pass a temporary arena allocator to the continuation in h_bind

src/parsers/bind.c

@@ -4,8 +4,34 @@ typedef struct {
     const HParser *p;
     HContinuation k;
     void *env;
+    HAllocator *mm__;
 } BindEnv;
 
+// an HAllocator backed by an HArena
+typedef struct {
+    HAllocator allocator;   // inherit  XXX is this the proper way to do it?
+    HArena *arena;
+} ArenaAllocator;
+
+void *aa_alloc(HAllocator *allocator, size_t size)
+{
+    HArena *arena = ((ArenaAllocator *)allocator)->arena;
+    return h_arena_malloc(arena, size);
+}
+
+void *aa_realloc(HAllocator *allocator, void *ptr, size_t size)
+{
+    HArena *arena = ((ArenaAllocator *)allocator)->arena;
+    assert(0);  // XXX realloc for arena allocator
+    return NULL;
+}
+
+void aa_free(HAllocator *allocator, void *ptr)
+{
+    HArena *arena = ((ArenaAllocator *)allocator)->arena;
+    h_arena_free(arena, ptr);
+}
+
 static HParseResult *parse_bind(void *be_, HParseState *state) {
     BindEnv *be = be_;
 
@@ -13,11 +39,20 @@ static HParseResult *parse_bind(void *be_, HParseState *state) {
     if(!res)
         return NULL;
 
-    HParser *kx = be->k(res->ast, be->env);
-    if(!kx)
-        return NULL;
+    // create a temporary arena allocator for the continuation
+    HArena *arena = h_new_arena(be->mm__, 0);
+    ArenaAllocator aa = {{aa_alloc, aa_realloc, aa_free}, arena};
 
-    return h_do_parse(kx, state);
+    HParser *kx = be->k((HAllocator *)&aa, res->ast, be->env);
+    if(!kx) {
+        h_delete_arena(arena);
+        return NULL;
+    }
+
+    res = h_do_parse(kx, state);
+
+    h_delete_arena(arena);
+    return res;
 }
 
 static const HParserVtable bind_vt = {
@@ -40,6 +75,7 @@ HParser *h_bind__m(HAllocator *mm__,
     be->p = p;
     be->k = k;
     be->env = env;
+    be->mm__ = mm__;
 
     return h_new_parser(mm__, &bind_vt, be);
 }