Add utf-8 display width info

Needed when using linenoise line editing with utf-8 support
Note that variable width support is not yet added to linenoise

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 60 insertions, 7 deletions

diff --git a/utf8.c b/utf8.c
index 3f00f39..0d94c0e 100644
--- a/utf8.c
+++ b/utf8.c
@@ -76,6 +76,19 @@ int utf8_strlen(const char *str, int bytelen)
     return charlen;
 }
 
+int utf8_strwidth(const char *str, int charlen)
+{
+    int width = 0;
+    while (charlen) {
+        int c;
+        int l = utf8_tounicode(str, &c);
+        width += utf8_width(c);
+        str += l;
+        charlen--;
+    }
+    return width;
+}
+
 int utf8_index(const char *str, int index)
 {
     const char *s = str;
@@ -144,6 +157,12 @@ struct casemap {
     unsigned short altcode;     /* alternate case code point */
 };
 
+struct utf8range {
+    unsigned lower;     /* lower inclusive */
+    unsigned upper;     /* upper exclusive */
+};
+
+
 /* Generated mapping tables */
 #include "_unicode_mapping.c"
 
@@ -168,10 +187,29 @@ static int utf8_map_case(const struct casemap *mapping, int num, int ch)
     return ch;
 }
 
-/* Some platforms don't have isascii */
-#ifndef isascii
-#define isascii(C) (!((C) & ~0x7f))
-#endif
+static int cmp_range(const void *key, const void *cm)
+{
+    const struct utf8range *range = (const struct utf8range *)cm;
+    int ch = *(int *)key;
+    if (ch < range->lower) {
+        return -1;
+    }
+    if (ch >= range->upper) {
+        return 1;
+    }
+    return 0;
+}
+
+static int utf8_in_range(const struct utf8range *range, int num, int ch)
+{
+    const struct utf8range *r =
+        bsearch(&ch, range, num, sizeof(*range), cmp_range);
+
+    if (r) {
+        return 1;
+    }
+    return 0;
+}
 
 int utf8_upper(int ch)
 {
@@ -191,11 +229,26 @@ int utf8_lower(int ch)
 
 int utf8_title(int ch)
 {
-    int newch = utf8_map_case(unicode_case_mapping_title, ARRAYSIZE(unicode_case_mapping_title), ch);
-    if (newch != ch) {
-        return newch ? newch : ch;
+    if (!isascii(ch)) {
+        int newch = utf8_map_case(unicode_case_mapping_title, ARRAYSIZE(unicode_case_mapping_title), ch);
+        if (newch != ch) {
+            return newch ? newch : ch;
+        }
     }
     return utf8_upper(ch);
 }
 
+int utf8_width(int ch)
+{
+    if (!isascii(ch)) {
+        if (utf8_in_range(unicode_range_combining, ARRAYSIZE(unicode_range_combining), ch)) {
+            return 0;
+        }
+        if (utf8_in_range(unicode_range_wide, ARRAYSIZE(unicode_range_wide), ch)) {
+            return 2;
+        }
+    }
+    return 1;
+}
+
 #endif /* JIM_BOOTSTRAP */