1 files changed, 59 insertions, 0 deletions
diff --git a/bdep/help.cxx b/bdep/help.cxx
new file mode 100644
index 0000000..ec2c4c2
--- /dev/null
+++ b/bdep/help.cxx
@@ -0,0 +1,59 @@
+// file      : bdep/help.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <bdep/help.hxx>
+
+#include <libbutl/pager.mxx>
+
+#include <bdep/diagnostics.hxx>
+#include <bdep/bdep-options.hxx>
+
+using namespace std;
+using namespace butl;
+
+namespace bdep
+{
+  int
+  help (const help_options& o, const string& t, usage_function* usage)
+  {
+    if (usage == nullptr) // Not a command.
+    {
+      if (t.empty ())             // General help.
+        usage = &print_bdep_usage;
+      //
+      // Help topics.
+      //
+      else if (t == "common-options")
+        usage = &print_bdep_common_options_long_usage;
+      else
+        fail << "unknown bdep command/help topic '" << t << "'" <<
+          info << "run 'bdep help' for more information";
+    }
+
+    try
+    {
+      pager p ("bdep " + (t.empty () ? "help" : t),
+               verb >= 2,
+               o.pager_specified () ? &o.pager () : nullptr,
+               &o.pager_option ());
+
+      usage (p.stream (), cli::usage_para::none);
+
+      // If the pager failed, assume it has issued some diagnostics.
+      //
+      return p.wait () ? 0 : 1;
+    }
+    // Catch io_error as std::system_error together with the pager-specific
+    // exceptions.
+    //
+    catch (const system_error& e)
+    {
+      error << "pager failed: " << e;
+
+      // Fall through.
+    }
+
+    throw failed ();
+  }
+}