From b0cd85bd211658a34bf4b59d60efcb685a9a59ab Mon Sep 17 00:00:00 2001
From: Vlasta Vesely <vlastavesely@protonmail.ch>
Date: Fri, 16 Apr 2021 10:03:08 +0200
Subject: [PATCH] velthuis.c - make bidirectional

---
 tests/velthuis.c | 40 +++++++++++++++++++++++++++++-----------
 velthuis.c       | 48 +++++++++++++++++++++++++++++++++++++++++++++---
 velthuis.h       |  3 ++-
 3 files changed, 76 insertions(+), 15 deletions(-)

diff --git a/tests/velthuis.c b/tests/velthuis.c
index 138afcf..30e7b20 100644
--- a/tests/velthuis.c
+++ b/tests/velthuis.c
@@ -2,27 +2,45 @@
 #include "velthuis.h"
 #include "../velthuis.h"
 
-static void test_encoding(const char *in, const char *expected)
+static void test_encoding_to_iast(const char *in, const char *expected)
 {
-	char *iast;
-	encode_velthuis_to_iast_punctation(in, &iast);
-	ck_assert_str_eq(expected, iast);
-	free(iast);
+	char *out;
+
+	encode_velthuis_to_iast(in, &out);
+	ck_assert_str_eq(expected, out);
+	free(out);
 }
 
-START_TEST(test_encode_punctation)
+static void test_encoding_to_velthuis(const char *in, const char *expected)
 {
-	test_encoding("sa.msk.rtam", "saṃskṛtam");
+	char *out;
 
-	test_encoding("yoga.h", "yogaḥ");
+	encode_iast_to_velthuis(in, &out);
+	ck_assert_str_eq(expected, out);
+	free(out);
+}
 
-	test_encoding("tantra\"saastram", "tantraśāstram");
+START_TEST(test_encode_velthuis_to_iast)
+{
+	test_encoding_to_iast("sa.msk.rtam", "saṃskṛtam");
+	test_encoding_to_iast("yoga.h", "yogaḥ");
+	test_encoding_to_iast("tantra\"saastram", "tantraśāstram");
+	test_encoding_to_iast("Aa AA - II Ii - .RR .Rr", "Ā Ā - Ī Ī - Ṝ Ṝ");
+	test_encoding_to_iast("atha prathamo.adhyaaya.h", "atha prathamo'dhyāyaḥ");
+}
+END_TEST
 
-	test_encoding("Aa AA - II Ii - .RR .Rr", "Ā Ā - Ī Ī - Ṝ Ṝ");
+START_TEST(test_encode_iast_to_velthuis)
+{
+	test_encoding_to_velthuis("saṃskṛtam", "sa.msk.rtam");
+	test_encoding_to_velthuis("tantraśāstram", "tantra\"saastram");
+	test_encoding_to_velthuis("Ā - Ī - Ṝ", "Aa - Ii - .Rr");
+	test_encoding_to_velthuis("atha prathamo'dhyāyaḥ", "atha prathamo.adhyaaya.h");
 }
 END_TEST
 
 void register_velthuis_encoder_tests(TCase *test_case)
 {
-	tcase_add_test(test_case, test_encode_punctation);
+	tcase_add_test(test_case, test_encode_velthuis_to_iast);
+	tcase_add_test(test_case, test_encode_iast_to_velthuis);
 }
diff --git a/velthuis.c b/velthuis.c
index 7a129c6..ab5bc35 100644
--- a/velthuis.c
+++ b/velthuis.c
@@ -34,12 +34,12 @@ static const struct encoder_tuple table[] = {
 	{".n",  "\u1e47"},  {".N",  "\u1e46"},
 	{".s",  "\u1e63"},  {".S",  "\u1e62"},
 
-	{"/",   "m\u0310"}
+	{"/",   "m\u0310"}, {".a",  "'"}
 };
 
 static const struct encoder_tuple *find_tuple(const char *text)
 {
-	int i;
+	unsigned int i;
 
 	for (i = 0; i < ARRAY_SIZE(table); i++) {
 		if (strncmp(text, table[i].from, strlen(table[i].from)) == 0) {
@@ -50,7 +50,20 @@ static const struct encoder_tuple *find_tuple(const char *text)
 	return NULL;
 }
 
-int encode_velthuis_to_iast_punctation(const char *text, char **out)
+static const struct encoder_tuple *find_tuple_reverse(const char *text)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(table); i++) {
+		if (strncmp(text, table[i].to, strlen(table[i].to)) == 0) {
+			return &table[i];
+		}
+	}
+
+	return NULL;
+}
+
+int encode_velthuis_to_iast(const char *text, char **out)
 {
 	const char *str = text, *end = str + strlen(str);
 	const struct encoder_tuple *tuple;
@@ -78,3 +91,32 @@ int encode_velthuis_to_iast_punctation(const char *text, char **out)
 
 	return 0;
 }
+
+int encode_iast_to_velthuis(const char *text, char **out)
+{
+	const char *str = text, *end = str + strlen(str);
+	const struct encoder_tuple *tuple;
+	char *buf, *dest;
+
+	buf = calloc(1, strlen(text) * 2); /* should be enough */
+	if (buf == NULL)
+		return ENOMEM;
+
+	dest = buf;
+	while (str < end) {
+		tuple = find_tuple_reverse(str);
+		if (tuple) {
+			sprintf(dest, "%s", tuple->from);
+			str += strlen(tuple->to);
+			dest += strlen(tuple->from);
+		} else {
+			sprintf(dest, "%c", *str);
+			str++;
+			dest++;
+		}
+	}
+
+	*out = buf;
+
+	return 0;
+}
diff --git a/velthuis.h b/velthuis.h
index 314b99e..22691a0 100644
--- a/velthuis.h
+++ b/velthuis.h
@@ -3,6 +3,7 @@
 #ifndef __VELTHUIS_H
 #define __VELTHUIS_H
 
-int encode_velthuis_to_iast_punctation(const char *text, char **out);
+int encode_velthuis_to_iast(const char *text, char **out);
+int encode_iast_to_velthuis(const char *text, char **out);
 
 #endif /* __VELTHUIS_H */