pipeline/etl/processor/

join.rs

// Copyright 2023 Greptime Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use ahash::HashSet;
use snafu::OptionExt;

use crate::etl::error::{
    Error, JoinSeparatorRequiredSnafu, KeyMustBeStringSnafu, ProcessorExpectStringSnafu,
    ProcessorMissingFieldSnafu, Result,
};
use crate::etl::field::{Fields, OneInputOneOutputField};
use crate::etl::processor::{
    yaml_bool, yaml_new_field, yaml_new_fields, yaml_string, Processor, ProcessorBuilder,
    ProcessorKind, FIELDS_NAME, FIELD_NAME, IGNORE_MISSING_NAME, SEPARATOR_NAME,
};
use crate::etl::value::{Array, Value};

pub(crate) const PROCESSOR_JOIN: &str = "join";

#[derive(Debug, Default)]
pub struct JoinProcessorBuilder {
    fields: Fields,
    separator: Option<String>,
    ignore_missing: bool,
}

impl ProcessorBuilder for JoinProcessorBuilder {
    fn output_keys(&self) -> HashSet<&str> {
        self.fields
            .iter()
            .map(|f| f.target_or_input_field())
            .collect()
    }

    fn input_keys(&self) -> HashSet<&str> {
        self.fields.iter().map(|f| f.input_field()).collect()
    }

    fn build(self, intermediate_keys: &[String]) -> Result<ProcessorKind> {
        self.build(intermediate_keys).map(ProcessorKind::Join)
    }
}

impl JoinProcessorBuilder {
    fn check(self) -> Result<Self> {
        if self.separator.is_none() {
            return JoinSeparatorRequiredSnafu.fail();
        }

        Ok(self)
    }

    pub fn build(self, intermediate_keys: &[String]) -> Result<JoinProcessor> {
        let mut real_fields = vec![];
        for field in self.fields.into_iter() {
            let input = OneInputOneOutputField::build(
                "join",
                intermediate_keys,
                field.input_field(),
                field.target_or_input_field(),
            )?;
            real_fields.push(input);
        }

        Ok(JoinProcessor {
            fields: real_fields,
            separator: self.separator,
            ignore_missing: self.ignore_missing,
        })
    }
}

/// A processor to join each element of an array into a single string using a separator string between each element
#[derive(Debug, Default)]
pub struct JoinProcessor {
    fields: Vec<OneInputOneOutputField>,
    separator: Option<String>,
    ignore_missing: bool,
}

impl JoinProcessor {
    fn process(&self, arr: &Array) -> Result<Value> {
        let sep = self.separator.as_ref().unwrap();
        let val = arr
            .iter()
            .map(|v| v.to_str_value())
            .collect::<Vec<String>>()
            .join(sep);

        Ok(Value::String(val))
    }

    fn check(self) -> Result<Self> {
        if self.separator.is_none() {
            return JoinSeparatorRequiredSnafu.fail();
        }

        Ok(self)
    }
}

impl TryFrom<&yaml_rust::yaml::Hash> for JoinProcessorBuilder {
    type Error = Error;

    fn try_from(value: &yaml_rust::yaml::Hash) -> Result<Self> {
        let mut fields = Fields::default();
        let mut separator = None;
        let mut ignore_missing = false;

        for (k, v) in value.iter() {
            let key = k
                .as_str()
                .with_context(|| KeyMustBeStringSnafu { k: k.clone() })?;

            match key {
                FIELD_NAME => {
                    fields = Fields::one(yaml_new_field(v, FIELD_NAME)?);
                }
                FIELDS_NAME => {
                    fields = yaml_new_fields(v, FIELDS_NAME)?;
                }
                SEPARATOR_NAME => {
                    separator = Some(yaml_string(v, SEPARATOR_NAME)?);
                }
                IGNORE_MISSING_NAME => {
                    ignore_missing = yaml_bool(v, IGNORE_MISSING_NAME)?;
                }
                _ => {}
            }
        }

        let builder = JoinProcessorBuilder {
            fields,
            separator,
            ignore_missing,
        };
        builder.check()
    }
}

impl Processor for JoinProcessor {
    fn kind(&self) -> &str {
        PROCESSOR_JOIN
    }

    fn ignore_missing(&self) -> bool {
        self.ignore_missing
    }

    fn exec_mut(&self, val: &mut Vec<Value>) -> Result<()> {
        for field in self.fields.iter() {
            let index = field.input_index();
            match val.get(index) {
                Some(Value::Array(arr)) => {
                    let result = self.process(arr)?;
                    let output_index = field.output_index();
                    val[output_index] = result;
                }
                Some(Value::Null) | None => {
                    if !self.ignore_missing {
                        return ProcessorMissingFieldSnafu {
                            processor: self.kind(),
                            field: field.input_name(),
                        }
                        .fail();
                    }
                }
                Some(v) => {
                    return ProcessorExpectStringSnafu {
                        processor: self.kind(),
                        v: v.clone(),
                    }
                    .fail();
                }
            }
        }

        Ok(())
    }
}

#[cfg(test)]
mod tests {

    use crate::etl::processor::join::JoinProcessor;
    use crate::etl::value::Value;

    #[test]
    fn test_join_processor() {
        let processor = JoinProcessor {
            separator: Some("-".to_string()),
            ..Default::default()
        };

        let arr = vec![
            Value::String("a".to_string()),
            Value::String("b".to_string()),
        ]
        .into();
        let result = processor.process(&arr).unwrap();
        assert_eq!(result, Value::String("a-b".to_string()));
    }
}