On Thu, Jun 13, 2019 at 12:52 AM Yanghao Hua yanghao.py@gmail.com wrote:
On Wed, Jun 12, 2019 at 11:27 PM Chris Angelico rosuav@gmail.com wrote:
Yes, you would need some sort of syntactic parser. There are a couple of ways to go about it. One is to make use of Python's own tools, like the ast module; the other is to mandate that your specific syntax be "tidier" than the rest of the Python code, which would permit you to use a more naive and simplistic parser (even a regex).
Yep ... I just tried to use MacroPy3 to handle this but failed, seems MacroPy3 does expect valid Python syntax in the first place for anything else to happen. I also tried the raw ast module which seems also the case. So it means if one want to use python ast module to parse user input, the user input has to be valid python syntax (e.g. no <==) at the first place. Seems this is a chicken-egg problem.
Attaching the trace:
Traceback (most recent call last): File "tt.py", line 34, in <module> main() File "tt.py", line 8, in main tree = ast.parse(source.read()) File "/usr/lib/python3.6/ast.py", line 35, in parse return compile(source, filename, mode, PyCF_ONLY_AST) File "<unknown>", line 1 x <== 3 ^ SyntaxError: invalid syntax