Define regex_t data structure and write build script

lib/regex.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) Camden Dixie O'Brien
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+#ifndef REGEX_H
+#define REGEX_H
+
+#include <stdbool.h>
+
+typedef struct {
+	bool negated;
+	int count, capacity;
+	char *contents;
+} class_t;
+
+typedef enum {
+	QUANTIFIER_NONE,
+	QUANTIFIER_ZERO_OR_MORE,
+	QUANTIFIER_ONE_OR_MORE,
+	QUANTIFIER_ZERO_OR_ONE,
+} quantifier_t;
+
+typedef enum {
+	TERM_TYPE_WILDCARD,
+	TERM_TYPE_CLASS,
+	TERM_TYPE_LITERAL,
+	TERM_TYPE_REGEX,
+} term_type_t;
+
+struct _term;
+typedef struct {
+	int len, capacity;
+	struct _term *contents;
+} sequence_t;
+
+typedef struct _regex {
+	sequence_t sequence;
+	struct _regex *alternative;
+} regex_t;
+
+typedef struct _term {
+	quantifier_t quantifier;
+	term_type_t type;
+	union {
+		class_t class;
+		char literal;
+		regex_t regex;
+	};
+} term_t;
+
+void regex_free_children(regex_t *r);
+
+#endif