doc/src/snippets/code/doc_src_layout.cpp


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
**     the names of its contributors may be used to endorse or promote
**     products derived from this software without specific prior written
**     permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
** $QT_END_LICENSE$
**
****************************************************************************/

//! [0]
#ifndef CARD_H
#define CARD_H

#include <QtGui>
#include <QList>

class CardLayout : public QLayout
{
public:
    CardLayout(QWidget *parent, int dist): QLayout(parent, 0, dist) {}
    CardLayout(QLayout *parent, int dist): QLayout(parent, dist) {}
    CardLayout(int dist): QLayout(dist) {}
    ~CardLayout();

    void addItem(QLayoutItem *item);
    QSize sizeHint() const;
    QSize minimumSize() const;
	QLayoutItem *count() const;
    QLayoutItem *itemAt(int) const;
    QLayoutItem *takeAt(int);
    void setGeometry(const QRect &rect);

private:
    QList<QLayoutItem*> list;
};
#endif
//! [0]


//! [1]
//#include "card.h"
//! [1]

//! [2]
QLayoutItem *CardLayout::count() const
{
	// QList::size() returns the number of QLayoutItems in the list
    return list.size();
}
//! [2]

//! [3]
QLayoutItem *CardLayout::itemAt(int idx) const
{
    // QList::value() performs index checking, and returns 0 if we are
    // outside the valid range
    return list.value(idx);
}

QLayoutItem *CardLayout::takeAt(int idx)
{
    // QList::take does not do index checking
    return idx >= 0 && idx < list.size() ? list.takeAt(idx) : 0;
}
//! [3]


//! [4]
void CardLayout::addItem(QLayoutItem *item)
{
    list.append(item);
}
//! [4]


//! [5]
CardLayout::~CardLayout()
{
     QLayoutItem *item;
     while ((item = takeAt(0)))
         delete item;
}
//! [5]


//! [6]
void CardLayout::setGeometry(const QRect &r)
{
    QLayout::setGeometry(r);

    if (list.size() == 0)
        return;

    int w = r.width() - (list.count() - 1) * spacing();
    int h = r.height() - (list.count() - 1) * spacing();
    int i = 0;
    while (i < list.size()) {
        QLayoutItem *o = list.at(i);
        QRect geom(r.x() + i * spacing(), r.y() + i * spacing(), w, h);
        o->setGeometry(geom);
        ++i;
    }
}
//! [6]


//! [7]
QSize CardLayout::sizeHint() const
{
    QSize s(0,0);
    int n = list.count();
    if (n > 0)
        s = QSize(100,70); //start with a nice default size
    int i = 0;
    while (i < n) {
        QLayoutItem *o = list.at(i);
        s = s.expandedTo(o->sizeHint());
        ++i;
    }
    return s + n*QSize(spacing(), spacing());
}

QSize CardLayout::minimumSize() const
{
    QSize s(0,0);
    int n = list.count();
    int i = 0;
    while (i < n) {
        QLayoutItem *o = list.at(i);
        s = s.expandedTo(o->minimumSize());
        ++i;
    }
    return s + n*QSize(spacing(), spacing());
}
//! [7]
#include "Python.h"
#include "code.h"  /* For DeprecationWarning about adding 'line'. */
#include "frameobject.h"

#define MODULE_NAME "_warnings"
#define DEFAULT_ACTION_NAME "default_action"

PyDoc_STRVAR(warnings__doc__,
MODULE_NAME " provides basic warning filtering support.\n"
"It is a helper module to speed up interpreter start-up.");

/* Both 'filters' and 'onceregistry' can be set in warnings.py;
   get_warnings_attr() will reset these variables accordingly. */
static PyObject *_filters;  /* List */
static PyObject *_once_registry;  /* Dict */


static int
check_matched(PyObject *obj, PyObject *arg)
{
    PyObject *result;
    int rc;

    if (obj == Py_None)
        return 1;
    result = PyObject_CallMethod(obj, "match", "O", arg);
    if (result == NULL)
        return -1;

    rc = PyObject_IsTrue(result);
    Py_DECREF(result);
    return rc;
}

/*
   Returns a new reference.
   A NULL return value can mean false or an error.
*/
static PyObject *
get_warnings_attr(const char *attr)
{
    static PyObject *warnings_str = NULL;
    PyObject *all_modules;
    PyObject *warnings_module;
    int result;

    if (warnings_str == NULL) {
        warnings_str = PyString_InternFromString("warnings");
        if (warnings_str == NULL)
            return NULL;
    }

    all_modules = PyImport_GetModuleDict();
    result = PyDict_Contains(all_modules, warnings_str);
    if (result == -1 || result == 0)
        return NULL;

    warnings_module = PyDict_GetItem(all_modules, warnings_str);
    if (!PyObject_HasAttrString(warnings_module, attr))
            return NULL;
    return PyObject_GetAttrString(warnings_module, attr);
}


static PyObject *
get_once_registry(void)
{
    PyObject *registry;

    registry = get_warnings_attr("onceregistry");
    if (registry == NULL) {
        if (PyErr_Occurred())
            return NULL;
        return _once_registry;
    }
    Py_DECREF(_once_registry);
    _once_registry = registry;
    return registry;
}


/* The item is a borrowed reference. */
static const char *
get_filter(PyObject *category, PyObject *text, Py_ssize_t lineno,
           PyObject *module, PyObject **item)
{
    PyObject *action, *m, *d;
    Py_ssize_t i;
    PyObject *warnings_filters;

    warnings_filters = get_warnings_attr("filters");
    if (warnings_filters == NULL) {
        if (PyErr_Occurred())
            return NULL;
    }
    else {
        Py_DECREF(_filters);
        _filters = warnings_filters;
    }

    if (!PyList_Check(_filters)) {
        PyErr_SetString(PyExc_ValueError,
                        MODULE_NAME ".filters must be a list");
        return NULL;
    }

    /* _filters could change while we are iterating over it. */
    for (i = 0; i < PyList_GET_SIZE(_filters); i++) {
        PyObject *tmp_item, *action, *msg, *cat, *mod, *ln_obj;
        Py_ssize_t ln;
        int is_subclass, good_msg, good_mod;

        tmp_item = *item = PyList_GET_ITEM(_filters, i);
        if (PyTuple_Size(tmp_item) != 5) {
            PyErr_Format(PyExc_ValueError,
                         MODULE_NAME ".filters item %zd isn't a 5-tuple", i);
            return NULL;
        }

        /* Python code: action, msg, cat, mod, ln = item */
        action = PyTuple_GET_ITEM(tmp_item, 0);
        msg = PyTuple_GET_ITEM(tmp_item, 1);
        cat = PyTuple_GET_ITEM(tmp_item, 2);
        mod = PyTuple_GET_ITEM(tmp_item, 3);
        ln_obj = PyTuple_GET_ITEM(tmp_item, 4);

        good_msg = check_matched(msg, text);
        good_mod = check_matched(mod, module);
        is_subclass = PyObject_IsSubclass(category, cat);
        ln = PyInt_AsSsize_t(ln_obj);
        if (good_msg == -1 || good_mod == -1 || is_subclass == -1 ||
            (ln == -1 && PyErr_Occurred()))
            return NULL;

        if (good_msg && is_subclass && good_mod && (ln == 0 || lineno == ln))
            return PyString_AsString(action);
    }

    m = PyImport_ImportModule(MODULE_NAME);
    if (m == NULL)
        return NULL;
    d = PyModule_GetDict(m);
    Py_DECREF(m);
    if (d == NULL)
        return NULL;
    action = PyDict_GetItemString(d, DEFAULT_ACTION_NAME);
    if (action != NULL)
        return PyString_AsString(action);

    PyErr_SetString(PyExc_ValueError,
                    MODULE_NAME "." DEFAULT_ACTION_NAME " not found");
    return NULL;
}

static int
already_warned(PyObject *registry, PyObject *key, int should_set)
{
    PyObject *already_warned;

    if (key == NULL)
        return -1;

    already_warned = PyDict_GetItem(registry, key);
    if (already_warned != NULL) {
        int rc = PyObject_IsTrue(already_warned);
        if (rc != 0)
            return rc;
    }

    /* This warning wasn't found in the registry, set it. */
    if (should_set)
        return PyDict_SetItem(registry, key, Py_True);
    return 0;
}

/* New reference. */
static PyObject *
normalize_module(PyObject *filename)
{
    PyObject *module;
    const char *mod_str;
    Py_ssize_t len;

    int rc = PyObject_IsTrue(filename);
    if (rc == -1)
        return NULL;
    else if (rc == 0)
        return PyString_FromString("<unknown>");

    mod_str = PyString_AsString(filename);
    if (mod_str == NULL)
	    return NULL;
    len = PyString_Size(filename);
    if (len < 0)
        return NULL;
    if (len >= 3 &&
	strncmp(mod_str + (len - 3), ".py", 3) == 0) {
        module = PyString_FromStringAndSize(mod_str, len-3);
    }
    else {
        module = filename;
        Py_INCREF(module);
    }
    return module;
}

static int
update_registry(PyObject *registry, PyObject *text, PyObject *category,
                int add_zero)
{
    PyObject *altkey, *zero = NULL;
    int rc;

    if (add_zero) {
        zero = PyInt_FromLong(0);
        if (zero == NULL)
            return -1;
        altkey = PyTuple_Pack(3, text, category, zero);
    }
    else
        altkey = PyTuple_Pack(2, text, category);

    rc = already_warned(registry, altkey, 1);
    Py_XDECREF(zero);
    Py_XDECREF(altkey);
    return rc;
}

static void
show_warning(PyObject *filename, int lineno, PyObject *text, PyObject
                *category, PyObject *sourceline)
{
    PyObject *f_stderr;
    PyObject *name;
    char lineno_str[128];

    PyOS_snprintf(lineno_str, sizeof(lineno_str), ":%d: ", lineno);

    name = PyObject_GetAttrString(category, "__name__");
    if (name == NULL)  /* XXX Can an object lack a '__name__' attribute? */
	    return;

    f_stderr = PySys_GetObject("stderr");
    if (f_stderr == NULL) {
        fprintf(stderr, "lost sys.stderr\n");
        Py_DECREF(name);
        return;
    }

    /* Print "filename:lineno: category: text\n" */
    PyFile_WriteObject(filename, f_stderr, Py_PRINT_RAW);
    PyFile_WriteString(lineno_str, f_stderr);
    PyFile_WriteObject(name, f_stderr, Py_PRINT_RAW);
    PyFile_WriteString(": ", f_stderr);
    PyFile_WriteObject(text, f_stderr, Py_PRINT_RAW);
    PyFile_WriteString("\n", f_stderr);
    Py_XDECREF(name);

    /* Print "  source_line\n" */
    if (sourceline) {
        char *source_line_str = PyString_AS_STRING(sourceline);
        while (*source_line_str == ' ' || *source_line_str == '\t' ||
                *source_line_str == '\014')
            source_line_str++;

        PyFile_WriteString(source_line_str, f_stderr);
        PyFile_WriteString("\n", f_stderr);
    }
    else
        _Py_DisplaySourceLine(f_stderr, PyString_AS_STRING(filename), 
                              lineno, 2);
    PyErr_Clear();
}

static PyObject *
warn_explicit(PyObject *category, PyObject *message,
              PyObject *filename, int lineno,
              PyObject *module, PyObject *registry, PyObject *sourceline)
{
    PyObject *key = NULL, *text = NULL, *result = NULL, *lineno_obj = NULL;
    PyObject *item = Py_None;
    const char *action;
    int rc;
    
    if (registry && !PyDict_Check(registry) && (registry != Py_None)) {
        PyErr_SetString(PyExc_TypeError, "'registry' must be a dict");
        return NULL;
    }

    /* Normalize module. */
    if (module == NULL) {
        module = normalize_module(filename);
        if (module == NULL)
            return NULL;
    }
    else
        Py_INCREF(module);

    /* Normalize message. */
    Py_INCREF(message);  /* DECREF'ed in cleanup. */
    rc = PyObject_IsInstance(message, PyExc_Warning);
    if (rc == -1) {
        goto cleanup;
    }
    if (rc == 1) {
        text = PyObject_Str(message);
        category = (PyObject*)message->ob_type;
    }
    else {
        text = message;
        message = PyObject_CallFunction(category, "O", message);
        if (message == NULL)
            goto cleanup;
    }

    lineno_obj = PyInt_FromLong(lineno);
    if (lineno_obj == NULL)
        goto cleanup;

    /* Create key. */
    key = PyTuple_Pack(3, text, category, lineno_obj);
    if (key == NULL)
        goto cleanup;

    if ((registry != NULL) && (registry != Py_None)) {
        rc = already_warned(registry, key, 0);
        if (rc == -1)
            goto cleanup;
	else if (rc == 1)
            goto return_none;
        /* Else this warning hasn't been generated before. */
    }

    action = get_filter(category, text, lineno, module, &item);
    if (action == NULL)
        goto cleanup;

    if (strcmp(action, "error") == 0) {
        PyErr_SetObject(category, message);
        goto cleanup;
    }

    /* Store in the registry that we've been here, *except* when the action
       is "always". */
    rc = 0;
    if (strcmp(action, "always") != 0) {
        if (registry != NULL && registry != Py_None &&
                PyDict_SetItem(registry, key, Py_True) < 0)
            goto cleanup;
        else if (strcmp(action, "ignore") == 0)
            goto return_none;
        else if (strcmp(action, "once") == 0) {
            if (registry == NULL || registry == Py_None) {
                registry = get_once_registry();
                if (registry == NULL)
                    goto cleanup;
            }
            /* _once_registry[(text, category)] = 1 */
            rc = update_registry(registry, text, category, 0);
        }
        else if (strcmp(action, "module") == 0) {
            /* registry[(text, category, 0)] = 1 */
            if (registry != NULL && registry != Py_None)
                rc = update_registry(registry, text, category, 0);
        }
        else if (strcmp(action, "default") != 0) {
            PyObject *to_str = PyObject_Str(item);
            const char *err_str = "???";

            if (to_str != NULL)
                err_str = PyString_AS_STRING(to_str);
            PyErr_Format(PyExc_RuntimeError,
                        "Unrecognized action (%s) in warnings.filters:\n %s",
                        action, err_str);
            Py_XDECREF(to_str);
            goto cleanup;
        }
    }

    if (rc == 1)  /* Already warned for this module. */
        goto return_none;
    if (rc == 0) {
        PyObject *show_fxn = get_warnings_attr("showwarning");
        if (show_fxn == NULL) {
            if (PyErr_Occurred())
                goto cleanup;
            show_warning(filename, lineno, text, category, sourceline);
        }
        else {
            const char *msg = "functions overriding warnings.showwarning() "
                                "must support the 'line' argument";
            const char *text_char = PyString_AS_STRING(text);

            if (strcmp(msg, text_char) == 0) {
                /* Prevent infinite recursion by using built-in implementation
                   of showwarning(). */
                show_warning(filename, lineno, text, category, sourceline);
            }
            else {
                PyObject *check_fxn;
                PyObject *defaults;
                PyObject *res;

                if (PyMethod_Check(show_fxn))
                    check_fxn = PyMethod_Function(show_fxn);
                else if (PyFunction_Check(show_fxn))
                    check_fxn = show_fxn;
                else {
                    PyErr_SetString(PyExc_TypeError,
                                    "warnings.showwarning() must be set to a "
                                    "function or method");
                    Py_DECREF(show_fxn);
                    goto cleanup;
                }

                defaults = PyFunction_GetDefaults(check_fxn);
                /* A proper implementation of warnings.showwarning() should
                    have at least two default arguments. */
                if ((defaults == NULL) || (PyTuple_Size(defaults) < 2)) {
	            PyCodeObject *code = (PyCodeObject *)
						PyFunction_GetCode(check_fxn);
		    if (!(code->co_flags & CO_VARARGS)) {
		        if (PyErr_WarnEx(PyExc_DeprecationWarning, msg, 1) <
				0) {
                            Py_DECREF(show_fxn);
                            goto cleanup;
                        }
                    }
		}
                res = PyObject_CallFunctionObjArgs(show_fxn, message, category,
                                                    filename, lineno_obj,
                                                    NULL);
                Py_DECREF(show_fxn);
                Py_XDECREF(res);
                if (res == NULL)
                    goto cleanup;
            }
        }
    }
    else /* if (rc == -1) */
        goto cleanup;

 return_none:
    result = Py_None;
    Py_INCREF(result);

 cleanup:
    Py_XDECREF(key);
    Py_XDECREF(text);
    Py_XDECREF(lineno_obj);
    Py_DECREF(module);
    Py_XDECREF(message);
    return result;  /* Py_None or NULL. */
}

/* filename, module, and registry are new refs, globals is borrowed */
/* Returns 0 on error (no new refs), 1 on success */
static int
setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
              PyObject **module, PyObject **registry)
{
    PyObject *globals;

    /* Setup globals and lineno. */
    PyFrameObject *f = PyThreadState_GET()->frame;
    while (--stack_level > 0 && f != NULL)
        f = f->f_back;

    if (f == NULL) {
        globals = PyThreadState_Get()->interp->sysdict;
        *lineno = 1;
    }
    else {
        globals = f->f_globals;
        *lineno = PyCode_Addr2Line(f->f_code, f->f_lasti);
    }

    *module = NULL;

    /* Setup registry. */
    assert(globals != NULL);
    assert(PyDict_Check(globals));
    *registry = PyDict_GetItemString(globals, "__warningregistry__");
    if (*registry == NULL) {
        int rc;

        *registry = PyDict_New();
        if (*registry == NULL)
            return 0;

         rc = PyDict_SetItemString(globals, "__warningregistry__", *registry);
         if (rc < 0)
            goto handle_error;
    }
    else
        Py_INCREF(*registry);

    /* Setup module. */
    *module = PyDict_GetItemString(globals, "__name__");
    if (*module == NULL) {
        *module = PyString_FromString("<string>");
        if (*module == NULL)
            goto handle_error;
    }
    else
        Py_INCREF(*module);

    /* Setup filename. */
    *filename = PyDict_GetItemString(globals, "__file__");
    if (*filename != NULL) {
	    Py_ssize_t len = PyString_Size(*filename);
        const char *file_str = PyString_AsString(*filename);
	    if (file_str == NULL || (len < 0 && PyErr_Occurred()))
            goto handle_error;

        /* if filename.lower().endswith((".pyc", ".pyo")): */
        if (len >= 4 &&
            file_str[len-4] == '.' &&
            tolower(file_str[len-3]) == 'p' &&
            tolower(file_str[len-2]) == 'y' &&
            (tolower(file_str[len-1]) == 'c' ||
                tolower(file_str[len-1]) == 'o'))
        {
            *filename = PyString_FromStringAndSize(file_str, len-1);
	        if (*filename == NULL)
		        goto handle_error;
	    }
	    else
            Py_INCREF(*filename);
    }
    else {
        const char *module_str = PyString_AsString(*module);
        if (module_str && strcmp(module_str, "__main__") == 0) {
            PyObject *argv = PySys_GetObject("argv");
            if (argv != NULL && PyList_Size(argv) > 0) {
                int is_true;
                *filename = PyList_GetItem(argv, 0);
                Py_INCREF(*filename);
                /* If sys.argv[0] is false, then use '__main__'. */
                is_true = PyObject_IsTrue(*filename);
                if (is_true < 0) {
                    Py_DECREF(*filename);
                    goto handle_error;
                }
                else if (!is_true) {
                    Py_DECREF(*filename);
                    *filename = PyString_FromString("__main__");
                    if (*filename == NULL)
                        goto handle_error;
                }
            }
            else {
                /* embedded interpreters don't have sys.argv, see bug #839151 */
                *filename = PyString_FromString("__main__");
	            if (*filename == NULL)
	                goto handle_error;
            }
        }
        if (*filename == NULL) {
            *filename = *module;
            Py_INCREF(*filename);
        }
    }

    return 1;

 handle_error:
    /* filename not XDECREF'ed here as there is no way to jump here with a
       dangling reference. */
    Py_XDECREF(*registry);
    Py_XDECREF(*module);
    return 0;
}

static PyObject *
get_category(PyObject *message, PyObject *category)
{
    int rc;

    /* Get category. */
    rc = PyObject_IsInstance(message, PyExc_Warning);
    if (rc == -1)
        return NULL;

    if (rc == 1)
        category = (PyObject*)message->ob_type;
    else if (category == NULL)
        category = PyExc_UserWarning;

    /* Validate category. */
    rc = PyObject_IsSubclass(category, PyExc_Warning);
    if (rc == -1)
        return NULL;
    if (rc == 0) {
        PyErr_SetString(PyExc_ValueError,
                        "category is not a subclass of Warning");
        return NULL;
    }

    return category;
}

static PyObject *
do_warn(PyObject *message, PyObject *category, Py_ssize_t stack_level)
{
    PyObject *filename, *module, *registry, *res;
    int lineno;

    if (!setup_context(stack_level, &filename, &lineno, &module, &registry))
        return NULL;

    res = warn_explicit(category, message, filename, lineno, module, registry,
                        NULL);
    Py_DECREF(filename);
    Py_DECREF(registry);
    Py_DECREF(module);
    return res;
}

static PyObject *
warnings_warn(PyObject *self, PyObject *args, PyObject *kwds)
{
    static char *kw_list[] = { "message", "category", "stacklevel", 0 };
    PyObject *message, *category = NULL;
    Py_ssize_t stack_level = 1;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|On:warn", kw_list,
                                     &message, &category, &stack_level))
        return NULL;

    category = get_category(message, category);
    if (category == NULL)
        return NULL;
    return do_warn(message, category, stack_level);
}

static PyObject *
warnings_warn_explicit(PyObject *self, PyObject *args, PyObject *kwds)
{
    static char *kwd_list[] = {"message", "category", "filename", "lineno",
                                "module", "registry", "module_globals", 0};
    PyObject *message;
    PyObject *category;
    PyObject *filename;
    int lineno;
    PyObject *module = NULL;
    PyObject *registry = NULL;
    PyObject *module_globals = NULL;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "OOOi|OOO:warn_explicit",
                kwd_list, &message, &category, &filename, &lineno, &module,
                &registry, &module_globals))
        return NULL;

    if (module_globals) {
        static PyObject *get_source_name = NULL;
        static PyObject *splitlines_name = NULL;
        PyObject *loader;
        PyObject *module_name;
        PyObject *source;
        PyObject *source_list;
        PyObject *source_line;
        PyObject *returned;

        if (get_source_name == NULL) {
            get_source_name = PyString_InternFromString("get_source");
            if (!get_source_name)
                return NULL;
        }
        if (splitlines_name == NULL) {
            splitlines_name = PyString_InternFromString("splitlines");
            if (!splitlines_name)
                return NULL;
        }

        /* Check/get the requisite pieces needed for the loader. */
        loader = PyDict_GetItemString(module_globals, "__loader__");
        module_name = PyDict_GetItemString(module_globals, "__name__");

        if (loader == NULL || module_name == NULL)
            goto standard_call;

        /* Make sure the loader implements the optional get_source() method. */
        if (!PyObject_HasAttrString(loader, "get_source"))
                goto standard_call;
        /* Call get_source() to get the source code. */
        source = PyObject_CallMethodObjArgs(loader, get_source_name,
                                                module_name, NULL);
        if (!source)
            return NULL;
        else if (source == Py_None) {
            Py_DECREF(Py_None);
            goto standard_call;
        }

        /* Split the source into lines. */
        source_list = PyObject_CallMethodObjArgs(source, splitlines_name,
                                                    NULL);
        Py_DECREF(source);
        if (!source_list)
            return NULL;

        /* Get the source line. */
        source_line = PyList_GetItem(source_list, lineno-1);
        if (!source_line) {
            Py_DECREF(source_list);
            return NULL;
        }

        /* Handle the warning. */
        returned = warn_explicit(category, message, filename, lineno, module,
                            registry, source_line);
        Py_DECREF(source_list);
        return returned;
    }

 standard_call:
    return warn_explicit(category, message, filename, lineno, module,
                                registry, NULL);
}


/* Function to issue a warning message; may raise an exception. */
int
PyErr_WarnEx(PyObject *category, const char *text, Py_ssize_t stack_level)
{
    PyObject *res;
    PyObject *message = PyString_FromString(text);
    if (message == NULL)
        return -1;

    if (category == NULL)
        category = PyExc_RuntimeWarning;

    res = do_warn(message, category, stack_level);
    Py_DECREF(message);
    if (res == NULL)
        return -1;
    Py_DECREF(res);

    return 0;
}

/* PyErr_Warn is only for backwards compatability and will be removed.
   Use PyErr_WarnEx instead. */

#undef PyErr_Warn

PyAPI_FUNC(int)
PyErr_Warn(PyObject *category, char *text)
{
    return PyErr_WarnEx(category, text, 1);
}

/* Warning with explicit origin */
int
PyErr_WarnExplicit(PyObject *category, const char *text,
                   const char *filename_str, int lineno,
                   const char *module_str, PyObject *registry)
{
    PyObject *res;
    PyObject *message = PyString_FromString(text);
    PyObject *filename = PyString_FromString(filename_str);
    PyObject *module = NULL;
    int ret = -1;

    if (message == NULL || filename == NULL)
        goto exit;
    if (module_str != NULL) {
        module = PyString_FromString(module_str);
            if (module == NULL)
                goto exit;
    }

    if (category == NULL)
        category = PyExc_RuntimeWarning;
    res = warn_explicit(category, message, filename, lineno, module, registry,
                        NULL);
    if (res == NULL)
        goto exit;
    Py_DECREF(res);
    ret = 0;

 exit:
    Py_XDECREF(message);
    Py_XDECREF(module);
    Py_XDECREF(filename);
    return ret;
}


PyDoc_STRVAR(warn_doc,
"Issue a warning, or maybe ignore it or raise an exception.");

PyDoc_STRVAR(warn_explicit_doc,
"Low-level inferface to warnings functionality.");

static PyMethodDef warnings_functions[] = {
    {"warn", (PyCFunction)warnings_warn, METH_VARARGS | METH_KEYWORDS,
        warn_doc},
    {"warn_explicit", (PyCFunction)warnings_warn_explicit,
        METH_VARARGS | METH_KEYWORDS, warn_explicit_doc},
    /* XXX(brett.cannon): add showwarning? */
    /* XXX(brett.cannon): Reasonable to add formatwarning? */
    {NULL, NULL}	        /* sentinel */
};


static PyObject *
create_filter(PyObject *category, const char *action)
{
    static PyObject *ignore_str = NULL;
    static PyObject *error_str = NULL;
    static PyObject *default_str = NULL;
    PyObject *action_obj = NULL;
    PyObject *lineno, *result;

    if (!strcmp(action, "ignore")) {
        if (ignore_str == NULL) {
            ignore_str = PyString_InternFromString("ignore");
            if (ignore_str == NULL)
                return NULL;
        }
        action_obj = ignore_str;
    }
    else if (!strcmp(action, "error")) {
        if (error_str == NULL) {
            error_str = PyString_InternFromString("error");
            if (error_str == NULL)
                return NULL;
        }
        action_obj = error_str;
    }
    else if (!strcmp(action, "default")) {
        if (default_str == NULL) {
            default_str = PyString_InternFromString("default");
            if (default_str == NULL)
                return NULL;
        }
        action_obj = default_str;
    }
    else {
        Py_FatalError("unknown action");
    }

    /* This assumes the line number is zero for now. */
    lineno = PyInt_FromLong(0);
    if (lineno == NULL)
        return NULL;
    result = PyTuple_Pack(5, action_obj, Py_None, category, Py_None, lineno);
    Py_DECREF(lineno);
    return result;
}

static PyObject *
init_filters(void)
{
    PyObject *filters = PyList_New(3);
    const char *bytes_action;
    if (filters == NULL)
        return NULL;

    PyList_SET_ITEM(filters, 0,
                    create_filter(PyExc_PendingDeprecationWarning, "ignore"));
    PyList_SET_ITEM(filters, 1, create_filter(PyExc_ImportWarning, "ignore"));
    if (Py_BytesWarningFlag > 1)
        bytes_action = "error";
    else if (Py_BytesWarningFlag)
        bytes_action = "default";
    else
        bytes_action = "ignore";
    PyList_SET_ITEM(filters, 2, create_filter(PyExc_BytesWarning,
                    bytes_action));

    if (PyList_GET_ITEM(filters, 0) == NULL ||
        PyList_GET_ITEM(filters, 1) == NULL ||
        PyList_GET_ITEM(filters, 2) == NULL) {
        Py_DECREF(filters);
        return NULL;
    }

    return filters;
}


PyMODINIT_FUNC
_PyWarnings_Init(void)
{
    PyObject *m, *default_action;

    m = Py_InitModule3(MODULE_NAME, warnings_functions, warnings__doc__);
    if (m == NULL)
        return;

    _filters = init_filters();
    if (_filters == NULL)
        return;
    Py_INCREF(_filters);
    if (PyModule_AddObject(m, "filters", _filters) < 0)
        return;

    _once_registry = PyDict_New();
    if (_once_registry == NULL)
        return;
    Py_INCREF(_once_registry);
    if (PyModule_AddObject(m, "once_registry", _once_registry) < 0)
        return;

    default_action = PyString_InternFromString("default");
    if (default_action == NULL)
        return;
    if (PyModule_AddObject(m, DEFAULT_ACTION_NAME, default_action) < 0)
        return;
}