Issue 6877: this patch makes it possible to link the readline extension

to the libedit emulation of the readline API on OSX 10.5 or later.

This also adds a minimal testsuite for readline to check that the
history manipuation functions have the same interface with both
C libraries.

diff --git a/Doc/library/readline.rst b/Doc/library/readline.rst
index 685b36f9c531bf02cf8e6d9a097d2a0dc63b1708..89addaa85b3a0eb0363b5b55cd699535843cf639 100644 (file)
--- a/Doc/library/readline.rst
+++ b/Doc/library/readline.rst
@@ -14,6 +14,17 @@ made using  this module affect the behaviour of both the interpreter's
 interactive prompt  and the prompts offered by the :func:`raw_input` and
 :func:`input` built-in functions.
 
+..note::
+
+  On MacOS X the :mod:`readline` module can be implemented using
+  the ``libedit`` library instead of GNU readline.
+
+  The configuration file for ``libedit`` is different from that
+  of GNU readline. If you programmaticly load configuration strings
+  you can check for the text "libedit" in :const:`readline.__doc__`
+  to differentiate between GNU readline and libedit.
+
+
 The :mod:`readline` module defines the following functions:
 
 
@@ -181,7 +192,6 @@ The :mod:`readline` module defines the following functions:
 
    Append a line to the history buffer, as if it was the last line typed.
 
-
 .. seealso::
 
    Module :mod:`rlcompleter`

diff --git a/Lib/test/test_readline.py b/Lib/test/test_readline.py
new file mode 100644 (file)
index 0000000..a2210d4
--- /dev/null
+++ b/Lib/test/test_readline.py
@@ -0,0 +1,42 @@
+"""
+Very minimal unittests for parts of the readline module.
+
+These tests were added to check that the libedit emulation on OSX and
+the "real" readline have the same interface for history manipulation. That's
+why the tests cover only a small subset of the interface.
+"""
+import unittest
+from test.test_support import run_unittest
+
+import readline
+
+class TestHistoryManipulation (unittest.TestCase):
+    def testHistoryUpdates(self):
+        readline.clear_history()
+
+        readline.add_history("first line")
+        readline.add_history("second line")
+
+        self.assertEqual(readline.get_history_item(0), None)
+        self.assertEqual(readline.get_history_item(1), "first line")
+        self.assertEqual(readline.get_history_item(2), "second line")
+
+        readline.replace_history_item(0, "replaced line")
+        self.assertEqual(readline.get_history_item(0), None)
+        self.assertEqual(readline.get_history_item(1), "replaced line")
+        self.assertEqual(readline.get_history_item(2), "second line")
+
+        self.assertEqual(readline.get_current_history_length(), 2)
+
+        readline.remove_history_item(0)
+        self.assertEqual(readline.get_history_item(0), None)
+        self.assertEqual(readline.get_history_item(1), "second line")
+
+        self.assertEqual(readline.get_current_history_length(), 1)
+
+
+def test_main():
+    run_unittest(TestHistoryManipulation)
+
+if __name__ == "__main__":
+    test_main()

diff --git a/Misc/NEWS b/Misc/NEWS
index bdd121cb8d34a536e79fc717c37c12168a4a833b..8261b6c21030749eeda26614501450b277ccd1d7 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1335,6 +1335,9 @@ C-API
 Extension Modules
 -----------------
 
+- Issue #6877: Make it possible to link the readline extension to libedit
+  on OSX.
+
 - Issue #6944: Fix a SystemError when socket.getnameinfo() was called
   with something other than a tuple as first argument.
 

diff --git a/Modules/readline.c b/Modules/readline.c
index d09f09c7311c3296adfd1290a87adad61ae3ee35..67f463180dd933c3bd64d6bb85bf0bce8fe3317f 100644 (file)
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -42,6 +42,25 @@ extern char **completion_matches(char *, CPFunction *);
 #endif
 #endif
 
+#ifdef __APPLE__
+/*
+ * It is possible to link the readline module to the readline
+ * emulation library of editline/libedit. 
+ * 
+ * On OSX this emulation library is not 100% API compatible
+ * with the "real" readline and cannot be detected at compile-time,
+ * hence we use a runtime check to detect if we're using libedit
+ *
+ * Currently there is one know API incompatibility: 
+ * - 'get_history' has a 1-based index with GNU readline, and a 0-based
+ *   index with libedit's emulation.
+ * - Note that replace_history and remove_history use a 0-based index
+ *   with both implementation.
+ */
+static int using_libedit_emulation = 0;
+static const char libedit_version_tag[] = "EditLine wrapper";
+#endif /* __APPLE__ */
+
 static void
 on_completion_display_matches_hook(char **matches,
                                   int num_matches, int max_length);
@@ -478,6 +497,29 @@ get_history_item(PyObject *self, PyObject *args)
 
        if (!PyArg_ParseTuple(args, "i:index", &idx))
                return NULL;
+#ifdef  __APPLE__
+       if (using_libedit_emulation) {
+               /* Libedit emulation uses 0-based indexes,
+                * the real one uses 1-based indexes,
+                * adjust the index to ensure that Python
+                * code doesn't have to worry about the
+                * difference.
+                */
+               HISTORY_STATE *hist_st;
+               hist_st = history_get_history_state();
+
+               idx --;
+
+               /*
+                * Apple's readline emulation crashes when
+                * the index is out of range, therefore 
+                * test for that and fail gracefully.
+                */
+               if (idx < 0 || idx >= hist_st->length) {
+                       Py_RETURN_NONE;
+               }
+       }
+#endif /* __APPLE__ */
        if ((hist_ent = history_get(idx)))
                return PyString_FromString(hist_ent->line);
        else {
@@ -978,6 +1020,15 @@ call_readline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
                char *line;
                HISTORY_STATE *state = history_get_history_state();
                if (state->length > 0)
+#ifdef __APPLE__
+                       if (using_libedit_emulation) {
+                               /* 
+                                * Libedit's emulation uses 0-based indexes,
+                                * the real readline uses 1-based indexes.
+                                */
+                               line = history_get(state->length - 1)->line;
+                       } else 
+#endif /* __APPLE__ */
                        line = history_get(state->length)->line;
                else
                        line = "";
@@ -1011,16 +1062,35 @@ call_readline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
 PyDoc_STRVAR(doc_module,
 "Importing this module enables command line editing using GNU readline.");
 
+#ifdef __APPLE__
+PyDoc_STRVAR(doc_module_le,
+"Importing this module enables command line editing using libedit readline.");
+#endif /* __APPLE__ */
+
 PyMODINIT_FUNC
 initreadline(void)
 {
        PyObject *m;
 
+#ifdef __APPLE__
+       if (strncmp(rl_library_version, libedit_version_tag, strlen(libedit_version_tag)) == 0) {
+               using_libedit_emulation = 1;
+       }
+
+       if (using_libedit_emulation) 
+               m = Py_InitModule4("readline", readline_methods, doc_module_le,
+                          (PyObject *)NULL, PYTHON_API_VERSION);
+       else
+
+#endif /* __APPLE__ */
+
        m = Py_InitModule4("readline", readline_methods, doc_module,
                           (PyObject *)NULL, PYTHON_API_VERSION);
        if (m == NULL)
                return;
 
+
+
        PyOS_ReadlineFunctionPointer = call_readline;
        setup_readline();
 }

diff --git a/setup.py b/setup.py
index adc72c894ed711500ec870bd890f529b7f7e1a38..d2290368ad65028a77c1bd0523c2c710bf31b2c7 100644 (file)
--- a/setup.py
+++ b/setup.py
@@ -546,16 +546,16 @@ class PyBuildExt(build_ext):
 
         # readline
         do_readline = self.compiler_obj.find_library_file(lib_dirs, 'readline')
-        if platform == 'darwin': # and os.uname()[2] < '9.':
-            # MacOSX 10.4 has a broken readline. Don't try to build
-            # the readline module unless the user has installed a fixed
-            # readline package
-            # FIXME: The readline emulation on 10.5 is better, but the
-            # readline module doesn't compile out of the box.
-            if find_file('readline/rlconf.h', inc_dirs, []) is None:
-                do_readline = False
+        if platform == 'darwin':
+            os_release = int(os.uname()[2].split('.')[0])
+            if os_release < 9:
+                # MacOSX 10.4 has a broken readline. Don't try to build
+                # the readline module unless the user has installed a fixed
+                # readline package
+                if find_file('readline/rlconf.h', inc_dirs, []) is None:
+                    do_readline = False
         if do_readline:
-            if sys.platform == 'darwin':
+            if platform == 'darwin' and os_release < 9:
                 # In every directory on the search path search for a dynamic
                 # library and then a static library, instead of first looking
                 # for dynamic libraries on the entiry path.