/src/cpython/Python/future.c

Source
#include "Python.h"
#include "pycore_ast.h"           // _PyAST_GetDocString()
#include "pycore_pyerrors.h"      // _Py_CalculateSuggestions()
#include "pycore_symtable.h"      // _PyFutureFeatures
#include "pycore_unicodeobject.h" // _PyUnicode_EqualToASCIIString()

#define UNDEFINED_FUTURE_FEATURE "future feature '%.100s' is not defined"

static int
future_check_features(_PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
{
    Py_ssize_t i;

    assert(s->kind == ImportFrom_kind);

    asdl_alias_seq *names = s->v.ImportFrom.names;
    for (i = 0; i < asdl_seq_LEN(names); i++) {
        alias_ty name = (alias_ty)asdl_seq_GET(names, i);
        const char *feature = PyUnicode_AsUTF8(name->name);
        if (!feature)
            return 0;
        if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_GENERATORS) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_DIVISION) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_BARRY_AS_BDFL) == 0) {
            ff->ff_features |= CO_FUTURE_BARRY_AS_BDFL;
        } else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
            continue;
        } else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
            ff->ff_features |= CO_FUTURE_ANNOTATIONS;
        } else if (strcmp(feature, "braces") == 0) {
            PyErr_SetString(PyExc_SyntaxError,
                            "not a chance");
            PyErr_RangedSyntaxLocationObject(filename,
                                             name->lineno,
                                             name->col_offset + 1,
                                             name->end_lineno,
                                             name->end_col_offset + 1);
            return 0;
        } else {
            // Keep this list in sync with the feature checks above.
            PyObject *future_features = Py_BuildValue("[ssssssssss]",
                                                      FUTURE_NESTED_SCOPES,
                                                      FUTURE_GENERATORS,
                                                      FUTURE_DIVISION,
                                                      FUTURE_ABSOLUTE_IMPORT,
                                                      FUTURE_WITH_STATEMENT,
                                                      FUTURE_PRINT_FUNCTION,
                                                      FUTURE_UNICODE_LITERALS,
                                                      FUTURE_BARRY_AS_BDFL,
                                                      FUTURE_GENERATOR_STOP,
                                                      FUTURE_ANNOTATIONS);
            PyObject *suggestion = NULL;
            if (future_features != NULL) {
                suggestion = _Py_CalculateSuggestions(future_features,
                                                      name->name);
            }
            if (suggestion != NULL) {
                PyErr_Format(PyExc_SyntaxError,
                             UNDEFINED_FUTURE_FEATURE ". Did you mean: %R?",
                             feature, suggestion);
                Py_DECREF(suggestion);
            }
            else {
                // Do not fail on missing suggestion,
                // just show the default message.
                PyErr_Format(PyExc_SyntaxError,
                             UNDEFINED_FUTURE_FEATURE,
                             feature);
            }
            Py_XDECREF(future_features);
            PyErr_RangedSyntaxLocationObject(filename,
                                             name->lineno,
                                             name->col_offset + 1,
                                             name->end_lineno,
                                             name->end_col_offset + 1);
            return 0;
        }
    }
    return 1;
}

static int
future_parse(_PyFutureFeatures *ff, mod_ty mod, PyObject *filename)
{
    if (!(mod->kind == Module_kind || mod->kind == Interactive_kind)) {
        return 1;
    }

    Py_ssize_t n = asdl_seq_LEN(mod->v.Module.body);
    if (n == 0) {
        return 1;
    }

    Py_ssize_t i = 0;
    if (_PyAST_GetDocString(mod->v.Module.body) != NULL) {
        i++;
    }

    for (; i < n; i++) {
        stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);

        /* The only things that can precede a future statement
         *  are another future statement and a doc string.
         */

        if (s->kind == ImportFrom_kind && s->v.ImportFrom.level == 0) {
            identifier modname = s->v.ImportFrom.module;
            if (modname &&
                _PyUnicode_EqualToASCIIString(modname, "__future__")) {
                if (!future_check_features(ff, s, filename)) {
                    return 0;
                }
                ff->ff_location = SRC_LOCATION_FROM_AST(s);
            }
            else {
                return 1;
            }
        }
        else {
            return 1;
        }
    }
    return 1;
}


int
_PyFuture_FromAST(mod_ty mod, PyObject *filename, _PyFutureFeatures *ff)
{
    ff->ff_features = 0;
    ff->ff_location = (_Py_SourceLocation){-1, -1, -1, -1};

    if (!future_parse(ff, mod, filename)) {
        return 0;
    }
    return 1;
}

Line	Count	Source
1		#include "Python.h"
2		#include "pycore_ast.h" // _PyAST_GetDocString()
3		#include "pycore_pyerrors.h" // _Py_CalculateSuggestions()
4		#include "pycore_symtable.h" // _PyFutureFeatures
5		#include "pycore_unicodeobject.h" // _PyUnicode_EqualToASCIIString()
6
7	111	#define UNDEFINED_FUTURE_FEATURE "future feature '%.100s' is not defined"
8
9		static int
10		future_check_features(_PyFutureFeatures ff, stmt_ty s, PyObject filename)
11	532	{
12	532	Py_ssize_t i;
13
14	532	assert(s->kind == ImportFrom_kind);
15
16	532	asdl_alias_seq *names = s->v.ImportFrom.names;
17	986	for (i = 0; i < asdl_seq_LEN(names); i++) {
18	565	alias_ty name = (alias_ty)asdl_seq_GET(names, i);
19	565	const char *feature = PyUnicode_AsUTF8(name->name);
20	565	if (!feature)
21	0	return 0;
22	565	if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
23	73	continue;
24	492	} else if (strcmp(feature, FUTURE_GENERATORS) == 0) {
25	12	continue;
26	480	} else if (strcmp(feature, FUTURE_DIVISION) == 0) {
27	70	continue;
28	410	} else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
29	77	continue;
30	333	} else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
31	11	continue;
32	322	} else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
33	10	continue;
34	312	} else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
35	28	continue;
36	284	} else if (strcmp(feature, FUTURE_BARRY_AS_BDFL) == 0) {
37	66	ff->ff_features \|= CO_FUTURE_BARRY_AS_BDFL;
38	218	} else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
39	18	continue;
40	200	} else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
41	89	ff->ff_features \|= CO_FUTURE_ANNOTATIONS;
42	111	} else if (strcmp(feature, "braces") == 0) {
43	0	PyErr_SetString(PyExc_SyntaxError,
44	0	"not a chance");
45	0	PyErr_RangedSyntaxLocationObject(filename,
46	0	name->lineno,
47	0	name->col_offset + 1,
48	0	name->end_lineno,
49	0	name->end_col_offset + 1);
50	0	return 0;
51	111	} else {
52		// Keep this list in sync with the feature checks above.
53	111	PyObject *future_features = Py_BuildValue("[ssssssssss]",
54	111	FUTURE_NESTED_SCOPES,
55	111	FUTURE_GENERATORS,
56	111	FUTURE_DIVISION,
57	111	FUTURE_ABSOLUTE_IMPORT,
58	111	FUTURE_WITH_STATEMENT,
59	111	FUTURE_PRINT_FUNCTION,
60	111	FUTURE_UNICODE_LITERALS,
61	111	FUTURE_BARRY_AS_BDFL,
62	111	FUTURE_GENERATOR_STOP,
63	111	FUTURE_ANNOTATIONS);
64	111	PyObject *suggestion = NULL;
65	111	if (future_features != NULL) {
66	111	suggestion = _Py_CalculateSuggestions(future_features,
67	111	name->name);
68	111	}
69	111	if (suggestion != NULL) {
70	25	PyErr_Format(PyExc_SyntaxError,
71	25	UNDEFINED_FUTURE_FEATURE ". Did you mean: %R?",
72	25	feature, suggestion);
73	25	Py_DECREF(suggestion);
74	25	}
75	86	else {
76		// Do not fail on missing suggestion,
77		// just show the default message.
78	86	PyErr_Format(PyExc_SyntaxError,
79	86	UNDEFINED_FUTURE_FEATURE,
80	86	feature);
81	86	}
82	111	Py_XDECREF(future_features);
83	111	PyErr_RangedSyntaxLocationObject(filename,
84	111	name->lineno,
85	111	name->col_offset + 1,
86	111	name->end_lineno,
87	111	name->end_col_offset + 1);
88	111	return 0;
89	111	}
90	565	}
91	421	return 1;
92	532	}
93
94		static int
95		future_parse(_PyFutureFeatures ff, mod_ty mod, PyObject filename)
96	8.29k	{
97	8.29k	if (!(mod->kind == Module_kind \|\| mod->kind == Interactive_kind)) {
98	172	return 1;
99	172	}
100
101	8.12k	Py_ssize_t n = asdl_seq_LEN(mod->v.Module.body);
102	8.12k	if (n == 0) {
103	1.42k	return 1;
104	1.42k	}
105
106	6.70k	Py_ssize_t i = 0;
107	6.70k	if (_PyAST_GetDocString(mod->v.Module.body) != NULL) {
108	435	i++;
109	435	}
110
111	7.12k	for (; i < n; i++) {
112	6.80k	stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
113
114		/* The only things that can precede a future statement
115		* are another future statement and a doc string.
116		*/
117
118	6.80k	if (s->kind == ImportFrom_kind && s->v.ImportFrom.level == 0) {
119	742	identifier modname = s->v.ImportFrom.module;
120	742	if (modname &&
121	742	_PyUnicode_EqualToASCIIString(modname, "__future__")) {
122	532	if (!future_check_features(ff, s, filename)) {
123	111	return 0;
124	111	}
125	421	ff->ff_location = SRC_LOCATION_FROM_AST(s);
126	421	}
127	210	else {
128	210	return 1;
129	210	}
130	742	}
131	6.06k	else {
132	6.06k	return 1;
133	6.06k	}
134	6.80k	}
135	321	return 1;
136	6.70k	}
137
138
139		int
140		_PyFuture_FromAST(mod_ty mod, PyObject filename, _PyFutureFeatures ff)
141	8.29k	{
142	8.29k	ff->ff_features = 0;
143	8.29k	ff->ff_location = (_Py_SourceLocation){-1, -1, -1, -1};
144
145	8.29k	if (!future_parse(ff, mod, filename)) {
146	111	return 0;
147	111	}
148	8.18k	return 1;
149	8.29k	}

Coverage Report

Created: 2026-10-31 06:21