files.rs

//! File helpers: reading a testmark document from disk.
//!
//! Free functions, not methods: `Document` itself has no notion of where its
//! text came from, and keeping I/O out of the document model keeps that model
//! pure. (The write-side helper, `write_back`, lives in the `check` module:
//! writing is only ever the return leg of a check-with-regen cycle.)

use std::fmt;
use std::path::{Path, PathBuf};

use crate::document::{Document, ParseError};

/// Read and parse a testmark file.
pub fn read_file(path: &Path) -> Result<Document, ReadFileError> {
	let text = std::fs::read_to_string(path).map_err(|source| ReadFileError::Io {
		path: path.to_path_buf(),
		source,
	})?;
	Document::parse(&text).map_err(|source| ReadFileError::Parse {
		path: path.to_path_buf(),
		source,
	})
}

/// Problems from [`read_file`].
#[derive(Debug)]
pub enum ReadFileError {
	Io {
		path: PathBuf,
		source: std::io::Error,
	},
	Parse {
		path: PathBuf,
		source: ParseError,
	},
}

impl fmt::Display for ReadFileError {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		match self {
			ReadFileError::Io {
				path,
				source,
			} => write!(f, "reading {}: {source}", path.display()),
			ReadFileError::Parse {
				path,
				source,
			} => write!(f, "{}: {source}", path.display()),
		}
	}
}

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