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//! Resource loading.
#[cfg(feature = "fs")]
mod fs;
#[cfg(feature = "fs")]
pub use fs::*;
use std::io;
use std::path::Path;
use serde::{Deserialize, Serialize};
use crate::font::FaceInfo;
/// Loads resources from a local or remote source.
pub trait Loader {
/// Descriptions of all font faces this loader serves.
fn faces(&self) -> &[FaceInfo];
/// Resolve a `path` relative to a `base` file.
///
/// This should return the same id for all paths pointing to the same file
/// and `None` if the file does not exist.
fn resolve_from(&self, base: FileId, path: &Path) -> io::Result<FileId>;
/// Load a file by id.
///
/// This must only be called with an `id` returned by a call to this
/// loader's `resolve_from` method.
fn load_file(&self, id: FileId) -> io::Result<Vec<u8>>;
}
/// A file id that can be [resolved](Loader::resolve_from) from a path.
///
/// Should be the same for all paths pointing to the same file.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
pub struct FileId(u64);
impl FileId {
/// Create a file id from a raw value.
pub fn from_raw(v: u64) -> Self {
Self(v)
}
/// Convert into the raw underlying value.
pub fn into_raw(self) -> u64 {
self.0
}
}
/// A loader which serves nothing.
pub struct BlankLoader;
impl Loader for BlankLoader {
fn faces(&self) -> &[FaceInfo] {
&[]
}
fn resolve_from(&self, _: FileId, _: &Path) -> io::Result<FileId> {
Err(io::ErrorKind::NotFound.into())
}
fn load_file(&self, _: FileId) -> io::Result<Vec<u8>> {
panic!("resolve_from never returns an id")
}
}
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