Implement __repr__

2 files changed, 142 insertions, 1 deletions

diff --git a/immutables/_map.c b/immutables/_map.c
index e1efe19..6f76318 100644
--- a/immutables/_map.c
+++ b/immutables/_map.c
@@ -2854,6 +2854,94 @@ map_py_dump(MapObject *self, PyObject *args)
 }
 
 
+static PyObject *
+map_py_repr(MapObject *self)
+{
+    Py_ssize_t i;
+    _PyUnicodeWriter writer;
+
+
+    i = Py_ReprEnter((PyObject *)self);
+    if (i != 0) {
+        return i > 0 ? PyUnicode_FromString("{...}") : NULL;
+    }
+
+    _PyUnicodeWriter_Init(&writer);
+
+    if (_PyUnicodeWriter_WriteASCIIString(
+            &writer, "<immutables.Map({", 17) < 0)
+    {
+        goto error;
+    }
+
+    MapIteratorState iter;
+    map_iter_t iter_res;
+    map_iterator_init(&iter, self->h_root);
+    int second = 0;
+    do {
+        PyObject *v_key;
+        PyObject *v_val;
+
+        iter_res = map_iterator_next(&iter, &v_key, &v_val);
+        if (iter_res == I_ITEM) {
+            if (second) {
+                if (_PyUnicodeWriter_WriteASCIIString(&writer, ", ", 2) < 0) {
+                    goto error;
+                }
+            }
+
+            PyObject *s = PyObject_Repr(v_key);
+            if (s == NULL) {
+                goto error;
+            }
+            if (_PyUnicodeWriter_WriteStr(&writer, s) < 0) {
+                Py_DECREF(s);
+                goto error;
+            }
+            Py_DECREF(s);
+
+            if (_PyUnicodeWriter_WriteASCIIString(&writer, ": ", 2) < 0) {
+                goto error;
+            }
+
+            s = PyObject_Repr(v_val);
+            if (s == NULL) {
+                goto error;
+            }
+            if (_PyUnicodeWriter_WriteStr(&writer, s) < 0) {
+                Py_DECREF(s);
+                goto error;
+            }
+            Py_DECREF(s);
+        }
+
+        second = 1;
+    } while (iter_res != I_END);
+
+    if (_PyUnicodeWriter_WriteASCIIString(&writer, "})", 2) < 0) {
+        goto error;
+    }
+
+    PyObject *addr = PyUnicode_FromFormat(" at %p>", self);
+    if (addr == NULL) {
+        goto error;
+    }
+    if (_PyUnicodeWriter_WriteStr(&writer, addr) < 0) {
+        Py_DECREF(addr);
+        goto error;
+    }
+    Py_DECREF(addr);
+
+    Py_ReprLeave((PyObject *)self);
+    return _PyUnicodeWriter_Finish(&writer);
+
+error:
+    _PyUnicodeWriter_Dealloc(&writer);
+    Py_ReprLeave((PyObject *)self);
+    return NULL;
+}
+
+
 static PyMethodDef Map_methods[] = {
     {"set", (PyCFunction)map_py_set, METH_VARARGS, NULL},
     {"get", (PyCFunction)map_py_get, METH_VARARGS, NULL},
@@ -2900,6 +2988,7 @@ PyTypeObject _Map_Type = {
     .tp_new = map_tp_new,
     .tp_weaklistoffset = offsetof(MapObject, h_weakreflist),
     .tp_hash = PyObject_HashNotImplemented,
+    .tp_repr = (reprfunc)map_py_repr,
 };
 
 
diff --git a/tests/test_map.py b/tests/test_map.py
index a17e005..06c82b9 100644
--- a/tests/test_map.py
+++ b/tests/test_map.py
@@ -16,6 +16,8 @@ class HashKey:
         self.error_on_eq_to = error_on_eq_to
 
     def __repr__(self):
+        if self._crasher is not None and self._crasher.error_on_repr:
+            raise ReprError
         return '<Key name:{} hash:{}>'.format(self.name, self.hash)
 
     def __hash__(self):
@@ -51,12 +53,19 @@ class KeyStr(str):
             raise EqError
         return super().__eq__(other)
 
+    def __repr__(self, other):
+        if HashKey._crasher is not None and HashKey._crasher.error_on_repr:
+            raise ReprError
+        return super().__eq__(other)
+
 
 class HaskKeyCrasher:
 
-    def __init__(self, *, error_on_hash=False, error_on_eq=False):
+    def __init__(self, *, error_on_hash=False, error_on_eq=False,
+                 error_on_repr=False):
         self.error_on_hash = error_on_hash
         self.error_on_eq = error_on_eq
+        self.error_on_repr = error_on_repr
 
     def __enter__(self):
         if HashKey._crasher is not None:
@@ -75,6 +84,10 @@ class EqError(Exception):
     pass
 
 
+class ReprError(Exception):
+    pass
+
+
 class MapTest(unittest.TestCase):
 
     def test_hashkey_helper_1(self):
@@ -705,6 +718,45 @@ class MapTest(unittest.TestCase):
             with HaskKeyCrasher(error_on_hash=True):
                 h[AA]
 
+    def test_repr_1(self):
+        h = Map()
+        self.assertTrue(repr(h).startswith('<immutables.Map({}) at 0x'))
+
+        h = h.set(1, 2).set(2, 3).set(3, 4)
+        self.assertTrue(repr(h).startswith(
+            '<immutables.Map({1: 2, 2: 3, 3: 4}) at 0x'))
+
+    def test_repr_2(self):
+        h = Map()
+        A = HashKey(100, 'A')
+
+        with self.assertRaises(ReprError):
+            with HaskKeyCrasher(error_on_repr=True):
+                repr(h.set(1, 2).set(A, 3).set(3, 4))
+
+        with self.assertRaises(ReprError):
+            with HaskKeyCrasher(error_on_repr=True):
+                repr(h.set(1, 2).set(2, A).set(3, 4))
+
+    def test_repr_3(self):
+        class Key:
+            def __init__(self):
+                self.val = None
+
+            def __hash__(self):
+                return 123
+
+            def __repr__(self):
+                return repr(self.val)
+
+        h = Map()
+        k = Key()
+        h = h.set(k, 1)
+        k.val = h
+
+        self.assertTrue(repr(h).startswith(
+            '<immutables.Map({{...}: 1}) at 0x'))
+
 
 if __name__ == "__main__":
     unittest.main()