| """ | |
| Error handling with a puppet | |
| ================================== | |
| This example demonstrates error handling using a parsing puppet in LALR | |
| When the parser encounters an UnexpectedToken exception, it creates a | |
| parsing puppet with the current parse-state, and lets you control how | |
| to proceed step-by-step. When you've achieved the correct parse-state, | |
| you can resume the run by returning True. | |
| """ | |
| from lark import Token | |
| from _json_parser import json_parser | |
| def ignore_errors(e): | |
| if e.token.type == 'COMMA': | |
| # Skip comma | |
| return True | |
| elif e.token.type == 'SIGNED_NUMBER': | |
| # Try to feed a comma and retry the number | |
| e.puppet.feed_token(Token('COMMA', ',')) | |
| e.puppet.feed_token(e.token) | |
| return True | |
| # Unhandled error. Will stop parse and raise exception | |
| return False | |
| def main(): | |
| s = "[0 1, 2,, 3,,, 4, 5 6 ]" | |
| res = json_parser.parse(s, on_error=ignore_errors) | |
| print(res) # prints [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0] | |
| main() | |