[PATCH 2/2] alpm version diff coloring

[David Gustavsson]

Use non-alphanumerics as branching points for diff coloring.

Signed-off-by: David Gustavsson <david.e.gustavsson at gmail.com>
---
 src/pacman/util.c | 83 +++++++++++++++++++++++++++++++++--------------
 src/pacman/util.h |  1 +
 2 files changed, 60 insertions(+), 24 deletions(-)

diff --git a/src/pacman/util.c b/src/pacman/util.c
index 10d7c573..242af8b2 100644
--- a/src/pacman/util.c
+++ b/src/pacman/util.c
@@ -34,6 +34,7 @@
 #include <limits.h>
 #include <wchar.h>
 #include <wctype.h>
+#include <ctype.h>
 #ifdef HAVE_TERMIOS_H
 #include <termios.h> /* tcflush */
 #endif
@@ -840,10 +841,13 @@ static alpm_list_t *create_verbose_row(pm_target_t *target)
 {
 	char *str;
 	off_t size = 0;
-  size_t i = 0;
+	int split;
 	double human_size;
 	const char *label;
-  const char *version;
+  const char *old_version_in;
+	const char *new_version_in;
+	char *old_version;
+	char *new_version;
 	alpm_list_t *ret = NULL;
 
 	/* a row consists of the package name, */
@@ -859,24 +863,29 @@ static alpm_list_t *create_verbose_row(pm_target_t *target)
 	}
 	add_table_cell(&ret, str, CELL_NORMAL | CELL_FREE);
 
+
 	/* old and new versions */
-  version = alpm_pkg_get_version(target->remove);
-  char old_version[strlen(version) + strlen(config->colstr.diffrem) + strlen(config->colstr.nocolor) + 1];
-  memcpy(old_version, (char *)version, strlen(version) + 1);
-  version = alpm_pkg_get_version(target->install);
-  char new_version[strlen(version) + strlen(config->colstr.diffadd) + strlen(config->colstr.nocolor) + 1];
-  memcpy(new_version, (char *)version, strlen(version) + 1);
-
-  i = 0;
-  while (old_version[i] != '\0' && new_version[i] != '\0' && old_version[i] == new_version[i]) {
-    i++;
-  }
-  insertstring(old_version, config->colstr.diffrem, i);
-  insertstring(new_version, config->colstr.diffadd, i);
-  snprintf(old_version + i + strlen(old_version + i),
-      strlen(config->colstr.nocolor) + 1, "%s", config->colstr.nocolor);
-  snprintf(new_version + i + strlen(new_version + i),
-      strlen(config->colstr.nocolor) + 1, "%s", config->colstr.nocolor);
+	if (target->remove) {
+		old_version_in = alpm_pkg_get_version(target->remove);
+	} else {
+		old_version_in = "";
+	}
+  old_version = malloc((strlen(old_version_in) + strlen(config->colstr.diffrem) + strlen(config->colstr.nocolor) + 1)*sizeof(char));
+  memcpy(old_version, (char *)old_version_in, strlen(old_version_in) + 1);
+
+	if (target->install) {
+		new_version_in = alpm_pkg_get_version(target->install);
+	} else {
+		new_version_in = "";
+	}
+  new_version = malloc((strlen(new_version_in) + strlen(config->colstr.diffadd) + strlen(config->colstr.nocolor) + 1)*sizeof(char));
+  memcpy(new_version, (char *)new_version_in, strlen(new_version_in) + 1);
+
+	split = alpm_diff(old_version_in, new_version_in);
+  insertstring(old_version, config->colstr.diffrem, split);
+	insertstring(old_version, config->colstr.nocolor, strlen(old_version));
+  insertstring(new_version, config->colstr.diffadd, split);
+	insertstring(new_version, config->colstr.nocolor, strlen(new_version));
 
   pm_asprintf(&str, "%s", old_version);
 	add_table_cell(&ret, str, CELL_NORMAL | CELL_FREE);
@@ -884,6 +893,9 @@ static alpm_list_t *create_verbose_row(pm_target_t *target)
   pm_asprintf(&str, "%s", new_version);
 	add_table_cell(&ret, str, CELL_NORMAL | CELL_FREE);
 
+	free(old_version);
+	free(new_version);
+
 	/* and size */
 	size -= target->remove ? alpm_pkg_get_isize(target->remove) : 0;
 	size += target->install ? alpm_pkg_get_isize(target->install) : 0;
@@ -1878,11 +1890,34 @@ void console_erase_line(void)
 	printf("\x1B[K");
 }
 
-/* inserts string insert into string at index i, modifying string */
+/* inserts string insert into string after index i, modifying string */
 void insertstring(char *string, const char *insert, size_t i)
 {
-  char temp[strlen(string) - i + 1];
-  memcpy(temp, string + i, strlen(string + i) + 1);
-  memcpy(string + i, insert, strlen(insert) + 1);
-  memcpy(string + i + strlen(insert), temp, strlen(temp) + 1);
+  char *temp = malloc((strlen(string) - i)*sizeof(char));
+  memcpy(temp, string + i + 1, strlen(string + i));
+  memcpy(string + i + 1, insert, strlen(insert) + 1);
+  memcpy(string + i + strlen(insert) + 1, temp, strlen(temp) + 1);
+	free(temp);
+}
+
+int alpm_diff(const char *a, const char *b)
+{
+	/*
+	 * Find the index of the last non-alphanumeric character
+	 * before `a` and `b` differ
+	 */
+	int i = 0;
+	int split = -1;
+	while(a[i] == b[i]) {
+		if(a[i] == '\0') {
+			split = i;
+			return split;
+		}
+		if(isalnum(a[i]) == 0) {
+			/* Non-alphanumeric character */
+			split = i;
+		}
+		i++;
+	}
+	return split;
 }
diff --git a/src/pacman/util.h b/src/pacman/util.h
index 003961eb..afac74c1 100644
--- a/src/pacman/util.h
+++ b/src/pacman/util.h
@@ -89,6 +89,7 @@ void console_cursor_move_end(void);
 /* Erases line from the current cursor position till the end of the line */
 void console_erase_line(void);
 void insertstring(char *string, const char *insert, size_t i);
+int alpm_diff(const char *a, const char *b);
 
 int pm_printf(alpm_loglevel_t level, const char *format, ...) __attribute__((format(printf,2,3)));
 int pm_asprintf(char **string, const char *format, ...) __attribute__((format(printf,2,3)));
-- 
2.35.1