New valexpr functions: id, idstring, magnitude

id returns a unique SHA1 id of a transaction.
idstring is the string that the SHA1 is based on.
magnitude is the sum of the positive side of a transaction.

src/filters.cc

@@ -133,21 +133,6 @@ void sort_posts::post_accumulated_posts()
   posts.clear();
 }
 
-namespace {
-  string to_hex(uint_least32_t * message_digest)
-  {
-    std::ostringstream buf;
-
-    for(int i = 0; i < 5 ; i++) {
-      buf.width(8);
-      buf.fill('0');
-      buf << std::hex << message_digest[i];
-      break;			// only output the first dword
-    }
-    return buf.str();
-  }
-}
-
 void anonymize_posts::operator()(post_t& post)
 {
   SHA1		 sha;

src/utils.h

@@ -594,6 +594,19 @@ inline char peek_next_nonws(std::istream& in) {
     *_p = '\0';						\
   }
 
+inline string to_hex(uint_least32_t * message_digest)
+{
+  std::ostringstream buf;
+
+  for(int i = 0; i < 5 ; i++) {
+    buf.width(8);
+    buf.fill('0');
+    buf << std::hex << message_digest[i];
+    break;			// only output the first dword
+  }
+  return buf.str();
+}
+
 extern const string version;
 
 } // namespace ledger

src/xact.cc

@@ -352,6 +352,33 @@ void xact_t::add_post(post_t * post)
 }
 
 namespace {
+  value_t get_magnitude(xact_t& xact) {
+    balance_t halfbal;
+    foreach (post_t * post, xact.posts)
+      if (post->amount.sign() > 0)
+	halfbal += post->amount.number();
+    return halfbal;
+  }
+
+  value_t get_idstring(xact_t& xact) {
+    std::ostringstream buf;
+    buf << *xact._date;
+    buf << xact.payee;
+
+    get_magnitude(xact).print(buf);
+
+    return string_value(buf.str());
+  }
+  value_t get_id(xact_t& xact) {
+    SHA1 sha;
+    sha.Reset();
+    sha << get_idstring(xact).as_string().c_str();
+
+    uint_least32_t message_digest[5];
+    sha.Result(message_digest);
+    return string_value(to_hex(message_digest));
+  }
+
   value_t get_code(xact_t& xact) {
     if (xact.code)
       return string_value(*xact.code);
@@ -377,6 +404,18 @@ expr_t::ptr_op_t xact_t::lookup(const string& name)
       return WRAP_FUNCTOR(get_wrapper<&get_code>);
     break;
 
+  case 'i':
+    if (name == "id")
+      return WRAP_FUNCTOR(get_wrapper<&get_id>);
+    else if (name == "idstring")
+      return WRAP_FUNCTOR(get_wrapper<&get_idstring>);
+    break;
+
+  case 'm':
+    if (name == "magnitude")
+      return WRAP_FUNCTOR(get_wrapper<&get_magnitude>);
+    break;
+
   case 'p':
     if (name[1] == '\0' || name == "payee")
       return WRAP_FUNCTOR(get_wrapper<&get_payee>);