Jeff Epler's xreadlines module, with slight reformatting and some

changes for safety and tuning.

diff --git a/Modules/Setup.dist b/Modules/Setup.dist
index e46eca4bd1730e43036a4e74bd14bafc7a671c4d..53ab1fb3baaa0c683451225e4112c8146894eb79 100644 (file)
--- a/Modules/Setup.dist
+++ b/Modules/Setup.dist
@@ -156,6 +156,9 @@ _socket socketmodule.c      # socket(2)
 # Memory-mapped files (also works on Win32).
 mmap mmapmodule.c
 
+# Dynamic readlines
+xreadlines xreadlinesmodule.c
+
 # Socket module compiled with SSL support; you must edit the SSL variable:
 #SSL=/usr/local/ssl
 #_socket socketmodule.c \

diff --git a/Modules/xreadlinesmodule.c b/Modules/xreadlinesmodule.c
new file mode 100644 (file)
index 0000000..c50dd06
--- /dev/null
+++ b/Modules/xreadlinesmodule.c
@@ -0,0 +1,118 @@
+#include "Python.h"
+
+static char xreadlines_doc [] =
+"xreadlines(f)\n\
+\n\
+Return an xreadlines object for the file f.";
+
+typedef struct {
+       PyObject_HEAD
+       PyObject *file;
+       PyObject *lines;
+       int lineslen;
+       int lineno;
+       int abslineno;
+} PyXReadlinesObject;
+
+staticforward PyTypeObject XReadlinesObject_Type;
+
+static void
+xreadlines_dealloc(PyXReadlinesObject *op) {
+       Py_XDECREF(op->file);
+       Py_XDECREF(op->lines);
+       PyObject_DEL(op);
+}
+
+/* A larger chunk size doesn't seem to make a difference */
+#define CHUNKSIZE  8192
+
+static PyXReadlinesObject *
+newreadlinesobject(PyObject *file) {
+       PyXReadlinesObject *op;
+       op = PyObject_NEW(PyXReadlinesObject, &XReadlinesObject_Type);
+       if (op == NULL)
+               return NULL;
+       Py_XINCREF(file);
+       op->file = file;
+       op->lines = NULL;
+       op->abslineno = op->lineno = op->lineslen = 0;
+       return op;
+}
+
+static PyObject *
+xreadlines(PyObject *self, PyObject *args) {
+       PyObject *file;
+       PyXReadlinesObject *ret;
+
+       if (!PyArg_ParseTuple(args, "O:xreadlines", &file))
+               return NULL;
+       ret = newreadlinesobject(file);
+       Py_XINCREF(ret);
+       return (PyObject*)ret;
+}
+
+static PyObject*
+xreadlines_item(PyXReadlinesObject *a, int i) {
+       if (i != a->abslineno) {
+               PyErr_SetString(PyExc_RuntimeError,
+                       "xreadlines object accessed out of order");
+               return NULL;
+       }
+       if (a->lineno >= a->lineslen) {
+               Py_XDECREF(a->lines);
+               a->lines = PyObject_CallMethod(a->file, "readlines", "(i)",
+                                              CHUNKSIZE);
+               if (a->lines == NULL)
+                       return NULL;
+               a->lineno = 0;
+               if ((a->lineslen = PySequence_Size(a->lines)) < 0)
+                       return NULL;
+       }
+       a->abslineno++;
+       return PySequence_GetItem(a->lines, a->lineno++);
+}
+
+static PySequenceMethods xreadlines_as_sequence = {
+       0, /*sq_length*/
+       0, /*sq_concat*/
+       0, /*sq_repeat*/
+       (intargfunc)xreadlines_item, /*sq_item*/
+};
+
+static PyTypeObject XReadlinesObject_Type = {
+       PyObject_HEAD_INIT(&PyType_Type)
+       0,
+       "xreadlines",
+       sizeof(PyXReadlinesObject) + PyGC_HEAD_SIZE,
+       0,
+       (destructor)xreadlines_dealloc, /*tp_dealloc*/
+       0, /*tp_print*/
+       0, /*tp_getattr*/
+       0, /*tp_setattr*/
+       0, /*tp_compare*/
+       0, /*tp_repr*/
+       0, /*tp_as_number*/
+       &xreadlines_as_sequence, /*tp_as_sequence*/
+       0,              /*tp_as_mapping*/
+       0,              /*tp_hash*/
+       0,              /*tp_call*/
+       0,              /*tp_str*/
+       0,              /*tp_getattro*/
+       0,              /*tp_setattro*/
+       0,              /*tp_as_buffer*/
+       Py_TPFLAGS_DEFAULT,     /*tp_flags*/
+       0,              /* tp_doc */
+};
+
+static PyMethodDef xreadlines_methods[] = {
+       {"xreadlines", xreadlines, METH_VARARGS, xreadlines_doc},
+       {NULL, NULL}
+};
+
+void
+initxreadlines(void)
+{
+       PyObject *m;
+
+       m = Py_InitModule("xreadlines", xreadlines_methods);
+}