Implement NFA construction for empty expression and literals

tests/construct_tests.c

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) Camden Dixie O'Brien
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+#include "construct.h"
+#include "testing.h"
+
+static void test_empty_expression(void)
+{
+	regex_term_t *terms = malloc(1 * sizeof(regex_term_t));
+	terms[0].quantifier = REGEX_QUANTIFIER_NONE;
+	terms[0].type = REGEX_TERM_EMPTY;
+	regex_sequence_t *alternatives = malloc(1 * sizeof(regex_sequence_t));
+	alternatives[0].count = alternatives[0].capacity = 1;
+	alternatives[0].contents = terms;
+	const regex_t regex
+	    = { .count = 1, .capacity = 1, .contents = alternatives };
+
+	fsa_t fsa;
+	construct(&regex, &fsa);
+
+	ASSERT_EQ(1, fsa.count);
+	ASSERT_TRUE(fsa.states[fsa.initial].final);
+	ASSERT_EQ(0, fsa.states[fsa.initial].count);
+
+	regex_free(&regex);
+	fsa_free(&fsa);
+}
+
+static void test_literal_expression(void)
+{
+	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 = 'a';
+	regex_sequence_t *alternatives = malloc(1 * sizeof(regex_sequence_t));
+	alternatives[0].count = alternatives[0].capacity = 1;
+	alternatives[0].contents = terms;
+	const regex_t regex
+	    = { .count = 1, .capacity = 1, .contents = alternatives };
+
+	fsa_t fsa;
+	construct(&regex, &fsa);
+
+	const fsa_state_t *initial = &fsa.states[fsa.initial];
+	ASSERT_EQ(2, fsa.count);
+	ASSERT_EQ(1, initial->count);
+	ASSERT_EQ('a', initial->rules[0].input);
+	ASSERT_TRUE(fsa.states[initial->rules[0].next].final);
+	ASSERT_EQ(0, fsa.states[initial->rules[0].next].count);
+
+	regex_free(&regex);
+	fsa_free(&fsa);
+}
+
+int main(void)
+{
+	TESTING_BEGIN();
+	test_empty_expression();
+	test_literal_expression();
+	return TESTING_END();
+}