mica-std 0.5.0

//! I/O facilities such as files.
//!
//! This feature is disabled by default as mica-std's I/O facilities are still under construction.

use std::io;

use mica_hl::{Engine, MutSelfFromRawValue, SelfFromRawValue, TypeBuilder, UserData};

struct File {
   // The file is `None` if the user calls `close/0`.
   file: Option<std::fs::File>,
}

impl File {
   fn open(path: &str) -> io::Result<Self> {
      Ok(Self {
         file: Some(std::fs::File::open(path)?),
      })
   }

   fn close(&mut self) -> Result<(), FileAlreadyClosed> {
      if let Some(file) = self.file.take() {
         drop(file);
         Ok(())
      } else {
         Err(FileAlreadyClosed)
      }
   }
}

#[derive(Debug)]
struct FileAlreadyClosed;

impl std::fmt::Display for FileAlreadyClosed {
   fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
      f.write_str("file is already closed")
   }
}

impl std::error::Error for FileAlreadyClosed {}

impl UserData for File {}

pub fn load_io(engine: &mut Engine) -> Result<(), mica_hl::Error> {
   engine.add_type(
      TypeBuilder::<File>::new("File")
         .add_constructor("open", |ctor| {
            move |name: String| -> io::Result<_> { Ok(ctor.construct(File::open(&name)?)) }
         })
         .add_function("close", File::close),
   )?;

   Ok(())
}