Segregated symbols into 5 separate namespaces

The different namespaces are:

  Function      Value expression functions, which receive a "context"
  Option        Command-line options
  Precommand    Commands which are invoked before reading the journal
  Command       Commands which are invoked after reading the journal
  Directive     Directives that occur at column 0 in a data file

This greatly eases the ability for Python uses to add intercept hooks to
change how the basic Ledger module functions.  An example of what should
be possible soon:

  import ledger

  def my_foo_handler(value):
      print "--foo received:", value

  ledger.add_handler(ledger.Option, "foo=", my_foo_handler)

1 files changed, 16 insertions, 13 deletions

diff --git a/src/session.cc b/src/session.cc
index 2b8d8d58..67f19ca9 100644
--- a/src/session.cc
+++ b/src/session.cc
@@ -284,23 +284,26 @@ option_t<session_t> * session_t::lookup_option(const char * p)
   return NULL;
 }
 
-expr_t::ptr_op_t session_t::lookup(const string& name)
+expr_t::ptr_op_t session_t::lookup(const symbol_t::kind_t kind,
+				   const string& name)
 {
-  const char * p = name.c_str();
-  switch (*p) {
-  case 'o':
-    if (WANT_OPT()) { p += OPT_PREFIX_LEN;
-      if (option_t<session_t> * handler = lookup_option(p))
-	return MAKE_OPT_HANDLER(session_t, handler);
-    }
+  switch (kind) {
+  case symbol_t::FUNCTION:
+    // Check if they are trying to access an option's setting or value.
+    if (option_t<session_t> * handler = lookup_option(name.c_str()))
+      return MAKE_OPT_FUNCTOR(session_t, handler);
     break;
-  }
 
-  // Check if they are trying to access an option's setting or value.
-  if (option_t<session_t> * handler = lookup_option(p))
-    return MAKE_OPT_FUNCTOR(session_t, handler);
+  case symbol_t::OPTION:
+    if (option_t<session_t> * handler = lookup_option(name.c_str()))
+      return MAKE_OPT_HANDLER(session_t, handler);
+    break;
+
+  default:
+    break;
+  }
 
-  return symbol_scope_t::lookup(name);
+  return symbol_scope_t::lookup(kind, name);
 }
 
 } // namespace ledger