viirya commented on code in PR #295:
URL: https://github.com/apache/iceberg-rust/pull/295#discussion_r1582281653


##########
crates/iceberg/src/arrow/reader.rs:
##########
@@ -186,4 +221,637 @@ impl ArrowReader {
             Ok(ProjectionMask::leaves(parquet_schema, indices))
         }
     }
+
+    fn get_row_filter(
+        &self,
+        parquet_schema: &SchemaDescriptor,
+        collector: &CollectFieldIdVisitor,
+    ) -> Result<Option<RowFilter>> {
+        if let Some(predicates) = &self.predicates {
+            let field_id_map = build_field_id_map(parquet_schema)?;
+
+            let column_indices = collector
+                .field_ids
+                .iter()
+                .map(|field_id| {
+                    field_id_map.get(field_id).cloned().ok_or_else(|| {
+                        Error::new(ErrorKind::DataInvalid, "Field id not found 
in schema")
+                    })
+                })
+                .collect::<Result<Vec<_>>>()?;
+
+            // Convert BoundPredicates to ArrowPredicates
+            let mut converter = PredicateConverter {
+                columns: &column_indices,
+                projection_mask: ProjectionMask::leaves(parquet_schema, 
column_indices.clone()),
+                parquet_schema,
+                column_map: &field_id_map,
+            };
+            let arrow_predicate = visit(&mut converter, predicates)?;
+            Ok(Some(RowFilter::new(vec![arrow_predicate])))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+/// Build the map of field id to Parquet column index in the schema.
+fn build_field_id_map(parquet_schema: &SchemaDescriptor) -> 
Result<HashMap<i32, usize>> {
+    let mut column_map = HashMap::new();
+    for (idx, field) in parquet_schema.columns().iter().enumerate() {
+        let field_type = field.self_type();
+        match field_type {
+            ParquetType::PrimitiveType { basic_info, .. } => {
+                if !basic_info.has_id() {
+                    return Err(Error::new(
+                        ErrorKind::DataInvalid,
+                        format!(
+                            "Leave column {:?} in schema doesn't have field 
id",
+                            field_type
+                        ),
+                    ));
+                }
+                column_map.insert(basic_info.id(), idx);
+            }
+            ParquetType::GroupType { .. } => {
+                return Err(Error::new(
+                    ErrorKind::DataInvalid,
+                    format!(
+                        "Leave column in schema should be primitive type but 
got {:?}",
+                        field_type
+                    ),
+                ));
+            }
+        };
+    }
+
+    Ok(column_map)
+}
+
+/// A visitor to collect field ids from bound predicates.
+struct CollectFieldIdVisitor {
+    field_ids: Vec<i32>,
+}
+
+impl BoundPredicateVisitor for CollectFieldIdVisitor {
+    type T = ();
+
+    fn always_true(&mut self) -> Result<Self::T> {
+        Ok(())
+    }
+
+    fn always_false(&mut self) -> Result<Self::T> {
+        Ok(())
+    }
+
+    fn and(&mut self, _lhs: Self::T, _rhs: Self::T) -> Result<Self::T> {
+        Ok(())
+    }
+
+    fn or(&mut self, _lhs: Self::T, _rhs: Self::T) -> Result<Self::T> {
+        Ok(())
+    }
+
+    fn not(&mut self, _inner: Self::T) -> Result<Self::T> {
+        Ok(())
+    }
+
+    fn is_null(
+        &mut self,
+        reference: &BoundReference,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn not_null(
+        &mut self,
+        reference: &BoundReference,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn is_nan(
+        &mut self,
+        reference: &BoundReference,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn not_nan(
+        &mut self,
+        reference: &BoundReference,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn less_than(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn less_than_or_eq(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn greater_than(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn greater_than_or_eq(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn eq(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn not_eq(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn starts_with(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn not_starts_with(
+        &mut self,
+        reference: &BoundReference,
+        _literal: &Datum,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn r#in(
+        &mut self,
+        reference: &BoundReference,
+        _literals: &FnvHashSet<Datum>,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+
+    fn not_in(
+        &mut self,
+        reference: &BoundReference,
+        _literals: &FnvHashSet<Datum>,
+        _predicate: &BoundPredicate,
+    ) -> Result<Self::T> {
+        self.field_ids.push(reference.field().id);
+        Ok(())
+    }
+}
+
+/// A visitor to convert Iceberg bound predicates to Arrow predicates.
+struct PredicateConverter<'a> {
+    /// The leaf column indices used in the predicates.
+    pub columns: &'a Vec<usize>,
+    /// The projection mask for the Arrow predicates.
+    pub projection_mask: ProjectionMask,
+    /// The Parquet schema descriptor.
+    pub parquet_schema: &'a SchemaDescriptor,
+    /// The map between field id and leaf column index in Parquet schema.
+    pub column_map: &'a HashMap<i32, usize>,
+}
+
+impl PredicateConverter<'_> {
+    /// When visiting a bound reference, we return the projection mask for the 
leaf column
+    /// which is used to project the column in the record batch.
+    fn bound_reference(&mut self, reference: &BoundReference) -> 
Result<ProjectionMask> {
+        // The leaf column's index in Parquet schema.
+        let column_idx = 
self.column_map.get(&reference.field().id).ok_or_else(|| {
+            Error::new(
+                ErrorKind::DataInvalid,
+                format!("Field id {} not found in schema", 
reference.field().id),
+            )
+        })?;
+
+        // Find the column index in projection mask.
+        let column_idx = self
+            .columns
+            .iter()
+            .position(|&x| x == *column_idx)
+            .ok_or_else(|| {
+                Error::new(
+                    ErrorKind::DataInvalid,
+                    format!("Column index {} not found in schema", 
*column_idx),
+                )
+            })?;
+
+        Ok(ProjectionMask::leaves(
+            self.parquet_schema,
+            vec![self.columns[column_idx]],
+        ))
+    }
+}
+
+fn get_arrow_datum(datum: &Datum) -> Result<Box<dyn ArrowDatum + Send>> {
+    match datum.literal() {
+        PrimitiveLiteral::Boolean(value) => 
Ok(Box::new(BooleanArray::new_scalar(*value))),
+        PrimitiveLiteral::Int(value) => 
Ok(Box::new(Int32Array::new_scalar(*value))),
+        PrimitiveLiteral::Long(value) => 
Ok(Box::new(Int64Array::new_scalar(*value))),
+        PrimitiveLiteral::Float(value) => 
Ok(Box::new(Float32Array::new_scalar(value.as_f32()))),
+        PrimitiveLiteral::Double(value) => 
Ok(Box::new(Float64Array::new_scalar(value.as_f64()))),
+        l => Err(Error::new(
+            ErrorKind::DataInvalid,
+            format!("Unsupported literal type: {:?}", l),
+        )),
+    }
+}
+
+/// Recursively get the leaf column from the record batch. Assume that the 
nested columns in
+/// struct is projected to a single column.
+fn get_leaf_column(column: &ArrayRef) -> std::result::Result<ArrayRef, 
ArrowError> {
+    match column.data_type() {
+        DataType::Struct(fields) => {
+            if fields.len() != 1 {
+                return Err(ArrowError::SchemaError(
+                    "Struct column should have only one field after projection"
+                        .parse()
+                        .unwrap(),
+                ));
+            }
+            let struct_array = 
column.as_any().downcast_ref::<StructArray>().unwrap();
+            get_leaf_column(struct_array.column(0))
+        }
+        _ => Ok(column.clone()),
+    }
+}
+
+impl<'a> BoundPredicateVisitor for PredicateConverter<'a> {
+    type T = Box<dyn ArrowPredicate>;
+
+    fn always_true(&mut self) -> Result<Self::T> {

Review Comment:
   Sure. I probably missed previous comment.



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