Subject: [PATCH v3 06/14] apply: only pass required data to gitdiff_* functions

From: Thomas Gummerer <[email-masked]>
Date: Mon, 8 Jul 2019 17:33:07 +0100

Currently the 'gitdiff_*()' functions take 'struct apply_state' as
parameter, even though they only needs the root, linenr and p_value
from that struct.

These functions are in the callchain of 'parse_git_header()', which we
want to make more generally useful in a subsequent commit.  To make
that happen we only want to pass in the required data to
'parse_git_header()', and not the whole 'struct apply_state', and thus
we want functions in the callchain of 'parse_git_header()' to only
take arguments they really need.

As these functions are called in a loop using their function pointers,
each function needs to be passed all the parameters even if only one
of the functions actually needs it.  We therefore pass this data along
in a struct to avoid adding too many unused parameters to each
function and making the code very verbose in the process.

Signed-off-by: Thomas Gummerer <[email-masked]>
---
 apply.c | 59 ++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 35 insertions(+), 24 deletions(-)

diff --git a/apply.c b/apply.c
index 3cd4e3d3b3..468f1d3fee 100644
--- a/apply.c
+++ b/apply.c
@@ -22,6 +22,12 @@
 #include "rerere.h"
 #include "apply.h"
 
+struct parse_git_header_state {
+	struct strbuf *root;
+	int linenr;
+	int p_value;
+};
+
 static void git_apply_config(void)
 {
 	git_config_get_string_const("apply.whitespace", &apply_default_whitespace);
@@ -914,7 +920,7 @@ static int parse_traditional_patch(struct apply_state *state,
 	return 0;
 }
 
-static int gitdiff_hdrend(struct apply_state *state,
+static int gitdiff_hdrend(struct parse_git_header_state *state,
 			  const char *line,
 			  struct patch *patch)
 {
@@ -933,14 +939,14 @@ static int gitdiff_hdrend(struct apply_state *state,
 #define DIFF_OLD_NAME 0
 #define DIFF_NEW_NAME 1
 
-static int gitdiff_verify_name(struct apply_state *state,
+static int gitdiff_verify_name(struct parse_git_header_state *state,
 			       const char *line,
 			       int isnull,
 			       char **name,
 			       int side)
 {
 	if (!*name && !isnull) {
-		*name = find_name(&state->root, line, NULL, state->p_value, TERM_TAB);
+		*name = find_name(state->root, line, NULL, state->p_value, TERM_TAB);
 		return 0;
 	}
 
@@ -949,7 +955,7 @@ static int gitdiff_verify_name(struct apply_state *state,
 		if (isnull)
 			return error(_("git apply: bad git-diff - expected /dev/null, got %s on line %d"),
 				     *name, state->linenr);
-		another = find_name(&state->root, line, NULL, state->p_value, TERM_TAB);
+		another = find_name(state->root, line, NULL, state->p_value, TERM_TAB);
 		if (!another || strcmp(another, *name)) {
 			free(another);
 			return error((side == DIFF_NEW_NAME) ?
@@ -965,7 +971,7 @@ static int gitdiff_verify_name(struct apply_state *state,
 	return 0;
 }
 
-static int gitdiff_oldname(struct apply_state *state,
+static int gitdiff_oldname(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
@@ -974,7 +980,7 @@ static int gitdiff_oldname(struct apply_state *state,
 				   DIFF_OLD_NAME);
 }
 
-static int gitdiff_newname(struct apply_state *state,
+static int gitdiff_newname(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
@@ -992,21 +998,21 @@ static int parse_mode_line(const char *line, int linenr, unsigned int *mode)
 	return 0;
 }
 
-static int gitdiff_oldmode(struct apply_state *state,
+static int gitdiff_oldmode(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
 	return parse_mode_line(line, state->linenr, &patch->old_mode);
 }
 
-static int gitdiff_newmode(struct apply_state *state,
+static int gitdiff_newmode(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
 	return parse_mode_line(line, state->linenr, &patch->new_mode);
 }
 
-static int gitdiff_delete(struct apply_state *state,
+static int gitdiff_delete(struct parse_git_header_state *state,
 			  const char *line,
 			  struct patch *patch)
 {
@@ -1016,7 +1022,7 @@ static int gitdiff_delete(struct apply_state *state,
 	return gitdiff_oldmode(state, line, patch);
 }
 
-static int gitdiff_newfile(struct apply_state *state,
+static int gitdiff_newfile(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
@@ -1026,47 +1032,47 @@ static int gitdiff_newfile(struct apply_state *state,
 	return gitdiff_newmode(state, line, patch);
 }
 
-static int gitdiff_copysrc(struct apply_state *state,
+static int gitdiff_copysrc(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
 	patch->is_copy = 1;
 	free(patch->old_name);
-	patch->old_name = find_name(&state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
+	patch->old_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
 	return 0;
 }
 
-static int gitdiff_copydst(struct apply_state *state,
+static int gitdiff_copydst(struct parse_git_header_state *state,
 			   const char *line,
 			   struct patch *patch)
 {
 	patch->is_copy = 1;
 	free(patch->new_name);
-	patch->new_name = find_name(&state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
+	patch->new_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
 	return 0;
 }
 
-static int gitdiff_renamesrc(struct apply_state *state,
+static int gitdiff_renamesrc(struct parse_git_header_state *state,
 			     const char *line,
 			     struct patch *patch)
 {
 	patch->is_rename = 1;
 	free(patch->old_name);
-	patch->old_name = find_name(&state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
+	patch->old_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
 	return 0;
 }
 
-static int gitdiff_renamedst(struct apply_state *state,
+static int gitdiff_renamedst(struct parse_git_header_state *state,
 			     const char *line,
 			     struct patch *patch)
 {
 	patch->is_rename = 1;
 	free(patch->new_name);
-	patch->new_name = find_name(&state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
+	patch->new_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
 	return 0;
 }
 
-static int gitdiff_similarity(struct apply_state *state,
+static int gitdiff_similarity(struct parse_git_header_state *state,
 			      const char *line,
 			      struct patch *patch)
 {
@@ -1076,7 +1082,7 @@ static int gitdiff_similarity(struct apply_state *state,
 	return 0;
 }
 
-static int gitdiff_dissimilarity(struct apply_state *state,
+static int gitdiff_dissimilarity(struct parse_git_header_state *state,
 				 const char *line,
 				 struct patch *patch)
 {
@@ -1086,7 +1092,7 @@ static int gitdiff_dissimilarity(struct apply_state *state,
 	return 0;
 }
 
-static int gitdiff_index(struct apply_state *state,
+static int gitdiff_index(struct parse_git_header_state *state,
 			 const char *line,
 			 struct patch *patch)
 {
@@ -1126,7 +1132,7 @@ static int gitdiff_index(struct apply_state *state,
  * This is normal for a diff that doesn't change anything: we'll fall through
  * into the next diff. Tell the parser to break out.
  */
-static int gitdiff_unrecognized(struct apply_state *state,
+static int gitdiff_unrecognized(struct parse_git_header_state *state,
 				const char *line,
 				struct patch *patch)
 {
@@ -1322,6 +1328,7 @@ static int parse_git_header(struct apply_state *state,
 			    struct patch *patch)
 {
 	unsigned long offset;
+	struct parse_git_header_state parse_hdr_state;
 
 	/* A git diff has explicit new/delete information, so we don't guess */
 	patch->is_new = 0;
@@ -1343,10 +1350,14 @@ static int parse_git_header(struct apply_state *state,
 	line += len;
 	size -= len;
 	state->linenr++;
+	parse_hdr_state.root = &state->root;
+	parse_hdr_state.linenr = state->linenr;
+	parse_hdr_state.p_value = state->p_value;
+
 	for (offset = len ; size > 0 ; offset += len, size -= len, line += len, state->linenr++) {
 		static const struct opentry {
 			const char *str;
-			int (*fn)(struct apply_state *, const char *, struct patch *);
+			int (*fn)(struct parse_git_header_state *, const char *, struct patch *);
 		} optable[] = {
 			{ "@@ -", gitdiff_hdrend },
 			{ "--- ", gitdiff_oldname },
@@ -1377,7 +1388,7 @@ static int parse_git_header(struct apply_state *state,
 			int res;
 			if (len < oplen || memcmp(p->str, line, oplen))
 				continue;
-			res = p->fn(state, line + oplen, patch);
+			res = p->fn(&parse_hdr_state, line + oplen, patch);
 			if (res < 0)
 				return -1;
 			if (check_header_line(state->linenr, patch))
-- 
2.22.0.510.g264f2c817a