native/spark-expr/src/datetime_funcs/timestamp_trunc.rs

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// specific language governing permissions and limitations
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use crate::utils::array_with_timezone;
use arrow::record_batch::RecordBatch;
use arrow_schema::{DataType, Schema, TimeUnit::Microsecond};
use datafusion::logical_expr::ColumnarValue;
use datafusion_common::{DataFusionError, ScalarValue::Utf8};
use datafusion_physical_expr::PhysicalExpr;
use std::hash::Hash;
use std::{
    any::Any,
    fmt::{Debug, Display, Formatter},
    sync::Arc,
};

use crate::kernels::temporal::{timestamp_trunc_array_fmt_dyn, timestamp_trunc_dyn};

#[derive(Debug, Eq)]
pub struct TimestampTruncExpr {
    /// An array with DataType::Timestamp(TimeUnit::Microsecond, None)
    child: Arc<dyn PhysicalExpr>,
    /// Scalar UTF8 string matching the valid values in Spark SQL: https://spark.apache.org/docs/latest/api/sql/index.html#date_trunc
    format: Arc<dyn PhysicalExpr>,
    /// String containing a timezone name. The name must be found in the standard timezone
    /// database (https://en.wikipedia.org/wiki/List_of_tz_database_time_zones). The string is
    /// later parsed into a chrono::TimeZone.
    /// Timestamp arrays in this implementation are kept in arrays of UTC timestamps (in micros)
    /// along with a single value for the associated TimeZone. The timezone offset is applied
    /// just before any operations on the timestamp
    timezone: String,
}

impl Hash for TimestampTruncExpr {
    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
        self.child.hash(state);
        self.format.hash(state);
        self.timezone.hash(state);
    }
}
impl PartialEq for TimestampTruncExpr {
    fn eq(&self, other: &Self) -> bool {
        self.child.eq(&other.child)
            && self.format.eq(&other.format)
            && self.timezone.eq(&other.timezone)
    }
}

impl TimestampTruncExpr {
    pub fn new(
        child: Arc<dyn PhysicalExpr>,
        format: Arc<dyn PhysicalExpr>,
        timezone: String,
    ) -> Self {
        TimestampTruncExpr {
            child,
            format,
            timezone,
        }
    }
}

impl Display for TimestampTruncExpr {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "TimestampTrunc [child:{}, format:{}, timezone: {}]",
            self.child, self.format, self.timezone
        )
    }
}

impl PhysicalExpr for TimestampTruncExpr {
    fn as_any(&self) -> &dyn Any {
        self
    }

    fn data_type(&self, input_schema: &Schema) -> datafusion_common::Result<DataType> {
        match self.child.data_type(input_schema)? {
            DataType::Dictionary(key_type, _) => Ok(DataType::Dictionary(
                key_type,
                Box::new(DataType::Timestamp(Microsecond, None)),
            )),
            _ => Ok(DataType::Timestamp(Microsecond, None)),
        }
    }

    fn nullable(&self, _: &Schema) -> datafusion_common::Result<bool> {
        Ok(true)
    }

    fn evaluate(&self, batch: &RecordBatch) -> datafusion_common::Result<ColumnarValue> {
        let timestamp = self.child.evaluate(batch)?;
        let format = self.format.evaluate(batch)?;
        let tz = self.timezone.clone();
        match (timestamp, format) {
            (ColumnarValue::Array(ts), ColumnarValue::Scalar(Utf8(Some(format)))) => {
                let ts = array_with_timezone(
                    ts,
                    tz.clone(),
                    Some(&DataType::Timestamp(Microsecond, Some(tz.into()))),
                )?;
                let result = timestamp_trunc_dyn(&ts, format)?;
                Ok(ColumnarValue::Array(result))
            }
            (ColumnarValue::Array(ts), ColumnarValue::Array(formats)) => {
                let ts = array_with_timezone(
                    ts,
                    tz.clone(),
                    Some(&DataType::Timestamp(Microsecond, Some(tz.into()))),
                )?;
                let result = timestamp_trunc_array_fmt_dyn(&ts, &formats)?;
                Ok(ColumnarValue::Array(result))
            }
            _ => Err(DataFusionError::Execution(
                "Invalid input to function TimestampTrunc. \
                    Expected (PrimitiveArray<TimestampMicrosecondType>, Scalar, String) or \
                    (PrimitiveArray<TimestampMicrosecondType>, StringArray, String)"
                    .to_string(),
            )),
        }
    }

    fn children(&self) -> Vec<&Arc<dyn PhysicalExpr>> {
        vec![&self.child]
    }

    fn with_new_children(
        self: Arc<Self>,
        children: Vec<Arc<dyn PhysicalExpr>>,
    ) -> Result<Arc<dyn PhysicalExpr>, DataFusionError> {
        Ok(Arc::new(TimestampTruncExpr::new(
            Arc::clone(&children[0]),
            Arc::clone(&self.format),
            self.timezone.clone(),
        )))
    }
}