New: --group-by=EXPR and --group-title-format=FMT

The --group-by option allows for most reports to be split up into
sections based on the varying value of EXPR.  For example, to see
register subtotals by payee, use:

  ledger reg --group-by=payee -s

This works for separated balances too:

  ledger bal --group-by=payee

Another interesting possibility is seeing a register of all the accounts
affected by a related account:

  ledger reg -r --group-by=payee

The option --group-title-format can be used to add a separator bar to
the group titles.  The option --no-titles can be used to drop titles
altogether.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/chain.h b/src/chain.h
index 935f2935..59b04eb8 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -91,11 +91,25 @@ typedef shared_ptr<item_handler<post_t> > post_handler_ptr;
 typedef shared_ptr<item_handler<account_t> > acct_handler_ptr;
 
 class report_t;
+
+post_handler_ptr
+chain_pre_post_handlers(report_t&	 report,
+			post_handler_ptr base_handler);
+
 post_handler_ptr
 chain_post_handlers(report_t&	     report,
 		    post_handler_ptr base_handler,
 		    bool             for_accounts_report = false);
 
+inline post_handler_ptr
+chain_handlers(report_t&	report,
+	       post_handler_ptr handler,
+	       bool             for_accounts_report = false) {
+  handler = chain_post_handlers(report, handler, for_accounts_report);
+  handler = chain_pre_post_handlers(report, handler);
+  return handler;
+}
+
 } // namespace ledger
 
 #endif // _CHAIN_H