From: Stefan Sperling <stsp@stsp.name>
Subject: Re: expose chunk offsets in the diff API
To: Mark Jamsek <mark@jamsek.com>
Cc: Game of Trees <gameoftrees@openbsd.org>
Date: Mon, 20 Feb 2023 13:10:14 +0100

On Mon, Feb 20, 2023 at 06:52:08PM +1100, Mark Jamsek wrote:
> Thanks, I think so too! The below diff amends the misleading comment,
> makes diff_chunk_type() public, and replaces the handrolled chunk type
> deduction with it in get_modified_file_content_status().
> 
> If ok, I'll commit the diff bits to diff.git and sync them over before
> committing the worktree.c change.

Thanks! ok by me.

> diffstat /home/mark/src/got
>  M  lib/diff_internal.h  |   0+  24-
>  M  lib/diff_main.c      |  16+   0-
>  M  lib/diff_main.h      |  12+   2-
>  M  lib/worktree.c       |   1+   4-
> 
> 4 files changed, 29 insertions(+), 30 deletions(-)
> 
> diff /home/mark/src/got
> commit - 2262237761cd6c8c89a4d4263a8d9c05a7a81d70
> path + /home/mark/src/got
> blob - 7c2bfddb8f77a9026ec782026f3775a07e004f5e
> file + lib/diff_internal.h
> --- lib/diff_internal.h
> +++ lib/diff_internal.h
> @@ -96,30 +96,6 @@ enum diff_chunk_type {
>  
>  #define DIFF_RESULT_ALLOC_BLOCKSIZE 128
>  
> -enum diff_chunk_type {
> -	CHUNK_EMPTY,
> -	CHUNK_PLUS,
> -	CHUNK_MINUS,
> -	CHUNK_SAME,
> -	CHUNK_ERROR,
> -};
> -
> -static inline enum diff_chunk_type
> -diff_chunk_type(const struct diff_chunk *chunk)
> -{
> -	if (!chunk->left_count && !chunk->right_count)
> -		return CHUNK_EMPTY;
> -	if (!chunk->solved)
> -		return CHUNK_ERROR;
> -	if (!chunk->right_count)
> -		return CHUNK_MINUS;
> -	if (!chunk->left_count)
> -		return CHUNK_PLUS;
> -	if (chunk->left_count != chunk->right_count)
> -		return CHUNK_ERROR;
> -	return CHUNK_SAME;
> -}
> -
>  struct diff_chunk_context;
>  
>  bool
> blob - 25d476df152bc9f65ca65f47590adcfc8ef6ae48
> file + lib/diff_main.c
> --- lib/diff_main.c
> +++ lib/diff_main.c
> @@ -35,6 +35,22 @@ static int
>  #include "diff_internal.h"
>  #include "diff_debug.h"
>  
> +inline enum diff_chunk_type
> +diff_chunk_type(const struct diff_chunk *chunk)
> +{
> +	if (!chunk->left_count && !chunk->right_count)
> +		return CHUNK_EMPTY;
> +	if (!chunk->solved)
> +		return CHUNK_ERROR;
> +	if (!chunk->right_count)
> +		return CHUNK_MINUS;
> +	if (!chunk->left_count)
> +		return CHUNK_PLUS;
> +	if (chunk->left_count != chunk->right_count)
> +		return CHUNK_ERROR;
> +	return CHUNK_SAME;
> +}
> +
>  static int
>  read_at(FILE *f, off_t at_pos, unsigned char *buf, size_t len)
>  {
> blob - fa9dc982956eab298f65b4b9ffca114a46b50b76
> file + lib/diff_main.h
> --- lib/diff_main.h
> +++ lib/diff_main.h
> @@ -28,8 +28,8 @@ struct diff_atom {
>  struct diff_atom {
>  	struct diff_data *root; /* back pointer to root diff data */
>  
> -	off_t pos;		/* if not memory-mapped */
> -	const uint8_t *at;	/* if memory-mapped */
> +	off_t pos;		/* set whether memory-mapped or not */
> +	const uint8_t *at;	/* only set if memory-mapped */
>  	off_t len;
>  
>  	/* This hash is just a very cheap speed up for finding *mismatching*
> @@ -142,6 +142,16 @@ struct diff_state;
>  	diff_chunk_arraylist_t chunks;
>  };
>  
> +enum diff_chunk_type {
> +	CHUNK_EMPTY,
> +	CHUNK_PLUS,
> +	CHUNK_MINUS,
> +	CHUNK_SAME,
> +	CHUNK_ERROR,
> +};
> +
> +enum diff_chunk_type diff_chunk_type(const struct diff_chunk *c);
> +
>  struct diff_state;
>  
>  /* Signature of a utility function to divide a file into diff atoms.
> blob - 010ea00d11c12ab19a0251310a86b1a87bc8a3e9
> file + lib/worktree.c
> --- lib/worktree.c
> +++ lib/worktree.c
> @@ -1561,17 +1561,14 @@ get_modified_file_content_status(unsigned char *status
>  		struct diff_chunk *c;
>  		struct diff_chunk_context cc = {};
>  		off_t pos;
> -		int clc, crc;
>  
>  		/*
>  		 * We can optimise a little by advancing straight
>  		 * to the next chunk if this one has no added lines.
>  		 */
>  		c = diff_chunk_get(r, n);
> -		clc = diff_chunk_get_left_count(c);
> -		crc = diff_chunk_get_right_count(c);
>  
> -		if (!crc || crc == clc) {
> +		if (diff_chunk_type(c) != CHUNK_PLUS) {
>  			nchunks_parsed = 1;
>  			continue;  /* removed or unchanged lines */
>  		}
> 
> -- 
> Mark Jamsek <fnc.bsdbox.org|got.bsdbox.org>
> GPG: F2FF 13DE 6A06 C471 CA80  E6E2 2930 DC66 86EE CF68
>