bltinmodule.c

/* Built-in functions */

#include "Python.h"
#include "Python-ast.h"

#include "node.h"
#include "code.h"

#include "asdl.h"
#include "ast.h"

#include <ctype.h>

#ifdef HAVE_LANGINFO_H
#include <langinfo.h>   /* CODESET */
#endif

/* The default encoding used by the platform file system APIs
   Can remain NULL for all platforms that don't have such a concept

   Don't forget to modify PyUnicode_DecodeFSDefault() if you touch any of the
   values for Py_FileSystemDefaultEncoding!
*/
#ifdef HAVE_MBCS
const char *Py_FileSystemDefaultEncoding = "mbcs";
int Py_HasFileSystemDefaultEncoding = 1;
#elif defined(__APPLE__)
const char *Py_FileSystemDefaultEncoding = "utf-8";
int Py_HasFileSystemDefaultEncoding = 1;
#else
const char *Py_FileSystemDefaultEncoding = NULL; /* set by initfsencoding() */
int Py_HasFileSystemDefaultEncoding = 0;
#endif

_Py_IDENTIFIER(fileno);
_Py_IDENTIFIER(flush);

static PyObject *
builtin___build_class__(PyObject *self, PyObject *args, PyObject *kwds)
{
    PyObject *func, *name, *bases, *mkw, *meta, *winner, *prep, *ns, *cell;
    PyObject *cls = NULL;
    Py_ssize_t nargs;
    int isclass;
    _Py_IDENTIFIER(__prepare__);

    assert(args != NULL);
    if (!PyTuple_Check(args)) {
        PyErr_SetString(PyExc_TypeError,
                        "__build_class__: args is not a tuple");
        return NULL;
    }
    nargs = PyTuple_GET_SIZE(args);
    if (nargs < 2) {
        PyErr_SetString(PyExc_TypeError,
                        "__build_class__: not enough arguments");
        return NULL;
    }
    func = PyTuple_GET_ITEM(args, 0); /* Better be callable */
    if (!PyFunction_Check(func)) {
        PyErr_SetString(PyExc_TypeError,
                        "__build__class__: func must be a function");
        return NULL;
    }
    name = PyTuple_GET_ITEM(args, 1);
    if (!PyUnicode_Check(name)) {
        PyErr_SetString(PyExc_TypeError,
                        "__build_class__: name is not a string");
        return NULL;
    }
    bases = PyTuple_GetSlice(args, 2, nargs);
    if (bases == NULL)
        return NULL;

    if (kwds == NULL) {
        meta = NULL;
        mkw = NULL;
    }
    else {
        mkw = PyDict_Copy(kwds); /* Don't modify kwds passed in! */
        if (mkw == NULL) {
            Py_DECREF(bases);
            return NULL;
        }
        meta = PyDict_GetItemString(mkw, "metaclass");
        if (meta != NULL) {
            Py_INCREF(meta);
            if (PyDict_DelItemString(mkw, "metaclass") < 0) {
                Py_DECREF(meta);
                Py_DECREF(mkw);
                Py_DECREF(bases);
                return NULL;
            }
            /* metaclass is explicitly given, check if it's indeed a class */
            isclass = PyType_Check(meta);
        }
    }
    if (meta == NULL) {
        /* if there are no bases, use type: */
        if (PyTuple_GET_SIZE(bases) == 0) {
            meta = (PyObject *) (&PyType_Type);
        }
        /* else get the type of the first base */
        else {
            PyObject *base0 = PyTuple_GET_ITEM(bases, 0);
            meta = (PyObject *) (base0->ob_type);
        }
        Py_INCREF(meta);
        isclass = 1;  /* meta is really a class */
    }

    if (isclass) {
        /* meta is really a class, so check for a more derived
           metaclass, or possible metaclass conflicts: */
        winner = (PyObject *)_PyType_CalculateMetaclass((PyTypeObject *)meta,
                                                        bases);
        if (winner == NULL) {
            Py_DECREF(meta);
            Py_XDECREF(mkw);
            Py_DECREF(bases);
            return NULL;
        }
        if (winner != meta) {
            Py_DECREF(meta);
            meta = winner;
            Py_INCREF(meta);
        }
    }
    /* else: meta is not a class, so we cannot do the metaclass
       calculation, so we will use the explicitly given object as it is */
    prep = _PyObject_GetAttrId(meta, &PyId___prepare__);
    if (prep == NULL) {
        if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
            PyErr_Clear();
            ns = PyDict_New();
        }
        else {
            Py_DECREF(meta);
            Py_XDECREF(mkw);
            Py_DECREF(bases);
            return NULL;
        }
    }
    else {
        PyObject *pargs = PyTuple_Pack(2, name, bases);
        if (pargs == NULL) {
            Py_DECREF(prep);
            Py_DECREF(meta);
            Py_XDECREF(mkw);
            Py_DECREF(bases);
            return NULL;
        }
        ns = PyEval_CallObjectWithKeywords(prep, pargs, mkw);
        Py_DECREF(pargs);
        Py_DECREF(prep);
    }
    if (ns == NULL) {
        Py_DECREF(meta);
        Py_XDECREF(mkw);
        Py_DECREF(bases);
        return NULL;
    }
    cell = PyEval_EvalCodeEx(PyFunction_GET_CODE(func), PyFunction_GET_GLOBALS(func), ns,
                             NULL, 0, NULL, 0, NULL, 0, NULL,
                             PyFunction_GET_CLOSURE(func));
    if (cell != NULL) {
        PyObject *margs;
        margs = PyTuple_Pack(3, name, bases, ns);
        if (margs != NULL) {
            cls = PyEval_CallObjectWithKeywords(meta, margs, mkw);
            Py_DECREF(margs);
        }
        if (cls != NULL && PyCell_Check(cell))
            PyCell_Set(cell, cls);
        Py_DECREF(cell);
    }
    Py_DECREF(ns);
    Py_DECREF(meta);
    Py_XDECREF(mkw);
    Py_DECREF(bases);
    return cls;
}

PyDoc_STRVAR(build_class_doc,
"__build_class__(func, name, *bases, metaclass=None, **kwds) -> class\n\
\n\
Internal helper function used by the class statement.");

static PyObject *
builtin___import__(PyObject *self, PyObject *args, PyObject *kwds)
{
    static char *kwlist[] = {"name", "globals", "locals", "fromlist",
                             "level", 0};
    PyObject *name, *globals = NULL, *locals = NULL, *fromlist = NULL;
    int level = 0;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "U|OOOi:__import__",
                    kwlist, &name, &globals, &locals, &fromlist, &level))
        return NULL;
    return PyImport_ImportModuleLevelObject(name, globals, locals,
                                            fromlist, level);
}

PyDoc_STRVAR(import_doc,
"__import__(name, globals=None, locals=None, fromlist=(), level=0) -> module\n\
\n\
Import a module. Because this function is meant for use by the Python\n\
interpreter and not for general use it is better to use\n\
importlib.import_module() to programmatically import a module.\n\
\n\
The globals argument is only used to determine the context;\n\
they are not modified.  The locals argument is unused.  The fromlist\n\
should be a list of names to emulate ``from name import ...'', or an\n\
empty list to emulate ``import name''.\n\
When importing a module from a package, note that __import__('A.B', ...)\n\
returns package A when fromlist is empty, but its submodule B when\n\
fromlist is not empty.  Level is used to determine whether to perform \n\
absolute or relative imports. 0 is absolute while a positive number\n\
is the number of parent directories to search relative to the current module.");


static PyObject *
builtin_abs(PyObject *self, PyObject *v)
{
    return PyNumber_Absolute(v);
}

PyDoc_STRVAR(abs_doc,
"abs(number) -> number\n\
\n\
Return the absolute value of the argument.");

static PyObject *
builtin_all(PyObject *self, PyObject *v)
{
    PyObject *it, *item;
    PyObject *(*iternext)(PyObject *);
    int cmp;

    it = PyObject_GetIter(v);
    if (it == NULL)
        return NULL;
    iternext = *Py_TYPE(it)->tp_iternext;

    for (;;) {
        item = iternext(it);
        if (item == NULL)
            break;
        cmp = PyObject_IsTrue(item);
        Py_DECREF(item);
        if (cmp < 0) {
            Py_DECREF(it);
            return NULL;
        }
        if (cmp == 0) {
            Py_DECREF(it);
            Py_RETURN_FALSE;
        }
    }
    Py_DECREF(it);
    if (PyErr_Occurred()) {
        if (PyErr_ExceptionMatches(PyExc_StopIteration))
            PyErr_Clear();
        else
            return NULL;
    }
    Py_RETURN_TRUE;
}

PyDoc_STRVAR(all_doc,
"all(iterable) -> bool\n\
\n\
Return True if bool(x) is True for all values x in the iterable.\n\
If the iterable is empty, return True.");

static PyObject *
builtin_any(PyObject *self, PyObject *v)
{
    PyObject *it, *item;
    PyObject *(*iternext)(PyObject *);
    int cmp;

    it = PyObject_GetIter(v);
    if (it == NULL)
        return NULL;
    iternext = *Py_TYPE(it)->tp_iternext;

    for (;;) {
        item = iternext(it);
        if (item == NULL)
            break;
        cmp = PyObject_IsTrue(item);
        Py_DECREF(item);
        if (cmp < 0) {
            Py_DECREF(it);
            return NULL;
        }
        if (cmp == 1) {
            Py_DECREF(it);
            Py_RETURN_TRUE;
        }
    }
    Py_DECREF(it);
    if (PyErr_Occurred()) {
        if (PyErr_ExceptionMatches(PyExc_StopIteration))
            PyErr_Clear();
        else
            return NULL;
    }
    Py_RETURN_FALSE;
}

PyDoc_STRVAR(any_doc,
"any(iterable) -> bool\n\
\n\
Return True if bool(x) is True for any x in the iterable.\n\
If the iterable is empty, return False.");

static PyObject *
builtin_ascii(PyObject *self, PyObject *v)
{
    return PyObject_ASCII(v);
}

PyDoc_STRVAR(ascii_doc,
"ascii(object) -> string\n\
\n\
As repr(), return a string containing a printable representation of an\n\
object, but escape the non-ASCII characters in the string returned by\n\
repr() using \\x, \\u or \\U escapes.  This generates a string similar\n\
to that returned by repr() in Python 2.");


static PyObject *
builtin_bin(PyObject *self, PyObject *v)
{
    return PyNumber_ToBase(v, 2);
}

PyDoc_STRVAR(bin_doc,
"bin(number) -> string\n\
\n\
Return the binary representation of an integer.");


static PyObject *
builtin_callable(PyObject *self, PyObject *v)
{
    return PyBool_FromLong((long)PyCallable_Check(v));
}

PyDoc_STRVAR(callable_doc,
"callable(object) -> bool\n\
\n\
Return whether the object is callable (i.e., some kind of function).\n\
Note that classes are callable, as are instances of classes with a\n\
__call__() method.");


typedef struct {
    PyObject_HEAD
    PyObject *func;
    PyObject *it;
} filterobject;

static PyObject *
filter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    PyObject *func, *seq;
    PyObject *it;
    filterobject *lz;

    if (type == &PyFilter_Type && !_PyArg_NoKeywords("filter()", kwds))
        return NULL;

    if (!PyArg_UnpackTuple(args, "filter", 2, 2, &func, &seq))
        return NULL;

    /* Get iterator. */
    it = PyObject_GetIter(seq);
    if (it == NULL)
        return NULL;

    /* create filterobject structure */
    lz = (filterobject *)type->tp_alloc(type, 0);
    if (lz == NULL) {
        Py_DECREF(it);
        return NULL;
    }
    Py_INCREF(func);
    lz->func = func;
    lz->it = it;

    return (PyObject *)lz;
}

static void
filter_dealloc(filterobject *lz)
{
    PyObject_GC_UnTrack(lz);
    Py_XDECREF(lz->func);
    Py_XDECREF(lz->it);
    Py_TYPE(lz)->tp_free(lz);
}

static int
filter_traverse(filterobject *lz, visitproc visit, void *arg)
{
    Py_VISIT(lz->it);
    Py_VISIT(lz->func);
    return 0;
}

static PyObject *
filter_next(filterobject *lz)
{
    PyObject *item;
    PyObject *it = lz->it;
    long ok;
    PyObject *(*iternext)(PyObject *);

    iternext = *Py_TYPE(it)->tp_iternext;
    for (;;) {
        item = iternext(it);
        if (item == NULL)
            return NULL;

        if (lz->func == Py_None || lz->func == (PyObject *)&PyBool_Type) {
            ok = PyObject_IsTrue(item);
        } else {
            PyObject *good;
            good = PyObject_CallFunctionObjArgs(lz->func,
                                                item, NULL);
            if (good == NULL) {
                Py_DECREF(item);
                return NULL;
            }
            ok = PyObject_IsTrue(good);
            Py_DECREF(good);
        }
        if (ok > 0)
            return item;
        Py_DECREF(item);
        if (ok < 0)
            return NULL;
    }
}

static PyObject *
filter_reduce(filterobject *lz)
{
    return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
}

PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");

static PyMethodDef filter_methods[] = {
    {"__reduce__",   (PyCFunction)filter_reduce,   METH_NOARGS, reduce_doc},
    {NULL,           NULL}           /* sentinel */
};

PyDoc_STRVAR(filter_doc,
"filter(function or None, iterable) --> filter object\n\
\n\
Return an iterator yielding those items of iterable for which function(item)\n\
is true. If function is None, return the items that are true.");

PyTypeObject PyFilter_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "filter",                           /* tp_name */
    sizeof(filterobject),               /* tp_basicsize */
    0,                                  /* tp_itemsize */
    /* methods */
    (destructor)filter_dealloc,         /* tp_dealloc */
    0,                                  /* tp_print */
    0,                                  /* tp_getattr */
    0,                                  /* tp_setattr */
    0,                                  /* tp_reserved */
    0,                                  /* tp_repr */
    0,                                  /* tp_as_number */
    0,                                  /* tp_as_sequence */
    0,                                  /* tp_as_mapping */
    0,                                  /* tp_hash */
    0,                                  /* tp_call */
    0,                                  /* tp_str */
    PyObject_GenericGetAttr,            /* tp_getattro */
    0,                                  /* tp_setattro */
    0,                                  /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
        Py_TPFLAGS_BASETYPE,            /* tp_flags */
    filter_doc,                         /* tp_doc */
    (traverseproc)filter_traverse,      /* tp_traverse */
    0,                                  /* tp_clear */
    0,                                  /* tp_richcompare */
    0,                                  /* tp_weaklistoffset */
    PyObject_SelfIter,                  /* tp_iter */
    (iternextfunc)filter_next,          /* tp_iternext */
    filter_methods,                     /* tp_methods */
    0,                                  /* 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 */
    PyType_GenericAlloc,                /* tp_alloc */
    filter_new,                         /* tp_new */
    PyObject_GC_Del,                    /* tp_free */
};


static PyObject *
builtin_format(PyObject *self, PyObject *args)
{
    PyObject *value;
    PyObject *format_spec = NULL;

    if (!PyArg_ParseTuple(args, "O|U:format", &value, &format_spec))
        return NULL;

    return PyObject_Format(value, format_spec);
}

PyDoc_STRVAR(format_doc,
"format(value[, format_spec]) -> string\n\
\n\
Returns value.__format__(format_spec)\n\
format_spec defaults to \"\"");

static PyObject *
builtin_chr(PyObject *self, PyObject *args)
{
    int x;

    if (!PyArg_ParseTuple(args, "i:chr", &x))
        return NULL;

    return PyUnicode_FromOrdinal(x);
}

PyDoc_STRVAR(chr_doc,
"chr(i) -> Unicode character\n\
\n\
Return a Unicode string of one character with ordinal i; 0 <= i <= 0x10ffff.");


static char *
source_as_string(PyObject *cmd, char *funcname, char *what, PyCompilerFlags *cf)
{
    char *str;
    Py_ssize_t size;

    if (PyUnicode_Check(cmd)) {
        cf->cf_flags |= PyCF_IGNORE_COOKIE;
        str = PyUnicode_AsUTF8AndSize(cmd, &size);
        if (str == NULL)
            return NULL;
    }
    else if (!PyObject_CheckReadBuffer(cmd)) {
        PyErr_Format(PyExc_TypeError,
          "%s() arg 1 must be a %s object",
          funcname, what);
        return NULL;
    }
    else if (PyObject_AsReadBuffer(cmd, (const void **)&str, &size) < 0) {
        return NULL;
    }

    if (strlen(str) != size) {
        PyErr_SetString(PyExc_TypeError,
                        "source code string cannot contain null bytes");
        return NULL;
    }
    return str;
}

static PyObject *
builtin_compile(PyObject *self, PyObject *args, PyObject *kwds)
{
    char *str;
    PyObject *filename;
    char *startstr;
    int mode = -1;
    int dont_inherit = 0;
    int supplied_flags = 0;
    int optimize = -1;
    int is_ast;
    PyCompilerFlags cf;
    PyObject *cmd;
    static char *kwlist[] = {"source", "filename", "mode", "flags",
                             "dont_inherit", "optimize", NULL};
    int start[] = {Py_file_input, Py_eval_input, Py_single_input};
    PyObject *result;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "OO&s|iii:compile",  kwlist,
                                     &cmd,
                                     PyUnicode_FSDecoder, &filename,
                                     &startstr, &supplied_flags,
                                     &dont_inherit, &optimize))
        return NULL;

    cf.cf_flags = supplied_flags | PyCF_SOURCE_IS_UTF8;

    if (supplied_flags &
        ~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_DONT_IMPLY_DEDENT | PyCF_ONLY_AST))
    {
        PyErr_SetString(PyExc_ValueError,
                        "compile(): unrecognised flags");
        goto error;
    }
    /* XXX Warn if (supplied_flags & PyCF_MASK_OBSOLETE) != 0? */

    if (optimize < -1 || optimize > 2) {
        PyErr_SetString(PyExc_ValueError,
                        "compile(): invalid optimize value");
        goto error;
    }

    if (!dont_inherit) {
        PyEval_MergeCompilerFlags(&cf);
    }

    if (strcmp(startstr, "exec") == 0)
        mode = 0;
    else if (strcmp(startstr, "eval") == 0)
        mode = 1;
    else if (strcmp(startstr, "single") == 0)
        mode = 2;
    else {
        PyErr_SetString(PyExc_ValueError,
                        "compile() arg 3 must be 'exec', 'eval' or 'single'");
        goto error;
    }

    is_ast = PyAST_Check(cmd);
    if (is_ast == -1)
        goto error;
    if (is_ast) {
        if (supplied_flags & PyCF_ONLY_AST) {
            Py_INCREF(cmd);
            result = cmd;
        }
        else {
            PyArena *arena;
            mod_ty mod;

            arena = PyArena_New();
            if (arena == NULL)
                goto error;
            mod = PyAST_obj2mod(cmd, arena, mode);
            if (mod == NULL) {
                PyArena_Free(arena);
                goto error;
            }
            if (!PyAST_Validate(mod)) {
                PyArena_Free(arena);
                goto error;
            }
            result = (PyObject*)PyAST_CompileObject(mod, filename,
                                                    &cf, optimize, arena);
            PyArena_Free(arena);
        }
        goto finally;
    }

    str = source_as_string(cmd, "compile", "string, bytes or AST", &cf);
    if (str == NULL)
        goto error;

    result = Py_CompileStringObject(str, filename, start[mode], &cf, optimize);
    goto finally;

error:
    result = NULL;
finally:
    Py_DECREF(filename);
    return result;
}

PyDoc_STRVAR(compile_doc,
"compile(source, filename, mode[, flags[, dont_inherit]]) -> code object\n\
\n\
Compile the source string (a Python module, statement or expression)\n\
into a code object that can be executed by exec() or eval().\n\
The filename will be used for run-time error messages.\n\
The mode must be 'exec' to compile a module, 'single' to compile a\n\
single (interactive) statement, or 'eval' to compile an expression.\n\
The flags argument, if present, controls which future statements influence\n\
the compilation of the code.\n\
The dont_inherit argument, if non-zero, stops the compilation inheriting\n\
the effects of any future statements in effect in the code calling\n\
compile; if absent or zero these statements do influence the compilation,\n\
in addition to any features explicitly specified.");

static PyObject *
builtin_dir(PyObject *self, PyObject *args)
{
    PyObject *arg = NULL;

    if (!PyArg_UnpackTuple(args, "dir", 0, 1, &arg))
        return NULL;
    return PyObject_Dir(arg);
}

PyDoc_STRVAR(dir_doc,
"dir([object]) -> list of strings\n"
"\n"
"If called without an argument, return the names in the current scope.\n"
"Else, return an alphabetized list of names comprising (some of) the attributes\n"
"of the given object, and of attributes reachable from it.\n"
"If the object supplies a method named __dir__, it will be used; otherwise\n"
"the default dir() logic is used and returns:\n"
"  for a module object: the module's attributes.\n"
"  for a class object:  its attributes, and recursively the attributes\n"
"    of its bases.\n"
"  for any other object: its attributes, its class's attributes, and\n"
"    recursively the attributes of its class's base classes.");

static PyObject *
builtin_divmod(PyObject *self, PyObject *args)
{
    PyObject *v, *w;

    if (!PyArg_UnpackTuple(args, "divmod", 2, 2, &v, &w))
        return NULL;
    return PyNumber_Divmod(v, w);
}

PyDoc_STRVAR(divmod_doc,
"divmod(x, y) -> (div, mod)\n\
\n\
Return the tuple ((x-x%y)/y, x%y).  Invariant: div*y + mod == x.");


static PyObject *
builtin_eval(PyObject *self, PyObject *args)
{
    PyObject *cmd, *result, *tmp = NULL;
    PyObject *globals = Py_None, *locals = Py_None;
    char *str;
    PyCompilerFlags cf;

    if (!PyArg_UnpackTuple(args, "eval", 1, 3, &cmd, &globals, &locals))
        return NULL;
    if (locals != Py_None && !PyMapping_Check(locals)) {
        PyErr_SetString(PyExc_TypeError, "locals must be a mapping");
        return NULL;
    }
    if (globals != Py_None && !PyDict_Check(globals)) {
        PyErr_SetString(PyExc_TypeError, PyMapping_Check(globals) ?
            "globals must be a real dict; try eval(expr, {}, mapping)"
            : "globals must be a dict");
        return NULL;
    }
    if (globals == Py_None) {
        globals = PyEval_GetGlobals();
        if (locals == Py_None)
            locals = PyEval_GetLocals();
    }
    else if (locals == Py_None)
        locals = globals;

    if (globals == NULL || locals == NULL) {
        PyErr_SetString(PyExc_TypeError,
            "eval must be given globals and locals "
            "when called without a frame");
        return NULL;
    }

    if (PyDict_GetItemString(globals, "__builtins__") == NULL) {
        if (PyDict_SetItemString(globals, "__builtins__",
                                 PyEval_GetBuiltins()) != 0)
            return NULL;
    }

    if (PyCode_Check(cmd)) {
        if (PyCode_GetNumFree((PyCodeObject *)cmd) > 0) {
            PyErr_SetString(PyExc_TypeError,
        "code object passed to eval() may not contain free variables");
            return NULL;
        }
        return PyEval_EvalCode(cmd, globals, locals);
    }

    cf.cf_flags = PyCF_SOURCE_IS_UTF8;
    str = source_as_string(cmd, "eval", "string, bytes or code", &cf);
    if (str == NULL)
        return NULL;

    while (*str == ' ' || *str == '\t')
        str++;

    (void)PyEval_MergeCompilerFlags(&cf);
    result = PyRun_StringFlags(str, Py_eval_input, globals, locals, &cf);
    Py_XDECREF(tmp);
    return result;
}

PyDoc_STRVAR(eval_doc,
"eval(source[, globals[, locals]]) -> value\n\
\n\
Evaluate the source in the context of globals and locals.\n\
The source may be a string representing a Python expression\n\
or a code object as returned by compile().\n\
The globals must be a dictionary and locals can be any mapping,\n\
defaulting to the current globals and locals.\n\
If only globals is given, locals defaults to it.\n");

static PyObject *
builtin_exec(PyObject *self, PyObject *args)
{
    PyObject *v;
    PyObject *prog, *globals = Py_None, *locals = Py_None;

    if (!PyArg_UnpackTuple(args, "exec", 1, 3, &prog, &globals, &locals))
        return NULL;

    if (globals == Py_None) {
        globals = PyEval_GetGlobals();
        if (locals == Py_None) {
            locals = PyEval_GetLocals();
        }
        if (!globals || !locals) {
            PyErr_SetString(PyExc_SystemError,
                            "globals and locals cannot be NULL");
            return NULL;
        }
    }
    else if (locals == Py_None)
        locals = globals;

    if (!PyDict_Check(globals)) {
        PyErr_Format(PyExc_TypeError, "exec() arg 2 must be a dict, not %.100s",
                     globals->ob_type->tp_name);
        return NULL;
    }
    if (!PyMapping_Check(locals)) {
        PyErr_Format(PyExc_TypeError,
            "arg 3 must be a mapping or None, not %.100s",
            locals->ob_type->tp_name);
        return NULL;
    }
    if (PyDict_GetItemString(globals, "__builtins__") == NULL) {
        if (PyDict_SetItemString(globals, "__builtins__",
                                 PyEval_GetBuiltins()) != 0)
            return NULL;
    }

    if (PyCode_Check(prog)) {
        if (PyCode_GetNumFree((PyCodeObject *)prog) > 0) {
            PyErr_SetString(PyExc_TypeError,
                "code object passed to exec() may not "
                "contain free variables");
            return NULL;
        }
        v = PyEval_EvalCode(prog, globals, locals);
    }
    else {
        char *str;
        PyCompilerFlags cf;
        cf.cf_flags = PyCF_SOURCE_IS_UTF8;
        str = source_as_string(prog, "exec",
                                     "string, bytes or code", &cf);
        if (str == NULL)
            return NULL;
        if (PyEval_MergeCompilerFlags(&cf))
            v = PyRun_StringFlags(str, Py_file_input, globals,
                                  locals, &cf);
        else
            v = PyRun_String(str, Py_file_input, globals, locals);
    }
    if (v == NULL)
        return NULL;
    Py_DECREF(v);
    Py_RETURN_NONE;
}

PyDoc_STRVAR(exec_doc,
"exec(object[, globals[, locals]])\n\
\n\
Read and execute code from an object, which can be a string or a code\n\
object.\n\
The globals and locals are dictionaries, defaulting to the current\n\
globals and locals.  If only globals is given, locals defaults to it.");


static PyObject *
builtin_getattr(PyObject *self, PyObject *args)
{
    PyObject *v, *result, *dflt = NULL;
    PyObject *name;

    if (!PyArg_UnpackTuple(args, "getattr", 2, 3, &v, &name, &dflt))
        return NULL;

    if (!PyUnicode_Check(name)) {
        PyErr_SetString(PyExc_TypeError,
                        "getattr(): attribute name must be string");
        return NULL;
    }
    result = PyObject_GetAttr(v, name);
    if (result == NULL && dflt != NULL &&
        PyErr_ExceptionMatches(PyExc_AttributeError))
    {
        PyErr_Clear();
        Py_INCREF(dflt);
        result = dflt;
    }
    return result;
}

PyDoc_STRVAR(getattr_doc,
"getattr(object, name[, default]) -> value\n\
\n\
Get a named attribute from an object; getattr(x, 'y') is equivalent to x.y.\n\
When a default argument is given, it is returned when the attribute doesn't\n\
exist; without it, an exception is raised in that case.");


static PyObject *
builtin_globals(PyObject *self)
{
    PyObject *d;

    d = PyEval_GetGlobals();
    Py_XINCREF(d);
    return d;
}

PyDoc_STRVAR(globals_doc,
"globals() -> dictionary\n\
\n\
Return the dictionary containing the current scope's global variables.");


static PyObject *
builtin_hasattr(PyObject *self, PyObject *args)
{
    PyObject *v;
    PyObject *name;

    if (!PyArg_UnpackTuple(args, "hasattr", 2, 2, &v, &name))
        return NULL;
    if (!PyUnicode_Check(name)) {
        PyErr_SetString(PyExc_TypeError,
                        "hasattr(): attribute name must be string");
        return NULL;
    }
    v = PyObject_GetAttr(v, name);
    if (v == NULL) {
        if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
            PyErr_Clear();
            Py_RETURN_FALSE;
        }
        return NULL;
    }
    Py_DECREF(v);
    Py_RETURN_TRUE;
}

PyDoc_STRVAR(hasattr_doc,
"hasattr(object, name) -> bool\n\
\n\
Return whether the object has an attribute with the given name.\n\
(This is done by calling getattr(object, name) and catching AttributeError.)");


static PyObject *
builtin_id(PyObject *self, PyObject *v)
{
    return PyLong_FromVoidPtr(v);
}

PyDoc_STRVAR(id_doc,
"id(object) -> integer\n\
\n\
Return the identity of an object.  This is guaranteed to be unique among\n\
simultaneously existing objects.  (Hint: it's the object's memory address.)");


/* map object ************************************************************/

typedef struct {
    PyObject_HEAD
    PyObject *iters;
    PyObject *func;
} mapobject;

static PyObject *
map_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    PyObject *it, *iters, *func;
    mapobject *lz;
    Py_ssize_t numargs, i;

    if (type == &PyMap_Type && !_PyArg_NoKeywords("map()", kwds))
        return NULL;

    numargs = PyTuple_Size(args);