| merge API | |
| ========= | |
| The merge API helps a program to reconcile two competing sets of | |
| improvements to some files (e.g., unregistered changes from the work | |
| tree versus changes involved in switching to a new branch), reporting | |
| conflicts if found. The library called through this API is | |
| responsible for a few things. | |
| * determining which trees to merge (recursive ancestor consolidation); | |
| * lining up corresponding files in the trees to be merged (rename | |
| detection, subtree shifting), reporting edge cases like add/add | |
| and rename/rename conflicts to the user; | |
| * performing a three-way merge of corresponding files, taking | |
| path-specific merge drivers (specified in `.gitattributes`) | |
| into account. | |
| Data structures | |
| --------------- | |
| * `mmbuffer_t`, `mmfile_t` | |
| These store data usable for use by the xdiff backend, for writing and | |
| for reading, respectively. See `xdiff/xdiff.h` for the definitions | |
| and `diff.c` for examples. | |
| * `struct ll_merge_options` | |
| This describes the set of options the calling program wants to affect | |
| the operation of a low-level (single file) merge. Some options: | |
| `virtual_ancestor`:: | |
| Behave as though this were part of a merge between common | |
| ancestors in a recursive merge. | |
| If a helper program is specified by the | |
| `[merge "<driver>"] recursive` configuration, it will | |
| be used (see linkgit:gitattributes[5]). | |
| `variant`:: | |
| Resolve local conflicts automatically in favor | |
| of one side or the other (as in 'git merge-file' | |
| `--ours`/`--theirs`/`--union`). Can be `0`, | |
| `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`, or | |
| `XDL_MERGE_FAVOR_UNION`. | |
| `renormalize`:: | |
| Resmudge and clean the "base", "theirs" and "ours" files | |
| before merging. Use this when the merge is likely to have | |
| overlapped with a change in smudge/clean or end-of-line | |
| normalization rules. | |
| Low-level (single file) merge | |
| ----------------------------- | |
| `ll_merge`:: | |
| Perform a three-way single-file merge in core. This is | |
| a thin wrapper around `xdl_merge` that takes the path and | |
| any merge backend specified in `.gitattributes` or | |
| `.git/info/attributes` into account. Returns 0 for a | |
| clean merge. | |
| Calling sequence: | |
| * Prepare a `struct ll_merge_options` to record options. | |
| If you have no special requests, skip this and pass `NULL` | |
| as the `opts` parameter to use the default options. | |
| * Allocate an mmbuffer_t variable for the result. | |
| * Allocate and fill variables with the file's original content | |
| and two modified versions (using `read_mmfile`, for example). | |
| * Call `ll_merge()`. | |
| * Read the merged content from `result_buf.ptr` and `result_buf.size`. | |
| * Release buffers when finished. A simple | |
| `free(ancestor.ptr); free(ours.ptr); free(theirs.ptr); | |
| free(result_buf.ptr);` will do. | |
| If the modifications do not merge cleanly, `ll_merge` will return a | |
| nonzero value and `result_buf` will generally include a description of | |
| the conflict bracketed by markers such as the traditional `<<<<<<<` | |
| and `>>>>>>>`. | |
| The `ancestor_label`, `our_label`, and `their_label` parameters are | |
| used to label the different sides of a conflict if the merge driver | |
| supports this. | |
| Everything else | |
| --------------- | |
| Talk about <merge-recursive.h> and merge_file(): | |
| - merge_trees() to merge with rename detection | |
| - merge_recursive() for ancestor consolidation | |
| - try_merge_command() for other strategies | |
| - conflict format | |
| - merge options | |
| (Daniel, Miklos, Stephan, JC) |