cpython/Objects/codeobject.c

#include "Python.h"
#include "code.h"
#include "structmember.h"

#define NAME_CHARS \
	"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"

/* all_name_chars(s): true iff all chars in s are valid NAME_CHARS */

static int
all_name_chars(Py_UNICODE *s)
{
	static char ok_name_char[256];
	static unsigned char *name_chars = (unsigned char *)NAME_CHARS;

	if (ok_name_char[*name_chars] == 0) {
		unsigned char *p;
		for (p = name_chars; *p; p++)
			ok_name_char[*p] = 1;
	}
	while (*s) {
		if (*s >= 128)
			return 0;
		if (ok_name_char[*s++] == 0)
			return 0;
	}
	return 1;
}

static void
intern_strings(PyObject *tuple)
{
	Py_ssize_t i;

	for (i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {
		PyObject *v = PyTuple_GET_ITEM(tuple, i);
		if (v == NULL || !PyUnicode_CheckExact(v)) {
			Py_FatalError("non-string found in code slot");
		}
		PyUnicode_InternInPlace(&PyTuple_GET_ITEM(tuple, i));
	}
}


PyCodeObject *
PyCode_New(int argcount, int kwonlyargcount,
	   int nlocals, int stacksize, int flags,
	   PyObject *code, PyObject *consts, PyObject *names,
	   PyObject *varnames, PyObject *freevars, PyObject *cellvars,
	   PyObject *filename, PyObject *name, int firstlineno,
	   PyObject *lnotab)
{
	PyCodeObject *co;
	Py_ssize_t i;

	/* Check argument types */
	if (argcount < 0 || kwonlyargcount < 0 || nlocals < 0 ||
	    code == NULL ||
	    consts == NULL || !PyTuple_Check(consts) ||
	    names == NULL || !PyTuple_Check(names) ||
	    varnames == NULL || !PyTuple_Check(varnames) ||
	    freevars == NULL || !PyTuple_Check(freevars) ||
	    cellvars == NULL || !PyTuple_Check(cellvars) ||
	    name == NULL || !PyUnicode_Check(name) ||
	    filename == NULL || !PyUnicode_Check(filename) ||
	    lnotab == NULL || !PyBytes_Check(lnotab) ||
	    !PyObject_CheckReadBuffer(code)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	intern_strings(names);
	intern_strings(varnames);
	intern_strings(freevars);
	intern_strings(cellvars);
	/* Intern selected string constants */
	for (i = PyTuple_Size(consts); --i >= 0; ) {
		PyObject *v = PyTuple_GetItem(consts, i);
		if (!PyUnicode_Check(v))
			continue;
		if (!all_name_chars(PyUnicode_AS_UNICODE(v)))
			continue;
		PyUnicode_InternInPlace(&PyTuple_GET_ITEM(consts, i));
	}
	co = PyObject_NEW(PyCodeObject, &PyCode_Type);
	if (co != NULL) {
		co->co_argcount = argcount;
		co->co_kwonlyargcount = kwonlyargcount;
		co->co_nlocals = nlocals;
		co->co_stacksize = stacksize;
		co->co_flags = flags;
		Py_INCREF(code);
		co->co_code = code;
		Py_INCREF(consts);
		co->co_consts = consts;
		Py_INCREF(names);
		co->co_names = names;
		Py_INCREF(varnames);
		co->co_varnames = varnames;
		Py_INCREF(freevars);
		co->co_freevars = freevars;
		Py_INCREF(cellvars);
		co->co_cellvars = cellvars;
		Py_INCREF(filename);
		co->co_filename = filename;
		Py_INCREF(name);
		co->co_name = name;
		co->co_firstlineno = firstlineno;
		Py_INCREF(lnotab);
		co->co_lnotab = lnotab;
                co->co_zombieframe = NULL;
	}
	return co;
}

PyCodeObject *
PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno)
{
	static PyObject *emptystring = NULL;
	static PyObject *nulltuple = NULL;
	PyObject *filename_ob = NULL;
	PyObject *funcname_ob = NULL;
	PyCodeObject *result = NULL;
	if (emptystring == NULL) {
		emptystring = PyBytes_FromString("");
		if (emptystring == NULL)
			goto failed;
	}
	if (nulltuple == NULL) {
		nulltuple = PyTuple_New(0);
		if (nulltuple == NULL)
			goto failed;
	}
	funcname_ob = PyUnicode_FromString(funcname);
	if (funcname_ob == NULL)
		goto failed;
	filename_ob = PyUnicode_DecodeFSDefault(filename);
	if (filename_ob == NULL)
		goto failed;

	result = PyCode_New(0,			/* argcount */
			    0,			/* kwonlyargcount */
			    0,			/* nlocals */
			    0,			/* stacksize */
			    0,			/* flags */
			    emptystring,	/* code */
			    nulltuple,		/* consts */
			    nulltuple,		/* names */
			    nulltuple,		/* varnames */
			    nulltuple,		/* freevars */
			    nulltuple,		/* cellvars */
			    filename_ob,	/* filename */
			    funcname_ob,	/* name */
			    firstlineno,	/* firstlineno */
			    emptystring		/* lnotab */
			    );

failed:
	Py_XDECREF(funcname_ob);
	Py_XDECREF(filename_ob);
	return result;
}

#define OFF(x) offsetof(PyCodeObject, x)

static PyMemberDef code_memberlist[] = {
	{"co_argcount",	T_INT,		OFF(co_argcount),	READONLY},
	{"co_kwonlyargcount",	T_INT,	OFF(co_kwonlyargcount),	READONLY},
	{"co_nlocals",	T_INT,		OFF(co_nlocals),	READONLY},
	{"co_stacksize",T_INT,		OFF(co_stacksize),	READONLY},
	{"co_flags",	T_INT,		OFF(co_flags),		READONLY},
	{"co_code",	T_OBJECT,	OFF(co_code),		READONLY},
	{"co_consts",	T_OBJECT,	OFF(co_consts),		READONLY},
	{"co_names",	T_OBJECT,	OFF(co_names),		READONLY},
	{"co_varnames",	T_OBJECT,	OFF(co_varnames),	READONLY},
	{"co_freevars",	T_OBJECT,	OFF(co_freevars),	READONLY},
	{"co_cellvars",	T_OBJECT,	OFF(co_cellvars),	READONLY},
	{"co_filename",	T_OBJECT,	OFF(co_filename),	READONLY},
	{"co_name",	T_OBJECT,	OFF(co_name),		READONLY},
	{"co_firstlineno", T_INT,	OFF(co_firstlineno),	READONLY},
	{"co_lnotab",	T_OBJECT,	OFF(co_lnotab),		READONLY},
	{NULL}	/* Sentinel */
};

/* Helper for code_new: return a shallow copy of a tuple that is
   guaranteed to contain exact strings, by converting string subclasses
   to exact strings and complaining if a non-string is found. */
static PyObject*
validate_and_copy_tuple(PyObject *tup)
{
	PyObject *newtuple;
	PyObject *item;
	Py_ssize_t i, len;

	len = PyTuple_GET_SIZE(tup);
	newtuple = PyTuple_New(len);
	if (newtuple == NULL)
		return NULL;

	for (i = 0; i < len; i++) {
		item = PyTuple_GET_ITEM(tup, i);
		if (PyUnicode_CheckExact(item)) {
			Py_INCREF(item);
		}
		else if (!PyUnicode_Check(item)) {
			PyErr_Format(
				PyExc_TypeError,
				"name tuples must contain only "
				"strings, not '%.500s'",
				item->ob_type->tp_name);
			Py_DECREF(newtuple);
			return NULL;
		}
		else {
			item = PyUnicode_FromUnicode(
				PyUnicode_AS_UNICODE(item),
				PyUnicode_GET_SIZE(item));
			if (item == NULL) {
				Py_DECREF(newtuple);
				return NULL;
			}
		}
		PyTuple_SET_ITEM(newtuple, i, item);
	}

	return newtuple;
}

PyDoc_STRVAR(code_doc,
"code(argcount, kwonlyargcount, nlocals, stacksize, flags, codestring,\n\
      constants, names, varnames, filename, name, firstlineno,\n\
      lnotab[, freevars[, cellvars]])\n\
\n\
Create a code object.  Not for the faint of heart.");

static PyObject *
code_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
	int argcount;
	int kwonlyargcount;
	int nlocals;
	int stacksize;
	int flags;
	PyObject *co = NULL;
	PyObject *code;
	PyObject *consts;
	PyObject *names, *ournames = NULL;
	PyObject *varnames, *ourvarnames = NULL;
	PyObject *freevars = NULL, *ourfreevars = NULL;
	PyObject *cellvars = NULL, *ourcellvars = NULL;
	PyObject *filename;
	PyObject *name;
	int firstlineno;
	PyObject *lnotab;

	if (!PyArg_ParseTuple(args, "iiiiiSO!O!O!UUiS|O!O!:code",
			      &argcount, &kwonlyargcount,
				  &nlocals, &stacksize, &flags,
			      &code,
			      &PyTuple_Type, &consts,
			      &PyTuple_Type, &names,
			      &PyTuple_Type, &varnames,
			      &filename, &name,
			      &firstlineno, &lnotab,
			      &PyTuple_Type, &freevars,
			      &PyTuple_Type, &cellvars))
		return NULL;

	if (argcount < 0) {
		PyErr_SetString(
			PyExc_ValueError,
			"code: argcount must not be negative");
		goto cleanup;
	}

	if (kwonlyargcount < 0) {
		PyErr_SetString(
			PyExc_ValueError,
			"code: kwonlyargcount must not be negative");
		goto cleanup;
	}
	if (nlocals < 0) {
		PyErr_SetString(
			PyExc_ValueError,
			"code: nlocals must not be negative");
		goto cleanup;
	}

	ournames = validate_and_copy_tuple(names);
	if (ournames == NULL)
		goto cleanup;
	ourvarnames = validate_and_copy_tuple(varnames);
	if (ourvarnames == NULL)
		goto cleanup;
	if (freevars)
		ourfreevars = validate_and_copy_tuple(freevars);
	else
		ourfreevars = PyTuple_New(0);
	if (ourfreevars == NULL)
		goto cleanup;
	if (cellvars)
		ourcellvars = validate_and_copy_tuple(cellvars);
	else
		ourcellvars = PyTuple_New(0);
	if (ourcellvars == NULL)
		goto cleanup;

	co = (PyObject *)PyCode_New(argcount, kwonlyargcount,
				    nlocals, stacksize, flags,
				    code, consts, ournames, ourvarnames,
				    ourfreevars, ourcellvars, filename,
				    name, firstlineno, lnotab);
  cleanup:
	Py_XDECREF(ournames);
	Py_XDECREF(ourvarnames);
	Py_XDECREF(ourfreevars);
	Py_XDECREF(ourcellvars);
	return co;
}

static void
code_dealloc(PyCodeObject *co)
{
	Py_XDECREF(co->co_code);
	Py_XDECREF(co->co_consts);
	Py_XDECREF(co->co_names);
	Py_XDECREF(co->co_varnames);
	Py_XDECREF(co->co_freevars);
	Py_XDECREF(co->co_cellvars);
	Py_XDECREF(co->co_filename);
	Py_XDECREF(co->co_name);
	Py_XDECREF(co->co_lnotab);
        if (co->co_zombieframe != NULL)
                PyObject_GC_Del(co->co_zombieframe);
	PyObject_DEL(co);
}

static PyObject *
code_repr(PyCodeObject *co)
{
	int lineno = -1;
	char *filename = "???";

	if (co->co_firstlineno != 0)
		lineno = co->co_firstlineno;
	if (co->co_filename && PyUnicode_Check(co->co_filename))
		filename = _PyUnicode_AsString(co->co_filename);
	return PyUnicode_FromFormat(
	                "<code object %.100U at %p, file \"%.300s\", line %d>",
	                co->co_name, co, filename, lineno);
}

static PyObject *
code_richcompare(PyObject *self, PyObject *other, int op)
{
	PyCodeObject *co, *cp;
	int eq;
	PyObject *res;

	if ((op != Py_EQ && op != Py_NE) ||
	    !PyCode_Check(self) ||
	    !PyCode_Check(other)) {
		Py_INCREF(Py_NotImplemented);
		return Py_NotImplemented;
	}

	co = (PyCodeObject *)self;
	cp = (PyCodeObject *)other;

	eq = PyObject_RichCompareBool(co->co_name, cp->co_name, Py_EQ);
	if (eq <= 0) goto unequal;
	eq = co->co_argcount == cp->co_argcount;
	if (!eq) goto unequal;
	eq = co->co_kwonlyargcount == cp->co_kwonlyargcount;
	if (!eq) goto unequal;
	eq = co->co_nlocals == cp->co_nlocals;
	if (!eq) goto unequal;
	eq = co->co_flags == cp->co_flags;
	if (!eq) goto unequal;
	eq = co->co_firstlineno == cp->co_firstlineno;
	if (!eq) goto unequal;
	eq = PyObject_RichCompareBool(co->co_code, cp->co_code, Py_EQ);
	if (eq <= 0) goto unequal;
	eq = PyObject_RichCompareBool(co->co_consts, cp->co_consts, Py_EQ);
	if (eq <= 0) goto unequal;
	eq = PyObject_RichCompareBool(co->co_names, cp->co_names, Py_EQ);
	if (eq <= 0) goto unequal;
	eq = PyObject_RichCompareBool(co->co_varnames, cp->co_varnames, Py_EQ);
	if (eq <= 0) goto unequal;
	eq = PyObject_RichCompareBool(co->co_freevars, cp->co_freevars, Py_EQ);
	if (eq <= 0) goto unequal;
	eq = PyObject_RichCompareBool(co->co_cellvars, cp->co_cellvars, Py_EQ);
	if (eq <= 0) goto unequal;

	if (op == Py_EQ)
		res = Py_True;
	else
		res = Py_False;
	goto done;

  unequal:
	if (eq < 0)
		return NULL;
	if (op == Py_NE)
		res = Py_True;
	else
		res = Py_False;

  done:
	Py_INCREF(res);
	return res;
}

static long
code_hash(PyCodeObject *co)
{
	long h, h0, h1, h2, h3, h4, h5, h6;
	h0 = PyObject_Hash(co->co_name);
	if (h0 == -1) return -1;
	h1 = PyObject_Hash(co->co_code);
	if (h1 == -1) return -1;
	h2 = PyObject_Hash(co->co_consts);
	if (h2 == -1) return -1;
	h3 = PyObject_Hash(co->co_names);
	if (h3 == -1) return -1;
	h4 = PyObject_Hash(co->co_varnames);
	if (h4 == -1) return -1;
	h5 = PyObject_Hash(co->co_freevars);
	if (h5 == -1) return -1;
	h6 = PyObject_Hash(co->co_cellvars);
	if (h6 == -1) return -1;
	h = h0 ^ h1 ^ h2 ^ h3 ^ h4 ^ h5 ^ h6 ^
		co->co_argcount ^ co->co_kwonlyargcount ^
		co->co_nlocals ^ co->co_flags;
	if (h == -1) h = -2;
	return h;
}

/* XXX code objects need to participate in GC? */

PyTypeObject PyCode_Type = {
	PyVarObject_HEAD_INIT(&PyType_Type, 0)
	"code",
	sizeof(PyCodeObject),
	0,
	(destructor)code_dealloc, 	/* tp_dealloc */
	0,				/* tp_print */
	0, 				/* tp_getattr */
	0,				/* tp_setattr */
	0,		 		/* tp_reserved */
	(reprfunc)code_repr,		/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	(hashfunc)code_hash, 		/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT,		/* tp_flags */
	code_doc,			/* tp_doc */
	0,				/* tp_traverse */
	0,				/* tp_clear */
	code_richcompare,		/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iternext */
	0,				/* tp_methods */
	code_memberlist,		/* tp_members */
	0,				/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	0,				/* tp_init */
	0,				/* tp_alloc */
	code_new,			/* tp_new */
};

/* Use co_lnotab to compute the line number from a bytecode index, addrq.  See
   lnotab_notes.txt for the details of the lnotab representation.
*/

int
PyCode_Addr2Line(PyCodeObject *co, int addrq)
{
	int size = PyBytes_Size(co->co_lnotab) / 2;
	unsigned char *p = (unsigned char*)PyBytes_AsString(co->co_lnotab);
	int line = co->co_firstlineno;
	int addr = 0;
	while (--size >= 0) {
		addr += *p++;
		if (addr > addrq)
			break;
		line += *p++;
	}
	return line;
}

/* Update *bounds to describe the first and one-past-the-last instructions in
   the same line as lasti.  Return the number of that line. */
int
_PyCode_CheckLineNumber(PyCodeObject* co, int lasti, PyAddrPair *bounds)
{
        int size, addr, line;
        unsigned char* p;

        p = (unsigned char*)PyBytes_AS_STRING(co->co_lnotab);
        size = PyBytes_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 lnotab_notes.txt for the description of
           co_lnotab.  A point to remember: increments to p
           come in (addr, line) pairs. */

        bounds->ap_lower = 0;
        while (size > 0) {
                if (addr + *p > lasti)
                        break;
                addr += *p++;
                if (*p) 
                        bounds->ap_lower = addr;
                line += *p++;
                --size;
        }

        if (size > 0) {
                while (--size >= 0) {
                        addr += *p++;
                        if (*p++)
                                break;
                }
                bounds->ap_upper = addr;
        }
        else {
                bounds->ap_upper = INT_MAX;
        }

        return line;
}