1merge API 2========= 3 4The merge API helps a program to reconcile two competing sets of 5improvements to some files (e.g., unregistered changes from the work 6tree versus changes involved in switching to a new branch), reporting 7conflicts if found. The library called through this API is 8responsible for a few things. 9 10 * determining which trees to merge (recursive ancestor consolidation); 11 12 * lining up corresponding files in the trees to be merged (rename 13 detection, subtree shifting), reporting edge cases like add/add 14 and rename/rename conflicts to the user; 15 16 * performing a three-way merge of corresponding files, taking 17 path-specific merge drivers (specified in `.gitattributes`) 18 into account. 19 20Data structures 21--------------- 22 23* `mmbuffer_t`, `mmfile_t` 24 25These store data usable for use by the xdiff backend, for writing and 26for reading, respectively. See `xdiff/xdiff.h` for the definitions 27and `diff.c` for examples. 28 29* `struct ll_merge_options` 30 31This describes the set of options the calling program wants to affect 32the operation of a low-level (single file) merge. Some options: 33 34`virtual_ancestor`:: 35 Behave as though this were part of a merge between common 36 ancestors in a recursive merge. 37 If a helper program is specified by the 38 `[merge "<driver>"] recursive` configuration, it will 39 be used (see linkgit:gitattributes[5]). 40 41`variant`:: 42 Resolve local conflicts automatically in favor 43 of one side or the other (as in 'git merge-file' 44 `--ours`/`--theirs`/`--union`). Can be `0`, 45 `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`, or 46 `XDL_MERGE_FAVOR_UNION`. 47 48`renormalize`:: 49 Resmudge and clean the "base", "theirs" and "ours" files 50 before merging. Use this when the merge is likely to have 51 overlapped with a change in smudge/clean or end-of-line 52 normalization rules. 53 54Low-level (single file) merge 55----------------------------- 56 57`ll_merge`:: 58 59 Perform a three-way single-file merge in core. This is 60 a thin wrapper around `xdl_merge` that takes the path and 61 any merge backend specified in `.gitattributes` or 62 `.git/info/attributes` into account. Returns 0 for a 63 clean merge. 64 65Calling sequence: 66 67* Prepare a `struct ll_merge_options` to record options. 68 If you have no special requests, skip this and pass `NULL` 69 as the `opts` parameter to use the default options. 70 71* Allocate an mmbuffer_t variable for the result. 72 73* Allocate and fill variables with the file's original content 74 and two modified versions (using `read_mmfile`, for example). 75 76* Call `ll_merge()`. 77 78* Read the merged content from `result_buf.ptr` and `result_buf.size`. 79 80* Release buffers when finished. A simple 81 `free(ancestor.ptr); free(ours.ptr); free(theirs.ptr); 82 free(result_buf.ptr);` will do. 83 84If the modifications do not merge cleanly, `ll_merge` will return a 85nonzero value and `result_buf` will generally include a description of 86the conflict bracketed by markers such as the traditional `<<<<<<<` 87and `>>>>>>>`. 88 89The `ancestor_label`, `our_label`, and `their_label` parameters are 90used to label the different sides of a conflict if the merge driver 91supports this. 92 93Everything else 94--------------- 95 96Talk about <merge-recursive.h> and merge_file(): 97 98 - merge_trees() to merge with rename detection 99 - merge_recursive() for ancestor consolidation 100 - try_merge_command() for other strategies 101 - conflict format 102 - merge options 103 104(Daniel, Miklos, Stephan, JC)