[RFC 5/8] mi/python: Polish MI output of python commands

[Jan Vrany <jan dot vrany at fit dot cvut dot cz>]

This commits makes MI representation of python-implemented MI command
more "natural". Add support for tuples, iterators and generic sequences.

gdb/Changelog:

	* python/py-micmd.c (parse_mi_result): Polish to make the output
	more "natural". Add support for tuples, iterators and general sequences.
	(py_mi_invoke): Do not call Py_DECREF on argument strings since
	PyList_SetItem borrows the reference. If python MI command returns
	None, do not print the result on MI output channel and just respond with
	^done.
---
 gdb/ChangeLog         |  7 ++++++
 gdb/python/py-micmd.c | 54 +++++++++++++++++++++++++------------------
 2 files changed, 39 insertions(+), 22 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 692b937fee..8bbaaba5ad 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2018-12-10  Jan Vrany  <jan.vrany@fit.cvut.cz>
+
+	* python/py-micmd.c (parse_mi_result): Polish to make the output
+	more "natural". Add support for tuples, iterators and general sequences.
+	(py_mi_invoke): If python MI command returns None, do not print the
+	result on MI output channel and just respond with "^done".
+
 2018-12-11  Jan Vrany  <jan.vrany@fit.cvut.cz>
 
 	* python/py-micmd.c (parse_mi_result): Use gdb::unique_xmalloc_ptr<>
diff --git a/gdb/python/py-micmd.c b/gdb/python/py-micmd.c
index 0683a02017..bbd746fa32 100644
--- a/gdb/python/py-micmd.c
+++ b/gdb/python/py-micmd.c
@@ -37,37 +37,47 @@ parse_mi_result (PyObject *result, const char *field_name)
 {
   struct ui_out *uiout = current_uiout;
 
-  if(!field_name)
-    field_name = "default";
-
-  if (PyString_Check(result))
-    {
-      const char *string = gdbpy_obj_to_string (result).release ();
-      uiout->field_string (field_name, string);
-      xfree ( (void *)string);
-    }
-  else if (PyList_Check (result))
+  if (PyString_Check (result))
     {
-      PyObject *item;
-      Py_ssize_t i = 0;      
-      ui_out_emit_list list_emitter (uiout, field_name);
-      for(i = 0; i < PyList_GET_SIZE (result); ++i)
-	{
-          ui_out_emit_tuple tuple_emitter (uiout, NULL);
-	  item = PyList_GetItem (result, i);
-	  parse_mi_result (item, NULL);
-	}      
+      goto generic;
     }
-  else if ( PyDict_Check (result))
+  else if (PyDict_Check (result))
     {
       PyObject *key, *value;
       Py_ssize_t pos = 0;
+      ui_out_emit_tuple tuple_emitter (uiout, field_name);
       while ( PyDict_Next (result, &pos, &key, &value) )
 	{
 	  gdb::unique_xmalloc_ptr<char> key_string (gdbpy_obj_to_string (key));
-	  parse_mi_result (value, key_string.get ());
+          parse_mi_result (value, key_string.get ());
 	}
     }
+  else if (PySequence_Check (result))
+    {
+      PyObject *item;
+      Py_ssize_t i = 0;
+      ui_out_emit_list list_emitter (uiout, field_name);
+      for(i = 0; i < PySequence_Size (result); ++i)
+        {
+          item = PySequence_GetItem (result, i);
+          parse_mi_result (item, NULL);
+        }
+    }
+  else if (PyIter_Check (result))
+    {
+      gdbpy_ref<> item;
+      ui_out_emit_list list_emitter (uiout, field_name);
+      while (item.reset(PyIter_Next (result)) , item != nullptr)
+        {
+          parse_mi_result (item.get (), NULL);
+        }
+    }
+  else
+    {
+      generic:
+      gdb::unique_xmalloc_ptr<char> string (gdbpy_obj_to_string (result));
+      uiout->field_string (field_name, string.get ());
+    }
 }
 
 /* Called from mi_command_py's invoke to invoke the command.  */
@@ -111,7 +121,7 @@ py_mi_invoke (void *py_obj, char **argv, int argc)
 
   if (result != nullptr)
     {
-      parse_mi_result (result.get (), NULL);
+      if (Py_None != result) parse_mi_result (result.get (), "result");
     }
 }
 
-- 
2.20.1