Implement repeat

Author: atpalmer

src/cstring.c

@@ -7,17 +7,18 @@ struct cstring {
 
 #define CSTRING_VALUE(self) (((struct cstring *)self)->value)
 
+static PyObject *_cstring_new(PyTypeObject *type, const char *value, int size) {
+    struct cstring *new = type->tp_alloc(type, size);
+    memcpy(new->value, value, size);
+    return (PyObject *)new;
+}
+
 static PyObject *cstring_new(PyTypeObject *type, PyObject *args, PyObject **kwargs) {
     char *value = NULL;
-
     if(!PyArg_ParseTuple(args, "s", &value))
         return NULL;
-
     int size = strlen(value) + 1;
-
-    struct cstring *new = type->tp_alloc(type, size);
-    memcpy(new->value, value, size);
-    return (PyObject *)new;
+    return _cstring_new(type, value, size);
 }
 
 static void cstring_dealloc(PyObject *self) {
@@ -58,9 +59,25 @@ static PyObject *cstring_concat(PyObject *left, PyObject *right) {
     return (PyObject *)new;
 }
 
+static PyObject *cstring_repeat(PyObject *self, Py_ssize_t count) {
+    if(!_ensure_cstring(self))
+        return NULL;
+    if(count <= 0)
+        return _cstring_new(Py_TYPE(self), "", 1);
+
+    Py_ssize_t size = (cstring_len(self) * count) + 1;
+
+    struct cstring *new = Py_TYPE(self)->tp_alloc(Py_TYPE(self), size);
+    for(Py_ssize_t i = 0; i < size - 1; i += cstring_len(self)) {
+        memcpy(&new->value[i], CSTRING_VALUE(self), Py_SIZE(self));
+    }
+    return (PyObject *)new;
+}
+
 static PySequenceMethods cstring_as_sequence = {
     .sq_length = cstring_len,
     .sq_concat = cstring_concat,
+    .sq_repeat = cstring_repeat,
 };
 
 static PyTypeObject cstring_type = {

test/test_cstring.py

@@ -7,6 +7,9 @@ def test_str():
     assert str(result) == 'hello, world'
 
 
+# Sequence API
+
+
 def test_len():
     result = cstring('hello, world')
     assert len(result) == 12
@@ -21,3 +24,13 @@ def test_concat_TypeError():
     with pytest.raises(TypeError, match='^Object must have type cstring, not str.$'):
         cstring('hello') + 'world'
 
+
+def test_repeat_zero():
+    result = cstring('hello') * 0
+    assert str(result) == str(cstring(''))  # TODO: implement cstring equality!
+
+
+def test_repeat_five():
+    result = cstring('hello') * 5
+    assert str(result) == str(cstring('hellohellohellohellohello'))  # TODO: implement cstring equality!
+