Custom displayhook

CMakeLists.txt

@@ -144,6 +144,7 @@ set(XEUSCLING_SRC
     src/main.cpp
     src/xpython_interpreter.cpp
     src/xpython_logger.cpp
+    src/xpython_display.cpp
     src/xpyt_config.hpp
 )
 

notebooks/xeus-python.ipynb

@@ -6,7 +6,8 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "a = 3"
+    "a = 3\n",
+    "a"
    ]
   },
   {
@@ -18,6 +19,56 @@
     "a"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "a += 6"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "print(a)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "a"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "b = 89\n",
+    "\n",
+    "def test(x):\n",
+    "    return x * 2\n",
+    "\n",
+    "test(b)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "test(4)"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -45,6 +96,15 @@
     "b = {\"a\": 2, \"b\": 3}"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "b"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,

src/xpython_display.cpp

@@ -0,0 +1,52 @@
+/***************************************************************************
+* Copyright (c) 2018, Martin Renou, Johan Mabille, Sylvain Corlay and      *
+* Wolf Vollprecht                                                          *
+*                                                                          *
+* Distributed under the terms of the BSD 3-Clause License.                 *
+*                                                                          *
+* The full license is in the file LICENSE, distributed with this software. *
+****************************************************************************/
+
+#include "pybind11/pybind11.h"
+#include "pybind11/embed.h"
+
+#include "xpython_display.hpp"
+
+namespace py = pybind11;
+
+namespace xpyt
+{
+    xdisplayhook::xdisplayhook() : m_execution_count(0)
+    {
+    }
+
+    xdisplayhook::~xdisplayhook()
+    {
+    }
+
+    void xdisplayhook::set_execution_count(int execution_count)
+    {
+        m_execution_count = execution_count;
+    }
+
+    void xdisplayhook::add_hook(hook_function_type hook)
+    {
+        m_hooks.push_back(hook);
+    }
+
+    void xdisplayhook::operator()(py::object obj)
+    {
+        for (auto it = m_hooks.begin(); it != m_hooks.end(); ++it)
+        {
+            it->operator()(m_execution_count, obj);
+        }
+    }
+
+    PYBIND11_EMBEDDED_MODULE(xeus_python_display, m) {
+        py::class_<xdisplayhook>(m, "XPythonDisplay")
+            .def(py::init<>())
+            .def("set_execution_count", &xdisplayhook::set_execution_count)
+            .def("add_hook", &xdisplayhook::add_hook)
+            .def("__call__", &xdisplayhook::operator());
+    }
+}

src/xpython_display.hpp

@@ -0,0 +1,44 @@
+/***************************************************************************
+* Copyright (c) 2018, Martin Renou, Johan Mabille, Sylvain Corlay and      *
+* Wolf Vollprecht                                                          *
+*                                                                          *
+* Distributed under the terms of the BSD 3-Clause License.                 *
+*                                                                          *
+* The full license is in the file LICENSE, distributed with this software. *
+****************************************************************************/
+
+#ifndef XPYT_PYTHON_DISPLAY_HPP
+#define XPYT_PYTHON_DISPLAY_HPP
+
+#include <functional>
+
+#include "pybind11/pybind11.h"
+#include "pybind11/functional.h"
+
+namespace py = pybind11;
+
+namespace xpyt
+{
+    class xdisplayhook
+    {
+
+    public:
+
+        using hook_function_type = std::function<void(int, py::object)>;
+        using hooks_type = std::vector<hook_function_type>;
+
+        xdisplayhook();
+        virtual ~xdisplayhook();
+
+        void set_execution_count(int execution_count);
+        void add_hook(hook_function_type hook);
+        void operator()(py::object obj);
+
+    private:
+
+        int m_execution_count;
+        hooks_type m_hooks;
+    };
+}
+
+#endif

src/xpython_interpreter.cpp

@@ -33,6 +33,7 @@ namespace xpyt
         py::initialize_interpreter();
 
         redirect_output();
+        redirect_display();
     }
 
     xpython_interpreter::~xpython_interpreter() {}
@@ -49,11 +50,44 @@ namespace xpyt
 
         try
         {
-            py::exec(code);
+            // Import AST ans builtins modules
+            py::module ast = py::module::import("ast");
+            py::module builtins = py::module::import("builtins");
+
+            // Parse code to AST
+            py::object code_ast = ast.attr("parse")(code, "<string>", "exec");
+            py::list expressions = code_ast.attr("body");
+
+            // If the last statement is an expression, we compile it seperately
+            // in an interactive mode (This will trigger the display hook)
+            py::object last_stmt = expressions[py::len(expressions) - 1];
+            if (py::isinstance(last_stmt, ast.attr("Expr")))
+            {
+                code_ast.attr("body").attr("pop")();
+
+                py::list interactive_nodes;
+                interactive_nodes.append(last_stmt);
+
+                py::object interactive_ast = ast.attr("Interactive")(interactive_nodes);
+
+                py::object compiled_code = builtins.attr("compile")(code_ast, "<ast>", "exec");
+                py::object compiled_interactive_code = builtins.attr("compile")(interactive_ast, "<ast>", "single");
+
+                m_displayhook.attr("set_execution_count")(execution_counter);
+
+                builtins.attr("exec")(compiled_code, py::globals());
+                builtins.attr("exec")(compiled_interactive_code, py::globals());
+            }
+            else
+            {
+                py::object compiled_code = builtins.attr("compile")(code_ast, "<ast>", "exec");
+                builtins.attr("exec")(compiled_code, py::globals());
+            }
 
             kernel_res["status"] = "ok";
             kernel_res["payload"] = xeus::xjson::array();
             kernel_res["user_expressions"] = xeus::xjson::object();
+
         } catch(const std::exception& e) {
 
             std::string ename = "Execution error";
@@ -167,4 +201,25 @@ namespace xpyt
         sys.attr("stdout") = out_logger;
         sys.attr("stderr") = err_logger;
     }
+
+    void xpython_interpreter::redirect_display()
+    {
+        py::module sys = py::module::import("sys");
+
+        py::module xeus_python_display = py::module::import("xeus_python_display");
+        m_displayhook = xeus_python_display.attr("XPythonDisplay")();
+
+        py::cpp_function publish_display = [this](int execution_counter, py::object obj){
+            if (!obj.is_none())
+            {
+                xeus::xjson pub_data;
+                pub_data["text/plain"] = py::str(obj);
+                publish_execution_result(execution_counter, std::move(pub_data), xeus::xjson::object());
+            }
+        };
+
+        m_displayhook.attr("add_hook")(publish_display);
+
+        sys.attr("displayhook") = m_displayhook;
+    }
 }

src/xpython_interpreter.hpp

@@ -12,9 +12,13 @@
 
 #include <string>
 
+#include "pybind11/pybind11.h"
+
 #include "xeus/xjson.hpp"
 #include "xeus/xinterpreter.hpp"
 
+namespace py = pybind11;
+
 namespace xpyt
 {
     class xpython_interpreter : public xeus::xinterpreter
@@ -57,6 +61,9 @@ namespace xpyt
         void input_reply_impl(const std::string& value) override;
 
         void redirect_output();
+        void redirect_display();
+
+        py::object m_displayhook;
     };
 }
 

src/xpython_logger.hpp

@@ -12,6 +12,7 @@
 
 #include <string>
 #include <vector>
+#include <functional>
 
 namespace xpyt
 {