Use tab-size from EditorConfig

For projects that use tab width != 8, we need to set the "tab-size"
config option.  Many projects these days state their preference in a
".editorconfig" file.

Add an optional dependency to the EditorConfig library to read such
files. Prefer the tab-size from EditorConfig, over the "tab-size"
config option. Not being able to override the EditorConfig tab-size
seems counterintuitive but I don't see why someone would want that, so
I'd wait until someone complains. If we want that we could implement a
"tab-size-from-editorconfig" option that defaults to true.

Implementation hiccups:

Unfortunately, we currently don't always fill "repo.worktree" - only
in the special cases where either of $GIT_WORK_TREE or core.worktree is
defined. Hence we need to run an extra "git rev-parse --show-toplevel".
We do run "git rev-parse --is-inside-worktree [...]" elsewhere but
we can't add "--show-toplevel" to that call or else we'd fail when
run in bare repos.

The use of diff_get_pathname() is a bit wasteful, we should probably
refactor this to just remember the last line of type LINE_DIFF_ADD_FILE
or LINE_DIFF_HEADER.

Closes jonas#840

configure.ac

@@ -58,6 +58,16 @@ AS_IF([test "x$with_pcre" != xno], [
 	])
 ])
 
+dnl Check for EditorConfig library
+AC_ARG_WITH(editorconfig, [AS_HELP_STRING([--without-editorconfig], [do not use the EditorConfig library])])
+AS_IF([test "x$with_editorconfig" != xno], [
+	AC_CHECK_HEADERS([editorconfig/editorconfig.h])
+	AS_IF([test "x$ac_cv_header_editorconfig_editorconfig_h" = xyes], [
+		AC_DEFINE([HAVE_EDITORCONFIG], [1], [Define if you have EditorConfig])
+		LIBS="$LIBS -leditorconfig"
+	])
+])
+
 dnl OS-specific
 case $(uname -s 2>/dev/null || echo unknown) in "OS400")
 	AC_CHECK_LIB(util, main, [LIBS="$LIBS -lutil"], AC_MSG_ERROR([Please install the libutil-devel package]))

include/tig/diff.h

@@ -16,7 +16,16 @@
 
 #include "tig/view.h"
 
+#if defined HAVE_EDITORCONFIG
+struct diff_common_state {
+		uint8_t tab_size;
+};
+#endif
+
 struct diff_state {
+#if defined HAVE_EDITORCONFIG
+	struct diff_common_state common;
+#endif
 	bool after_commit_title;
 	bool after_diff;
 	bool reading_diff_chunk;

include/tig/pager.h

@@ -18,10 +18,12 @@
 
 bool pager_get_column_data(struct view *view, const struct line *line, struct view_column_data *column_data);
 bool pager_read(struct view *view, struct buffer *buf, bool force_stop);
-bool pager_common_read(struct view *view, const char *data, enum line_type type, struct line **line);
+bool pager_common_read(struct view *view, const char *data, enum line_type type, bool is_diff, struct line **line);
 enum request pager_request(struct view *view, enum request request, struct line *line);
 void pager_select(struct view *view, struct line *line);
 
+uint8_t editorconfig_tab_size(const char file[]);
+
 extern struct view pager_view;
 
 static inline void

include/tig/view.h

@@ -39,6 +39,9 @@ struct box {
 struct line {
 	enum line_type type;
 	unsigned int lineno:24;
+#if defined HAVE_EDITORCONFIG
+	unsigned int tab_size:8;
+#endif
 
 	/* State flags */
 	unsigned int selected:1;

src/blob.c

@@ -14,6 +14,7 @@
 #include "tig/refdb.h"
 #include "tig/parse.h"
 #include "tig/repo.h"
+#include "tig/diff.h"
 #include "tig/display.h"
 #include "tig/draw.h"
 #include "tig/ui.h"
@@ -22,6 +23,9 @@
 #include "tig/blob.h"
 
 struct blob_state {
+#if defined HAVE_EDITORCONFIG
+	struct diff_common_state common;
+#endif
 	char commit[SIZEOF_REF];
 	const char *file;
 };
@@ -90,6 +94,10 @@ blob_open(struct view *view, enum open_flags flags)
 	else
 		string_copy_rev(view->ref, view->ops->id);
 
+#if defined HAVE_EDITORCONFIG
+	state->common.tab_size = editorconfig_tab_size(view->env->file);
+#endif
+
 	return begin_update(view, NULL, argv, flags);
 }
 
@@ -104,7 +112,7 @@ blob_read(struct view *view, struct buffer *buf, bool force_stop)
 		return true;
 	}
 
-	return pager_common_read(view, buf->data, LINE_DEFAULT, NULL);
+	return pager_common_read(view, buf->data, LINE_DEFAULT, false, NULL);
 }
 
 static void

src/diff.c

@@ -263,7 +263,7 @@ diff_common_read_diff_wdiff_group(struct diff_stat_context *context)
 	return true;
 }
 
-static bool
+static struct line *
 diff_common_read_diff_wdiff(struct view *view, const char *text)
 {
 	struct diff_stat_context context = { text, LINE_DEFAULT };
@@ -282,7 +282,7 @@ diff_common_read_diff_wdiff(struct view *view, const char *text)
 	return diff_common_add_line(view, text, LINE_DEFAULT, &context);
 }
 
-static bool
+static struct line *
 diff_common_highlight(struct view *view, const char *text, enum line_type type)
 {
 	struct diff_stat_context context = { text, type, true };
@@ -303,6 +303,7 @@ bool
 diff_common_read(struct view *view, const char *data, struct diff_state *state)
 {
 	enum line_type type = get_line_type(data);
+	struct line *line;
 
 	/* ADD2 and DEL2 are only valid in combined diff hunks */
 	if (!state->combined_diff && (type == LINE_DIFF_ADD2 || type == LINE_DIFF_DEL2))
@@ -334,7 +335,7 @@ diff_common_read(struct view *view, const char *data, struct diff_state *state)
 	}
 
 	if (!state->after_commit_title && !prefixcmp(data, "    ")) {
-		struct line *line = add_line_text(view, data, LINE_DEFAULT);
+		line = add_line_text(view, data, LINE_DEFAULT);
 
 		if (line)
 			line->commit_title = 1;
@@ -345,13 +346,11 @@ diff_common_read(struct view *view, const char *data, struct diff_state *state)
 	if (type == LINE_DIFF_HEADER) {
 		state->after_diff = true;
 		state->reading_diff_chunk = false;
-
 	} else if (type == LINE_DIFF_CHUNK) {
 		const int len = chunk_header_marker_length(data);
 		const char *context = strstr(data + len, "@@");
-		struct line *line =
-			context ? add_line_text_at(view, view->lines, data, LINE_DIFF_CHUNK, len)
-				: NULL;
+		line = context ? add_line_text_at(view, view->lines, data, LINE_DIFF_CHUNK, len)
+			       : NULL;
 		struct box *box;
 
 		if (!line)
@@ -363,21 +362,34 @@ diff_common_read(struct view *view, const char *data, struct diff_state *state)
 		box->cell[box->cells++].type = LINE_DIFF_STAT;
 		state->combined_diff = (len > 2);
 		state->reading_diff_chunk = true;
-		return true;
+		goto set_tab_width;
 
 	} else if (type == LINE_COMMIT) {
 		state->reading_diff_chunk = false;
 
 	} else if (state->highlight && strchr(data, 0x1b)) {
-		return diff_common_highlight(view, data, type);
-
+		if (!(line = diff_common_highlight(view, data, type)))
+			return false;
+		goto set_tab_width;
 	} else if (opt_word_diff && state->reading_diff_chunk &&
 		   /* combined diff format is not using word diff */
 		   !state->combined_diff) {
-		return diff_common_read_diff_wdiff(view, data);
+		if (!(line = diff_common_read_diff_wdiff(view, data)))
+			return false;
+		goto set_tab_width;
 	}
 
-	return pager_common_read(view, data, type, NULL);
+	return pager_common_read(view, data, type, true, &line);
+
+set_tab_width:
+#if defined HAVE_EDITORCONFIG
+	if (type == LINE_DIFF_CHUNK || type == LINE_DEFAULT ||
+	    type == LINE_DIFF_ADD || type == LINE_DIFF_ADD2 ||
+	    type == LINE_DIFF_DEL || type == LINE_DIFF_DEL2) {
+		line->tab_size = state->common.tab_size;
+	}
+#endif
+	return true;
 }
 
 static bool

src/draw.c

@@ -471,6 +471,12 @@ view_column_draw(struct view *view, struct line *line, unsigned int lineno)
 {
 	struct view_column *column = view->columns;
 	struct view_column_data column_data = {0};
+	int tab_size;
+#if defined HAVE_EDITORCONFIG
+	tab_size = line->tab_size ? line->tab_size : opt_tab_size;
+#else
+	tab_size = opt_tab_size;
+#endif
 
 	if (!view->ops->get_column_data(view, line, &column_data))
 		return true;
@@ -582,13 +588,13 @@ view_column_draw(struct view *view, struct line *line, unsigned int lineno)
 						indent = 0;
 					}
 
-					if (draw_textn(view, cell->type, text, length, opt_tab_size))
+					if (draw_textn(view, cell->type, text, length, tab_size))
 						return true;
 
 					text += length;
 				}
 
-			} else if (draw_text(view, type, text, opt_tab_size)) {
+			} else if (draw_text(view, type, text, tab_size)) {
 				return true;
 			}
 		}

src/log.c

@@ -19,6 +19,9 @@
 #include "tig/pager.h"
 
 struct log_state {
+#if defined HAVE_EDITORCONFIG
+	struct diff_common_state common;
+#endif
 	/* Used for tracking when we need to recalculate the previous
 	 * commit, for example when the user scrolls up or uses the page
 	 * up/down in the log view. */
@@ -142,7 +145,7 @@ log_read(struct view *view, struct buffer *buf, bool force_stop)
 		state->reading_diff_stat = false;
 	}
 
-	if (!pager_common_read(view, data, type, &line))
+	if (!pager_common_read(view, data, type, true, &line))
 		return false;
 	if (line && state->graph_indent)
 		line->graph_indent = 1;

src/pager.c

@@ -15,12 +15,16 @@
 #include "tig/pager.h"
 #include "tig/options.h"
 #include "tig/request.h"
+#include "tig/repo.h"
 #include "tig/line.h"
 #include "tig/keys.h"
 #include "tig/display.h"
 #include "tig/view.h"
 #include "tig/draw.h"
 #include "tig/diff.h"
+#if defined HAVE_EDITORCONFIG
+	#include "editorconfig/editorconfig.h"
+#endif
 
 /*
  * Pager backend
@@ -75,12 +79,19 @@ pager_wrap_line(struct view *view, const char *data, enum line_type type)
 	bool has_first_line = false;
 	size_t datalen = strlen(data);
 	size_t lineno = 0;
+	int tab_size;
+#if defined HAVE_EDITORCONFIG
+	struct diff_common_state *state = view->private;
+	tab_size = state->tab_size ? state->tab_size : opt_tab_size;
+#else
+	tab_size = opt_tab_size;
+#endif
 
 	while (datalen > 0 || !has_first_line) {
 		int width;
 		int trimmed;
 		bool wrapped = !!first_line;
-		size_t linelen = utf8_length(&data, datalen, 0, &width, view->width, &trimmed, wrapped, opt_tab_size);
+		size_t linelen = utf8_length(&data, datalen, 0, &width, view->width, &trimmed, wrapped, tab_size);
 		struct line *line;
 
 		line = add_line_text_at_(view, view->lines, data, linelen, type, 1, wrapped);
@@ -105,7 +116,7 @@ pager_wrap_line(struct view *view, const char *data, enum line_type type)
 }
 
 bool
-pager_common_read(struct view *view, const char *data, enum line_type type, struct line **line_ptr)
+pager_common_read(struct view *view, const char *data, enum line_type type, bool is_diff, struct line **line_ptr)
 {
 	struct line *line;
 
@@ -130,7 +141,18 @@ pager_common_read(struct view *view, const char *data, enum line_type type, stru
 			data++;
 		add_pager_refs(view, data);
 	}
-
+#if defined HAVE_EDITORCONFIG
+	else if (is_diff && type == LINE_DIFF_ADD_FILE) {
+		struct diff_common_state *state = view->private;
+		const char *file = diff_get_pathname(view, line, false);
+		state->tab_size = file ? editorconfig_tab_size(file) : 0;
+	} else if  (type == LINE_DIFF_CHUNK || type == LINE_DEFAULT ||
+		    type == LINE_DIFF_ADD || type == LINE_DIFF_ADD2 ||
+		    type == LINE_DIFF_DEL || type == LINE_DIFF_DEL2) {
+		struct diff_common_state *state = view->private;
+		line->tab_size = state->tab_size;
+	}
+#endif
 	return true;
 }
 
@@ -208,6 +230,64 @@ pager_open(struct view *view, enum open_flags flags)
 	return diff_init_highlight(view, view->private);
 }
 
+#if defined HAVE_EDITORCONFIG
+static editorconfig_handle the_editorconfig_handle;
+
+static void
+destroy_the_editorconfig_handle() {
+	editorconfig_handle_destroy(the_editorconfig_handle);
+}
+
+uint8_t
+editorconfig_tab_size(const char file[]) {
+	static argv_string abspath;
+	static int worktree_path_size;
+	int tab_size, i, n;
+	const char *indent_size_str = NULL, *tab_width_str = NULL;
+	const char *name, *value;
+
+	if (!*file)
+		return 0;
+
+	if (!*abspath) {
+		the_editorconfig_handle = editorconfig_handle_init();
+		atexit(destroy_the_editorconfig_handle);
+
+		if (!*repo.worktree) {
+			const char *rev_parse_argv[] = {
+				"git", "rev-parse", "--show-toplevel", NULL
+			};
+			if (!io_run_buf(rev_parse_argv, repo.worktree, sizeof(repo.worktree) - strlen("/"), NULL, false))
+				die("Not a git repository"); // should never happen
+		}
+
+		strcpy(abspath, repo.worktree);
+		abspath[strlen(abspath)] = '/';
+		worktree_path_size = strlen(abspath);
+	}
+
+	if (worktree_path_size + strlen(file) + 1 >= sizeof(abspath))
+		return 0;
+	strcpy(abspath + worktree_path_size, file);
+	if (editorconfig_parse(abspath, the_editorconfig_handle))
+		return 0;
+
+	n = editorconfig_handle_get_name_value_count(the_editorconfig_handle);
+	for (i = 0; i < n; i++) {
+		editorconfig_handle_get_name_value(the_editorconfig_handle, i, &name, &value);
+		if (!strcmp(name, "indent_size"))
+			indent_size_str = value;
+		if (!strcmp(name, "tab_width"))
+			tab_width_str = value;
+	}
+	if (!tab_width_str)
+		tab_width_str = indent_size_str;
+	if (!tab_width_str || parse_int(&tab_size, tab_width_str, 1, 255) != SUCCESS)
+		return 0;
+	return tab_size;
+}
+#endif
+
 static struct view_ops pager_ops = {
 	"line",
 	"",

src/stage.c

@@ -760,6 +760,11 @@ stage_open(struct view *view, enum open_flags flags)
 	if (stage_line_type != LINE_STAT_UNTRACKED)
 		diff_save_line(view, &state->diff, flags);
 
+#if defined HAVE_EDITORCONFIG
+	if (stage_line_type == LINE_STAT_UNTRACKED)
+		state->diff.common.tab_size = editorconfig_tab_size(stage_status.new.name);
+#endif
+
 	view->vid[0] = 0;
 	code = begin_update(view, repo.exec_dir, argv, flags);
 	if (code == SUCCESS && stage_line_type != LINE_STAT_UNTRACKED) {
@@ -777,7 +782,7 @@ stage_read(struct view *view, struct buffer *buf, bool force_stop)
 	struct stage_state *state = view->private;
 
 	if (stage_line_type == LINE_STAT_UNTRACKED)
-		return pager_common_read(view, buf ? buf->data : NULL, LINE_DEFAULT, NULL);
+		return pager_common_read(view, buf ? buf->data : NULL, LINE_DEFAULT, false, NULL);
 
 	if (!buf) {
 		if (!diff_done_highlight(&state->diff)) {