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
|
"""Utilities dealing with code objects."""
import sys
import string
import traceback
def compile_command(source, filename="<input>", symbol="single"):
r"""Compile a command and determine whether it is incomplete.
Arguments:
source -- the source string; may contain \n characters
filename -- optional filename from which source was read; default "<input>"
symbol -- optional grammar start symbol; "single" (default) or "eval"
Return value / exception raised:
- Return a code object if the command is complete and valid
- Return None if the command is incomplete
- Raise SyntaxError if the command is a syntax error
Approach:
Compile three times: as is, with \n, and with \n\n appended. If
it compiles as is, it's complete. If it compiles with one \n
appended, we expect more. If it doesn't compile either way, we
compare the error we get when compiling with \n or \n\n appended.
If the errors are the same, the code is broken. But if the errors
are different, we expect more. Not intuitive; not even guaranteed
to hold in future releases; but this matches the compiler's
behavior in Python 1.4 and 1.5.
"""
err = err1 = err2 = None
code = code1 = code2 = None
try:
code = compile(source, filename, symbol)
except SyntaxError, err:
pass
try:
code1 = compile(source + "\n", filename, symbol)
except SyntaxError, err1:
pass
try:
code2 = compile(source + "\n\n", filename, symbol)
except SyntaxError, err2:
pass
if code:
return code
try:
e1 = err1.__dict__
except AttributeError:
e1 = err1
try:
e2 = err2.__dict__
except AttributeError:
e2 = err2
if not code1 and e1 == e2:
raise SyntaxError, err1
class InteractiveConsole:
"""Closely emulate the behavior of the interactive Python interpreter.
After code by Jeff Epler and Fredrik Lundh.
"""
def __init__(self, filename="<console>", locals=None):
"""Constructor.
The optional filename argument specifies the (file)name of the
input stream; it will show up in tracebacks. It defaults to
'<console>'.
"""
self.filename = filename
if locals is None:
locals = {}
self.locals = locals
self.resetbuffer()
def resetbuffer(self):
"""Reset the input buffer (but not the variables!)."""
self.buffer = []
def interact(self, banner=None):
"""Closely emulate the interactive Python console."""
try:
sys.ps1
except AttributeError:
sys.ps1 = ">>> "
try:
sys.ps2
except AttributeError:
sys.ps2 = "... "
if banner is None:
self.write("Python %s on %s\n%s\n(%s)\n" %
(sys.version, sys.platform, sys.copyright,
self.__class__.__name__))
else:
self.write("%s\n" % str(banner))
more = 0
while 1:
try:
if more:
prompt = sys.ps2
else:
prompt = sys.ps1
try:
line = self.raw_input(prompt)
except EOFError:
self.write("\n")
break
else:
more = self.push(line)
except KeyboardInterrupt:
self.write("\nKeyboardInterrupt\n")
self.resetbuffer()
more = 0
def push(self, line):
"""Push a line to the interpreter.
The line should not have a trailing newline.
One of three things will happen:
1) The input is incorrect; compile_command() raised
SyntaxError. A syntax traceback will be printed.
2) The input is incomplete, and more input is required;
compile_command() returned None.
3) The input is complete; compile_command() returned a code
object. The code is executed. When an exception occurs, a
traceback is printed. All exceptions are caught except
SystemExit, which is reraised.
The return value is 1 in case 2, 0 in the other cases. (The
return value can be used to decide whether to use sys.ps1 or
sys.ps2 to prompt the next line.)
A note about KeyboardInterrupt: this exception may occur
elsewhere in this code, and will not always be caught. The
caller should be prepared to deal with it.
"""
self.buffer.append(line)
try:
x = compile_command(string.join(self.buffer, "\n"),
filename=self.filename)
except SyntaxError:
# Case 1
self.showsyntaxerror()
self.resetbuffer()
return 0
if x is None:
# Case 2
return 1
# Case 3
try:
exec x in self.locals
except SystemExit:
raise
except:
self.showtraceback()
self.resetbuffer()
return 0
def showsyntaxerror(self):
"""Display the syntax error that just occurred.
This doesn't display a stack trace because there isn't one.
The output is written by self.write(), below.
"""
type, value = sys.exc_info()[:2]
# Work hard to stuff the correct filename in the exception
try:
msg, (filename, lineno, offset, line) = value
except:
pass
else:
try:
value = SyntaxError(msg, (self.filename, lineno, offset, line))
except:
value = msg, (self.filename, lineno, offset, line)
list = traceback.format_exception_only(type, value)
map(self.write, list)
def showtraceback(self):
"""Display the exception that just occurred.
We remove the first stack item because it is our own code.
The output is written by self.write(), below.
"""
try:
type, value, tb = sys.exc_info()
tblist = traceback.extract_tb(tb)
del tblist[0]
list = traceback.format_list(tblist)
list[len(list):] = traceback.format_exception_only(type, value)
finally:
tblist = tb = None
map(self.write, list)
def write(self, data):
"""Write a string.
The base implementation writes to sys.stderr; a subclass may
replace this with a different implementation.
"""
sys.stderr.write(data)
def raw_input(self, prompt=""):
"""Write a prompt and read a line.
The returned line does not include the trailing newline.
When the user enters the EOF key sequence, EOFError is raised.
The base implementation uses the built-in function
raw_input(); a subclass may replace this with a different
implementation.
"""
return raw_input(prompt)
def interact(banner=None, readfunc=None, locals=None):
"""Closely emulate the interactive Python interpreter.
This is a backwards compatible interface to the InteractiveConsole
class. It attempts to import the readline module to enable GNU
readline if it is available.
Arguments (all optional, all default to None):
banner -- passed to InteractiveConsole.interact()
readfunc -- if not None, replaces InteractiveConsole.raw_input()
locals -- passed to InteractiveConsole.__init__()
"""
try:
import readline
except:
pass
console = InteractiveConsole(locals=locals)
if readfunc is not None:
console.raw_input = readfunc
console.interact(banner)
if __name__ == '__main__':
interact()
|
