#ifndef LICHEN_EXPRESSION_H
#define LICHEN_EXPRESSION_H

/****************************************************************
 * 
 * a grammar is built on both nonterminals and terminals. both are
 * represented by integers; nonterminals must be less than MAX_NONTERMINAL
 * and terminals must be greater. the intended way to do this is to define
 * an enum with all symbols, and have a MAX_NONTERMINAL symbol dividing the
 * (low) nonterminals from the (high) terminals.
 *
 ****************************************************************
 */

struct li_production_t {
  int *seq;
  size_t seq_len;
  struct li_production_t *next;  
};

struct li_production_t * li_production_alloc(size_t seq_len);
void li_production_free(struct li_production_t *prod);

struct li_production_rule_t {
  size_t num_productions;
  struct li_production_t *head;
};

struct li_production_rule_t * li_prod_rule_alloc();
void li_prod_rule_free(struct li_production_rule_t *rule);
int li_prod_rule_add(struct li_production_rule_t *rule, size_t seq_len, int *seq);

typedef struct li_grammar_t {
  struct li_production_rule_t *rules;
  size_t num_nonterminal;
} li_grammar_t;

li_rammar_t * li_grammar_alloc(size_t num_nonterminal);
void li_grammar_free(li_grammar_t *grammar);
int li_grammar_rule_add(li_grammar_t *grammar, int nonterminal, size_t seq_len, int *seq);

#endif