add punctation encoder

Makefile

@@ -1,6 +1,6 @@
 .PHONY: main test install uninstall clean
 
-OBJS = syllable.o utf8.o transliteration.o iast.o iast-czech.o
+OBJS = syllable.o utf8.o transliteration.o iast.o iast-czech.o encoder.o
 
 
 iast: main.o $(OBJS)

encoder.c

@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "encoder.h"
+#include "utf8.h"
+
+struct encoder_tuple {
+	const char *from;
+	const char *to;
+};
+
+static const struct encoder_tuple table[] = {
+	{"a-", "ā"},
+	{"i-", "ī"},
+	{"u-", "ū"},
+	{"r.", "ṛ"},
+	{"r.-", "ṝ"},
+	{"l.-", "ḹ"},
+	{"n^.", "ṅ"},
+	{"n~", "ñ"},
+	{"s,", "ś"},
+	{"t.", "ṭ"},
+	{"d.", "ḍ"},
+	{"n.", "ṇ"},
+	{"s.", "ṣ"},
+	{"m.", "ṃ"},
+	{"h.", "ḥ"},
+	{NULL, NULL}
+};
+
+const struct encoder_tuple *find_tuple(const char *text)
+{
+	const struct encoder_tuple *walk = table;
+
+	while (walk->from != NULL) {
+		if (strncmp(text, walk->from, strlen(walk->from)) == 0) {
+			return walk;
+		}
+		walk++;
+	}
+
+	return NULL;
+}
+
+char *encode_iast_punctation(const char *text)
+{
+	const char *str = text, *end = str + strlen(str);
+	const struct encoder_tuple *tuple;
+	char *buf, *dest;
+
+	buf = malloc(strlen(text) << 1);
+	buf[0] = 0;
+	dest = buf;
+
+	while (str < end) {
+		tuple = find_tuple(str);
+		if (tuple) {
+			sprintf(dest, "%s", tuple->to);
+			str += strlen(tuple->from);
+			dest += strlen(tuple->to);
+		} else {
+			sprintf(dest, "%c", *str);
+			str++;
+			dest++;
+		}
+	}
+
+	return buf;
+}

encoder.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ENCODER_H
+#define __ENCODER_H
+
+char *encode_iast_punctation(const char *text);
+
+#endif /* __ENCODER_H */