diff --git a/libasn1parser/asn1p_expr.c b/libasn1parser/asn1p_expr.c
new file mode 100644
index 0000000..23ab4cb
--- /dev/null
+++ b/libasn1parser/asn1p_expr.c
@@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "asn1parser.h"
+
+/*
+ * Construct a new empty types collection.
+ */
+asn1p_expr_t *
+asn1p_expr_new(int _lineno) {
+	asn1p_expr_t *expr;
+
+	expr = calloc(1, sizeof *expr);
+	if(expr) {
+		TQ_INIT(&(expr->members));
+		expr->_lineno = _lineno;
+	}
+
+	return expr;
+}
+
+asn1p_expr_t *
+asn1p_expr_clone(asn1p_expr_t *expr) {
+	asn1p_expr_t *clone;
+	asn1p_expr_t *tcmemb;	/* Child of tc */
+
+	clone = asn1p_expr_new(expr->_lineno);
+	if(clone == NULL) return NULL;
+
+#define	CLCOPY(field)	do { clone->field = expr->field; } while(0)
+#define	CLCLONE(field, func)	do { if(expr->field) {		\
+			clone->field = func(expr->field);	\
+			if(clone->field == NULL) {		\
+				asn1p_expr_free(clone);		\
+				return NULL;			\
+			}					\
+		} } while(0)
+
+	/*
+	 * Copy simple fields.
+	 */
+	CLCOPY(meta_type);
+	CLCOPY(expr_type);
+	CLCOPY(tag);
+	CLCOPY(marker);
+	CLCOPY(_mark);
+
+	clone->data = 0;	/* Do not clone this */
+	clone->data_free = 0;	/* Do not clone this */
+
+	/*
+	 * Clone complex fields.
+	 */
+	CLCLONE(Identifier, strdup);
+	CLCLONE(reference, asn1p_ref_clone);
+	CLCLONE(constraints, asn1p_constraint_clone);
+	CLCLONE(params, asn1p_paramlist_clone);
+	CLCLONE(value, asn1p_value_clone);
+	CLCLONE(with_syntax, asn1p_wsyntx_clone);
+
+	/*
+	 * Copy all the children of this expr.
+	 */
+	TQ_FOR(tcmemb, &(expr->members), next) {
+		asn1p_expr_t *cmemb = asn1p_expr_clone(tcmemb);
+		if(cmemb == NULL) {
+			asn1p_expr_free(clone);
+			return NULL;
+		}
+		TQ_ADD(&(clone->members), cmemb, next);
+	}
+
+	return clone;
+}
+
+/*
+ * Destruct the types collection structure.
+ */
+void
+asn1p_expr_free(asn1p_expr_t *expr) {
+	if(expr) {
+		asn1p_expr_t *tm;
+
+		if(expr->Identifier)
+			free(expr->Identifier);
+		if(expr->reference)
+			asn1p_ref_free(expr->reference);
+		if(expr->constraints)
+			asn1p_constraint_free(expr->constraints);
+		if(expr->params)
+			asn1p_paramlist_free(expr->params);
+		if(expr->value)
+			asn1p_value_free(expr->value);
+		if(expr->with_syntax)
+			asn1p_wsyntx_free(expr->with_syntax);
+
+		/* Remove all children */
+		while((tm = TQ_REMOVE(&(expr->members), next))) {
+			asn1p_expr_free(tm);
+		}
+
+		if(expr->data && expr->data_free)
+			expr->data_free(expr->data);
+
+		memset(expr, 0, sizeof(*expr));
+		free(expr);
+	}
+}
+