xC: make fancy-prompt.lua alignment more reliable

And generally clean up that script.

1 files changed, 30 insertions, 3 deletions

diff --git a/xC.c b/xC.c
index 9cb97c8..7b61fb9 100644
--- a/xC.c
+++ b/xC.c
@@ -3776,7 +3776,7 @@ explode_text (struct exploder *self, const char *text)
 		if (!strchr ("\a\b\x0e\x0f\x1b" /* BEL BS SO SI ESC */, *p))
 			str_append_c (&filtered, *p);
 
-	size_t term_len = 0;
+	size_t term_len = 0, processed = 0, len;
 	char *term = iconv_xstrdup (self->ctx->term_from_utf8,
 		filtered.str, filtered.len + 1, &term_len);
 	str_free (&filtered);
@@ -3785,11 +3785,10 @@ explode_text (struct exploder *self, const char *text)
 	memset (&ps, 0, sizeof ps);
 
 	wchar_t wch;
-	size_t len, processed = 0;
 	while ((len = mbrtowc (&wch, term + processed, term_len - processed, &ps)))
 	{
 		hard_assert (len != (size_t) -2 && len != (size_t) -1);
-		processed += len;
+		hard_assert ((processed += len) <= term_len);
 
 		struct line_char *c = line_char_new (wch);
 		c->attrs = self->attrs;
@@ -10528,6 +10527,33 @@ lua_plugin_get_screen_size (lua_State *L)
 }
 
 static int
+lua_plugin_measure (lua_State *L)
+{
+	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
+	const char *line = lua_plugin_check_utf8 (L, 1);
+
+	size_t term_len = 0, processed = 0, width = 0, len;
+	char *term = iconv_xstrdup (plugin->ctx->term_from_utf8,
+		(char *) line, strlen (line) + 1, &term_len);
+
+	mbstate_t ps;
+	memset (&ps, 0, sizeof ps);
+
+	wchar_t wch;
+	while ((len = mbrtowc (&wch, term + processed, term_len - processed, &ps)))
+	{
+		hard_assert (len != (size_t) -2 && len != (size_t) -1);
+		hard_assert ((processed += len) <= term_len);
+
+		int wch_width = wcwidth (wch);
+		width += MAX (0, wch_width);
+	}
+	free (term);
+	lua_pushinteger (L, width);
+	return 1;
+}
+
+static int
 lua_ctx_gc (lua_State *L)
 {
 	return lua_weak_gc (L, &lua_ctx_info);
@@ -10547,6 +10573,7 @@ static luaL_Reg lua_plugin_library[] =
 	// And these are methods:
 
 	{ "get_screen_size", lua_plugin_get_screen_size },
+	{ "measure",         lua_plugin_measure         },
 	{ "__gc",            lua_ctx_gc                 },
 	{ NULL,              NULL                       },
 };