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920dae64 AT |
1 | """Utilities needed to emulate Python's interactive interpreter. |
2 | ||
3 | """ | |
4 | ||
5 | # Inspired by similar code by Jeff Epler and Fredrik Lundh. | |
6 | ||
7 | ||
8 | import sys | |
9 | import traceback | |
10 | from codeop import CommandCompiler, compile_command | |
11 | ||
12 | __all__ = ["InteractiveInterpreter", "InteractiveConsole", "interact", | |
13 | "compile_command"] | |
14 | ||
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 | |
27 | ||
28 | class InteractiveInterpreter: | |
29 | """Base class for InteractiveConsole. | |
30 | ||
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). | |
34 | ||
35 | """ | |
36 | ||
37 | def __init__(self, locals=None): | |
38 | """Constructor. | |
39 | ||
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. | |
44 | ||
45 | """ | |
46 | if locals is None: | |
47 | locals = {"__name__": "__console__", "__doc__": None} | |
48 | self.locals = locals | |
49 | self.compile = CommandCompiler() | |
50 | ||
51 | def runsource(self, source, filename="<input>", symbol="single"): | |
52 | """Compile and run some source in the interpreter. | |
53 | ||
54 | Arguments are as for compile_command(). | |
55 | ||
56 | One several things can happen: | |
57 | ||
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. | |
61 | ||
62 | 2) The input is incomplete, and more input is required; | |
63 | compile_command() returned None. Nothing happens. | |
64 | ||
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). | |
68 | ||
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. | |
73 | ||
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 | |
81 | ||
82 | if code is None: | |
83 | # Case 2 | |
84 | return True | |
85 | ||
86 | # Case 3 | |
87 | self.runcode(code) | |
88 | return False | |
89 | ||
90 | def runcode(self, code): | |
91 | """Execute a code object. | |
92 | ||
93 | When an exception occurs, self.showtraceback() is called to | |
94 | display a traceback. All exceptions are caught except | |
95 | SystemExit, which is reraised. | |
96 | ||
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. | |
100 | ||
101 | """ | |
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 | ||
111 | ||
112 | def showsyntaxerror(self, filename=None): | |
113 | """Display the syntax error that just occurred. | |
114 | ||
115 | This doesn't display a stack trace because there isn't one. | |
116 | ||
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). | |
120 | ||
121 | The output is written by self.write(), below. | |
122 | ||
123 | """ | |
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) | |
140 | ||
141 | def showtraceback(self): | |
142 | """Display the exception that just occurred. | |
143 | ||
144 | We remove the first stack item because it is our own code. | |
145 | ||
146 | The output is written by self.write(), below. | |
147 | ||
148 | """ | |
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) | |
163 | ||
164 | def write(self, data): | |
165 | """Write a string. | |
166 | ||
167 | The base implementation writes to sys.stderr; a subclass may | |
168 | replace this with a different implementation. | |
169 | ||
170 | """ | |
171 | sys.stderr.write(data) | |
172 | ||
173 | ||
174 | class InteractiveConsole(InteractiveInterpreter): | |
175 | """Closely emulate the behavior of the interactive Python interpreter. | |
176 | ||
177 | This class builds on InteractiveInterpreter and adds prompting | |
178 | using the familiar sys.ps1 and sys.ps2, and input buffering. | |
179 | ||
180 | """ | |
181 | ||
182 | def __init__(self, locals=None, filename="<console>"): | |
183 | """Constructor. | |
184 | ||
185 | The optional locals argument will be passed to the | |
186 | InteractiveInterpreter base class. | |
187 | ||
188 | The optional filename argument should specify the (file)name | |
189 | of the input stream; it will show up in tracebacks. | |
190 | ||
191 | """ | |
192 | InteractiveInterpreter.__init__(self, locals) | |
193 | self.filename = filename | |
194 | self.resetbuffer() | |
195 | ||
196 | def resetbuffer(self): | |
197 | """Reset the input buffer.""" | |
198 | self.buffer = [] | |
199 | ||
200 | def interact(self, banner=None): | |
201 | """Closely emulate the interactive Python console. | |
202 | ||
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!). | |
209 | ||
210 | """ | |
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 | |
244 | ||
245 | def push(self, line): | |
246 | """Push a line to the interpreter. | |
247 | ||
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()). | |
257 | ||
258 | """ | |
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 | |
265 | ||
266 | def raw_input(self, prompt=""): | |
267 | """Write a prompt and read a line. | |
268 | ||
269 | The returned line does not include the trailing newline. | |
270 | When the user enters the EOF key sequence, EOFError is raised. | |
271 | ||
272 | The base implementation uses the built-in function | |
273 | raw_input(); a subclass may replace this with a different | |
274 | implementation. | |
275 | ||
276 | """ | |
277 | return raw_input(prompt) | |
278 | ||
279 | ||
280 | def interact(banner=None, readfunc=None, local=None): | |
281 | """Closely emulate the interactive Python interpreter. | |
282 | ||
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. | |
286 | ||
287 | Arguments (all optional, all default to None): | |
288 | ||
289 | banner -- passed to InteractiveConsole.interact() | |
290 | readfunc -- if not None, replaces InteractiveConsole.raw_input() | |
291 | local -- passed to InteractiveInterpreter.__init__() | |
292 | ||
293 | """ | |
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) | |
303 | ||
304 | ||
305 | if __name__ == '__main__': | |
306 | import pdb | |
307 | pdb.run("interact()\n") |