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//! typed-format-version: load format.version.{major,minor} from a structured file.
//!
//! This library tries to parse a format.version "section" in some raw data that
//! may have been loaded from a configuration file, and determines whether that
//! section contains valid "major" and "minor" integer values. The caller can
//! then choose the correct schema to validate the loaded data against, e.g. by
//! using a `serde`-derived library with the correct top-level dataclass definition.
//!
//! The most commonly used function will probably be `get_version_from_str()`:
//! it takes a string and a deserialization function and returns a `Version` object
//! with a `major` and `minor` integer attributes, if the data contained a valid
//! "format" element with a "version" element within it.
//!
//! ```rust
//! // This would usually be read from a file.
//! let contents = r#"{"format": {"version": {"major": 1, "minor": 3}}, "data": ["hello"]}"#;
//!
//! let fver = typed_format_version::get_version_from_str(&contents, serde_json::from_str)
//! .expect("Could not get the data format version");
//! if (fver.major(), fver.minor()) != (1, 3) {
//! panic!("Unexpected data format version {}.{}", fver.major(), fver.minor());
//! }
//! // Load the data as usual using e.g. serde_json::from_str().
//! ```
//!
//! Examining the returned version also allows loading data in different formats
//! using e.g. deserialization of different top-level structures and then performing
//! some kind of data migration to the preferred one.
/*
* Copyright (c) 2022 Peter Pentchev <roam@ringlet.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#![deny(missing_docs)]
use std::error::Error;
use std::fmt::{Display, Error as FmtError, Formatter};
use anyhow::{Context, Error as AnyError};
use serde::{Deserialize, Deserializer};
use thiserror::Error;
#[cfg(test)]
mod tests;
/// An error that occurred during the processing of the format data.
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum LoadError {
/// Could not parse the format.version.{major,minor} structure.
#[error("Could not parse format.version: {0}")]
Format(#[source] AnyError),
}
/// A trivial representation of a major.minor version string.
pub type VersionTuple = (u32, u32);
impl From<&Version> for VersionTuple {
#[inline]
fn from(ver: &Version) -> Self {
(ver.major, ver.minor)
}
}
/// The representation of a major.minor version string.
#[derive(Debug, Deserialize, PartialEq, Eq)]
pub struct Version {
/// The major version number.
major: u32,
/// The minor version number.
minor: u32,
}
impl Version {
/// Construct a new version object.
#[must_use]
#[inline]
pub const fn new(major: u32, minor: u32) -> Self {
Self { major, minor }
}
/// Get the major version number.
#[allow(clippy::must_use_candidate)]
#[inline]
pub const fn major(&self) -> u32 {
self.major
}
/// Get the minor version number.
#[allow(clippy::must_use_candidate)]
#[inline]
pub const fn minor(&self) -> u32 {
self.minor
}
/// Return the major.minor information as a tuple.
#[allow(clippy::must_use_candidate)]
#[inline]
pub const fn as_version_tuple(&self) -> VersionTuple {
(self.major, self.minor)
}
}
impl Display for Version {
#[inline]
fn fmt(&self, writer: &mut Formatter<'_>) -> Result<(), FmtError> {
write!(writer, "{}.{}", self.major, self.minor)
}
}
/// The metadata about the file format, currently the version information.
#[derive(Debug, Deserialize)]
pub struct Format {
/// The file format version information.
version: Version,
}
impl Format {
/// Get the version information.
#[allow(clippy::must_use_candidate)]
#[inline]
pub const fn version(&self) -> &Version {
&self.version
}
}
/// The top-level element containing a "format" structure.
#[derive(Debug, Deserialize)]
pub struct FormatOnlyTop {
/// The metadata about the file format.
format: Format,
}
/// Parse the format section from a string.
///
/// # Errors
/// [`LoadError::Format`] if the string cannot be parsed into
/// a structure containing a valid "format" substructure.
#[inline]
pub fn get_format_from_str<'contents, 'data, E, F>(
contents: &'contents str,
from_str_fn: F,
) -> Result<Format, LoadError>
where
'contents: 'data,
E: Error + Send + Sync + 'static,
F: Fn(&'data str) -> Result<FormatOnlyTop, E>,
{
Ok(from_str_fn(contents)
.context("Could not parse the input data")
.map_err(LoadError::Format)?
.format)
}
/// Parse format.version from a string.
///
/// # Errors
/// Any error returned by the [`get_format_from_str()`] function.
#[inline]
pub fn get_version_from_str<'contents, 'data, E, F>(
contents: &'contents str,
from_str_fn: F,
) -> Result<Version, LoadError>
where
'contents: 'data,
E: Error + Send + Sync + 'static,
F: Fn(&'data str) -> Result<FormatOnlyTop, E>,
{
Ok(get_format_from_str(contents, from_str_fn)?.version)
}
/// Parse the format section from an arbitrary deserializable value.
/// The `value` parameter may be a struct similar to `serde_json::Value`,
/// `serde_yaml::Value`, or `toml::Value`.
///
/// # Errors
/// [`LoadError::Format`] if the value cannot be parsed into
/// a structure containing a valid "format" substructure.
#[inline]
pub fn get_format_from_value<V: Deserializer<'static> + 'static>(
value: V,
) -> Result<Format, LoadError>
where
V::Error: Send + Sync,
{
let ftop: FormatOnlyTop = FormatOnlyTop::deserialize(value)
.context("Could not extract the top-level format object")
.map_err(LoadError::Format)?;
Ok(ftop.format)
}
/// Parse format.version from an arbitrary value.
/// The `value` parameter may be a struct similar to `serde_json::Value`,
/// `serde_yaml::Value`, or `toml::Value`.
///
/// # Errors
/// Any error returned by the [`get_format_from_value()`] function.
#[inline]
pub fn get_version_from_value<V: Deserializer<'static> + 'static>(
value: V,
) -> Result<Version, LoadError>
where
V::Error: Send + Sync,
{
Ok(get_format_from_value(value)?.version)
}