merge-ll.h

   1 /*
   2  * Low level 3-way in-core file merge.
   3  */
   4
   5 #ifndef LL_MERGE_H
   6 #define LL_MERGE_H
   7
   8 #include "xdiff/xdiff.h"
   9
  10 /**
  11  *
  12  * Calling sequence:
  13  * ----------------
  14  *
  15  * - Prepare a `struct ll_merge_options` to record options.
  16  *   If you have no special requests, skip this and pass `NULL`
  17  *   as the `opts` parameter to use the default options.
  18  *
  19  * - Allocate an mmbuffer_t variable for the result.
  20  *
  21  * - Allocate and fill variables with the file's original content
  22  *   and two modified versions (using `read_mmfile`, for example).
  23  *
  24  * - Call `ll_merge()`.
  25  *
  26  * - Read the merged content from `result_buf.ptr` and `result_buf.size`.
  27  *
  28  * - Release buffers when finished.  A simple
  29  *   `free(ancestor.ptr); free(ours.ptr); free(theirs.ptr);
  30  *   free(result_buf.ptr);` will do.
  31  *
  32  * If the modifications do not merge cleanly, `ll_merge` will return a
  33  * nonzero value and `result_buf` will generally include a description of
  34  * the conflict bracketed by markers such as the traditional `<<<<<<<`
  35  * and `>>>>>>>`.
  36  *
  37  * The `ancestor_label`, `our_label`, and `their_label` parameters are
  38  * used to label the different sides of a conflict if the merge driver
  39  * supports this.
  40  */
  41
  42
  43 struct index_state;
  44
  45 /**
  46  * This describes the set of options the calling program wants to affect
  47  * the operation of a low-level (single file) merge.
  48  */
  49 struct ll_merge_options {
  50
  51         /**
  52          * Behave as though this were part of a merge between common ancestors in
  53          * a recursive merge (merges of binary files may need to be handled
  54          * differently in such cases, for example). If a helper program is
  55          * specified by the `[merge "<driver>"] recursive` configuration, it will
  56          * be used.
  57          */
  58         unsigned virtual_ancestor : 1;
  59
  60         /**
  61          * Resolve local conflicts automatically in favor of one side or the other
  62          * (as in 'git merge-file' `--ours`/`--theirs`/`--union`).  Can be `0`,
  63          * `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`,
  64          * or `XDL_MERGE_FAVOR_UNION`.
  65          */
  66         unsigned variant : 2;
  67
  68         /**
  69          * Resmudge and clean the "base", "theirs" and "ours" files before merging.
  70          * Use this when the merge is likely to have overlapped with a change in
  71          * smudge/clean or end-of-line normalization rules.
  72          */
  73         unsigned renormalize : 1;
  74
  75         /**
  76          * Increase the length of conflict markers so that nested conflicts
  77          * can be differentiated.
  78          */
  79         unsigned extra_marker_size;
  80
  81         /* Override the global conflict style. */
  82         int conflict_style;
  83
  84         /* Extra xpparam_t flags as defined in xdiff/xdiff.h. */
  85         long xdl_opts;
  86 };
  87
  88 #define LL_MERGE_OPTIONS_INIT { .conflict_style = -1 }
  89
  90 enum ll_merge_result {
  91         LL_MERGE_ERROR = -1,
  92         LL_MERGE_OK = 0,
  93         LL_MERGE_CONFLICT,
  94         LL_MERGE_BINARY_CONFLICT,
  95 };
  96
  97 /**
  98  * Perform a three-way single-file merge in core.  This is a thin wrapper
  99  * around `xdl_merge` that takes the path and any merge backend specified in
 100  * `.gitattributes` or `.git/info/attributes` into account.
 101  * Returns 0 for a clean merge.
 102  */
 103 enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 104              const char *path,
 105              mmfile_t *ancestor, const char *ancestor_label,
 106              mmfile_t *ours, const char *our_label,
 107              mmfile_t *theirs, const char *their_label,
 108              struct index_state *istate,
 109              const struct ll_merge_options *opts);
 110
 111 int ll_merge_marker_size(struct index_state *istate, const char *path);
 112 void reset_merge_attributes(void);
 113
 114 #endif