Exceptions raised during renaming in rotating file handlers are now passed to handleE...
[python.git] / Lib / code.py
blob6bdc658add03d8cea96ca87f7fbefbb86dc859f2
1 """Utilities needed to emulate Python's interactive interpreter.
3 """
5 # Inspired by similar code by Jeff Epler and Fredrik Lundh.
8 import sys
9 import traceback
10 from codeop import CommandCompiler, compile_command
12 __all__ = ["InteractiveInterpreter", "InteractiveConsole", "interact",
13 "compile_command"]
15 def softspace(file, newvalue):
16 oldvalue = 0
17 try:
18 oldvalue = file.softspace
19 except AttributeError:
20 pass
21 try:
22 file.softspace = newvalue
23 except (AttributeError, TypeError):
24 # "attribute-less object" or "read-only attributes"
25 pass
26 return oldvalue
28 class InteractiveInterpreter:
29 """Base class for InteractiveConsole.
31 This class deals with parsing and interpreter state (the user's
32 namespace); it doesn't deal with input buffering or prompting or
33 input file naming (the filename is always passed in explicitly).
35 """
37 def __init__(self, locals=None):
38 """Constructor.
40 The optional 'locals' argument specifies the dictionary in
41 which code will be executed; it defaults to a newly created
42 dictionary with key "__name__" set to "__console__" and key
43 "__doc__" set to None.
45 """
46 if locals is None:
47 locals = {"__name__": "__console__", "__doc__": None}
48 self.locals = locals
49 self.compile = CommandCompiler()
51 def runsource(self, source, filename="<input>", symbol="single"):
52 """Compile and run some source in the interpreter.
54 Arguments are as for compile_command().
56 One several things can happen:
58 1) The input is incorrect; compile_command() raised an
59 exception (SyntaxError or OverflowError). A syntax traceback
60 will be printed by calling the showsyntaxerror() method.
62 2) The input is incomplete, and more input is required;
63 compile_command() returned None. Nothing happens.
65 3) The input is complete; compile_command() returned a code
66 object. The code is executed by calling self.runcode() (which
67 also handles run-time exceptions, except for SystemExit).
69 The return value is True in case 2, False in the other cases (unless
70 an exception is raised). The return value can be used to
71 decide whether to use sys.ps1 or sys.ps2 to prompt the next
72 line.
74 """
75 try:
76 code = self.compile(source, filename, symbol)
77 except (OverflowError, SyntaxError, ValueError):
78 # Case 1
79 self.showsyntaxerror(filename)
80 return False
82 if code is None:
83 # Case 2
84 return True
86 # Case 3
87 self.runcode(code)
88 return False
90 def runcode(self, code):
91 """Execute a code object.
93 When an exception occurs, self.showtraceback() is called to
94 display a traceback. All exceptions are caught except
95 SystemExit, which is reraised.
97 A note about KeyboardInterrupt: this exception may occur
98 elsewhere in this code, and may not always be caught. The
99 caller should be prepared to deal with it.
102 try:
103 exec code in self.locals
104 except SystemExit:
105 raise
106 except:
107 self.showtraceback()
108 else:
109 if softspace(sys.stdout, 0):
110 print
112 def showsyntaxerror(self, filename=None):
113 """Display the syntax error that just occurred.
115 This doesn't display a stack trace because there isn't one.
117 If a filename is given, it is stuffed in the exception instead
118 of what was there before (because Python's parser always uses
119 "<string>" when reading from a string).
121 The output is written by self.write(), below.
124 type, value, sys.last_traceback = sys.exc_info()
125 sys.last_type = type
126 sys.last_value = value
127 if filename and type is SyntaxError:
128 # Work hard to stuff the correct filename in the exception
129 try:
130 msg, (dummy_filename, lineno, offset, line) = value
131 except:
132 # Not the format we expect; leave it alone
133 pass
134 else:
135 # Stuff in the right filename
136 value = SyntaxError(msg, (filename, lineno, offset, line))
137 sys.last_value = value
138 list = traceback.format_exception_only(type, value)
139 map(self.write, list)
141 def showtraceback(self):
142 """Display the exception that just occurred.
144 We remove the first stack item because it is our own code.
146 The output is written by self.write(), below.
149 try:
150 type, value, tb = sys.exc_info()
151 sys.last_type = type
152 sys.last_value = value
153 sys.last_traceback = tb
154 tblist = traceback.extract_tb(tb)
155 del tblist[:1]
156 list = traceback.format_list(tblist)
157 if list:
158 list.insert(0, "Traceback (most recent call last):\n")
159 list[len(list):] = traceback.format_exception_only(type, value)
160 finally:
161 tblist = tb = None
162 map(self.write, list)
164 def write(self, data):
165 """Write a string.
167 The base implementation writes to sys.stderr; a subclass may
168 replace this with a different implementation.
171 sys.stderr.write(data)
174 class InteractiveConsole(InteractiveInterpreter):
175 """Closely emulate the behavior of the interactive Python interpreter.
177 This class builds on InteractiveInterpreter and adds prompting
178 using the familiar sys.ps1 and sys.ps2, and input buffering.
182 def __init__(self, locals=None, filename="<console>"):
183 """Constructor.
185 The optional locals argument will be passed to the
186 InteractiveInterpreter base class.
188 The optional filename argument should specify the (file)name
189 of the input stream; it will show up in tracebacks.
192 InteractiveInterpreter.__init__(self, locals)
193 self.filename = filename
194 self.resetbuffer()
196 def resetbuffer(self):
197 """Reset the input buffer."""
198 self.buffer = []
200 def interact(self, banner=None):
201 """Closely emulate the interactive Python console.
203 The optional banner argument specify the banner to print
204 before the first interaction; by default it prints a banner
205 similar to the one printed by the real Python interpreter,
206 followed by the current class name in parentheses (so as not
207 to confuse this with the real interpreter -- since it's so
208 close!).
211 try:
212 sys.ps1
213 except AttributeError:
214 sys.ps1 = ">>> "
215 try:
216 sys.ps2
217 except AttributeError:
218 sys.ps2 = "... "
219 cprt = 'Type "help", "copyright", "credits" or "license" for more information.'
220 if banner is None:
221 self.write("Python %s on %s\n%s\n(%s)\n" %
222 (sys.version, sys.platform, cprt,
223 self.__class__.__name__))
224 else:
225 self.write("%s\n" % str(banner))
226 more = 0
227 while 1:
228 try:
229 if more:
230 prompt = sys.ps2
231 else:
232 prompt = sys.ps1
233 try:
234 line = self.raw_input(prompt)
235 except EOFError:
236 self.write("\n")
237 break
238 else:
239 more = self.push(line)
240 except KeyboardInterrupt:
241 self.write("\nKeyboardInterrupt\n")
242 self.resetbuffer()
243 more = 0
245 def push(self, line):
246 """Push a line to the interpreter.
248 The line should not have a trailing newline; it may have
249 internal newlines. The line is appended to a buffer and the
250 interpreter's runsource() method is called with the
251 concatenated contents of the buffer as source. If this
252 indicates that the command was executed or invalid, the buffer
253 is reset; otherwise, the command is incomplete, and the buffer
254 is left as it was after the line was appended. The return
255 value is 1 if more input is required, 0 if the line was dealt
256 with in some way (this is the same as runsource()).
259 self.buffer.append(line)
260 source = "\n".join(self.buffer)
261 more = self.runsource(source, self.filename)
262 if not more:
263 self.resetbuffer()
264 return more
266 def raw_input(self, prompt=""):
267 """Write a prompt and read a line.
269 The returned line does not include the trailing newline.
270 When the user enters the EOF key sequence, EOFError is raised.
272 The base implementation uses the built-in function
273 raw_input(); a subclass may replace this with a different
274 implementation.
277 return raw_input(prompt)
280 def interact(banner=None, readfunc=None, local=None):
281 """Closely emulate the interactive Python interpreter.
283 This is a backwards compatible interface to the InteractiveConsole
284 class. When readfunc is not specified, it attempts to import the
285 readline module to enable GNU readline if it is available.
287 Arguments (all optional, all default to None):
289 banner -- passed to InteractiveConsole.interact()
290 readfunc -- if not None, replaces InteractiveConsole.raw_input()
291 local -- passed to InteractiveInterpreter.__init__()
294 console = InteractiveConsole(local)
295 if readfunc is not None:
296 console.raw_input = readfunc
297 else:
298 try:
299 import readline
300 except ImportError:
301 pass
302 console.interact(banner)
305 if __name__ == '__main__':
306 import pdb
307 pdb.run("interact()\n")