future, since
  git_xmerge_config() can call git_default_config(), which can do much
  more than just parsing.

Handle them by creating a KVI_INIT macro that initializes "struct
key_value_info" to a reasonable default, and use that to construct the
"ctx" arg.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-28 14:06:39 -07:00

75 lines
2.8 KiB
C

#ifndef XDIFF_INTERFACE_H
#define XDIFF_INTERFACE_H
#include "hash-ll.h"
#include "xdiff/xdiff.h"
/*
* xdiff isn't equipped to handle content over a gigabyte;
* we make the cutoff 1GB - 1MB to give some breathing
* room for constant-sized additions (e.g., merge markers)
*/
#define MAX_XDIFF_SIZE (1024UL * 1024 * 1023)
/**
* The `xdiff_emit_line_fn` function can return 1 to abort early, or 0
* to continue processing. Note that doing so is an all-or-nothing
* affair, as returning 1 will return all the way to the top-level,
* e.g. the xdi_diff_outf() call to generate the diff.
*
* Thus returning 1 means you won't be getting any more diff lines. If
* you need something in-between those two options you'll to use
* `xdl_emit_hunk_consume_func_t` and implement your own version of
* xdl_emit_diff().
*
* We may extend the interface in the future to understand other more
* granular return values. While you should return 1 to exit early,
* doing so will currently make your early return indistinguishable
* from an error internal to xdiff, xdiff itself will see that
* non-zero return and translate it to -1.
*
* See "diff_grep" in diffcore-pickaxe.c for a trick to work around
* this, i.e. using the "consume_callback_data" to note the desired
* early return.
*/
typedef int (*xdiff_emit_line_fn)(void *, char *, unsigned long);
typedef void (*xdiff_emit_hunk_fn)(void *data,
long old_begin, long old_nr,
long new_begin, long new_nr,
const char *func, long funclen);
int xdi_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, xdemitconf_t const *xecfg, xdemitcb_t *ecb);
int xdi_diff_outf(mmfile_t *mf1, mmfile_t *mf2,
xdiff_emit_hunk_fn hunk_fn,
xdiff_emit_line_fn line_fn,
void *consume_callback_data,
xpparam_t const *xpp, xdemitconf_t const *xecfg);
int read_mmfile(mmfile_t *ptr, const char *filename);
void read_mmblob(mmfile_t *ptr, const struct object_id *oid);
int buffer_is_binary(const char *ptr, unsigned long size);
void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
void xdiff_clear_find_func(xdemitconf_t *xecfg);
struct config_context;
int git_xmerge_config(const char *var, const char *value,
const struct config_context *ctx, void *cb);
extern int git_xmerge_style;
/*
* Compare the strings l1 with l2 which are of size s1 and s2 respectively.
* Returns 1 if the strings are deemed equal, 0 otherwise.
* The `flags` given as XDF_WHITESPACE_FLAGS determine how white spaces
* are treated for the comparison.
*/
int xdiff_compare_lines(const char *l1, long s1,
const char *l2, long s2, long flags);
/*
* Returns a hash of the string s of length len.
* The `flags` given as XDF_WHITESPACE_FLAGS determine how white spaces
* are treated for the hash.
*/
unsigned long xdiff_hash_string(const char *s, size_t len, long flags);
#endif