summaryrefslogtreecommitdiffstats
path: root/Objects/frameobject.c
blob: 0f6372bb194536421e5ce4c7ec617fb21ccc3ee2 (plain)
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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351

/* Frame object implementation */

#include "Python.h"

#include "compile.h"
#include "frameobject.h"
#include "opcode.h"
#include "structmember.h"

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

static struct memberlist frame_memberlist[] = {
	{"f_back",	T_OBJECT,	OFF(f_back),	RO},
	{"f_code",	T_OBJECT,	OFF(f_code),	RO},
	{"f_builtins",	T_OBJECT,	OFF(f_builtins),RO},
	{"f_globals",	T_OBJECT,	OFF(f_globals),	RO},
	{"f_locals",	T_OBJECT,	OFF(f_locals),	RO},
	{"f_lasti",	T_INT,		OFF(f_lasti),	RO},
	{"f_lineno",	T_INT,		OFF(f_lineno),	RO},
	{"f_restricted",T_INT,		OFF(f_restricted),RO},
	{"f_trace",	T_OBJECT,	OFF(f_trace)},
	{"f_exc_type",	T_OBJECT,	OFF(f_exc_type)},
	{"f_exc_value",	T_OBJECT,	OFF(f_exc_value)},
	{"f_exc_traceback", T_OBJECT,	OFF(f_exc_traceback)},
	{NULL}	/* Sentinel */
};

static PyObject *
frame_getattr(PyFrameObject *f, char *name)
{
	if (strcmp(name, "f_locals") == 0)
		PyFrame_FastToLocals(f);
	return PyMember_Get((char *)f, frame_memberlist, name);
}

static int
frame_setattr(PyFrameObject *f, char *name, PyObject *value)
{
	return PyMember_Set((char *)f, frame_memberlist, name, value);
}

/* Stack frames are allocated and deallocated at a considerable rate.
   In an attempt to improve the speed of function calls, we maintain a
   separate free list of stack frames (just like integers are
   allocated in a special way -- see intobject.c).  When a stack frame
   is on the free list, only the following members have a meaning:
	ob_type		== &Frametype
	f_back		next item on free list, or NULL
	f_nlocals	number of locals
	f_stacksize	size of value stack
   Note that the value and block stacks are preserved -- this can save
   another malloc() call or two (and two free() calls as well!).
   Also note that, unlike for integers, each frame object is a
   malloc'ed object in its own right -- it is only the actual calls to
   malloc() that we are trying to save here, not the administration.
   After all, while a typical program may make millions of calls, a
   call depth of more than 20 or 30 is probably already exceptional
   unless the program contains run-away recursion.  I hope.
*/

static PyFrameObject *free_list = NULL;

static void
frame_dealloc(PyFrameObject *f)
{
	int i;
	PyObject **fastlocals;

	Py_TRASHCAN_SAFE_BEGIN(f)
	/* Kill all local variables */
	fastlocals = f->f_localsplus;
	for (i = f->f_nlocals; --i >= 0; ++fastlocals) {
		Py_XDECREF(*fastlocals);
	}

	Py_XDECREF(f->f_back);
	Py_XDECREF(f->f_code);
	Py_XDECREF(f->f_builtins);
	Py_XDECREF(f->f_globals);
	Py_XDECREF(f->f_locals);
	Py_XDECREF(f->f_closure);
	Py_XDECREF(f->f_trace);
	Py_XDECREF(f->f_exc_type);
	Py_XDECREF(f->f_exc_value);
	Py_XDECREF(f->f_exc_traceback);
	f->f_back = free_list;
	free_list = f;
	Py_TRASHCAN_SAFE_END(f)
}

PyTypeObject PyFrame_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"frame",
	sizeof(PyFrameObject),
	0,
	(destructor)frame_dealloc, /*tp_dealloc*/
	0,		/*tp_print*/
	(getattrfunc)frame_getattr, /*tp_getattr*/
	(setattrfunc)frame_setattr, /*tp_setattr*/
	0,		/*tp_compare*/
	0,		/*tp_repr*/
	0,		/*tp_as_number*/
	0,		/*tp_as_sequence*/
	0,		/*tp_as_mapping*/
};

PyFrameObject *
PyFrame_New(PyThreadState *tstate, PyCodeObject *code, PyObject *globals, 
	    PyObject *locals, PyObject *closure)
{
	PyFrameObject *back = tstate->frame;
	static PyObject *builtin_object;
	PyFrameObject *f;
	PyObject *builtins;
	int extras, ncells;

	if (builtin_object == NULL) {
		builtin_object = PyString_InternFromString("__builtins__");
		if (builtin_object == NULL)
			return NULL;
	}
	if ((back != NULL && !PyFrame_Check(back)) ||
	    code == NULL || !PyCode_Check(code) ||
	    globals == NULL || !PyDict_Check(globals) ||
	    (locals != NULL && !PyDict_Check(locals))) {
		PyErr_BadInternalCall();
		return NULL;
	}
	extras = code->co_stacksize + code->co_nlocals;
	ncells = PyTuple_GET_SIZE(code->co_cellvars);
	if (back == NULL || back->f_globals != globals) {
		builtins = PyDict_GetItem(globals, builtin_object);
		if (builtins != NULL && PyModule_Check(builtins))
			builtins = PyModule_GetDict(builtins);
	}
	else {
		/* If we share the globals, we share the builtins.
		   Save a lookup and a call. */
		builtins = back->f_builtins;
	}
	if (builtins != NULL && !PyDict_Check(builtins))
		builtins = NULL;
	if (free_list == NULL) {
		/* PyObject_New is inlined */
		f = (PyFrameObject *)
			PyObject_MALLOC(sizeof(PyFrameObject) +
					extras*sizeof(PyObject *));
		if (f == NULL)
			return (PyFrameObject *)PyErr_NoMemory();
		PyObject_INIT(f, &PyFrame_Type);
	}
	else {
		f = free_list;
		free_list = free_list->f_back;
		if (f->f_nlocals + f->f_stacksize < extras) {
			f = (PyFrameObject *)
				PyObject_REALLOC(f, sizeof(PyFrameObject) +
						 extras*sizeof(PyObject *));
			if (f == NULL)
				return (PyFrameObject *)PyErr_NoMemory();
		}
		else
			extras = f->f_nlocals + f->f_stacksize;
		PyObject_INIT(f, &PyFrame_Type);
	}
	if (builtins == NULL) {
		/* No builtins!  Make up a minimal one. */
		builtins = PyDict_New();
		if (builtins == NULL || /* Give them 'None', at least. */
		    PyDict_SetItemString(builtins, "None", Py_None) < 0) {
			Py_DECREF(f);
			return NULL;
		}
	}
	else
		Py_XINCREF(builtins);
	f->f_builtins = builtins;
	Py_XINCREF(back);
	f->f_back = back;
	Py_INCREF(code);
	f->f_code = code;
	Py_INCREF(globals);
	f->f_globals = globals;
	if (code->co_flags & CO_NEWLOCALS) {
		if (code->co_flags & CO_OPTIMIZED)
			locals = NULL; /* Let fast_2_locals handle it */
		else {
			locals = PyDict_New();
			if (locals == NULL) {
				Py_DECREF(f);
				return NULL;
			}
		}
	}
	else {
		if (locals == NULL)
			locals = globals;
		Py_INCREF(locals);
	}
	if (closure || ncells) {
		int i, size;
		size = ncells;
		if (closure)
			size += PyTuple_GET_SIZE(closure);
		f->f_closure = PyTuple_New(size);
		for (i = 0; i < ncells; ++i)
			PyTuple_SET_ITEM(f->f_closure, i, PyCell_New(NULL));
		for (i = ncells; i < size; ++i) {
			PyObject *o = PyTuple_GET_ITEM(closure, i - ncells);
			Py_INCREF(o);
			PyTuple_SET_ITEM(f->f_closure, i, o);
		}
	}
	else
		f->f_closure = NULL;
	f->f_locals = locals;
	f->f_trace = NULL;
	f->f_exc_type = f->f_exc_value = f->f_exc_traceback = NULL;
	f->f_tstate = tstate;

	f->f_lasti = 0;
	f->f_lineno = code->co_firstlineno;
	f->f_restricted = (builtins != tstate->interp->builtins);
	f->f_iblock = 0;
	f->f_nlocals = code->co_nlocals;
	f->f_stacksize = extras - code->co_nlocals;

	while (--extras >= 0)
		f->f_localsplus[extras] = NULL;

	f->f_valuestack = f->f_localsplus + f->f_nlocals;

	return f;
}

/* Block management */

void
PyFrame_BlockSetup(PyFrameObject *f, int type, int handler, int level)
{
	PyTryBlock *b;
	if (f->f_iblock >= CO_MAXBLOCKS)
		Py_FatalError("XXX block stack overflow");
	b = &f->f_blockstack[f->f_iblock++];
	b->b_type = type;
	b->b_level = level;
	b->b_handler = handler;
}

PyTryBlock *
PyFrame_BlockPop(PyFrameObject *f)
{
	PyTryBlock *b;
	if (f->f_iblock <= 0)
		Py_FatalError("XXX block stack underflow");
	b = &f->f_blockstack[--f->f_iblock];
	return b;
}

/* Convert between "fast" version of locals and dictionary version */

void
PyFrame_FastToLocals(PyFrameObject *f)
{
	/* Merge fast locals into f->f_locals */
	PyObject *locals, *map;
	PyObject **fast;
	PyObject *error_type, *error_value, *error_traceback;
	int j;
	if (f == NULL)
		return;
	locals = f->f_locals;
	if (locals == NULL) {
		locals = f->f_locals = PyDict_New();
		if (locals == NULL) {
			PyErr_Clear(); /* Can't report it :-( */
			return;
		}
	}
	if (f->f_nlocals == 0)
		return;
	map = f->f_code->co_varnames;
	if (!PyDict_Check(locals) || !PyTuple_Check(map))
		return;
	PyErr_Fetch(&error_type, &error_value, &error_traceback);
	fast = f->f_localsplus;
	j = PyTuple_Size(map);
	if (j > f->f_nlocals)
		j = f->f_nlocals;
	for (; --j >= 0; ) {
		PyObject *key = PyTuple_GetItem(map, j);
		PyObject *value = fast[j];
		if (value == NULL) {
			PyErr_Clear();
			if (PyDict_DelItem(locals, key) != 0)
				PyErr_Clear();
		}
		else {
			if (PyDict_SetItem(locals, key, value) != 0)
				PyErr_Clear();
		}
	}
	PyErr_Restore(error_type, error_value, error_traceback);
}

void
PyFrame_LocalsToFast(PyFrameObject *f, int clear)
{
	/* Merge f->f_locals into fast locals */
	PyObject *locals, *map;
	PyObject **fast;
	PyObject *error_type, *error_value, *error_traceback;
	int j;
	if (f == NULL)
		return;
	locals = f->f_locals;
	map = f->f_code->co_varnames;
	if (locals == NULL || f->f_code->co_nlocals == 0)
		return;
	if (!PyDict_Check(locals) || !PyTuple_Check(map))
		return;
	PyErr_Fetch(&error_type, &error_value, &error_traceback);
	fast = f->f_localsplus;
	j = PyTuple_Size(map);
	if (j > f->f_nlocals)
		j = f->f_nlocals;
	for (; --j >= 0; ) {
		PyObject *key = PyTuple_GetItem(map, j);
		PyObject *value = PyDict_GetItem(locals, key);
		Py_XINCREF(value);
		if (value != NULL || clear) {
			Py_XDECREF(fast[j]);
			fast[j] = value;
		}
	}
	PyErr_Restore(error_type, error_value, error_traceback);
}

/* Clear out the free list */

void
PyFrame_Fini(void)
{
	while (free_list != NULL) {
		PyFrameObject *f = free_list;
		free_list = free_list->f_back;
		PyObject_DEL(f);
	}
}