From 8026e94f6cf35c75a0a4f928c580b077f546a452 Mon Sep 17 00:00:00 2001
From: Vivien Kraus <vivien@planete-kraus.eu>
Date: Tue, 3 Aug 2021 23:53:41 +0200
Subject: [PATCH 3/4] Export the wcwidth function

The wcwidth function computes the number of columns that a character
spans. It is in gnulib, but not documented. It is part of POSIX, and its
own module in Gnulib [1].

[1]: https://www.gnu.org/software/gnulib/manual/html_node/wcwidth.html
---
 doc/ref/api-data.texi |  7 +++++++
 libguile/chars.c      | 12 ++++++++++++
 libguile/chars.h      |  1 +
 3 files changed, 20 insertions(+)

diff --git a/doc/ref/api-data.texi b/doc/ref/api-data.texi
index 2ad13f5a5..a6647c3bf 100644
--- a/doc/ref/api-data.texi
+++ b/doc/ref/api-data.texi
@@ -2275,6 +2275,13 @@ with their meanings.
 @end multitable
 @end deffn
 
+@deffn {Scheme Procedure} wcwidth chr
+@deffnx {C Function} scm_wcwidth (chr)
+Return the number of columns that @var{chr} spans. This function depends
+on the @code{LC_CTYPE} locale category. Return @code{-1} if @var{chr} is
+not recognized.
+@end deffn
+
 @rnindex char->integer
 @deffn {Scheme Procedure} char->integer chr
 @deffnx {C Function} scm_char_to_integer (chr)
diff --git a/libguile/chars.c b/libguile/chars.c
index fe55f9e2e..7b31e0601 100644
--- a/libguile/chars.c
+++ b/libguile/chars.c
@@ -504,6 +504,18 @@ SCM_DEFINE (scm_char_general_category, "char-general-category", 1, 0, 0,
 }
 #undef FUNC_NAME
 
+SCM_DEFINE (scm_wcwidth, "wcwidth", 1, 0, 0,
+           (SCM chr),
+            "Return the number of columns that @var{chr} spans.")
+#define FUNC_NAME s_scm_wcwidth
+{
+  int width;
+  SCM_VALIDATE_CHAR (1, chr);
+  width = wcwidth (SCM_CHAR(chr));
+  return scm_from_int (width);
+}
+#undef FUNC_NAME
+
 
 
 
diff --git a/libguile/chars.h b/libguile/chars.h
index f6d4c6354..1bf7c2aa2 100644
--- a/libguile/chars.h
+++ b/libguile/chars.h
@@ -86,6 +86,7 @@ SCM_API SCM scm_char_upcase (SCM chr);
 SCM_API SCM scm_char_downcase (SCM chr);
 SCM_API SCM scm_char_titlecase (SCM chr);
 SCM_API SCM scm_char_general_category (SCM chr);
+SCM_API SCM scm_wcwidth (SCM chr);
 
 SCM_INLINE SCM scm_c_make_char (scm_t_wchar c);
 SCM_API scm_t_wchar scm_c_upcase (scm_t_wchar c);
-- 
2.32.0