1 files changed, 110 insertions, 0 deletions
diff --git a/expression.c b/expression.c
new file mode 100644
index 0000000..11904fc
--- /dev/null
+++ b/expression.c
@@ -0,0 +1,110 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include "expression.h"
+
+
+struct li_production_t * li_production_alloc(size_t seq_len) {
+  struct li_production_t *prod = malloc(sizeof(struct li_production_t));
+  if (prod == NULL) {
+    fprintf(stderr, "failed to allocate production rule\n");
+    return NULL;
+  }
+  prod->seq = malloc(seq_len * sizeof(int));
+  if (prod->seq == NULL) {
+    fprintf(stderr, "failed to allocate production sequence buffer\n");
+    free(prod);
+    return NULL;
+  }
+  prod->seq_len = seq_len;
+  prod->next = NULL;
+  return prod;
+}
+
+
+void li_production_free(struct li_production_t *prod) {
+  if (prod != NULL) {
+    li_production_free(prod->next);
+    free(prod->seq);
+    free(prod);
+  }
+}
+
+
+struct li_production_rule_t * li_prod_rule_alloc() {
+  struct li_production_rule_t *rule = malloc(sizeof(struct li_production_rule_t));
+  if (rule == NULL) {
+    fprintf(stderr, "failed to allocate production rule\n");
+    return NULL;
+}
+  rule->num_productions = 0;
+  rule->head = NULL;
+  return rule;
+}
+
+
+void li_prod_rule_free(struct li_production_rule_t *rule) {
+  if (rule != NULL) {
+    li_production_free(rule->head);
+    free(rule);
+  }
+}
+
+
+int li_prod_rule_add(
+  struct li_production_rule_t *rule, size_t seq_len, int *seq
+) {
+  struct li_production_t *prod = li_production_alloc(seq_len);
+  if (prod == NULL) {
+    return 1;
+  }
+  memcpy(prod->seq, seq, seq_len*sizeof(int));
+  prod->next = rule->head;
+  rule->head = prod;
+  rule->num_productions += 1;
+  return 0;
+}
+
+
+li_grammar_t * li_grammar_alloc(size_t num_nonterminal) {
+  li_grammar_t *grammar = malloc(sizeof(li_grammar_t));
+  if (grammar == NULL) {
+    fprintf(stderr, "failed to allocate grammar\n");
+    return NULL;
+  }
+  grammar->rules = malloc(num_nonterminal * sizeof(struct li_production_rule_t));
+  if (grammar->rules == NULL) {
+    fprintf(stderr, "failed to allocate grammar rules buffer\n");
+    free(grammar);
+    return NULL;
+  }
+  for (size_t i=0; i<num_nonterminal; i++) {
+    grammar->rules[i].num_productions = 0;
+    grammar->rules[i].head = NULL;
+  }
+  grammar->num_nonterminal = NULL;
+  return grammar;
+}
+
+
+void li_grammar_free(li_grammar_t *grammar) {
+  if (grammar != NULL) {
+    for (size_t i=0; i<grammar->num_nonterminal; i++) {
+      li_production_free(grammar->rules[i].head);
+    }
+    free(grammar->rules);
+    free(grammar);
+  }
+}
+
+
+int li_grammar_rule_add(
+  li_grammar_t *grammar, int nonterminal, size_t seq_len, int *seq
+) {
+  if (nonterminal < 0 || nonterminal >= grammar->num_nonterminal) {
+    return 2;
+  }
+  return li_prod_rule_add(grammar->rules + nonterminal, seq_len, seq);
+}
+
+
+