linkrs-query 0.1.0

Query engine, parser, and executor for Linkrs
Documentation 
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//! Implementation of type conversion functions

use crate::executor::expression::ExpressionError;
use linkrs_core::value::NullType;
use linkrs_core::Value;

define_function_enum! {
    /// Type conversion function enumeration
    pub enum ConversionFunction {
        ToString => {
            name: "to_string",
            arity: 1,
            variadic: false,
            description: "Convert to String",
            handler: execute_to_string
        },
        ToInt => {
            name: "to_int",
            arity: 1,
            variadic: false,
            description: "convert to an integer (math.)",
            handler: execute_to_int
        },
        ToFloat => {
            name: "to_float",
            arity: 1,
            variadic: false,
            description: "convert to floating point",
            handler: execute_to_float
        },
        ToBool => {
            name: "to_bool",
            arity: 1,
            variadic: false,
            description: "Convert to Boolean",
            handler: execute_to_bool
        },
    }
}

fn execute_to_string(args: &[Value]) -> Result<Value, ExpressionError> {
    match &args[0] {
        Value::Null(_) => Ok(Value::Null(NullType::Null)),
        _ => args[0]
            .to_string()
            .map(Value::string)
            .map_err(ExpressionError::type_error),
    }
}

fn execute_to_int(args: &[Value]) -> Result<Value, ExpressionError> {
    match &args[0] {
        Value::Null(_) => Ok(Value::Null(NullType::Null)),
        _ => {
            let result = args[0].to_int();
            if let Value::Null(NullType::BadData) = result {
                Err(ExpressionError::type_error(
                    "The to_int function does not support this type",
                ))
            } else {
                Ok(result)
            }
        }
    }
}

fn execute_to_float(args: &[Value]) -> Result<Value, ExpressionError> {
    match &args[0] {
        Value::Null(_) => Ok(Value::Null(NullType::Null)),
        _ => {
            let result = args[0].to_float();
            if let Value::Null(NullType::BadData) = result {
                Err(ExpressionError::type_error(
                    "The to_float function does not support the type",
                ))
            } else {
                Ok(result)
            }
        }
    }
}

fn execute_to_bool(args: &[Value]) -> Result<Value, ExpressionError> {
    match &args[0] {
        Value::Null(_) => Ok(Value::Null(NullType::Null)),
        _ => {
            let result = args[0].to_bool();
            if let Value::Null(NullType::BadData) = result {
                Err(ExpressionError::type_error(
                    "The to_bool function does not support this type",
                ))
            } else {
                Ok(result)
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_to_string() {
        let func = ConversionFunction::ToString;
        let result = func
            .execute(&[Value::Int(42)])
            .expect("Implementation should not fail");
        assert_eq!(result, Value::string("42"));
    }

    #[test]
    fn test_to_int() {
        let func = ConversionFunction::ToInt;
        let result = func
            .execute(&[Value::string("42")])
            .expect("Implementation should not fail");
        assert_eq!(result, Value::Int(42));
    }

    #[test]
    fn test_to_float() {
        let func = ConversionFunction::ToFloat;
        let result = func
            .execute(&[Value::Int(42)])
            .expect("Implementation should not fail");
        assert_eq!(result, Value::Float(42.0));
    }

    #[test]
    fn test_to_bool() {
        let func = ConversionFunction::ToBool;
        let result = func
            .execute(&[Value::Int(1)])
            .expect("Implementation should not fail");
        assert_eq!(result, Value::Bool(true));
    }

    #[test]
    fn test_null_handling() {
        let func = ConversionFunction::ToString;
        let result = func
            .execute(&[Value::Null(NullType::Null)])
            .expect("Implementation should not fail");
        assert_eq!(result, Value::Null(NullType::Null));
    }
}