datafusion-functions-json 0.53.0

use std::any::Any;

use datafusion::arrow::array::StringArray;
use datafusion::arrow::datatypes::DataType;
use datafusion::common::Result as DataFusionResult;
use datafusion::logical_expr::{ColumnarValue, ScalarFunctionArgs, ScalarUDFImpl, Signature, Volatility};

use crate::common::{get_err, invoke, jiter_json_find, return_type_check, GetError, JsonPath};
use crate::common_macros::make_udf_function;

make_udf_function!(
    JsonGetJson,
    json_get_json,
    json_data path,
    r#"Get a nested raw JSON string from a JSON string by its "path""#
);

#[derive(Debug, PartialEq, Eq, Hash)]
pub(super) struct JsonGetJson {
    signature: Signature,
    aliases: [String; 1],
}

impl Default for JsonGetJson {
    fn default() -> Self {
        Self {
            signature: Signature::variadic_any(Volatility::Immutable),
            aliases: ["json_get_json".to_string()],
        }
    }
}

impl ScalarUDFImpl for JsonGetJson {
    fn as_any(&self) -> &dyn Any {
        self
    }

    fn name(&self) -> &str {
        self.aliases[0].as_str()
    }

    fn signature(&self) -> &Signature {
        &self.signature
    }

    fn return_type(&self, arg_types: &[DataType]) -> DataFusionResult<DataType> {
        return_type_check(arg_types, self.name(), DataType::Utf8)
    }

    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> DataFusionResult<ColumnarValue> {
        invoke::<StringArray>(&args.args, jiter_json_get_json)
    }

    fn aliases(&self) -> &[String] {
        &self.aliases
    }

    fn placement(
        &self,
        args: &[datafusion::logical_expr::ExpressionPlacement],
    ) -> datafusion::logical_expr::ExpressionPlacement {
        // If the first argument is a column and the remaining arguments are literals (a path)
        // then we can push this UDF down to the leaf nodes.
        if args.len() >= 2
            && matches!(args[0], datafusion::logical_expr::ExpressionPlacement::Column)
            && args[1..]
                .iter()
                .all(|arg| matches!(arg, datafusion::logical_expr::ExpressionPlacement::Literal))
        {
            datafusion::logical_expr::ExpressionPlacement::MoveTowardsLeafNodes
        } else {
            datafusion::logical_expr::ExpressionPlacement::KeepInPlace
        }
    }
}

fn jiter_json_get_json(opt_json: Option<&str>, path: &[JsonPath]) -> Result<String, GetError> {
    if let Some((mut jiter, peek)) = jiter_json_find(opt_json, path) {
        let start = jiter.current_index();
        jiter.known_skip(peek)?;
        let object_slice = jiter.slice_to_current(start);
        let object_string = std::str::from_utf8(object_slice)?;
        Ok(object_string.to_owned())
    } else {
        get_err!()
    }
}