Add a script to generate wcwidth as well

Generated function is more efficient than the implementation from
wcwidth9 and also makes it easy to update when the unicode standard
changes.

kitty/emoji.h

@@ -1,9 +1,17 @@
+// unicode data, built from the unicode standard on: 2017-12-20
+// see gen-wcwidth.py
 #pragma once
 #include "data-types.h"
 
 START_ALLOW_CASE_RANGE
-static inline bool is_emoji(uint32_t code) {
+
+static inline bool
+is_emoji(char_type code) {
 	switch(code) {
+		case 0x2194 ... 0x2199:
+			return true;
+		case 0x21a9 ... 0x21aa:
+			return true;
 		case 0x231a ... 0x231b:
 			return true;
 		case 0x2328:
@@ -274,14 +282,16 @@ static inline bool is_emoji(uint32_t code) {
 			return true;
 		default: return false;
 	}
-	return false;
+	return false; 
 }
-static inline bool is_emoji_modifier(uint32_t code) {
+static inline bool
+is_emoji_modifier(char_type code) {
 	switch(code) {
 		case 0x1f3fb ... 0x1f3ff:
 			return true;
 		default: return false;
 	}
-	return false;
+	return false; 
 }
+
 END_ALLOW_CASE_RANGE

kitty/screen.c

@@ -18,7 +18,7 @@
 #include <fcntl.h>
 #include "unicode-data.h"
 #include "modes.h"
-#include "wcwidth9.h"
+#include "wcwidth-std.h"
 #include "control-codes.h"
 
 static const ScreenModes empty_modes = {0, .mDECAWM=true, .mDECTCEM=true, .mDECARM=true};
@@ -275,8 +275,8 @@ safe_wcwidth(uint32_t ch) {
 }
 
 void
-change_wcwidth(bool use9) {
-    wcwidth_impl = (use9) ? wcwidth9 : wcwidth;
+change_wcwidth(bool use_std) {
+    wcwidth_impl = use_std ? wcwidth_std : wcwidth;
 }