mirror of
https://github.com/python/cpython.git
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589 lines
17 KiB
C
589 lines
17 KiB
C
#include "Python.h"
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#include "code.h"
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#include "structmember.h"
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#define NAME_CHARS \
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"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"
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/* all_name_chars(s): true iff all chars in s are valid NAME_CHARS */
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static int
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all_name_chars(unsigned char *s)
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{
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static char ok_name_char[256];
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static unsigned char *name_chars = (unsigned char *)NAME_CHARS;
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if (ok_name_char[*name_chars] == 0) {
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unsigned char *p;
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for (p = name_chars; *p; p++)
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ok_name_char[*p] = 1;
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}
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while (*s) {
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if (ok_name_char[*s++] == 0)
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return 0;
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}
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return 1;
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}
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static void
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intern_strings(PyObject *tuple)
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{
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Py_ssize_t i;
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for (i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {
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PyObject *v = PyTuple_GET_ITEM(tuple, i);
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if (v == NULL || !PyString_CheckExact(v)) {
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Py_FatalError("non-string found in code slot");
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}
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PyString_InternInPlace(&PyTuple_GET_ITEM(tuple, i));
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}
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}
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PyCodeObject *
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PyCode_New(int argcount, int nlocals, int stacksize, int flags,
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PyObject *code, PyObject *consts, PyObject *names,
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PyObject *varnames, PyObject *freevars, PyObject *cellvars,
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PyObject *filename, PyObject *name, int firstlineno,
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PyObject *lnotab)
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{
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PyCodeObject *co;
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Py_ssize_t i;
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/* Check argument types */
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if (argcount < 0 || nlocals < 0 ||
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code == NULL ||
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consts == NULL || !PyTuple_Check(consts) ||
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names == NULL || !PyTuple_Check(names) ||
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varnames == NULL || !PyTuple_Check(varnames) ||
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freevars == NULL || !PyTuple_Check(freevars) ||
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cellvars == NULL || !PyTuple_Check(cellvars) ||
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name == NULL || !PyString_Check(name) ||
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filename == NULL || !PyString_Check(filename) ||
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lnotab == NULL || !PyString_Check(lnotab) ||
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!PyObject_CheckReadBuffer(code)) {
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PyErr_BadInternalCall();
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return NULL;
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}
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intern_strings(names);
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intern_strings(varnames);
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intern_strings(freevars);
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intern_strings(cellvars);
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/* Intern selected string constants */
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for (i = PyTuple_Size(consts); --i >= 0; ) {
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PyObject *v = PyTuple_GetItem(consts, i);
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if (!PyString_Check(v))
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continue;
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if (!all_name_chars((unsigned char *)PyString_AS_STRING(v)))
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continue;
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PyString_InternInPlace(&PyTuple_GET_ITEM(consts, i));
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}
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co = PyObject_NEW(PyCodeObject, &PyCode_Type);
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if (co != NULL) {
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co->co_argcount = argcount;
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co->co_nlocals = nlocals;
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co->co_stacksize = stacksize;
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co->co_flags = flags;
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Py_INCREF(code);
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co->co_code = code;
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Py_INCREF(consts);
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co->co_consts = consts;
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Py_INCREF(names);
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co->co_names = names;
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Py_INCREF(varnames);
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co->co_varnames = varnames;
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Py_INCREF(freevars);
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co->co_freevars = freevars;
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Py_INCREF(cellvars);
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co->co_cellvars = cellvars;
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Py_INCREF(filename);
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co->co_filename = filename;
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Py_INCREF(name);
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co->co_name = name;
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co->co_firstlineno = firstlineno;
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Py_INCREF(lnotab);
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co->co_lnotab = lnotab;
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co->co_zombieframe = NULL;
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}
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return co;
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}
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#define OFF(x) offsetof(PyCodeObject, x)
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static PyMemberDef code_memberlist[] = {
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{"co_argcount", T_INT, OFF(co_argcount), READONLY},
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{"co_nlocals", T_INT, OFF(co_nlocals), READONLY},
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{"co_stacksize",T_INT, OFF(co_stacksize), READONLY},
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{"co_flags", T_INT, OFF(co_flags), READONLY},
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{"co_code", T_OBJECT, OFF(co_code), READONLY},
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{"co_consts", T_OBJECT, OFF(co_consts), READONLY},
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{"co_names", T_OBJECT, OFF(co_names), READONLY},
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{"co_varnames", T_OBJECT, OFF(co_varnames), READONLY},
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{"co_freevars", T_OBJECT, OFF(co_freevars), READONLY},
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{"co_cellvars", T_OBJECT, OFF(co_cellvars), READONLY},
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{"co_filename", T_OBJECT, OFF(co_filename), READONLY},
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{"co_name", T_OBJECT, OFF(co_name), READONLY},
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{"co_firstlineno", T_INT, OFF(co_firstlineno), READONLY},
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{"co_lnotab", T_OBJECT, OFF(co_lnotab), READONLY},
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{NULL} /* Sentinel */
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};
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/* Helper for code_new: return a shallow copy of a tuple that is
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guaranteed to contain exact strings, by converting string subclasses
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to exact strings and complaining if a non-string is found. */
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static PyObject*
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validate_and_copy_tuple(PyObject *tup)
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{
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PyObject *newtuple;
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PyObject *item;
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Py_ssize_t i, len;
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len = PyTuple_GET_SIZE(tup);
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newtuple = PyTuple_New(len);
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if (newtuple == NULL)
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return NULL;
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for (i = 0; i < len; i++) {
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item = PyTuple_GET_ITEM(tup, i);
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if (PyString_CheckExact(item)) {
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Py_INCREF(item);
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}
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else if (!PyString_Check(item)) {
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PyErr_Format(
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PyExc_TypeError,
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"name tuples must contain only "
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"strings, not '%.500s'",
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item->ob_type->tp_name);
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Py_DECREF(newtuple);
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return NULL;
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}
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else {
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item = PyString_FromStringAndSize(
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PyString_AS_STRING(item),
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PyString_GET_SIZE(item));
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if (item == NULL) {
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Py_DECREF(newtuple);
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return NULL;
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}
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}
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PyTuple_SET_ITEM(newtuple, i, item);
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}
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return newtuple;
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}
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PyDoc_STRVAR(code_doc,
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"code(argcount, nlocals, stacksize, flags, codestring, constants, names,\n\
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varnames, filename, name, firstlineno, lnotab[, freevars[, cellvars]])\n\
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\n\
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Create a code object. Not for the faint of heart.");
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static PyObject *
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code_new(PyTypeObject *type, PyObject *args, PyObject *kw)
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{
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int argcount;
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int nlocals;
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int stacksize;
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int flags;
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PyObject *co = NULL;
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PyObject *code;
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PyObject *consts;
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PyObject *names, *ournames = NULL;
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PyObject *varnames, *ourvarnames = NULL;
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PyObject *freevars = NULL, *ourfreevars = NULL;
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PyObject *cellvars = NULL, *ourcellvars = NULL;
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PyObject *filename;
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PyObject *name;
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int firstlineno;
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PyObject *lnotab;
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if (!PyArg_ParseTuple(args, "iiiiSO!O!O!SSiS|O!O!:code",
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&argcount, &nlocals, &stacksize, &flags,
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&code,
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&PyTuple_Type, &consts,
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&PyTuple_Type, &names,
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&PyTuple_Type, &varnames,
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&filename, &name,
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&firstlineno, &lnotab,
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&PyTuple_Type, &freevars,
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&PyTuple_Type, &cellvars))
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return NULL;
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if (argcount < 0) {
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PyErr_SetString(
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PyExc_ValueError,
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"code: argcount must not be negative");
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goto cleanup;
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}
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if (nlocals < 0) {
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PyErr_SetString(
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PyExc_ValueError,
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"code: nlocals must not be negative");
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goto cleanup;
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}
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ournames = validate_and_copy_tuple(names);
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if (ournames == NULL)
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goto cleanup;
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ourvarnames = validate_and_copy_tuple(varnames);
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if (ourvarnames == NULL)
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goto cleanup;
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if (freevars)
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ourfreevars = validate_and_copy_tuple(freevars);
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else
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ourfreevars = PyTuple_New(0);
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if (ourfreevars == NULL)
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goto cleanup;
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if (cellvars)
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ourcellvars = validate_and_copy_tuple(cellvars);
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else
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ourcellvars = PyTuple_New(0);
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if (ourcellvars == NULL)
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goto cleanup;
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co = (PyObject *)PyCode_New(argcount, nlocals, stacksize, flags,
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code, consts, ournames, ourvarnames,
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ourfreevars, ourcellvars, filename,
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name, firstlineno, lnotab);
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cleanup:
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Py_XDECREF(ournames);
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Py_XDECREF(ourvarnames);
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Py_XDECREF(ourfreevars);
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Py_XDECREF(ourcellvars);
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return co;
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}
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static void
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code_dealloc(PyCodeObject *co)
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{
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Py_XDECREF(co->co_code);
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Py_XDECREF(co->co_consts);
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Py_XDECREF(co->co_names);
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Py_XDECREF(co->co_varnames);
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Py_XDECREF(co->co_freevars);
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Py_XDECREF(co->co_cellvars);
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Py_XDECREF(co->co_filename);
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Py_XDECREF(co->co_name);
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Py_XDECREF(co->co_lnotab);
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if (co->co_zombieframe != NULL)
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PyObject_GC_Del(co->co_zombieframe);
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PyObject_DEL(co);
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}
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static PyObject *
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code_repr(PyCodeObject *co)
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{
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char buf[500];
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int lineno = -1;
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char *filename = "???";
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char *name = "???";
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if (co->co_firstlineno != 0)
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lineno = co->co_firstlineno;
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if (co->co_filename && PyString_Check(co->co_filename))
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filename = PyString_AS_STRING(co->co_filename);
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if (co->co_name && PyString_Check(co->co_name))
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name = PyString_AS_STRING(co->co_name);
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PyOS_snprintf(buf, sizeof(buf),
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"<code object %.100s at %p, file \"%.300s\", line %d>",
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name, co, filename, lineno);
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return PyString_FromString(buf);
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}
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static int
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code_compare(PyCodeObject *co, PyCodeObject *cp)
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{
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int cmp;
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cmp = PyObject_Compare(co->co_name, cp->co_name);
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if (cmp) return cmp;
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cmp = co->co_argcount - cp->co_argcount;
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if (cmp) goto normalize;
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cmp = co->co_nlocals - cp->co_nlocals;
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if (cmp) goto normalize;
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cmp = co->co_flags - cp->co_flags;
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if (cmp) goto normalize;
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cmp = co->co_firstlineno - cp->co_firstlineno;
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if (cmp) goto normalize;
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cmp = PyObject_Compare(co->co_code, cp->co_code);
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if (cmp) return cmp;
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cmp = PyObject_Compare(co->co_consts, cp->co_consts);
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if (cmp) return cmp;
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cmp = PyObject_Compare(co->co_names, cp->co_names);
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if (cmp) return cmp;
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cmp = PyObject_Compare(co->co_varnames, cp->co_varnames);
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if (cmp) return cmp;
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cmp = PyObject_Compare(co->co_freevars, cp->co_freevars);
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if (cmp) return cmp;
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cmp = PyObject_Compare(co->co_cellvars, cp->co_cellvars);
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return cmp;
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normalize:
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if (cmp > 0)
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return 1;
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else if (cmp < 0)
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return -1;
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else
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return 0;
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}
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static long
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code_hash(PyCodeObject *co)
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{
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long h, h0, h1, h2, h3, h4, h5, h6;
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h0 = PyObject_Hash(co->co_name);
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if (h0 == -1) return -1;
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h1 = PyObject_Hash(co->co_code);
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if (h1 == -1) return -1;
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h2 = PyObject_Hash(co->co_consts);
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if (h2 == -1) return -1;
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h3 = PyObject_Hash(co->co_names);
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if (h3 == -1) return -1;
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h4 = PyObject_Hash(co->co_varnames);
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if (h4 == -1) return -1;
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h5 = PyObject_Hash(co->co_freevars);
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if (h5 == -1) return -1;
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h6 = PyObject_Hash(co->co_cellvars);
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if (h6 == -1) return -1;
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h = h0 ^ h1 ^ h2 ^ h3 ^ h4 ^ h5 ^ h6 ^
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co->co_argcount ^ co->co_nlocals ^ co->co_flags;
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if (h == -1) h = -2;
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return h;
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}
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/* XXX code objects need to participate in GC? */
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PyTypeObject PyCode_Type = {
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PyVarObject_HEAD_INIT(&PyType_Type, 0)
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"code",
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sizeof(PyCodeObject),
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0,
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(destructor)code_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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(cmpfunc)code_compare, /* tp_compare */
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(reprfunc)code_repr, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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(hashfunc)code_hash, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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code_doc, /* tp_doc */
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0, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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0, /* tp_iter */
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0, /* tp_iternext */
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0, /* tp_methods */
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code_memberlist, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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0, /* tp_init */
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0, /* tp_alloc */
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code_new, /* tp_new */
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};
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/* All about c_lnotab.
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c_lnotab is an array of unsigned bytes disguised as a Python string. In -O
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mode, SET_LINENO opcodes aren't generated, and bytecode offsets are mapped
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to source code line #s (when needed for tracebacks) via c_lnotab instead.
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The array is conceptually a list of
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(bytecode offset increment, line number increment)
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pairs. The details are important and delicate, best illustrated by example:
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byte code offset source code line number
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0 1
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6 2
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50 7
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350 307
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361 308
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The first trick is that these numbers aren't stored, only the increments
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from one row to the next (this doesn't really work, but it's a start):
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0, 1, 6, 1, 44, 5, 300, 300, 11, 1
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The second trick is that an unsigned byte can't hold negative values, or
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values larger than 255, so (a) there's a deep assumption that byte code
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offsets and their corresponding line #s both increase monotonically, and (b)
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if at least one column jumps by more than 255 from one row to the next, more
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than one pair is written to the table. In case #b, there's no way to know
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from looking at the table later how many were written. That's the delicate
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part. A user of c_lnotab desiring to find the source line number
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corresponding to a bytecode address A should do something like this
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lineno = addr = 0
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for addr_incr, line_incr in c_lnotab:
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addr += addr_incr
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if addr > A:
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return lineno
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lineno += line_incr
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In order for this to work, when the addr field increments by more than 255,
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the line # increment in each pair generated must be 0 until the remaining addr
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increment is < 256. So, in the example above, com_set_lineno should not (as
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was actually done until 2.2) expand 300, 300 to 255, 255, 45, 45, but to
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255, 0, 45, 255, 0, 45.
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*/
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int
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PyCode_Addr2Line(PyCodeObject *co, int addrq)
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{
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int size = PyString_Size(co->co_lnotab) / 2;
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unsigned char *p = (unsigned char*)PyString_AsString(co->co_lnotab);
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int line = co->co_firstlineno;
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int addr = 0;
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while (--size >= 0) {
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addr += *p++;
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if (addr > addrq)
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break;
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line += *p++;
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}
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return line;
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}
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/*
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Check whether the current instruction is at the start of a line.
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*/
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/* The theory of SET_LINENO-less tracing.
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In a nutshell, we use the co_lnotab field of the code object
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to tell when execution has moved onto a different line.
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As mentioned above, the basic idea is so set things up so
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that
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*instr_lb <= frame->f_lasti < *instr_ub
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is true so long as execution does not change lines.
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This is all fairly simple. Digging the information out of
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co_lnotab takes some work, but is conceptually clear.
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Somewhat harder to explain is why we don't *always* call the
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line trace function when the above test fails.
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Consider this code:
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1: def f(a):
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2: if a:
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3: print 1
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4: else:
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5: print 2
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which compiles to this:
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2 0 LOAD_FAST 0 (a)
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3 JUMP_IF_FALSE 9 (to 15)
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6 POP_TOP
|
|
|
|
3 7 LOAD_CONST 1 (1)
|
|
10 PRINT_ITEM
|
|
11 PRINT_NEWLINE
|
|
12 JUMP_FORWARD 6 (to 21)
|
|
>> 15 POP_TOP
|
|
|
|
5 16 LOAD_CONST 2 (2)
|
|
19 PRINT_ITEM
|
|
20 PRINT_NEWLINE
|
|
>> 21 LOAD_CONST 0 (None)
|
|
24 RETURN_VALUE
|
|
|
|
If 'a' is false, execution will jump to instruction at offset
|
|
15 and the co_lnotab will claim that execution has moved to
|
|
line 3. This is at best misleading. In this case we could
|
|
associate the POP_TOP with line 4, but that doesn't make
|
|
sense in all cases (I think).
|
|
|
|
What we do is only call the line trace function if the co_lnotab
|
|
indicates we have jumped to the *start* of a line, i.e. if the
|
|
current instruction offset matches the offset given for the
|
|
start of a line by the co_lnotab.
|
|
|
|
This also takes care of the situation where 'a' is true.
|
|
Execution will jump from instruction offset 12 to offset 21.
|
|
Then the co_lnotab would imply that execution has moved to line
|
|
5, which is again misleading.
|
|
|
|
Why do we set f_lineno when tracing? Well, consider the code
|
|
above when 'a' is true. If stepping through this with 'n' in
|
|
pdb, you would stop at line 1 with a "call" type event, then
|
|
line events on lines 2 and 3, then a "return" type event -- but
|
|
you would be shown line 5 during this event. This is a change
|
|
from the behaviour in 2.2 and before, and I've found it
|
|
confusing in practice. By setting and using f_lineno when
|
|
tracing, one can report a line number different from that
|
|
suggested by f_lasti on this one occasion where it's desirable.
|
|
*/
|
|
|
|
|
|
int
|
|
PyCode_CheckLineNumber(PyCodeObject* co, int lasti, PyAddrPair *bounds)
|
|
{
|
|
int size, addr, line;
|
|
unsigned char* p;
|
|
|
|
p = (unsigned char*)PyString_AS_STRING(co->co_lnotab);
|
|
size = PyString_GET_SIZE(co->co_lnotab) / 2;
|
|
|
|
addr = 0;
|
|
line = co->co_firstlineno;
|
|
assert(line > 0);
|
|
|
|
/* possible optimization: if f->f_lasti == instr_ub
|
|
(likely to be a common case) then we already know
|
|
instr_lb -- if we stored the matching value of p
|
|
somwhere we could skip the first while loop. */
|
|
|
|
/* see comments in compile.c for the description of
|
|
co_lnotab. A point to remember: increments to p
|
|
should come in pairs -- although we don't care about
|
|
the line increments here, treating them as byte
|
|
increments gets confusing, to say the least. */
|
|
|
|
bounds->ap_lower = 0;
|
|
while (size > 0) {
|
|
if (addr + *p > lasti)
|
|
break;
|
|
addr += *p++;
|
|
if (*p)
|
|
bounds->ap_lower = addr;
|
|
line += *p++;
|
|
--size;
|
|
}
|
|
|
|
/* If lasti and addr don't match exactly, we don't want to
|
|
change the lineno slot on the frame or execute a trace
|
|
function. Return -1 instead.
|
|
*/
|
|
if (addr != lasti)
|
|
line = -1;
|
|
|
|
if (size > 0) {
|
|
while (--size >= 0) {
|
|
addr += *p++;
|
|
if (*p++)
|
|
break;
|
|
}
|
|
bounds->ap_upper = addr;
|
|
}
|
|
else {
|
|
bounds->ap_upper = INT_MAX;
|
|
}
|
|
|
|
return line;
|
|
}
|