bytestring.c: Cache empty and singleton strings.

[catacomb-python] / bytestring.c

diff --git a/bytestring.c b/bytestring.c
index 0c68d43..124ae9a 100644 (file)
--- a/bytestring.c
+++ b/bytestring.c
@@ -32,10 +32,12 @@
 
 PyTypeObject *bytestring_pytype;
 
-static PyObject *dowrap(PyTypeObject *ty, const void *p, size_t n)
+static PyObject *empty, *bytev[256];
+
+static PyObject *allocate(PyTypeObject *ty, size_t n)
 {
-  PyStringObject *x = (PyStringObject *)ty->tp_alloc(ty, n);
-  if (p) memcpy(x->ob_sval, p, n);
+  PyStringObject *x;
+  x = (PyStringObject *)ty->tp_alloc(ty, n);
   x->ob_sval[n] = 0;
 #if defined(CACHE_HASH) || PY_VERSION_HEX >= 0x02030000
   x->ob_shash = -1;
@@ -44,6 +46,27 @@ static PyObject *dowrap(PyTypeObject *ty, const void *p, size_t n)
   return ((PyObject *)x);
 }
 
+static PyObject *dowrap(PyTypeObject *ty, const void *p, size_t n)
+{
+  PyObject *x;
+  int ch;
+
+  if (p && ty == bytestring_pytype) {
+    if (!n) {
+      if (!empty) empty = allocate(ty, 0);
+      Py_INCREF(empty); return (empty);
+    } else if (n == 1 && (ch = *(unsigned char *)p) < sizeof(bytev)) {
+      if (!bytev[ch])
+       { bytev[ch] = allocate(ty, 1); *PyString_AS_STRING(bytev[ch]) = ch; }
+      Py_INCREF(bytev[ch]); return (bytev[ch]);
+    }
+  }
+
+  x = allocate(ty, n);
+  if (p) memcpy(PyString_AS_STRING(x), p, n);
+  return (x);
+}
+
 PyObject *bytestring_pywrap(const void *p, size_t n)
   { return (dowrap(bytestring_pytype, p, n)); }
 
@@ -55,8 +78,8 @@ static PyObject *bytestring_pynew(PyTypeObject *ty,
 {
   const char *p;
   Py_ssize_t n;
-  static char *kwlist[] = { "data", 0 };
-  if (!PyArg_ParseTupleAndKeywords(arg, kw, "s#:new", kwlist, &p, &n))
+  static const char *const kwlist[] = { "data", 0 };
+  if (!PyArg_ParseTupleAndKeywords(arg, kw, "s#:new", KWLIST, &p, &n))
     return (0);
   return (dowrap(ty, p, n));
 }