[PATCH] diff: use strncmp to check for "diff." prefix

["Rose via GitGitGadget" <gitgitgadget@gmail.com>]

From: Seija Kijin <doremylover123@gmail.com>

This would be a lot more efficient than
checking for the full string, as
so many of the accepted values
begin with "diff."

This allows the computer to skip most checks
if var did not start with diff at all.

It would also let us add more "diff." strings
in the future without having to duplicate
these 5 character so many times.

Signed-off-by: Seija Kijin <doremylover123@gmail.com>
---
    diff: use strncmp to check for "diff." prefix
    
    This would be a lot more efficient than checking for the full string, as
    so many of the accepted values begin with "diff."
    
    This allows the computer to skip most checks if var did not start with
    diff at all.
    
    It would also let us add more "diff." strings in the future without
    having to duplicate these 5 character so many times.
    
    Signed-off-by: Seija Kijin doremylover123@gmail.com

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1403%2FAtariDreams%2Fdiff-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1403/AtariDreams/diff-v1
Pull-Request: https://github.com/git/git/pull/1403

 diff.c | 158 +++++++++++++++++++++++++++++++--------------------------
 1 file changed, 87 insertions(+), 71 deletions(-)

diff --git a/diff.c b/diff.c
index 4dfe824c858..e0fddbe6009 100644
--- a/diff.c
+++ b/diff.c
@@ -345,82 +345,98 @@ static unsigned parse_color_moved_ws(const char *arg)
 
 int git_diff_ui_config(const char *var, const char *value, void *cb)
 {
-	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
+	if (!strcmp(var, "color.diff")) {
 		diff_use_color_default = git_config_colorbool(var, value);
 		return 0;
 	}
-	if (!strcmp(var, "diff.colormoved")) {
-		int cm = parse_color_moved(value);
-		if (cm < 0)
-			return -1;
-		diff_color_moved_default = cm;
-		return 0;
-	}
-	if (!strcmp(var, "diff.colormovedws")) {
-		unsigned cm = parse_color_moved_ws(value);
-		if (cm & COLOR_MOVED_WS_ERROR)
-			return -1;
-		diff_color_moved_ws_default = cm;
-		return 0;
-	}
-	if (!strcmp(var, "diff.context")) {
-		diff_context_default = git_config_int(var, value);
-		if (diff_context_default < 0)
-			return -1;
-		return 0;
-	}
-	if (!strcmp(var, "diff.interhunkcontext")) {
-		diff_interhunk_context_default = git_config_int(var, value);
-		if (diff_interhunk_context_default < 0)
-			return -1;
-		return 0;
-	}
-	if (!strcmp(var, "diff.renames")) {
-		diff_detect_rename_default = git_config_rename(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "diff.autorefreshindex")) {
-		diff_auto_refresh_index = git_config_bool(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "diff.mnemonicprefix")) {
-		diff_mnemonic_prefix = git_config_bool(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "diff.noprefix")) {
-		diff_no_prefix = git_config_bool(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "diff.relative")) {
-		diff_relative = git_config_bool(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "diff.statgraphwidth")) {
-		diff_stat_graph_width = git_config_int(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "diff.external"))
-		return git_config_string(&external_diff_cmd_cfg, var, value);
-	if (!strcmp(var, "diff.wordregex"))
-		return git_config_string(&diff_word_regex_cfg, var, value);
-	if (!strcmp(var, "diff.orderfile"))
-		return git_config_pathname(&diff_order_file_cfg, var, value);
 
-	if (!strcmp(var, "diff.ignoresubmodules"))
-		handle_ignore_submodules_arg(&default_diff_options, value);
-
-	if (!strcmp(var, "diff.submodule")) {
-		if (parse_submodule_params(&default_diff_options, value))
-			warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
-				value);
-		return 0;
-	}
+	if (!strncmp(var, "diff.", 5)) {
+		const char *tmp = var + 5;
+		if (!strcmp(var, "color")) {
+			diff_use_color_default =
+				git_config_colorbool(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "colormoved")) {
+			int cm = parse_color_moved(value);
+			if (cm < 0)
+				return -1;
+			diff_color_moved_default = cm;
+			return 0;
+		}
+		if (!strcmp(tmp, "colormovedws")) {
+			unsigned cm = parse_color_moved_ws(value);
+			if (cm & COLOR_MOVED_WS_ERROR)
+				return -1;
+			diff_color_moved_ws_default = cm;
+			return 0;
+		}
+		if (!strcmp(tmp, "context")) {
+			diff_context_default = git_config_int(var, value);
+			if (diff_context_default < 0)
+				return -1;
+			return 0;
+		}
+		if (!strcmp(tmp, "interhunkcontext")) {
+			diff_interhunk_context_default =
+				git_config_int(var, value);
+			if (diff_interhunk_context_default < 0)
+				return -1;
+			return 0;
+		}
+		if (!strcmp(tmp, "renames")) {
+			diff_detect_rename_default =
+				git_config_rename(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "autorefreshindex")) {
+			diff_auto_refresh_index = git_config_bool(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "mnemonicprefix")) {
+			diff_mnemonic_prefix = git_config_bool(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "noprefix")) {
+			diff_no_prefix = git_config_bool(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "relative")) {
+			diff_relative = git_config_bool(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "statgraphwidth")) {
+			diff_stat_graph_width = git_config_int(var, value);
+			return 0;
+		}
+		if (!strcmp(tmp, "external"))
+			return git_config_string(&external_diff_cmd_cfg, var,
+						 value);
+		if (!strcmp(tmp, "wordregex"))
+			return git_config_string(&diff_word_regex_cfg, var,
+						 value);
+		if (!strcmp(tmp, "orderfile"))
+			return git_config_pathname(&diff_order_file_cfg, var,
+						   value);
+
+		if (!strcmp(tmp, "ignoresubmodules"))
+			handle_ignore_submodules_arg(&default_diff_options,
+						     value);
+
+		if (!strcmp(tmp, "submodule")) {
+			if (parse_submodule_params(&default_diff_options,
+						   value))
+				warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
+					value);
+			return 0;
+		}
 
-	if (!strcmp(var, "diff.algorithm")) {
-		diff_algorithm = parse_algorithm_value(value);
-		if (diff_algorithm < 0)
-			return -1;
-		return 0;
+		if (!strcmp(tmp, "algorithm")) {
+			diff_algorithm = parse_algorithm_value(value);
+			if (diff_algorithm < 0)
+				return -1;
+			return 0;
+		}
 	}
 
 	if (git_color_config(var, value, cb) < 0)

base-commit: 7c2ef319c52c4997256f5807564523dfd4acdfc7
-- 
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