Implement union construction

tests/construct_tests.c

@@ -102,11 +102,42 @@ static void test_sequence(void)
 	fsa_free(&fsa);
 }
 
+static void test_union(void)
+{
+	const char *literals = "abc";
+	regex_sequence_t *alternatives = malloc(3 * sizeof(regex_sequence_t));
+	for (int i = 0; i < 3; ++i) {
+		regex_term_t *terms = malloc(1 * sizeof(regex_term_t));
+		terms[0].quantifier = REGEX_QUANTIFIER_NONE;
+		terms[0].type = REGEX_TERM_LITERAL;
+		terms[0].literal = literals[i];
+
+		alternatives[i].count = alternatives[i].capacity = 1;
+		alternatives[i].contents = terms;
+	}
+	regex_t regex = { .count = 3, .capacity = 3, .contents = alternatives };
+
+	fsa_t fsa;
+	construct(&regex, &fsa);
+
+	const fsa_state_t *initial = &fsa.states[fsa.initial];
+	ASSERT_EQ(3, initial->count);
+	for (int i = 0; i < 3; ++i) {
+		ASSERT_EQ(literals[i], initial->rules[i].input);
+		const int next = initial->rules[i].next;
+		ASSERT_TRUE(fsa.states[next].final);
+	}
+
+	regex_free(&regex);
+	fsa_free(&fsa);
+}
+
 int main(void)
 {
 	TESTING_BEGIN();
 	test_empty_expression();
 	test_literal_expression();
 	test_sequence();
+	test_union();
 	return TESTING_END();
 }