Description

Fixed issue #56 where the lexer would incorrectly handle the ESCAPE clause when using a backslash character. Previously, when parsing a query like:

SELECT 1 WHERE 'test_temp_test' LIKE '%\_temp\_%' ESCAPE '\'

The lexer would incorrectly treat '\' as an incomplete string instead of a valid string token containing a single backslash character.

The scanString method was not properly handling the case where a backslash character appears before a quote. In the ESCAPE clause context, the backslash is treated as a literal character rather than an escape character.

Modified the scanString method to track escaped quotes separately from the general escape state. This allows us to:

1. Properly handle escaped quotes in regular strings (e.g. '\'123')
2. Correctly parse single backslash characters in ESCAPE clauses (e.g. ESCAPE '\')

Testing

The fix has been verified with test cases covering:

• ESCAPE clause with backslash: ESCAPE '\'
• Escaped quotes in strings: '\'123'
• LIKE patterns with escaped characters: '%\_temp\_%'