add monadic bind combinator h_bind

src/parsers/bind.c

@@ -0,0 +1,42 @@
+#include "parser_internal.h"
+
+typedef struct {
+    const HParser *p;
+    HContinuation k;
+    void *env;
+} BindEnv;
+
+static HParseResult *parse_bind(void *be_, HParseState *state) {
+    BindEnv *be = be_;
+
+    HParseResult *res = h_do_parse(be->p, state);
+    if(!res)
+        return NULL;
+
+    HParser *kx = be->k(res->ast, be->env);
+    return h_do_parse(kx, state);
+}
+
+static const HParserVtable bind_vt = {
+    .parse = parse_bind,
+    .isValidRegular = h_false,
+    .isValidCF = h_false,
+    .compile_to_rvm = h_not_regular,
+};
+
+HParser *h_bind(const HParser *p, HContinuation k, void *env)
+{
+    return h_bind__m(&system_allocator, p, k, env);
+}
+
+HParser *h_bind__m(HAllocator *mm__,
+                   const HParser *p, HContinuation k, void *env)
+{
+    BindEnv *be = h_new(BindEnv, 1);
+
+    be->p = p;
+    be->k = k;
+    be->env = env;
+
+    return h_new_parser(mm__, &bind_vt, be);
+}