mercurial/cext/dirs.c

43228:0d609ed185ea

 *
 * A few implementation notes:
 *
 * We modify Python integers for refcounting, but those integers are
 * never visible to Python code.
 *
 * We mutate strings in-place, but leave them immutable once they can
 * be seen by Python code.
 */
typedef struct {
	PyObject_HEAD
	PyObject *dict;
} dirsObject;

	* The implementation, therefore, is heavily dependent on CPython
	* implementation details. We also commit violations of the Python
	* "protocol" such as mutating immutable objects. But since we only
	* mutate objects created in this function or in other well-defined
	* locations, the references are known so these violations should go
	* unnoticed. The code for adjusting the length of a PyBytesObject is
	* essentially a minimal version of _PyBytes_Resize. */
	while ((pos = _finddir(cpath, pos - 1)) != -1) {
		PyObject *val;

		if (pos < 2) {
			key = PyBytes_FromStringAndSize(cpath, pos);
			if (key == NULL)
				goto bail;
		} else {
			/* It's likely that every prefix already has an entry
			   in our dict. Try to avoid allocating and
			   deallocating a string for each prefix we check. */
			if (key != NULL)
				((PyBytesObject *)key)->ob_shash = -1;
			else {
				/* We know pos >= 2, so we won't get a small
				 * shared string. */
				key = PyBytes_FromStringAndSize(cpath, pos);
				if (key == NULL)
					goto bail;
			}
			/* Py_SIZE(o) refers to the ob_size member of
			 * the struct. Yes, assigning to what looks
			 * like a function seems wrong. */
			Py_SIZE(key) = pos;
			((PyBytesObject *)key)->ob_sval[pos] = '\0';
		}

		val = PyDict_GetItem(dirs, key);
		if (val != NULL) {
			PYLONG_VALUE(val) += 1;
			if (pos < 2) {
				/* This was a short string, so we
				 * probably got a small shared string
				 * we can't mutate on the next loop
				 * iteration. Clear it.
				 */
				Py_CLEAR(key);
			}
			break;
		}

		/* Force Python to not reuse a small shared int. */
#ifdef IS_PY3K

43229:9fa941faef94

 *
 * A few implementation notes:
 *
 * We modify Python integers for refcounting, but those integers are
 * never visible to Python code.
 */
typedef struct {
	PyObject_HEAD
	PyObject *dict;
} dirsObject;

	* The implementation, therefore, is heavily dependent on CPython
	* implementation details. We also commit violations of the Python
	* "protocol" such as mutating immutable objects. But since we only
	* mutate objects created in this function or in other well-defined
	* locations, the references are known so these violations should go
	* unnoticed. */
	while ((pos = _finddir(cpath, pos - 1)) != -1) {
		PyObject *val;

		key = PyBytes_FromStringAndSize(cpath, pos);
		if (key == NULL)
			goto bail;

		val = PyDict_GetItem(dirs, key);
		if (val != NULL) {
			PYLONG_VALUE(val) += 1;
			Py_CLEAR(key);
			break;
		}

		/* Force Python to not reuse a small shared int. */
#ifdef IS_PY3K