Add comment on mbstring East Asian Width table

diff --git a/ext/mbstring/libmbfl/mbfl/eaw_table.h b/ext/mbstring/libmbfl/mbfl/eaw_table.h
index 834b134dd406e42087c637f4ff151cfb08284cef..495945445116b69b1b422398dfba1f00ceb534ee 100644 (file)
--- a/ext/mbstring/libmbfl/mbfl/eaw_table.h
+++ b/ext/mbstring/libmbfl/mbfl/eaw_table.h
@@ -1,3 +1,14 @@
+/* East Asian Width table
+ *
+ * Some characters in East Asian languages are intended to be displayed in a space
+ * which is roughly square. (This contrasts with others such as the Latin alphabet,
+ * which are taller than they are wide.) To display these East Asian characters
+ * properly, twice the horizontal space is used. This must be taken into account
+ * when doing things like wrapping text to a specific width.
+ *
+ * Each pair of numbers in the below table is a range of Unicode codepoints
+ * which should be displayed as double-width. */
+
 static const struct {
        int begin;
        int end;