astvalidate 0.2.0

Easy AST validation

ASTValidate

A series of AST validators for validating the integrity of the tree.

Interface

The stable interface is validate(tree: AST, level: Optional[int] = None) -> bool, which comes directly from the root of the package. It takes the tree, and optionally the validation level. Validation level specifies the strictness degree; for an example if it is 1, tree will be only checked by some basic checks that is similiar to PyAST_Validate interface in Python/ast.c. Increasing levels means increasing checks and strictness.

import ast
from astvalidate import validate

tree = ast.parse("def x(): raise X from Y")
assert validate(tree)

If the validator encounters with anything that shouldn't be, it raises a SyntaxError with the node's line number and column offset. Also the original node that caused the error is attached to the exception's node attribute.

tree.body[0].body[0].exc = None
assert validate(tree)

SyntaxError: Raise's cause can't be used without setting an exception

Validator	Level	Description
Syntatical	1	Emulates syntax warnings that are normally generated by compiler.
Simple	1	Does simple verifications, similiar to PyAST_Validate interface
Symbolic	2	Emulates syntax error that are normally generated by symbol table
Contextual	3	Ensures everything is in the right context.