v10-0002-Add-define-for-UNICODE_CASEMAP_BUFSZ.patch

From bccff163e0ce2c0b1f9cb0cfdeecb32ededb898d Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Wed, 19 Nov 2025 10:11:52 -0800
Subject: [PATCH v10 02/11] Add #define for UNICODE_CASEMAP_BUFSZ.

Useful for mapping a single codepoint at a time into a
statically-allocated buffer.

Discussion: https://postgr.es/m/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel@j-davis.com
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
---
 src/include/utils/pg_locale.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 683e1a0eef8..54193a17a90 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -26,6 +26,20 @@
 /* use for libc locale names */
 #define LOCALE_NAME_BUFLEN 128
 
+/*
+ * Maximum number of bytes needed to map a single codepoint. Useful for
+ * mapping and processing a single input codepoint at a time with a
+ * statically-allocated buffer.
+ *
+ * With full case mapping, an input codepoint may be mapped to as many as
+ * three output codepoints. See Unicode 16.0.0, section 5.18.2, "Change in
+ * Length":
+ *
+ * https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-5/#G29675
+ */
+#define UNICODE_CASEMAP_LEN		3
+#define UNICODE_CASEMAP_BUFSZ	(UNICODE_CASEMAP_LEN * sizeof(char32_t))
+
 /* GUC settings */
 extern PGDLLIMPORT char *locale_messages;
 extern PGDLLIMPORT char *locale_monetary;
-- 
2.43.0