From d2569edaafac2c92a9782327370ad11e1f878495 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <m@maandree.se>
Date: Mon, 26 Jan 2026 18:31:24 +0100
Subject: Add metrical
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Signed-off-by: Mattias Andrée <m@maandree.se>
---
 Makefile               |  6 ++++--
 convert-to-metrical.c  |  4 ++++
 libcharconv.h          | 14 ++++++++++++++
 libcharconv_latin.c    | 13 +++++++++++++
 libcharconv_metrical.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 86 insertions(+), 2 deletions(-)
 create mode 100644 convert-to-metrical.c
 create mode 100644 libcharconv_metrical.c

diff --git a/Makefile b/Makefile
index 615f7f2..0fa5b3a 100644
--- a/Makefile
+++ b/Makefile
@@ -81,7 +81,8 @@ BIN =\
 	convert-to-rotated-45deg-ccw\
 	convert-to-rotated-90deg-ccw\
 	convert-to-invisible\
-	convert-to-enclosed
+	convert-to-enclosed\
+	convert-to-metrical
 
 LIBOBJ =\
 	libcharconv_decode_utf8_.o\
@@ -155,7 +156,8 @@ LIBOBJ =\
 	libcharconv_rotated_90deg_ccw.o\
 	libcharconv_invisible.o\
 	libcharconv_enclosed_positive.o\
-	libcharconv_enclosed_negative.o
+	libcharconv_enclosed_negative.o\
+	libcharconv_metrical.o
 
 LOBJ = $(LIBOBJ:.o=.lo)
 
diff --git a/convert-to-metrical.c b/convert-to-metrical.c
new file mode 100644
index 0000000..3f7b843
--- /dev/null
+++ b/convert-to-metrical.c
@@ -0,0 +1,4 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+SIMPLE(libcharconv_metrical)
diff --git a/libcharconv.h b/libcharconv.h
index 1c8c4b9..6693376 100644
--- a/libcharconv.h
+++ b/libcharconv.h
@@ -472,6 +472,20 @@ LIBCHARCONV_FUNC_(libcharconv_enclosed_positive);
  */
 LIBCHARCONV_FUNC_(libcharconv_enclosed_negative);
 
+/**
+ * Convert
+ * '1' to METRICAL BREVE,
+ * '2' to METRICAL TWO SHORTS JOINED,
+ * '-1' to METRICAL LONG OVER SHORT,
+ * '-2' to METRICAL LONG OVER TWO SHORTS,
+ * '_1' to METRICAL SHORT OVER LONG,
+ * '_2' to METRICAL TWO SHORTS OVER LONG,
+ * '3' to METRICAL TRISEME,
+ * '4' to METRICAL TETRASEME, and
+ * '5' to METRICAL PENTASEME
+ */
+LIBCHARCONV_FUNC_(libcharconv_metrical);
+
 
 #undef LIBCHARCONV_FUNC_
 #endif
diff --git a/libcharconv_latin.c b/libcharconv_latin.c
index 4b41391..2693ea4 100644
--- a/libcharconv_latin.c
+++ b/libcharconv_latin.c
@@ -550,6 +550,16 @@ libcharconv_latin(const char *s, size_t slen, size_t *n, uint_least32_t *cp, siz
 			c2 = (char)(c - (UINT32_C(0x278A) - (uint_least32_t)'1'));
 			c3 = ')';
 			goto conv3;
+		} else if (UINT32_C(0x23D6) <= c && c <= UINT32_C(0x23D9)) {
+			/* metrical */
+			c -= (uint_least32_t)UINT32_C(0x23D6) - (uint_least32_t)'2';
+			goto conv;
+		} else if (UINT32_C(0x23D2) <= c && c <= UINT32_C(0x23D5)) {
+			/* metrical */
+			c -= (uint_least32_t)UINT32_C(0x23D2);
+			c1 = (c & 1u) ? '_' : '-';
+			c2 = (c & 2u) ? '2' : '1';
+			goto conv2;
 
 		} else {
 		use_switch:
@@ -981,6 +991,9 @@ libcharconv_latin(const char *s, size_t slen, size_t *n, uint_least32_t *cp, siz
 			case UINT32_C(0x2793): c1 = '('; c2 = '1'; c3 = '0'; c4 = ')'; goto conv4;
 			case UINT32_C(0x1F10C): c1 = '('; c2 = '0'; c3 = ')'; goto conv3;
 
+			/* metrical */
+			case UINT32_C(0x23D1): c1 = '1'; goto conv1;
+
 			default:
 			no_match:
 				*n += clen;
diff --git a/libcharconv_metrical.c b/libcharconv_metrical.c
new file mode 100644
index 0000000..2518a2b
--- /dev/null
+++ b/libcharconv_metrical.c
@@ -0,0 +1,51 @@
+/* See LICENSE file for copyright and license details. */
+#include "lib-common.h"
+
+
+enum libcharconv_result
+libcharconv_metrical(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
+{
+	uint_least32_t c;
+	*n = 0;
+	for (; slen--; s++) {
+		switch (*s) {
+		case '1': c = UINT32_C(0x23D1); goto conv;
+		case '2': c = UINT32_C(0x23D6); goto conv;
+		case '3': c = UINT32_C(0x23D7); goto conv;
+		case '4': c = UINT32_C(0x23D8); goto conv;
+		case '5': c = UINT32_C(0x23D9); goto conv;
+		case '-':
+		case '_':
+			if (!slen)
+				return LIBCHARCONV_INDETERMINATE;
+			if (s[1] != '1' && s[1] != '2')
+				goto no_match;
+			c = UINT32_C(0x23D2) + (s[0] == '_' ? 1u : 0u) + (s[1] == '2' ? 2u : 0u);
+			goto conv2;
+		default:
+		no_match:
+			*n += 1u;
+			break;
+		}
+	}
+no_conv:
+	return LIBCHARCONV_NO_CONVERT;
+
+conv:
+	if (*n)
+		goto no_conv;
+	if (*ncp)
+		*cp = c;
+	*n += 1u;
+	*ncp = 1u;
+	return LIBCHARCONV_CONVERTED;
+
+conv2:
+	if (*n)
+		goto no_conv;
+	if (*ncp)
+		*cp = c;
+	*n += 2u;
+	*ncp = 1u;
+	return LIBCHARCONV_CONVERTED;
+}
-- 
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