Moved parse_state_t into internal.h, had to add some things for Warth's recursion. More documentary comments.

src/hammer.c

@@ -35,7 +35,36 @@ guint djbhash(const uint8_t *buf, size_t len) {
   return hash;
 }
 
-void setupLR(const parser_t *p, GQueue *stack, LR_t *recDetect) {
+parser_cache_value_t* recall(parser_cache_key_t *k, parse_state_t *state) {
+  parser_cache_value_t *cached = g_hash_table_lookup(state->cache, k);
+  head_t *head = g_hash_table_lookup(state->recursion_heads, &(state->input_stream));
+  if (!head) { // No heads found
+    return cached;
+  } else { // Some heads found
+    if (!cached && head->head_parser != k->parser && !g_slist_find(head->involved_set, k->parser)) {
+      // Nothing in the cache, and the key parser is not involved
+      return /* TODO(mlp): figure out what to return here instead of Some(MemoEntry(Right(Failure("dummy", in")))) */ NULL;
+    }
+    if (g_slist_find(head->eval_set, k->parser)) {
+      // Something is in the cache, and the key parser is in the eval set. Remove the key parser from the eval set of the head. 
+      head->eval_set = g_slist_remove_all(head->eval_set, k->parser);
+      parse_result_t *tmp_res = k->parser->fn(k->parser->env, state);
+      if (tmp_res)
+	tmp_res->arena = state->arena;
+      // we know that cached has an entry here, modify it
+      cached->value_type = PC_RIGHT;
+      cached->right = tmp_res;
+    }
+    return cached;
+  }
+}
+
+void setupLR(const parser_t *p, GQueue *stack, LR_t *rec_detect) {
+  if (!rec_detect->head) {
+    head_t *some = g_new(head_t, 1);
+    some->head_parser = p; some->involved_set = NULL; some->eval_set = NULL;
+    rec_detect->head = some;
+  }
   
 }
 
@@ -47,6 +76,7 @@ parse_result_t* grow(const parser_t *p, parse_state_t *state, head_t *head) {
   return NULL;
 }
 
+/* Warth's recursion. Hi Alessandro! */
 parse_result_t* do_parse(const parser_t* parser, parse_state_t *state) {
   // TODO(thequux): add caching here.
   parser_cache_key_t *key = a_new(parser_cache_key_t, 1);
@@ -67,7 +97,8 @@ parse_result_t* do_parse(const parser_t* parser, parse_state_t *state) {
     parse_result_t *tmp_res;
     if (parser) {
       tmp_res = parser->fn(parser->env, state);
-      tmp_res->arena = state->arena;
+      if (tmp_res)
+	tmp_res->arena = state->arena;
     } else
       tmp_res = NULL;
     if (state->input_stream.overrun)

src/hammer.h

@@ -20,37 +20,15 @@
 #include <glib.h>
 #include <stdint.h>
 #include "allocator.h"
-/* The state of the parser.
- *
- * Members:
- *   input - the entire string being parsed
- *   index - current position in input
- *   length - size of input
- *   cache - a hash table describing the state of the parse, including partial parse_results. It's a hash table from parser_cache_key_t to parse_state_t. 
- *
- */
+
 #define BYTE_BIG_ENDIAN 0x1
 #define BIT_BIG_ENDIAN 0x2
 #define BIT_LITTLE_ENDIAN 0x0
 #define BYTE_LITTLE_ENDIAN 0x0
 
 typedef int bool;
-typedef struct input_stream {
-  // This should be considered to be a really big value type.
-  const uint8_t *input;
-  size_t index;
-  size_t length;
-  char bit_offset;
-  char endianness;
-  char overrun;
-} input_stream_t;
-  
-typedef struct parse_state {
-  GHashTable *cache; 
-  input_stream_t input_stream;
-  arena_t arena;
-  GQueue *lr_stack;
-} parse_state_t;
+
+typedef struct parse_state parse_state_t;
 
 typedef enum token_type {
   TT_NONE,

src/internal.h

@@ -32,28 +32,85 @@
 #define false 0
 #define true 1
 
+typedef struct input_stream {
+  // This should be considered to be a really big value type.
+  const uint8_t *input;
+  size_t index;
+  size_t length;
+  char bit_offset;
+  char endianness;
+  char overrun;
+} input_stream_t;
+
+/* The state of the parser.
+ *
+ * Members:
+ *   cache - a hash table describing the state of the parse, including partial parse_results. It's a hash table from parser_cache_key_t to parser_cache_value_t. 
+ *   input_stream - the input stream at this state.
+ *   arena - the arena that has been allocated for the parse this state is in.
+ *   lr_stack - used in Warth's recursion
+ *   recursion_heads - used in Warth's recursion
+ *
+ */
+  
+typedef struct parse_state {
+  GHashTable *cache; 
+  input_stream_t input_stream;
+  arena_t arena;
+  GQueue *lr_stack;
+  GHashTable *recursion_heads;
+} parse_state_t;
+
+/* The (location, parser) tuple used to key the cache.
+ */
+
 typedef struct parser_cache_key {
   input_stream_t input_pos;
   const parser_t *parser;
 } parser_cache_key_t;
 
+/* A value in the cache is either of value Left or Right (this is a 
+ * holdover from Scala, which used Either here). Left corresponds to
+ * LR_t, which is for left recursion; Right corresponds to 
+ * parse_result_t.
+ */
+
 typedef enum parser_cache_value_type {
   PC_LEFT,
   PC_RIGHT
 } parser_cache_value_type_t;
 
+
+/* A recursion head.
+ *
+ * Members:
+ *   head_parser -
+ *   involved_set -
+ *   eval_set - 
+ */
 typedef struct head {
-  parser_t *head_parser;
+  const parser_t *head_parser;
   GSList *involved_set;
   GSList *eval_set;
 } head_t;
 
+
+/* A left recursion.
+ *
+ * Members:
+ *   seed -
+ *   rule -
+ *   head -
+ */
 typedef struct LR {
   parse_result_t *seed;
   const parser_t *rule;
   head_t *head;
 } LR_t;
 
+/* Tagged union for values in the cache: either LR's (Left) or 
+ * parse_result_t's (Right).
+ */
 typedef struct parser_cache_value {
   parser_cache_value_type_t value_type;
   union {