lineedit: first shot at optional unicode bidi input support

function                                             old     new   delta
read_line_input                                     4886    5003    +117
in_uint16_table                                        -      97     +97
in_interval_table                                      -      78     +78
static.rtl_b                                           -      68     +68
unicode_isrtl                                          -      55     +55
isrtl_str                                              -      51     +51
static.rtl_p                                           -      42     +42
unicode_conv_to_printable2                           633     477    -156
------------------------------------------------------------------------------
(add/remove: 6/0 grow/shrink: 1/1 up/down: 508/-156)          Total: 352 bytes

Signed-off-by: Tomas Heinrich <heinrich.tomas@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/include/unicode.h b/include/unicode.h
index 857aab1..05bdbca 100644
--- a/include/unicode.h
+++ b/include/unicode.h
@@ -18,6 +18,8 @@
 	UNICODE_ON = 2,
 };
 
+#define unicode_isrtl(wc) 0
+
 #if !ENABLE_FEATURE_ASSUME_UNICODE
 
 # define unicode_strlen(string) strlen(string)
@@ -26,6 +28,17 @@
 
 #else
 
+# if CONFIG_LAST_SUPPORTED_WCHAR < 126 || CONFIG_LAST_SUPPORTED_WCHAR >= 0x30000
+#  define LAST_SUPPORTED_WCHAR 0x2ffff
+# else
+#  define LAST_SUPPORTED_WCHAR CONFIG_LAST_SUPPORTED_WCHAR
+# endif
+
+# if LAST_SUPPORTED_WCHAR < 0x590
+#  undef  ENABLE_UNICODE_BIDI_SUPPORT
+#  define ENABLE_UNICODE_BIDI_SUPPORT 0
+# endif
+
 size_t FAST_FUNC unicode_strlen(const char *string);
 enum {
 	UNI_FLAG_PAD = (1 << 0),
@@ -78,6 +91,10 @@
 int iswspace(wint_t wc) FAST_FUNC;
 int iswalnum(wint_t wc) FAST_FUNC;
 int iswpunct(wint_t wc) FAST_FUNC;
+#  if ENABLE_UNICODE_BIDI_SUPPORT
+#   undef unicode_isrtl
+int unicode_isrtl(wint_t wc) FAST_FUNC;
+#  endif
 
 
 # endif /* !LOCALE_SUPPORT */