From 2ff51ab9c36dfc0fc723c38d26009048413e9e37 Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Mon, 14 Jan 2013 21:25:46 +0100
Subject: [PATCH] rework dns example syntax into H_RULE style

---
 examples/dns.c | 119 +++++++++++++++++++++++++------------------------
 1 file changed, 61 insertions(+), 58 deletions(-)

diff --git a/examples/dns.c b/examples/dns.c
index 676855e..010c462 100644
--- a/examples/dns.c
+++ b/examples/dns.c
@@ -10,6 +10,10 @@
 #define false 0
 #define true 1
 
+#define H_RULE(rule, def) const HParser *rule = def
+#define H_ARULE(rule, def) const HParser *rule = h_action(def, act_ ## rule)
+
+
 bool is_zero(HParseResult *p) {
   if (TT_UINT != p->ast->token_type)
     return false;
@@ -283,7 +287,7 @@ void set_rr(struct dns_rr rr, HCountedArray *rdata) {
   }
 }
 
-const HParsedToken* pack_dns_struct(const HParseResult *p) {
+const HParsedToken* act_dns_message(const HParseResult *p) {
   h_pprint(stdout, p->ast, 0, 2);
   HParsedToken *ret = h_arena_malloc(p->arena, sizeof(HParsedToken));
   ret->token_type = TT_DNS_MESSAGE;
@@ -360,66 +364,65 @@ const HParsedToken* pack_dns_struct(const HParseResult *p) {
   return ret;
 }
 
+// The action equivalent of h_ignore.
+const HParsedToken *act_ignore(const HParseResult *p)
+{
+  return NULL;
+}
+
+#define act_dns_hdzero act_ignore
+
 const HParser* init_parser() {
-  static HParser *dns_message = NULL;
-  if (dns_message)
-    return dns_message;
+  static const HParser *ret = NULL;
+  if (ret)
+    return ret;
 
-  const HParser *domain = init_domain();
+  H_RULE (domain,     init_domain());
+  H_ARULE(dns_hdzero, h_attr_bool(h_bits(3, false), is_zero));
+  H_RULE (dns_header, h_sequence(h_bits(16, false), // ID
+				 h_bits(1, false),  // QR
+				 h_bits(4, false),  // opcode
+				 h_bits(1, false),  // AA
+				 h_bits(1, false),  // TC
+				 h_bits(1, false),  // RD
+				 h_bits(1, false),  // RA
+				 dns_hdzero,        // Z
+				 h_bits(4, false),  // RCODE
+				 h_uint16(), // QDCOUNT
+				 h_uint16(), // ANCOUNT
+				 h_uint16(), // NSCOUNT
+				 h_uint16(), // ARCOUNT
+				 NULL));
+  H_RULE (type,       h_int_range(h_uint16(), 1, 16));
+  H_RULE (qtype,      h_choice(type, 
+			       h_int_range(h_uint16(), 252, 255),
+			       NULL));
+  H_RULE (class,      h_int_range(h_uint16(), 1, 4));
+  H_RULE (qclass,     h_choice(class,
+			       h_int_range(h_uint16(), 255, 255),
+			       NULL));
+  H_RULE (dns_question, h_sequence(h_sequence(h_many1(h_length_value(h_int_range(h_uint8(), 1, 255), 
+								     h_uint8())), 
+					      h_ch('\x00'),
+					      NULL),  // QNAME
+				   qtype,             // QTYPE
+				   qclass,            // QCLASS
+				   NULL));
+  H_RULE (dns_rr,     h_sequence(domain,              // NAME
+				 type,                // TYPE
+				 class,               // CLASS
+				 h_uint32(),          // TTL
+				 h_length_value(h_uint16(), h_uint8()), // RDLENGTH+RDATA
+				 NULL));
+  H_ARULE(dns_message, h_attr_bool(h_sequence(dns_header,
+					      h_many(dns_question),
+					      h_many(dns_rr),
+					      h_end_p(),
+					      NULL),
+				   validate_dns));
 
-  const HParser *dns_header = h_sequence(h_bits(16, false), // ID
-					 h_bits(1, false),  // QR
-					 h_bits(4, false),  // opcode
-					 h_bits(1, false),  // AA
-					 h_bits(1, false),  // TC
-					 h_bits(1, false),  // RD
-					 h_bits(1, false),  // RA
-					 h_ignore(h_attr_bool(h_bits(3, false), is_zero)), // Z
-					 h_bits(4, false),  // RCODE
-					 h_uint16(), // QDCOUNT
-					 h_uint16(), // ANCOUNT
-					 h_uint16(), // NSCOUNT
-					 h_uint16(), // ARCOUNT
-					 NULL);
-
-  const HParser *type = h_int_range(h_uint16(), 1, 16);
-
-  const HParser *qtype = h_choice(type, 
-				  h_int_range(h_uint16(), 252, 255),
-				  NULL);
-
-  const HParser *class = h_int_range(h_uint16(), 1, 4);
-  
-  const HParser *qclass = h_choice(class,
-				   h_int_range(h_uint16(), 255, 255),
-				   NULL);
-
-  const HParser *dns_question = h_sequence(h_sequence(h_many1(h_length_value(h_int_range(h_uint8(), 1, 255), 
-									     h_uint8())), 
-						      h_ch('\x00'),
-						      NULL),  // QNAME
-					   qtype,           // QTYPE
-					   qclass,          // QCLASS
-					   NULL);
- 
-
-  const HParser *dns_rr = h_sequence(domain,                          // NAME
-				     type,                            // TYPE
-				     class,                           // CLASS
-				     h_uint32(),                        // TTL
-				     h_length_value(h_uint16(), h_uint8()), // RDLENGTH+RDATA
-				     NULL);
-
-
-  dns_message = (HParser*)h_action(h_attr_bool(h_sequence(dns_header,
-							  h_many(dns_question),
-							  h_many(dns_rr),
-							  h_end_p(),
-							  NULL),
-					       validate_dns),
-				   pack_dns_struct);
-
-  return dns_message;
+  ret = dns_message;
+  return ret;
 }
 
 int start_listening() {