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, 11 insertions, 1 deletions

diff --git a/src/print.cc b/src/print.cc
index 5c46f4e7..a8aa5872 100644
--- a/src/print.cc
+++ b/src/print.cc
@@ -42,7 +42,7 @@ namespace ledger {
 
 print_xacts::print_xacts(report_t& _report,
 			 bool      _print_raw)
-  : report(_report), print_raw(_print_raw)
+  : report(_report), print_raw(_print_raw), first_title(true)
 {
   TRACE_CTOR(print_xacts, "report&, bool");
 }
@@ -221,6 +221,16 @@ namespace {
   }
 }
 
+void print_xacts::title(const string&)
+{
+  if (first_title) {
+    first_title = false;
+  } else {
+    std::ostream& out(report.output_stream);
+    out << '\n';
+  }
+}
+
 void print_xacts::flush()
 {
   std::ostream& out(report.output_stream);