Expose current 'print' settings to Python

PR python/17291 asks for access to the current print options.  While I
think this need is largely satisfied by the existence of
Value.format_string, it seemed to me that a bit more could be done.

First, while Value.format_string uses the user's settings, it does not
react to temporary settings such as "print/x".  This patch changes
this.

Second, there is no good way to examine the current settings (in
particular the temporary ones in effect for just a single "print").
This patch adds this as well.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17291

gdb/python/py-prettyprint.c

@@ -39,6 +39,10 @@ enum gdbpy_string_repr_result
     string_repr_ok
   };
 
+/* If non-null, points to options that are in effect while
+   printing.  */
+const struct value_print_options *gdbpy_current_print_options;
+
 /* Helper function for find_pretty_printer which iterates over a list,
    calls each function and inspects output.  This will return a
    printer object if one recognizes VALUE.  If no printer is found, it
@@ -604,6 +608,9 @@ gdbpy_apply_val_pretty_printer (const struct extension_language_defn *extlang,
   if (printer == Py_None)
     return EXT_LANG_RC_NOP;
 
+  scoped_restore set_options = make_scoped_restore (&gdbpy_current_print_options,
+						    options);
+
   /* If we are printing a map, we want some special formatting.  */
   gdb::unique_xmalloc_ptr<char> hint (gdbpy_get_display_hint (printer.get ()));
 
@@ -632,8 +639,12 @@ gdbpy_apply_val_pretty_printer (const struct extension_language_defn *extlang,
 gdbpy_ref<>
 apply_varobj_pretty_printer (PyObject *printer_obj,
 			     struct value **replacement,
-			     struct ui_file *stream)
+			     struct ui_file *stream,
+			     const value_print_options *opts)
 {
+  scoped_restore set_options = make_scoped_restore (&gdbpy_current_print_options,
+						    opts);
+
   *replacement = NULL;
   gdbpy_ref<> py_str = pretty_print_one_value (printer_obj, replacement);
 
@@ -688,3 +699,88 @@ gdbpy_default_visualizer (PyObject *self, PyObject *args)
 
   return find_pretty_printer (val_obj).release ();
 }
+
+/* Helper function to set a boolean in a dictionary.  */
+static int
+set_boolean (PyObject *dict, const char *name, bool val)
+{
+  gdbpy_ref<> val_obj (PyBool_FromLong (val));
+  if (val_obj == nullptr)
+    return -1;
+  return PyDict_SetItemString (dict, name, val_obj.get ());
+}
+
+/* Helper function to set an integer in a dictionary.  */
+static int
+set_unsigned (PyObject *dict, const char *name, unsigned int val)
+{
+  gdbpy_ref<> val_obj = gdb_py_object_from_ulongest (val);
+  if (val_obj == nullptr)
+    return -1;
+  return PyDict_SetItemString (dict, name, val_obj.get ());
+}
+
+/* Implement gdb.print_options.  */
+PyObject *
+gdbpy_print_options (PyObject *unused1, PyObject *unused2)
+{
+  gdbpy_ref<> result (PyDict_New ());
+  if (result == nullptr)
+    return nullptr;
+
+  value_print_options opts;
+  gdbpy_get_print_options (&opts);
+
+  if (set_boolean (result.get (), "raw",
+		   opts.raw) < 0
+      || set_boolean (result.get (), "pretty_arrays",
+		      opts.prettyformat_arrays) < 0
+      || set_boolean (result.get (), "pretty_structs",
+		      opts.prettyformat_structs) < 0
+      || set_boolean (result.get (), "array_indexes",
+		      opts.print_array_indexes) < 0
+      || set_boolean (result.get (), "symbols",
+		      opts.symbol_print) < 0
+      || set_boolean (result.get (), "unions",
+		      opts.unionprint) < 0
+      || set_boolean (result.get (), "address",
+		      opts.addressprint) < 0
+      || set_boolean (result.get (), "deref_refs",
+		      opts.deref_ref) < 0
+      || set_boolean (result.get (), "actual_objects",
+		      opts.objectprint) < 0
+      || set_boolean (result.get (), "static_members",
+		      opts.static_field_print) < 0
+      || set_boolean (result.get (), "deref_refs",
+		      opts.deref_ref) < 0
+      || set_unsigned (result.get (), "max_elements",
+		       opts.print_max) < 0
+      || set_unsigned (result.get (), "max_depth",
+		       opts.max_depth) < 0
+      || set_unsigned (result.get (), "repeat_threshold",
+		       opts.repeat_count_threshold) < 0)
+    return nullptr;
+
+  if (opts.format != 0)
+    {
+      char str[2] = { (char) opts.format, 0 };
+      gdbpy_ref<> fmtstr = host_string_to_python_string (str);
+      if (fmtstr == nullptr)
+	return nullptr;
+      if (PyDict_SetItemString (result.get (), "format", fmtstr.get ()) < 0)
+	return nullptr;
+    }
+
+  return result.release ();
+}
+
+/* Helper function that either finds the prevailing print options, or
+   calls get_user_print_options.  */
+void
+gdbpy_get_print_options (value_print_options *opts)
+{
+  if (gdbpy_current_print_options != nullptr)
+    *opts = *gdbpy_current_print_options;
+  else
+    get_user_print_options (opts);
+}

gdb/python/py-value.c

@@ -673,7 +673,7 @@ valpy_format_string (PyObject *self, PyObject *args, PyObject *kw)
     }
 
   struct value_print_options opts;
-  get_user_print_options (&opts);
+  gdbpy_get_print_options (&opts);
   opts.deref_ref = 0;
 
   /* We need objects for booleans as the "p" flag for bools is new in
@@ -1163,7 +1163,7 @@ valpy_str (PyObject *self)
 {
   struct value_print_options opts;
 
-  get_user_print_options (&opts);
+  gdbpy_get_print_options (&opts);
   opts.deref_ref = 0;
 
   string_file stb;

gdb/python/py-varobj.c

@@ -17,13 +17,15 @@
 #include "python-internal.h"
 #include "varobj.h"
 #include "varobj-iter.h"
+#include "valprint.h"
 
 /* A dynamic varobj iterator "class" for python pretty-printed
    varobjs.  This inherits struct varobj_iter.  */
 
 struct py_varobj_iter : public varobj_iter
 {
-  py_varobj_iter (struct varobj *var, gdbpy_ref<> &&pyiter);
+  py_varobj_iter (struct varobj *var, gdbpy_ref<> &&pyiter,
+		  const value_print_options *opts);
   ~py_varobj_iter () override;
 
   std::unique_ptr<varobj_item> next () override;
@@ -41,6 +43,9 @@ private:
   /* The python iterator returned by the printer's 'children' method,
      or NULL if not available.  */
   PyObject *m_iter;
+
+  /* The print options to use.  */
+  value_print_options m_opts;
 };
 
 /* Implementation of the 'dtor' method of pretty-printed varobj
@@ -67,6 +72,9 @@ py_varobj_iter::next ()
 
   gdbpy_enter_varobj enter_py (m_var);
 
+  scoped_restore set_options = make_scoped_restore (&gdbpy_current_print_options,
+						    &m_opts);
+
   gdbpy_ref<> item (PyIter_Next (m_iter));
 
   if (item == NULL)
@@ -124,9 +132,11 @@ py_varobj_iter::next ()
    whose children the iterator will be iterating over.  PYITER is the
    python iterator actually responsible for the iteration.  */
 
-py_varobj_iter::py_varobj_iter (struct varobj *var, gdbpy_ref<> &&pyiter)
+py_varobj_iter::py_varobj_iter (struct varobj *var, gdbpy_ref<> &&pyiter,
+				const value_print_options *opts)
   : m_var (var),
-    m_iter (pyiter.release ())
+    m_iter (pyiter.release ()),
+    m_opts (*opts)
 {
 }
 
@@ -134,13 +144,17 @@ py_varobj_iter::py_varobj_iter (struct varobj *var, gdbpy_ref<> &&pyiter)
    over VAR's children.  */
 
 std::unique_ptr<varobj_iter>
-py_varobj_get_iterator (struct varobj *var, PyObject *printer)
+py_varobj_get_iterator (struct varobj *var, PyObject *printer,
+			const value_print_options *opts)
 {
   gdbpy_enter_varobj enter_py (var);
 
   if (!PyObject_HasAttr (printer, gdbpy_children_cst))
     return NULL;
 
+  scoped_restore set_options = make_scoped_restore (&gdbpy_current_print_options,
+						    opts);
+
   gdbpy_ref<> children (PyObject_CallMethodObjArgs (printer, gdbpy_children_cst,
 						    NULL));
   if (children == NULL)
@@ -157,5 +171,6 @@ py_varobj_get_iterator (struct varobj *var, PyObject *printer)
     }
 
   return std::unique_ptr<varobj_iter> (new py_varobj_iter (var,
-							   std::move (iter)));
+							   std::move (iter),
+							   opts));
 }

gdb/python/python-internal.h

@@ -746,11 +746,16 @@ int gdbpy_is_value_object (PyObject *obj);
    other pretty-printer functions, because they refer to PyObject.  */
 gdbpy_ref<> apply_varobj_pretty_printer (PyObject *print_obj,
 					 struct value **replacement,
-					 struct ui_file *stream);
+					 struct ui_file *stream,
+					 const value_print_options *opts);
 gdbpy_ref<> gdbpy_get_varobj_pretty_printer (struct value *value);
 gdb::unique_xmalloc_ptr<char> gdbpy_get_display_hint (PyObject *printer);
 PyObject *gdbpy_default_visualizer (PyObject *self, PyObject *args);
 
+PyObject *gdbpy_print_options (PyObject *self, PyObject *args);
+void gdbpy_get_print_options (value_print_options *opts);
+extern const struct value_print_options *gdbpy_current_print_options;
+
 void bpfinishpy_pre_stop_hook (struct gdbpy_breakpoint_object *bp_obj);
 void bpfinishpy_post_stop_hook (struct gdbpy_breakpoint_object *bp_obj);
 
@@ -784,8 +789,10 @@ int gdb_pymodule_addobject (PyObject *module, const char *name,
 
 struct varobj_iter;
 struct varobj;
-std::unique_ptr<varobj_iter> py_varobj_get_iterator (struct varobj *var,
-						     PyObject *printer);
+std::unique_ptr<varobj_iter> py_varobj_get_iterator
+     (struct varobj *var,
+      PyObject *printer,
+      const value_print_options *opts);
 
 /* Deleter for Py_buffer unique_ptr specialization.  */
 

gdb/python/python.c

@@ -2560,6 +2560,10 @@ the returned string is 'ADDRESS <SYMBOL+OFFSET>' without the quotes." },
     "current_language () -> string\n\
 Return the name of the currently selected language." },
 
+  { "print_options", gdbpy_print_options, METH_NOARGS,
+    "print_options () -> dict\n\
+Return the current print options." },
+
   {NULL, NULL, 0, NULL}
 };