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//! This library helps with easily including and serving assets (like JS or CSS
//! files) in your web application. It is fairly configurable and supports a
//! variety of features. In particular, it can embed all assets into your
//! executable at compile time to get an easy to deploy standalone-executable.
//!
//!
//! # Quick start
//!
//! To use `reinda`, you mostly need to do three things: (1) define your assets
//! with [`assets!`], (2) create an [`Assets`] instance, (3) call
//! [`Assets::get`] to serve your asset.
//!
//! ```ignore
//! use reinda::{assets, Assets, Config, Setup};
//!
//! const ASSETS: Setup = assets! {
//! // Folder which contains your assets, relative to your `Cargo.toml`.
//! #![base_path = "assets"]
//!
//! // List of assets to include, with different settings.
//! "index.html": { template },
//! "bundle.js": { hash },
//! };
//!
//!
//! #[tokio::main]
//! async fn main() -> Result<(), reinda::Error> {
//! // Initialize assets
//! let assets = Assets::new(ASSETS, Config::default()).await?;
//!
//! // Retrieve specific asset. You can now send this data via HTTP or use
//! // it however you like.
//! let bytes /*: Option<bytes::Bytes> */ = assets.get("index.html").await?;
//!
//! Ok(())
//! }
//! ```
//!
//! The `hash` keyword in the macro invocation means that `bundle.js` will be
//! obtainable only with a filename that contains a hash of its content, e.g.
//! `bundle.JdeK1YeQ90aJ.js`. This is useful for caching on the web: you can now
//! serve the `bundle.js` with a very large `max-age` in the `cache-control`
//! header. Whenever your asset changes, the URI changes as well, so the browser
//! has to re-request it.
//!
//! But how do you include the correct JS bundle path in your HTML file? That's
//! what `template` is for. `reinda` supports very basic templating. If you
//! define your HTML file like this:
//!
//! ```text
//! <html>
//! <head></head>
//! <body>
//! <script src="{{: path:bundle.js :}}" />
//! </body>
//! </html>
//! ```
//!
//! Then the `{{: ... :}}` part will be replaced by the actual, hashed path of
//! `bundle.js`. There are more uses for the template, as you can see below.
//!
//! To learn more about this library, keep reading, or check out the docs for
//! [`assets!`] for information on asset specification, or checkout [`Config`]
//! for information about runtime configuration.
//!
//!
//! # Embed or loaded at runtime: dev vs. prod mode
//!
//! This library has two different modes: **dev** (short for development) and
//! **prod** (short for production). The name "prod" is deliberately not the
//! same as "release" (the typical Rust term for it), because those two are not
//! always the same.
//!
//! There are several differences between the two modes:
//!
//! | | dev mode | prod mode |
//! | - | -------- | --------- |
//! | Normal assets | Loaded from filesystem when requested | Embedded into binary |
//! | `dynamic: true` assets | Loaded from filesystem when requested | Loaded in [`Assets::new`] |
//! | `hash: true` assets | Filename not modified | Hash inserted into filename |
//! | Base path | `config.base_path` with current workdir as fallback | Given via `#![base_path]` |
//!
//!
//! By default, if you compile in Cargo debug mode (e.g. `cargo build`), *dev*
//! mode is used. If you compile in Cargo's release mode (e.g. `cargo build
//! --release`), *prod* mode is used. You can instruct `reinda` to always use
//! prod mode by enabling the feature `debug-is-prod`:
//!
//! ```text
//! reinda = { version = "...", features = ["debug-is-prod"] }
//! ```
//!
//!
//! # Template
//!
//! `reinda` has a simple template system. The input file is checked for
//! *fragments* which have the syntax `{{: foo :}}`. The start token is actually
//! `{{: ` (note the whitespace!). So `{{:foo:}}` is not recognized as fragment.
//! The syntax was chosen to not conflict with other template syntax that might
//! be present in the asset files. Please let me know if some other template
//! engine out there uses the `{{:` syntax! Then I might change the syntax of
//! `reinda`.
//!
//! Inside a fragment, there are different replacement functions you can use:
//!
//! - **`include:`** allows you to include the content of another file in place
//! of the template fragment. If the included file is a template as well, that
//! will be rendered before being included. Example:
//! `{{: include:colors.css }}`.
//!
//! - **`path:`** replaces the fragment with the potential hashed path of
//! another asset. This only makes sense for hashed asset paths as otherwise
//! you could just insert the path directly. Example:
//! `{{: path:bundle.js :}}`.
//!
//! - **`var:`** replaces the fragment with a runtime provided variable. See
//! [`Config::variables`]. Example: `{{: var:main-color :}}`.
//!
//! Fragments have two other intended limitations: they must not contain a
//! newline and must not be longer than 256 characters. This is to further
//! prevent the template accidentally picking up start tokens that are not
//! intended for `reinda`.
//!
//!
//! ### Example
//!
//! **`index.html`**:
//!
//! ```text
//! <html>
//! <head>
//! <script type="application/json">{ "accentColor": "{{: var:color :}}" }</script>
//! <style>{{: include:style.css :}}</style>
//! </head>
//! <body>
//! <script src="{{: path:bundle.js :}}" />
//! </body>
//! </html>
//! ```
//!
//! **`style.css`**
//!
//! ```text
//! body {
//! margin: 0;
//! }
//! ```
//!
//! And assuming `bundle.js` was declared with `hash` (to hash its filename) and
//! the `config.variables` contained the entry `"color": "blue"`, then the
//! resulting `index.html` looks like this:
//!
//! ```text
//! <html>
//! <head>
//! <script type="application/json">{ "accentColor": "blue" }</script>
//! <style>body {
//! margin: 0;
//! }</style>
//! </head>
//! <body>
//! <script src="bundle.JdeK1YeQ90aJ.js" />
//! </body>
//! </html>
//! ```
//!
//!
//! # Cargo features
//!
//! - **`compress`** (enabled by default): if enabled, embedded files are
//! compressed. This often noticably reduces the binary size of the
//! executable. This feature adds the `flate2` dependency.
//!
//! - **`hash`** (enabled by default): is required for support of filename
//! hashing (see above). This feature adds the `base64` and `sha2`
//! dependencies.
//!
//! - **`debug-is-prod`**: see the section about "prod" and "dev" mode above.
//!
//!
//! # Notes, Requirements and Limitations
//!
//! - `reinda` actually consists of three crates: `reinda-core`, `reinda-macros`
//! and the main crate. To detect whether Cargo compiles in debug or release
//! mode, `cfg(debug_assertions)` is used. All three of these crates have to
//! be compiled with with the same setting regarding debug assertions,
//! otherwise you will either see strange compile errors or strange runtime
//! behavior (no UB though). This shouldn't be a concern, as all crates in
//! your dependency graph are compiled with the same codegen settings, unless
//! you include per-dependency overrides in your `Cargo.toml`. So just don't
//! do that.
//! - The environment variable `CARGO_MANIFEST_DIR` has to be set when expanding
//! the `assets!` macro. Cargo does this automatically. But if you, for some
//! reason, compile manually with `rustc`, you have to set that value.
#![deny(missing_debug_implementations)]
use std::{collections::HashMap, path::PathBuf};
use bytes::Bytes;
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
use ahash::AHashMap;
use reinda_core::template;
use crate::resolve::Resolver;
mod dep_graph;
mod hash;
mod resolve;
/// Compile time configuration of assets. Returns a [`Setup`].
///
/// Simple example:
///
/// ```ignore
/// use reinda::{assets, Setup};
///
/// const ASSETS: Setup = assets! {
/// #![base_path = "frontend/build"]
///
/// "index.html": { template },
/// "bundle.js": { hash },
/// };
/// ```
///
///
/// # Syntax
///
/// The basic syntax looks like this:
///
/// ```ignore
/// use reinda::{assets, Setup};
///
/// const ASSETS: Setup = assets! {
/// #![global_setting1 = "value1"]
/// #![global_setting2 = 3]
///
/// "path/to/asset-x.html": {
/// asset_setting_a: false,
/// asset_setting_b: "data",
/// },
/// "another-path/asset-y.js": {
/// asset_setting_b: "other data",
/// },
/// };
/// ```
///
/// ## Global settings
///
/// - **`base_path`** (string, required): specifies a base path. It is relative to
/// `CARGO_MANIFEST_DIR`. The resulting compile time path of an asset is
/// `$CARGO_MANIFEST_DIR/$base_path/$asset_path`. When assets are loaded at
/// runtime, everything is relative to the current directory instead of
/// `CARGO_MANIFEST_DIR`. You can overwrite the base path for the runtime via
/// [`Config::base_path`].
///
/// ## Assets
///
/// Each asset is defined by a path, followed by colon and then a set of
/// settings for that asset. In many cases, the path can simply be a file name.
/// See the `base_path` global setting.
///
/// The settings are specified with the Rust struct initializer syntax. However,
/// you can just omit fields for which you want to use the default value. Also,
/// boolean fields can omit their value if it is `true`. For example,
/// `"bundle.js": { template }` is the same as `"bundle.js": { template: true
/// }`.
///
///
/// Asset settings:
///
/// - **`serve`** (bool, default: `true`): if set to `false`, this asset cannot
/// be directly retrieved via [`Assets::get`]. This only makes sense for
/// assets that are intended to be included by another asset.
///
/// - **`template`** (bool, default: `false`): if set to `true`, the included
/// file is treated as a template with the `reinda` specific template syntax.
/// Otherwise it is treated as verbatim file.
///
/// - **`dynamic`** (bool, default: `false`): if set to `true`, this is treated
/// as a dynamic asset which has to be loaded at runtime and cannot be
/// embedded. In dev mode, the asset is loaded on each [`Assets::get`] (like
/// all other assets); in prod mode, it is loaded from the file system in
/// [`Assets::new`].
///
/// - **`hash`** (optional pair of strings, disabled by default): see section
/// about hashed filenames below.
///
/// - **`prepend`/`append`** (optional string, default: `None`): if specified, a
/// fixed string is prepended or appended to the included asset before any
/// other processing (e.g. template) takes place.
///
///
/// ### Hashed filename
///
/// If `hash` is specified for an asset, a hash of the asset's contents are
/// included into its filename. [`Assets::get`] won't serve it with the path you
/// specified in this macro, but with a path that includes a hash. Filename
/// hashing is disable in dev mode.
///
/// By default, the hash (and an additional `.`) will be inserted before the
/// first `.` in the filename of the asset's path. If that filename does not
/// contain a `.`, a `-` and the hash is appended to the filename. For
/// example:
///
/// - `sub/main.js.map` → `sub/main.JdeK1YeQ90aJ.js.map`
/// - `folder/raw-data` → `folder/raw-data-JdeK1YeQ90aJ`
///
/// If that doesn't suit you, you can override this behavior by specifying two
/// strings in between which the hash will be inserted. For example:
///
/// ```text
/// "main-v1.0-min.js.map": {
/// hash: "main-v1.0-min." ... ".js.map",
/// }
/// ```
///
/// The resulting filename would be `main-v1.0-min.JdeK1YeQ90aJ.js.map` for
/// example.
///
pub use reinda_macros::assets;
/// An opaque structure that holds metadata and (in prod mode) the included raw
/// asset data.
///
/// **Note**: the fields of this struct are public in order for it to be
/// const-constructed in [`assets!`]. There are also a some public methods on
/// this type for a similar reason. However, the fields and methods are not
/// considered part of the public API of `reinda` and as such you shouldn't use
/// them as they might change in minor version updates. Treat this type as
/// opaque! (In case you were wondering, all those fields and methods have been
/// hidden in the docs).
pub use reinda_core::Setup;
// We don't really want to expose those, but we are forced to in order for
// `assets!` to work.
pub use reinda_core::{AssetDef, AssetId, PathToIdMap};
/// Runtime configuration.
#[derive(Debug, Clone, Default)]
pub struct Config {
/// The base path from which all non-embedded assets are loaded. *Default*:
/// `None`.
///
/// The per-asset paths you defined in the `asset!` invocation are prepended
/// by this path. This path can be absolute or relative. If this is not
/// defined, the base path set in `assets!` is used.
pub base_path: Option<PathBuf>,
/// Key-value map for template variables. *Default*: empty.
///
/// These can be inserted into assets via `{{: var:foo :}}`.
pub variables: HashMap<String, String>,
/// A list of path overrides for specific non-embedded assets. The key is
/// the asset path you specified in [`assets!`] and the value is a path to
/// that specific asset. This override is then used instead of
/// `self.base_path.join(asset_path)`. If the override is a relative path,
/// it's relative to the current working directory.
// TODO: mention they are just for `dynamic` assets
pub path_overrides: HashMap<String, PathBuf>,
}
/// A set of assets.
///
/// This is one of the two main entry points of this library. You create an
/// instance of this type via [`Assets::new`] and then retrieve asset data via
/// [`Assets::get`]. [The macro `assets!`][assets!] is the other main entry
/// point of this library. It generates a `Setup` value at compile time which
/// you have to pass to `Assets::new`.
#[derive(Debug)]
pub struct Assets {
setup: Setup,
#[allow(dead_code)] // In some modes, this is not read
config: Config,
/// Stores the hashed paths of assets. This contains entries for hashed
/// paths only; assets without `hash` are not present here.
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
public_paths: AHashMap<AssetId, String>,
/// Stores the actual asset data. The key is the public path. So this is
/// basically the whole implementation of `Assets::get` in prod mode.
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
assets: AHashMap<Box<str>, (AssetId, Bytes)>,
}
impl Assets {
/// Creates a new instance of this type and, in prod mode, prepares all
/// assets.
pub async fn new(setup: Setup, config: Config) -> Result<Self, Error> {
Self::new_impl(setup, config).await
}
/// Returns the file contents of the asset referred to by `public_path`.
///
/// The given path is the "public" path, as it is a part of the actual
/// request URI. This doesn't mean this parameter has to be the full path
/// component from the request URI; you likely want to serve your assets in
/// a subdirectory, like `/assets/` which you would have to remove from the
/// URI-path before calling this method. However, for assets with hashed
/// filenames, this method expects the hashed path and not the one you
/// specified in [`assets!`].
///
/// If no asset with the specified path exists, `Ok(None)` is returned. An
/// error is returned in debug mode for a variety of reasons. In prod mode,
/// this method always returns `Ok(_)`. See [`GetError`].
pub async fn get(&self, public_path: &str) -> Result<Option<Bytes>, GetError> {
#[cfg(all(debug_assertions, not(feature = "debug-is-prod")))]
{
self.load_from_fs(public_path).await
}
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
{
Ok(self.assets.get(public_path).map(|(_, bytes)| bytes.clone()))
}
}
/// Resolves the public path to an asset ID. If the public path does not
/// match any asset, `None` is returned.
pub fn lookup(&self, public_path: &str) -> Option<AssetId> {
#[cfg(all(debug_assertions, not(feature = "debug-is-prod")))]
{
self.setup.path_to_id(public_path)
}
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
{
self.assets.get(public_path).map(|(id, _)| *id)
}
}
/// Returns an iterator over the IDs of all assets.
pub fn asset_ids(&self) -> impl Iterator<Item = AssetId> {
(0..self.setup.assets.len()).map(|i| AssetId(i as u32))
}
/// Returns meta information about a specific asset. Panics if no asset with
/// the given ID exists.
pub fn asset_info(&self, id: AssetId) -> Info<'_> {
let def = self.setup.assets.get(id.0 as usize)
.expect("Assets::asset_info: no asset with the given ID exists");
let public_path = {
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
{
self.public_paths.get(&id).map(|s| &**s)
}
#[cfg(all(debug_assertions, not(feature = "debug-is-prod")))]
{
None
}
};
Info { def, public_path }
}
}
// Private functions & methods.
impl Assets {
/// Implementation of `new` for dev builds.
#[cfg(all(debug_assertions, not(feature = "debug-is-prod")))]
async fn new_impl(setup: Setup, config: Config) -> Result<Self, Error> {
Ok(Self { setup, config })
}
/// Implementation of `new` for prod builds.
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
async fn new_impl(setup: Setup, config: Config) -> Result<Self, Error> {
use crate::resolve::ResolveResult;
// TODO: check that no path_overrides are given for embedded assets.
// Error otherwise.
let resolver = Resolver::for_all_assets(&setup, &config).await?;
let ResolveResult { assets, public_paths } = resolver.resolve(&setup, &config)?;
let assets = assets.into_iter()
.filter(|(id, _)| setup.def(*id).serve)
.map(|(id, bytes)| {
let public_path = public_paths.get(&id)
.map(|s| &**s)
.unwrap_or(setup.def(id).path)
.into();
(public_path, (id, bytes))
})
.collect();
Ok(Self {
setup,
config,
public_paths,
assets,
})
}
/// Loads an asset from filesystem, dynamically resolving all includes and
/// paths. This is the dev-build implementation of `Assets::get`.
#[cfg(all(debug_assertions, not(feature = "debug-is-prod")))]
async fn load_from_fs(&self, start_path: &str) -> Result<Option<Bytes>, Error> {
let id = match self.setup.path_to_id(start_path) {
None => return Ok(None),
Some(id) => id,
};
let setup = &self.setup;
let config = &self.config;
if !self.setup.def(id).serve {
return Ok(None);
}
let resolver = Resolver::for_single_asset_from_fs(id, setup, config).await?;
let resolved = resolver.resolve(setup, config)?;
let out = {resolved.assets}.remove(&id)
.expect("resolver did not contain requested file");
Ok(Some(out))
}
}
/// Error type for [`Assets::get`], which is different for dev and prod builds.
///
/// In dev mode, all required files are loaded from file system when you call
/// `Assets::get`. This can lead to errors (e.g. IO errors), so `Assets::get`
/// returns a `Result<_, Error>`. As such, in dev mode, `GetError` is just an
/// alias for [`Error`].
///
/// In prod mode however, all files are loaded and prepared in [`Assets::new`].
/// The `Assets::get` method will never produce an error. Therefore, in prod
/// mode, `GetError` is an alias to the never type, signaling that an error will
/// never happen.
#[cfg(all(debug_assertions, not(feature = "debug-is-prod")))]
pub type GetError = Error;
/// See above.
#[cfg(any(not(debug_assertions), feature = "debug-is-prod"))]
pub type GetError = std::convert::Infallible;
/// All errors that might be returned by `reinda`.
#[derive(Debug, thiserror::Error)]
#[non_exhaustive]
pub enum Error {
#[error("IO error while accessing '{path}'")]
Io {
err: std::io::Error,
path: PathBuf,
},
#[error("template error in '{file}': {err}")]
Template {
err: template::Error,
file: String,
},
#[error("cyclic include detected: {0:?}")]
CyclicInclude(Vec<String>),
#[error("unresolved include in '{in_file}': asset '{included}' does not exist")]
UnresolvedInclude {
in_file: String,
included: String,
},
#[error("invalid path reference `{{{{: path:{referenced} :}}}}` in '{in_file}': \
referenced asset does not exist")]
UnresolvedPath {
in_file: String,
referenced: String,
},
#[error("variable '{key}' is used in '{file}', but that variable has not been defined")]
MissingVariable {
key: String,
file: String,
},
}
/// Contains meta information about an asset.
#[derive(Debug)]
pub struct Info<'a> {
public_path: Option<&'a str>,
def: &'a AssetDef,
}
impl<'a> Info<'a> {
/// Returns the original path specified in the [`assets!`] invocation.
pub fn original_path(&self) -> &'static str {
self.def.path
}
/// Returns the public path, which might be the same as `original_path` or
/// might contain a hash if `hash` was specified in [`assets!`] for this
/// asset.
pub fn public_path(&self) -> &'a str {
self.public_path.unwrap_or(self.def.path)
}
/// Returns whether or not this asset is publicly served. Equals the `serve`
/// specification in the [`assets!`] macro.
pub fn is_served(&self) -> bool {
self.def.serve
}
/// Returns whether this asset is always loaded at runtime (either at
/// startup or when requested) as opposed to being embeded. Equals the
/// `dynamic` specification in the [`assets!`] macro.
pub fn is_dynamic(&self) -> bool {
self.def.dynamic
}
/// Returns whether this asset's filename currently (in this compilation
/// mode) includes a hash of the asset's content. In dev mode, this always
/// returns `false`; in prod mode, this returns `true` if `hash` was
/// specified in `assets!`.
pub fn is_filename_hashed(&self) -> bool {
self.public_path.is_some()
}
}