+// ------------------------------------------------------------
+
+/**
+ * Part of a pattern to match - essentially a record holding a pointer to the
+ * storage for the component to match, along with the appropriate type.
+ */
+class s_pattern {
+public:
+ s_pattern(s_expression *&s) : p_expr(&s), type(EXPR) { }
+ s_pattern(s_list *&s) : p_list(&s), type(LIST) { }
+ s_pattern(s_symbol *&s) : p_symbol(&s), type(SYMBOL) { }
+ s_pattern(s_number *&s) : p_number(&s), type(NUMBER) { }
+ s_pattern(s_int *&s) : p_int(&s), type(INT) { }
+ s_pattern(const char *str) : literal(str), type(STRING) { }
+
+ bool match(s_expression *expr);
+
+private:
+ union {
+ s_expression **p_expr;
+ s_list **p_list;
+ s_symbol **p_symbol;
+ s_number **p_number;
+ s_int **p_int;
+ const char *literal;
+ };
+ enum { EXPR, LIST, SYMBOL, NUMBER, INT, STRING } type;
+};
+
+bool
+s_match(s_expression *top, unsigned n, s_pattern *pattern, bool partial);
+