nushell/src/object/types.rs

use crate::object::base as value;
use crate::prelude::*;
use log::trace;

pub trait ExtractType: Sized {
    fn extract(value: &Tagged<Value>) -> Result<Self, ShellError>;
}

impl<T> ExtractType for T {
    default fn extract(_value: &Tagged<Value>) -> Result<T, ShellError> {
        let name = std::any::type_name::<T>();
        Err(ShellError::unimplemented(format!(
            "<T> ExtractType for {}",
            name
        )))
    }
}
impl<T: ExtractType> ExtractType for Option<T> {
    fn extract(value: &Tagged<Value>) -> Result<Option<T>, ShellError> {
        let name = std::any::type_name::<T>();
        trace!("<Option> Extracting {:?} for Option<{}>", value, name);

        let result = match value.item() {
            Value::Primitive(Primitive::Nothing) => None,
            _ => Some(T::extract(value)?),
        };

        Ok(result)
    }
}

impl<T: ExtractType> ExtractType for Tagged<T> {
    fn extract(value: &Tagged<Value>) -> Result<Tagged<T>, ShellError> {
        let name = std::any::type_name::<T>();
        trace!("<Tagged> Extracting {:?} for Tagged<{}>", value, name);

        Ok(T::extract(value)?.tagged(value.tag()))
    }
}

impl ExtractType for Value {
    fn extract(value: &Tagged<Value>) -> Result<Value, ShellError> {
        trace!("<Tagged> Extracting {:?} for Value", value);

        Ok(value.item().clone())
    }
}

impl ExtractType for bool {
    fn extract(value: &Tagged<Value>) -> Result<bool, ShellError> {
        trace!("Extracting {:?} for bool", value);

        match &value {
            Tagged {
                item: Value::Primitive(Primitive::Boolean(b)),
                ..
            } => Ok(*b),
            Tagged {
                item: Value::Primitive(Primitive::Nothing),
                ..
            } => Ok(false),
            other => Err(ShellError::type_error("Boolean", other.tagged_type_name())),
        }
    }
}

impl ExtractType for std::path::PathBuf {
    fn extract(value: &Tagged<Value>) -> Result<std::path::PathBuf, ShellError> {
        trace!("Extracting {:?} for PathBuf", value);

        match &value {
            Tagged {
                item: Value::Primitive(Primitive::Path(p)),
                ..
            } => Ok(p.clone()),
            other => Err(ShellError::type_error("Path", other.tagged_type_name())),
        }
    }
}

impl ExtractType for i64 {
    fn extract(value: &Tagged<Value>) -> Result<i64, ShellError> {
        trace!("Extracting {:?} for i64", value);

        match &value {
            &Tagged {
                item: Value::Primitive(Primitive::Int(int)),
                ..
            } => Ok(int.tagged(value.tag).coerce_into("converting to i64")?),
            other => Err(ShellError::type_error("Integer", other.tagged_type_name())),
        }
    }
}

impl ExtractType for u64 {
    fn extract(value: &Tagged<Value>) -> Result<u64, ShellError> {
        trace!("Extracting {:?} for u64", value);

        match &value {
            &Tagged {
                item: Value::Primitive(Primitive::Int(int)),
                ..
            } => Ok(int.tagged(value.tag).coerce_into("converting to u64")?),
            other => Err(ShellError::type_error("Integer", other.tagged_type_name())),
        }
    }
}

impl ExtractType for String {
    fn extract(value: &Tagged<Value>) -> Result<String, ShellError> {
        trace!("Extracting {:?} for String", value);

        match value {
            Tagged {
                item: Value::Primitive(Primitive::String(string)),
                ..
            } => Ok(string.clone()),
            other => Err(ShellError::type_error("String", other.tagged_type_name())),
        }
    }
}

impl ExtractType for value::Block {
    fn extract(value: &Tagged<Value>) -> Result<value::Block, ShellError> {
        match value {
            Tagged {
                item: Value::Block(block),
                ..
            } => Ok(block.clone()),
            other => Err(ShellError::type_error("Block", other.tagged_type_name())),
        }
    }
}