implement basic grammatical expansionc-version

1 files changed, 20 insertions, 2 deletions

diff --git a/expression.h b/expression.h
index 36a0e02..e288a77 100644
--- a/expression.h
+++ b/expression.h
@@ -1,6 +1,8 @@
 #ifndef LICHEN_EXPRESSION_H
 #define LICHEN_EXPRESSION_H
 
+#include <stdint.h>
+
 /****************************************************************
  * 
  * a grammar is built on both nonterminals and terminals. both are
@@ -32,11 +34,27 @@ 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;
+  int num_nonterminal;
 } li_grammar_t;
 
-li_rammar_t * li_grammar_alloc(size_t num_nonterminal);
+li_grammar_t * li_grammar_alloc(int 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);
 
+// expand a symbol into only nonterminals
+// dst is a buffer to place the expansion into, and len should initially contain the size of the buffer
+// stack is a buffer used internally to expand the rule, and stack_sz is the size of the stack
+// symbol is the symbol to start with
+// randomness is a sequence of random values, from any source, and rand_sz is the length of the sequence
+// if successful, this function will return 0 and dst will contain the expanded sequence, with len containing
+// the length of the actual expansion
+// if unsuccessful, this function will return nonzero. dst, len, and stack may be modified in unpredictable ways.
+int li_grammar_rule_expand(
+  li_grammar_t *grammar, 
+  int *dst, size_t *len, 
+  int *stack, size_t stack_sz, 
+  int symbol, 
+  const uint8_t *randomness, size_t rand_sz
+);
+
 #endif