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use std::sync::Arc;
use arrow::{
datatypes::{DataType, Schema},
record_batch::RecordBatch,
};
use crate::PhysicalExpr;
use datafusion_common::Result;
use datafusion_expr::ColumnarValue;
#[derive(Debug, Hash, PartialEq, Eq, Clone)]
pub struct Column {
name: String,
index: usize,
}
impl Column {
pub fn new(name: &str, index: usize) -> Self {
Self {
name: name.to_owned(),
index,
}
}
pub fn new_with_schema(name: &str, schema: &Schema) -> Result<Self> {
Ok(Column::new(name, schema.index_of(name)?))
}
pub fn name(&self) -> &str {
&self.name
}
pub fn index(&self) -> usize {
self.index
}
}
impl std::fmt::Display for Column {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(f, "{}@{}", self.name, self.index)
}
}
impl PhysicalExpr for Column {
fn as_any(&self) -> &dyn std::any::Any {
self
}
fn data_type(&self, input_schema: &Schema) -> Result<DataType> {
Ok(input_schema.field(self.index).data_type().clone())
}
fn nullable(&self, input_schema: &Schema) -> Result<bool> {
Ok(input_schema.field(self.index).is_nullable())
}
fn evaluate(&self, batch: &RecordBatch) -> Result<ColumnarValue> {
Ok(ColumnarValue::Array(batch.column(self.index).clone()))
}
}
pub fn col(name: &str, schema: &Schema) -> Result<Arc<dyn PhysicalExpr>> {
Ok(Arc::new(Column::new_with_schema(name, schema)?))
}