I need to parse python code line by line. Code:
ast.parse("""if True:
print 'Yes' """)
returns AST object, but this line not:
ast.parse("if True:")
Is there way to parse that somehow? (except text parsing with RE)
I need this to modify python code, line by line after user interactive input of python code.
You can only parse a complete valid python statement or expression. if True: is incomplete: if you were to attempt to parse it you would get a syntax error.
The solution is to first determine if you have a complete statement or expression; if you do not, buffer the line and keep reading new lines until you encounter a syntax error or a complete expression. Then use ast on your buffered input.
The compile_command function can distinguish between string of code which could be incomplete rather than incorrect. If the code appears incomplete, it returns None; otherwise it returns a code object (if valid) or raises a SyntaxError.
We can use this function to determine whether to buffer or parse a line. Untested code below:
linebuffer = []
while True:
line = raw_input()
linebuffer.append(line)
try:
compiled = code.compile_command(''.join(linebuffer))
except SyntaxError:
linebuffer = []
else:
if compiled is not None:
tree = ast.parse(''.join(linebuffer))
linebuffer = []
if True: by itself is a syntax error. Perhaps you should step back and restate your broader problem, because you can't get an ast line-by-line, only statement-by-statement or expression-by-expression, and it's hard to imagine what possible AST manipulations you would want to do line-by-line!
I think the only way here is regexp.
after user interactive input of python code.
It seems like your python code is in fact only text object, but not python code...
why is regexp unsuitable to you here?
if True:is incomplete: if you were to attempt to parse it you would get a syntax error.