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