from prompt_toolkit.validation import ValidationError, Validator

__all__ = ["PythonValidator"]

class PythonValidator(Validator):

"""

Validation of Python input.

:param get_compiler_flags: Callable that returns the currently

active compiler flags.

"""

def __init__(self, get_compiler_flags=None):

self.get_compiler_flags = get_compiler_flags

def validate(self, document):

"""

Check input for Python syntax errors.

"""

text = document.text

# If the input is single line, remove leading whitespace.

# (This doesn't have to be a syntax error.)

if len(text.splitlines()) == 1:

text = text.strip()

# When the input starts with Ctrl-Z, always accept. This means EOF in a

# Python REPL.

if text.startswith("\x1a"):

return

try:

if self.get_compiler_flags:

flags = self.get_compiler_flags()

else:

flags = 0

compile(text, "<input>", "exec", flags=flags, dont_inherit=True)

except SyntaxError as e:

# Note, the 'or 1' for offset is required because Python 2.7

# gives `None` as offset in case of '4=4' as input. (Looks like

# fixed in Python 3.)

index = document.translate_row_col_to_index(

e.lineno - 1, (e.offset or 1) - 1

)

raise ValidationError(index, f"Syntax Error: {e}")

except TypeError as e:

# e.g. "compile() expected string without null bytes"

raise ValidationError(0, str(e))

except ValueError as e:

# In Python 2, compiling "\x9" (an invalid escape sequence) raises

# ValueError instead of SyntaxError.

raise ValidationError(0, "Syntax Error: %s" % e)