|
| 1 | +"""Utilities dealing with code objects.""" |
| 2 | + |
| 3 | +def compile_command(source, filename="<input>", symbol="single"): |
| 4 | + r"""Compile a command and determine whether it is incomplete. |
| 5 | +
|
| 6 | + Arguments: |
| 7 | +
|
| 8 | + source -- the source string; may contain \n characters |
| 9 | + filename -- optional filename from which source was read; default "<input>" |
| 10 | + symbol -- optional grammar start symbol; "single" (default) or "eval" |
| 11 | +
|
| 12 | + Return value / exception raised: |
| 13 | +
|
| 14 | + - Return a code object if the command is complete and valid |
| 15 | + - Return None if the command is incomplete |
| 16 | + - Raise SyntaxError if the command is a syntax error |
| 17 | +
|
| 18 | + Approach: |
| 19 | + |
| 20 | + Compile three times: as is, with \n, and with \n\n appended. If |
| 21 | + it compiles as is, it's complete. If it compiles with one \n |
| 22 | + appended, we expect more. If it doesn't compile either way, we |
| 23 | + compare the error we get when compiling with \n or \n\n appended. |
| 24 | + If the errors are the same, the code is broken. But if the errors |
| 25 | + are different, we expect more. Not intuitive; not even guaranteed |
| 26 | + to hold in future releases; but this matches the compiler's |
| 27 | + behavior in Python 1.4 and 1.5. |
| 28 | +
|
| 29 | + """ |
| 30 | + |
| 31 | + err = err1 = err2 = None |
| 32 | + code = code1 = code2 = None |
| 33 | + |
| 34 | + try: |
| 35 | + code = compile(source, filename, symbol) |
| 36 | + except SyntaxError, err: |
| 37 | + pass |
| 38 | + |
| 39 | + try: |
| 40 | + code1 = compile(source + "\n", filename, symbol) |
| 41 | + except SyntaxError, err1: |
| 42 | + pass |
| 43 | + |
| 44 | + try: |
| 45 | + code2 = compile(source + "\n\n", filename, symbol) |
| 46 | + except SyntaxError, err2: |
| 47 | + pass |
| 48 | + |
| 49 | + if code: |
| 50 | + return code |
| 51 | + if not code1 and err1 == err2: |
| 52 | + raise SyntaxError, err1 |
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