Feature Request: Add string comparison operators (CONTAINS, STARTS WITH, ENDS WITH) #77

Summary

The Cypher parser currently doesn't support string comparison operators like CONTAINS, STARTS WITH, and ENDS WITH. These are commonly used Cypher operators for filtering nodes/relationships by partial string matching.

Current Behavior

Queries using string operators fail with a parsing error:

MATCH (s:Symbol) WHERE s.name CONTAINS 'Auth' RETURN s.name LIMIT 5

Error:

Cypher query error: Failed to parse Cypher query: Cypher parse error at position 0: 
Failed to parse Cypher query: Parsing Error: Error { input: "WHERE s.name CONTAINS 'Auth' RETURN s.name LIMIT 5", code: Tag }

Expected Behavior

String comparison operators should be parsed and translated to SQL equivalents:

Technical Context

Looking at src/parser.rs, the comparison_operator function (lines 356-366) only handles:

• =, <>, !=
• <, >, <=, >=

And comparison_expression handles:

• IN [...]
• IS NULL, IS NOT NULL

String operators would need to be added as additional branches, likely with a new StringOperator enum or extending ComparisonOperator.

Use Case

We're using lance-graph for a code analysis tool where users query a knowledge graph of code symbols. Partial name matching is essential:

-- Find all authentication-related functions
MATCH (s:Symbol) WHERE s.name CONTAINS 'auth' RETURN s

-- Find all test files  
MATCH (f:File) WHERE f.path ENDS WITH '.test.ts' RETURN f

-- Find functions starting with 'handle'
MATCH (s:Symbol) WHERE s.name STARTS WITH 'handle' RETURN s

Workaround

Currently we're using exact matches or fetching all results and filtering client-side, which is inefficient.

References

• Neo4j Cypher String Operators
• openCypher spec - String matching