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# Error handling using an interactive parser

This example demonstrates error handling using an interactive parser in LALR

When the parser encounters an UnexpectedToken exception, it creates a an interactive parser 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.interactive_parser.feed_token(Token('COMMA', ','))
            e.interactive_parser.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()

Total running time of the script: ( 0 minutes 0.000 seconds)

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