feat: implement the LIKE pattern matching (#73)

* feat: implement the LIKE pattern matching

Author: ChunxuTang

rust/lance-graph/src/datafusion_planner/expression.rs

@@ -60,7 +60,16 @@ pub(crate) fn to_df_boolean_expr(expr: &BooleanExpression) -> Expr {
         ))),
         BE::IsNull(expression) => Expr::IsNull(Box::new(to_df_value_expr(expression))),
         BE::IsNotNull(expression) => Expr::IsNotNull(Box::new(to_df_value_expr(expression))),
-        _ => lit(true),
+        BE::Like {
+            expression,
+            pattern,
+        } => Expr::Like(datafusion::logical_expr::Like {
+            negated: false,
+            expr: Box::new(to_df_value_expr(expression)),
+            pattern: Box::new(lit(pattern.clone())),
+            escape_char: None,
+            case_insensitive: false,
+        }),
     }
 }
 
@@ -414,6 +423,55 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_boolean_expr_like() {
+        let expr = BooleanExpression::Like {
+            expression: ValueExpression::Property(PropertyRef {
+                variable: "p".into(),
+                property: "name".into(),
+            }),
+            pattern: "A%".into(),
+        };
+
+        if let Expr::Like(like_expr) = to_df_boolean_expr(&expr) {
+            assert!(!like_expr.negated, "Should not be negated");
+            assert!(!like_expr.case_insensitive, "Should be case sensitive");
+            assert_eq!(like_expr.escape_char, None, "Should have no escape char");
+            match *like_expr.expr {
+                Expr::Column(ref col_expr) => {
+                    assert_eq!(col_expr.name(), "p__name");
+                }
+                other => panic!("Expected column expression, got {:?}", other),
+            }
+            // Check pattern is a literal
+            match *like_expr.pattern {
+                Expr::Literal(..) => {} // Success
+                other => panic!("Expected literal pattern, got {:?}", other),
+            }
+        } else {
+            panic!("Expected Like expression");
+        }
+    }
+
+    #[test]
+    fn test_boolean_expr_like_with_wildcard() {
+        let expr = BooleanExpression::Like {
+            expression: ValueExpression::Property(PropertyRef {
+                variable: "p".into(),
+                property: "email".into(),
+            }),
+            pattern: "%@example.com".into(),
+        };
+
+        let df_expr = to_df_boolean_expr(&expr);
+        let s = format!("{:?}", df_expr);
+        assert!(
+            s.contains("Like") || s.contains("like"),
+            "Should be a LIKE expression"
+        );
+        assert!(s.contains("p__email"), "Should contain column reference");
+    }
+
     // ========================================================================
     // Unit tests for to_df_value_expr()
     // ========================================================================

rust/lance-graph/src/parser.rs

@@ -329,6 +329,18 @@ fn comparison_expression(input: &str) -> IResult<&str, BooleanExpression> {
             },
         ));
     }
+    // Match LIKE pattern
+    if let Ok((input_after_like, (_, _, pattern))) =
+        tuple((tag_no_case("LIKE"), multispace0, string_literal))(input)
+    {
+        return Ok((
+            input_after_like,
+            BooleanExpression::Like {
+                expression: left,
+                pattern,
+            },
+        ));
+    }
     // Match is null
     if let Ok((rest, ())) = is_null_comparison(input) {
         return Ok((rest, BooleanExpression::IsNull(left_clone)));
@@ -1018,4 +1030,76 @@ mod tests {
             _ => panic!("Expected Function expression"),
         }
     }
+
+    #[test]
+    fn test_parse_like_pattern() {
+        let query = "MATCH (n:Person) WHERE n.name LIKE 'A%' RETURN n.name";
+        let result = parse_cypher_query(query);
+        assert!(result.is_ok(), "LIKE pattern should parse successfully");
+
+        let ast = result.unwrap();
+        let where_clause = ast.where_clause.expect("Expected WHERE clause");
+
+        match where_clause.expression {
+            BooleanExpression::Like {
+                expression,
+                pattern,
+            } => {
+                match expression {
+                    ValueExpression::Property(prop) => {
+                        assert_eq!(prop.variable, "n");
+                        assert_eq!(prop.property, "name");
+                    }
+                    _ => panic!("Expected property expression"),
+                }
+                assert_eq!(pattern, "A%");
+            }
+            _ => panic!("Expected LIKE expression"),
+        }
+    }
+
+    #[test]
+    fn test_parse_like_with_double_quotes() {
+        let query = r#"MATCH (n:Person) WHERE n.email LIKE "%@example.com" RETURN n.email"#;
+        let result = parse_cypher_query(query);
+        assert!(result.is_ok(), "LIKE with double quotes should parse");
+
+        let ast = result.unwrap();
+        let where_clause = ast.where_clause.expect("Expected WHERE clause");
+
+        match where_clause.expression {
+            BooleanExpression::Like { pattern, .. } => {
+                assert_eq!(pattern, "%@example.com");
+            }
+            _ => panic!("Expected LIKE expression"),
+        }
+    }
+
+    #[test]
+    fn test_parse_like_in_complex_where() {
+        let query = "MATCH (n:Person) WHERE n.age > 20 AND n.name LIKE 'J%' RETURN n.name";
+        let result = parse_cypher_query(query);
+        assert!(result.is_ok(), "LIKE in complex WHERE should parse");
+
+        let ast = result.unwrap();
+        let where_clause = ast.where_clause.expect("Expected WHERE clause");
+
+        match where_clause.expression {
+            BooleanExpression::And(left, right) => {
+                // Left should be age > 20
+                match *left {
+                    BooleanExpression::Comparison { .. } => {}
+                    _ => panic!("Expected comparison on left"),
+                }
+                // Right should be LIKE
+                match *right {
+                    BooleanExpression::Like { pattern, .. } => {
+                        assert_eq!(pattern, "J%");
+                    }
+                    _ => panic!("Expected LIKE expression on right"),
+                }
+            }
+            _ => panic!("Expected AND expression"),
+        }
+    }
 }

rust/lance-graph/tests/test_datafusion_pipeline.rs

@@ -3776,3 +3776,134 @@ async fn test_datafusion_is_not_null_relationship_property() {
         );
     }
 }
+
+// ============================================================================
+// LIKE Pattern Matching Tests
+// ============================================================================
+
+#[tokio::test]
+async fn test_datafusion_like_contains_match() {
+    // Test LIKE with contains pattern (anywhere in string)
+    let config = create_graph_config();
+    let person_batch = create_person_dataset();
+
+    let query = CypherQuery::new(
+        "MATCH (p:Person) \
+         WHERE p.city LIKE '%ea%' \
+         RETURN p.name ORDER BY p.name",
+    )
+    .unwrap()
+    .with_config(config);
+
+    let mut datasets = HashMap::new();
+    datasets.insert("Person".to_string(), person_batch);
+
+    let result = query
+        .execute(datasets, Some(ExecutionStrategy::DataFusion))
+        .await
+        .unwrap();
+
+    // Should match: Seattle (Eve)
+    assert_eq!(result.num_rows(), 1);
+    let names = result
+        .column(0)
+        .as_any()
+        .downcast_ref::<StringArray>()
+        .unwrap();
+    assert_eq!(names.value(0), "Eve");
+}
+
+#[tokio::test]
+async fn test_datafusion_like_with_and_condition() {
+    let config = create_graph_config();
+    let person_batch = create_person_dataset();
+
+    let query = CypherQuery::new(
+        "MATCH (p:Person) \
+         WHERE p.age > 30 AND p.name LIKE '%e' \
+         RETURN p.name",
+    )
+    .unwrap()
+    .with_config(config);
+
+    let mut datasets = HashMap::new();
+    datasets.insert("Person".to_string(), person_batch);
+
+    let result = query
+        .execute(datasets, Some(ExecutionStrategy::DataFusion))
+        .await
+        .unwrap();
+
+    // Should match: Charlie (age 30 is NOT > 30, so excluded)
+    // Bob (age 35), David (age 40), Eve (age 28 not > 30)
+    // Names ending with 'e': Alice, Charlie, Eve
+    // age > 30 AND name ends with 'e': None (Alice is 25, Charlie is 30, Eve is 28)
+    assert_eq!(result.num_rows(), 0);
+}
+
+#[tokio::test]
+async fn test_datafusion_like_in_relationship_query() {
+    let config = create_graph_config();
+    let person_batch = create_person_dataset();
+    let knows_batch = create_knows_dataset();
+
+    let query = CypherQuery::new(
+        "MATCH (a:Person)-[r:KNOWS]->(b:Person) \
+         WHERE a.name LIKE 'A%' \
+         RETURN a.name, b.name ORDER BY b.name",
+    )
+    .unwrap()
+    .with_config(config);
+
+    let mut datasets = HashMap::new();
+    datasets.insert("Person".to_string(), person_batch);
+    datasets.insert("KNOWS".to_string(), knows_batch);
+
+    let result = query
+        .execute(datasets, Some(ExecutionStrategy::DataFusion))
+        .await
+        .unwrap();
+
+    // Alice knows Bob and Charlie
+    assert_eq!(result.num_rows(), 2);
+    let a_names = result
+        .column(0)
+        .as_any()
+        .downcast_ref::<StringArray>()
+        .unwrap();
+    let b_names = result
+        .column(1)
+        .as_any()
+        .downcast_ref::<StringArray>()
+        .unwrap();
+
+    assert_eq!(a_names.value(0), "Alice");
+    assert_eq!(b_names.value(0), "Bob");
+    assert_eq!(a_names.value(1), "Alice");
+    assert_eq!(b_names.value(1), "Charlie");
+}
+
+#[tokio::test]
+async fn test_datafusion_like_case_sensitive() {
+    let config = create_graph_config();
+    let person_batch = create_person_dataset();
+
+    let query = CypherQuery::new(
+        "MATCH (p:Person) \
+         WHERE p.name LIKE 'a%' \
+         RETURN p.name",
+    )
+    .unwrap()
+    .with_config(config);
+
+    let mut datasets = HashMap::new();
+    datasets.insert("Person".to_string(), person_batch);
+
+    let result = query
+        .execute(datasets, Some(ExecutionStrategy::DataFusion))
+        .await
+        .unwrap();
+
+    // Should not match 'Alice' (lowercase 'a' vs uppercase 'A')
+    assert_eq!(result.num_rows(), 0);
+}