fix desugaring of h_whitespace and add reshape action

src/parsers/whitespace.c

 #include <ctype.h>
+#include <assert.h>
 #include "parser_internal.h"
 
 static HParseResult* parse_whitespace(void* env, HParseState *state) {
@@ -14,28 +15,47 @@ static HParseResult* parse_whitespace(void* env, HParseState *state) {
   return h_do_parse((HParser*)env, state);
 }
 
+static const char SPACE_CHRS[6] = {' ', '\f', '\n', '\r', '\t', '\v'};
+
+static const HParsedToken *h_act_last(const HParseResult *p) {
+  assert(p->ast);
+  assert(p->ast->token_type == TT_SEQUENCE);
+
+  return p->ast->seq->elements[p->ast->seq->used-1];
+}
+
 static HCFChoice* desugar_whitespace(HAllocator *mm__, void *env) {
-  HCFChoice *ret = h_new(HCFChoice, 1);
-  ret->type = HCF_CHOICE;
-  ret->seq = h_new(HCFSequence*, 3);
+  HCFChoice *ws = h_new(HCFChoice, 1);
+  ws->type = HCF_CHOICE;
+  ws->seq = h_new(HCFSequence*, 3);
   HCFSequence *nonempty = h_new(HCFSequence, 1);
   nonempty->items = h_new(HCFChoice*, 3);
   nonempty->items[0] = h_new(HCFChoice, 1);
   nonempty->items[0]->type = HCF_CHARSET;
   nonempty->items[0]->charset = new_charset(mm__);
-  charset_set(nonempty->items[0]->charset, '\t', 1);
-  charset_set(nonempty->items[0]->charset, ' ', 1);
-  charset_set(nonempty->items[0]->charset, '\n', 1);
-  charset_set(nonempty->items[0]->charset, '\r', 1);
-  nonempty->items[1] = ret; // yay circular pointer!
+  for(size_t i=0; i<sizeof(SPACE_CHRS); i++)
+    charset_set(nonempty->items[0]->charset, SPACE_CHRS[i], 1);
+  nonempty->items[1] = ws; // yay circular pointer!
   nonempty->items[2] = NULL;
-  ret->seq[0] = nonempty;
+  ws->seq[0] = nonempty;
   HCFSequence *empty = h_new(HCFSequence, 1);
   empty->items = h_new(HCFChoice*, 1);
   empty->items[0] = NULL;
-  ret->seq[1] = empty;
-  ret->seq[2] = NULL;
-  ret->action = NULL;
+  ws->seq[1] = empty;
+  ws->seq[2] = NULL;
+
+  HCFChoice *ret = h_new(HCFChoice, 1);
+  ret->type = HCF_CHOICE;
+  ret->seq = h_new(HCFSequence*, 2);
+  ret->seq[0] = h_new(HCFSequence, 1);
+  ret->seq[0]->items = h_new(HCFChoice*, 3);
+  ret->seq[0]->items[0] = ws;
+  ret->seq[0]->items[1] = h_desugar(mm__, (HParser *)env);
+  ret->seq[0]->items[2] = NULL;
+  ret->seq[1] = NULL;
+
+  ret->reshape = h_act_last;
+  
   return ret;
 }
 
@@ -53,7 +73,6 @@ static bool ws_ctrvm(HRVMProg *prog, void *env) {
   HParser *p = (HParser*)env;
   uint16_t start = h_rvm_get_ip(prog);
   uint16_t next;
-  const char SPACE_CHRS[6] = {' ', '\f', '\n', '\r', '\t', '\v'};
 
   for (int i = 0; i < 6; i++) {
     next = h_rvm_insert_insn(prog, RVM_FORK, 0);