# Iftree: Include File Tree 🌳

Include many files in your Rust code for self-contained binaries.

**Highlights**:

- Include or exclude files with **path patterns**.
- File lookups **checked** at compile time are **fast** at runtime (constant
  time).
- **Customizable**: associate any data with files.
- Many [**examples**](https://github.com/evolutics/iftree/tree/main/examples),
  including [recipes](#recipes).

See also [**related projects**](#related-work).

![Test](https://github.com/evolutics/iftree/actions/workflows/test.yaml/badge.svg)
[![crates.io](https://img.shields.io/crates/v/iftree.svg)](https://crates.io/crates/iftree)

## Motivation

Self-contained binaries are easy to ship, as they come with any required file
data such as game assets, web templates, etc.

The standard library's `std::include_str!` includes the contents of a given
file. Iftree generalizes this in two ways:

- Not just one, but many files can be included at once with **path patterns** in
  a `.gitignore`-like format. Patterns are flexible: you can include multiple
  folders, skip hidden files, filter by filename extension, select a fixed file
  list, etc.
- Instead of including the file contents only, files can be associated with
  **any data** fields such as additional file metadata.

Conceptually:

```text
std:       include_str!("my_file")
Iftree:    any_macro!("my_files/**")
```

## Usage

Now that you know the why and the what, learn the how. The following quick start
shows the basic usage.

### Quick start

```rust
// Say you have these files:
//
//     my_assets/
//     ├── file_a
//     ├── file_b
//     └── folder/
//         └── file_c

// Include data from this file tree in your code like so:
#[iftree::include_file_tree("paths = '/my_assets/**'")]
pub struct MyAsset {
    relative_path: &'static str,
    contents_str: &'static str,
}

fn main() {
    // Based on this, an array `ASSETS` of `MyAsset` instances is generated:
    assert_eq!(ASSETS.len(), 3);
    assert_eq!(ASSETS[0].relative_path, "my_assets/file_a");
    assert_eq!(ASSETS[0].contents_str, "… contents file_a\n");
    assert_eq!(ASSETS[1].contents_str, "… contents file_b\n");
    assert_eq!(ASSETS[2].contents_str, "… file_c\n");

    // Also, variables `base::x::y::MY_FILE` are generated (named by file path):
    assert_eq!(base::my_assets::FILE_A.relative_path, "my_assets/file_a");
    assert_eq!(base::my_assets::FILE_A.contents_str, "… contents file_a\n");
    assert_eq!(base::my_assets::FILE_B.contents_str, "… contents file_b\n");
    assert_eq!(base::my_assets::folder::FILE_C.contents_str, "… file_c\n");
}
```

### Detailed guide

1. Add the **dependency** `iftree = "1.0"` to your manifest (`Cargo.toml`).

1. Define your **asset type**, which is just a custom `struct` or type alias.
   Example:

   ```rust
   pub struct MyAsset;
   ```

1. Next, **filter files** to be included by annotating your asset type. Example:

   ```rust
   #[iftree::include_file_tree("paths = '/my_assets/**'")]
   pub struct MyAsset;
   ```

   The macro argument is a [TOML](https://toml.io) string literal. Its `paths`
   option here supports `.gitignore`-like path patterns, with one pattern per
   line. These paths are relative to the folder with your manifest by default.
   See the [`paths` configuration](#paths) for more.

1. Define the **data fields** of your asset type. Example:

   ```rust
   #[iftree::include_file_tree("paths = '/my_assets/**'")]
   pub struct MyAsset {
       relative_path: &'static str,
       contents_bytes: &'static [u8],
   }
   ```

   When building your project, code is generated that instantiates the asset
   type once per file.

   By default, a field `relative_path` (if any) is populated with the file path,
   a field `contents_bytes` is populated with the raw file contents, and a
   couple of other [standard fields](#standard-fields) are recognized by name.

   However, you can [customize](#custom-file-data) this to include arbitrary
   file data.

1. Now you can **access** your file data via the generated `ASSETS` array.
   Example:

   ```rust
   assert_eq!(ASSETS[0].relative_path, "my_assets/my_file");
   assert_eq!(ASSETS[0].contents_bytes, b"file contents");
   ```

   Additionally, for each file `x/y/my_file`, a variable `base::x::y::MY_FILE`
   is generated (unless disabled via
   [`template.identifiers` configuration](#templateidentifiers)). Such a
   variable is a reference to the respective element of the `ASSETS` array.
   Example:

   ```rust
   assert_eq!(base::my_assets::MY_FILE.relative_path, "my_assets/my_file");
   assert_eq!(base::my_assets::MY_FILE.contents_bytes, b"file contents");
   ```

### Examples

If you like to explore by example, there is an
[**`examples` folder**](https://github.com/evolutics/iftree/tree/main/examples).
The documentation links to individual examples where helpful.

You could get started with the
[basic example](https://github.com/evolutics/iftree/blob/main/examples/basic.rs).
For a more complex case, see the
[showcase example](https://github.com/evolutics/iftree/blob/main/examples/showcase.rs).

Note that some examples need extra dependencies from the `dev-dependencies` of
the [manifest](https://github.com/evolutics/iftree/tree/main/Cargo.toml).

### Standard fields

When you use a subset of the following fields only, an initializer for your
asset type is generated without further configuration. See
[example](https://github.com/evolutics/iftree/blob/main/examples/basics_standard_fields.rs).

- **`contents_bytes`**`: &'static [u8]`

  File contents as a byte array, using
  [`std::include_bytes`](https://doc.rust-lang.org/std/macro.include_bytes.html).

- **`contents_str`**`: &'static str`

  File contents interpreted as a UTF-8 string, using
  [`std::include_str`](https://doc.rust-lang.org/std/macro.include_str.html).

- **`get_bytes`**`: fn() -> std::borrow::Cow<'static, [u8]>`

  In debug builds (that is, when
  [`debug_assertions`](https://doc.rust-lang.org/reference/conditional-compilation.html#debug_assertions)
  is enabled), this function reads the file afresh on each call at runtime. It
  panics if there is any error such as if the file does not exist. This helps
  with faster development, as it avoids rebuilding if asset file contents are
  changed only (note that you still need to rebuild if assets are added,
  renamed, or removed). The asset file is located based on its absolute path in
  the build environment, likely rendering the binary unfit for distribution.

  In release builds, it returns the file contents included at compile time,
  using
  [`std::include_bytes`](https://doc.rust-lang.org/std/macro.include_bytes.html).

- **`get_str`**`: fn() -> std::borrow::Cow<'static, str>`

  Same as `get_bytes` but for the file contents interpreted as a UTF-8 string,
  using
  [`std::include_str`](https://doc.rust-lang.org/std/macro.include_str.html).

- **`relative_path`**`: &'static str`

  File path relative to the base folder, which is the folder with your manifest
  (`Cargo.toml`) by default. Path components are separated by a slash `/`,
  independent of your platform.

### Custom file data

To associate custom data with your files, you can plug in a macro that
initializes each asset. Toy example:

```rust
macro_rules! my_initialize {
    ($relative_path:literal, $absolute_path:literal) => {
        MyAsset {
            path: $relative_path,
            size_in_bytes: include_bytes!($absolute_path).len(),
        }
    };
}

#[iftree::include_file_tree(
    "
paths = '/my_assets/**'
template.initializer = 'my_initialize'
"
)]
pub struct MyAsset {
    path: &'static str,
    size_in_bytes: usize,
}

fn main() {
    assert_eq!(base::my_assets::FILE_A.path, "my_assets/file_a");
    assert_eq!(base::my_assets::FILE_A.size_in_bytes, 20);
    assert_eq!(base::my_assets::FILE_B.path, "my_assets/file_b");
}
```

The initializer macro (`my_initialize` above) must return a constant expression.
Non-constant data can still be computed (lazily) with
[`std::sync::LazyLock`](https://doc.rust-lang.org/std/sync/struct.LazyLock.html).

For even more control over code generation, there is the concept of
[visitors](#template-visitors).

### Name sanitization

When generating identifiers based on paths, names are sanitized. For example, a
filename `404_not_found.md` is sanitized to an identifier `_404_NOT_FOUND_MD`.

The sanitization process is designed to generate valid, conventional
[identifiers](https://doc.rust-lang.org/reference/identifiers.html).
Essentially, it replaces invalid identifier characters by underscores `"_"` and
adjusts the letter case to the context.

More precisely, these transformations are applied in order:

1. The case of letters is adjusted to respect naming conventions:
   - All lowercase for folders (because they map to module names).
   - All uppercase for filenames (because they map to static variables).
1. Characters without the property `XID_Continue` are replaced by `"_"`. The set
   of `XID_Continue` characters in ASCII is `[0-9A-Z_a-z]`.
1. If the first character does not belong to `XID_Start` and is not `"_"`, then
   `"_"` is prepended. The set of `XID_Start` characters in ASCII is `[A-Za-z]`.
1. If the name is `"_"`, `"crate"`, `"self"`, `"Self"`, or `"super"`, then `"_"`
   is appended.

### Portable file paths

To prevent issues when developing on different platforms, your file paths should
follow these recommendations:

- Path components are separated by a slash `/` (even on Windows).
- Filenames do not contain backslashes `\` (even on Unix-like systems).

### Troubleshooting

To inspect the generated code, there is a [`debug` configuration](#debug).

## Recipes

Here are example solutions for given problems.

### Kinds of asset types

- [Type alias](https://github.com/evolutics/iftree/blob/main/examples/basics_type_alias.rs)
  (`type X = …`)
- [Struct](https://github.com/evolutics/iftree/blob/main/examples/basics_type_named_fields.rs)
  (`struct` with named fields)
- [Tuple struct](https://github.com/evolutics/iftree/blob/main/examples/basics_type_tuple_fields.rs)
  (`struct` with unnamed fields)
- [Unit-like struct](https://github.com/evolutics/iftree/blob/main/examples/basics_type_unit.rs)
  (`struct` without field list)

### Integration with other libraries

- Compression with
  [`include_flate`](https://github.com/evolutics/iftree/blob/main/examples/library_include_flate.rs)
- File server with
  [Actix Web](https://github.com/evolutics/iftree/blob/main/examples/library_actix_web.rs)
- File server with
  [Rocket](https://github.com/evolutics/iftree/blob/main/examples/library_rocket.rs)
- File server with
  [Tide](https://github.com/evolutics/iftree/blob/main/examples/library_tide.rs)
- File server with
  [warp](https://github.com/evolutics/iftree/blob/main/examples/library_warp.rs)
- Media types with
  [`mime_guess`](https://github.com/evolutics/iftree/blob/main/examples/library_mime_guess.rs)
- Templates with
  [Handlebars](https://github.com/evolutics/iftree/blob/main/examples/library_handlebars.rs)

### Including file metadata

- [File permissions](https://github.com/evolutics/iftree/blob/main/examples/scenario_file_permissions.rs)
- [File timestamps](https://github.com/evolutics/iftree/blob/main/examples/scenario_file_timestamps.rs)
  (creation, last access, last modification)
- [Filename](https://github.com/evolutics/iftree/blob/main/examples/scenario_filename.rs)
- [Filename extension](https://github.com/evolutics/iftree/blob/main/examples/scenario_filename_extension.rs)
- Hash with [SHA-256](https://github.com/evolutics/iftree/blob/main/examples/scenario_hash_sha_256.rs)
- [Media type](https://github.com/evolutics/iftree/blob/main/examples/scenario_media_type.rs)
  (formerly MIME type)

### Custom constructions

- [Hash map](https://github.com/evolutics/iftree/blob/main/examples/scenario_hash_map.rs)
- [Lazy initialization](https://github.com/evolutics/iftree/blob/main/examples/scenario_lazy_initialization.rs)
- [Nested hash map](https://github.com/evolutics/iftree/blob/main/examples/scenario_nested_hash_map.rs)

## Related work

Originally, I've worked on Iftree because I couldn't find a library for this use
case: including files from a folder filtered by filename extension. The project
has since developed into something more flexible.

Here is how I think Iftree compares to related projects for the given criteria.
Generally, while Iftree has defaults to address common use cases, it comes with
first-class support for arbitrary file data.

[//]: # "Update-worthy."

| Project                                                                            | File selection                                      | Included file data       | Data access via                                                                                     |
| ---------------------------------------------------------------------------------- | --------------------------------------------------- | ------------------------ | --------------------------------------------------------------------------------------------------- |
| [**`include_dir`**](https://github.com/Michael-F-Bryan/include_dir) 0.7            | Single folder                                       | Path, contents, metadata | File path, nested iterators, glob patterns                                                          |
| [**`includedir`**](https://github.com/tilpner/includedir) 0.6                      | Multiple files, multiple folders                    | Path, contents           | File path, iterator                                                                                 |
| [**Rust Embed**](https://pyrossh.dev/repos/rust-embed) 8.9                         | Single folder, inclusion-exclusion path patterns    | Path, contents, metadata | File path, iterator                                                                                 |
| [**`std::include_bytes`**](https://doc.rust-lang.org/std/macro.include_bytes.html) | Single file                                         | Contents                 | File path                                                                                           |
| [**`std::include_str`**](https://doc.rust-lang.org/std/macro.include_str.html)     | Single file                                         | Contents                 | File path                                                                                           |
| **Iftree**                                                                         | Multiple files by inclusion-exclusion path patterns | Path, contents, custom   | File path (via `base::x::y::MY_FILE` variables in constant time), iterator (`ASSETS` array), custom |

## Configuration reference

The `iftree::include_file_tree` macro is configured via a
[TOML](https://toml.io) string with the following fields.

### `base_folder`

Path patterns are interpreted as relative to this folder.

Unless this path is absolute, it is interpreted as relative to the folder given
by the environment variable `CARGO_MANIFEST_DIR`. That is, a path pattern
`x/y/z` resolves to `[CARGO_MANIFEST_DIR]/[base_folder]/x/y/z`.

See the [`root_folder_variable` configuration](#root_folder_variable) to
customize this.

**Default**: `""`

See
[example](https://github.com/evolutics/iftree/blob/main/examples/configuration_base_folder.rs).

### `debug`

Whether to generate a string variable `DEBUG` with debug information such as the
generated code.

**Default**: `false`

See
[example](https://github.com/evolutics/iftree/blob/main/examples/configuration_debug.rs).

### `paths`

A string with a path pattern per line to filter files.

It works like a `.gitignore` file with inverted meaning:

- If the last matching pattern is negated (with `!`), the file is excluded.
- If the last matching pattern is not negated, the file is included.
- If no pattern matches, the file is excluded.

The pattern language is as documented in the
[`.gitignore` reference](https://git-scm.com/docs/gitignore), with this
difference: you must use `x/y/*` instead of `x/y/` to include files in a folder
`x/y/`; to also include subfolders (recursively), use `x/y/**`.

By default, path patterns are relative to the environment variable
`CARGO_MANIFEST_DIR`, which is the folder with your manifest (`Cargo.toml`). See
the [`base_folder` configuration](#base_folder) to customize this.

Common patterns:

- Exclude hidden files: `!.*`
- Include files with filename extension `xyz` only: `*.xyz`

This is a **required** option without default.

See
[example](https://github.com/evolutics/iftree/blob/main/examples/configuration_paths.rs).

### `root_folder_variable`

An environment variable that is used to resolve a relative
[`base_folder`](#base_folder) to an absolute path.

The value of the environment variable should be an absolute path.

**Default**: `"CARGO_MANIFEST_DIR"`

### `template.identifiers`

Whether to generate an identifier per file.

Given a file `x/y/my_file`, a static variable `base::x::y::MY_FILE` is
generated, nested in modules for folders. Their root module is `base`, which
represents the base folder.

Each variable is a reference to the corresponding element of the `ASSETS` array.

Generated identifiers are subject to [name sanitization](#name-sanitization).
Because of this, two files may map to the same identifier, causing an error
about a name being defined multiple times. The code generation does not try to
resolve such collisions automatically, as this would likely cause confusion
about which identifier refers to which file. Instead, you need to rename any
affected paths (but if you have no use for the generated identifiers, you can
just disable them with `template.identifiers = false`).

**Default**: `true`

See
[example](https://github.com/evolutics/iftree/blob/main/examples/configuration_template_identifiers.rs).

### `template.initializer`

A macro name used to instantiate the asset type per file.

As inputs, the macro is passed the following arguments, separated by comma:

1. Relative file path as a string literal. Path components are separated by `/`.
1. Absolute file path as a string literal.

As an output, the macro must return a
[constant expression](https://doc.rust-lang.org/reference/const_eval.html#constant-expressions).

**Default**: A default initializer is constructed by recognizing
[standard fields](#standard-fields).

See
[example](https://github.com/evolutics/iftree/blob/main/examples/configuration_template_initializer.rs).

### `template` visitors

This is the most flexible customization of the code generation process.

Essentially, a visitor transforms the tree of selected files into code. It does
so by calling custom macros at these levels:

- For the base folder, a `visit_base` macro is called to wrap everything (top
  level).
- For each folder, a `visit_folder` macro is called, wrapping the code generated
  from its files and subfolders (recursively).
- For each file, a `visit_file` macro is called (bottom level).

These macros are passed the following inputs, separated by comma:

- `visit_base`:
  1. Total number of selected files as a `usize` literal.
  1. Outputs of the visitor applied to the base folder entries, ordered by
     filename in Unicode code point order.
- `visit_folder`:
  1. Folder name as a string literal.
  1. [Sanitized](#name-sanitization) folder name as an identifier.
  1. Outputs of the visitor applied to the folder entries, ordered by filename
     in Unicode code point order.
- `visit_file`:
  1. Filename as a string literal.
  1. [Sanitized](#name-sanitization) filename as an identifier.
  1. Zero-based index of the file among the selected files as a `usize` literal.
  1. Relative file path as a string literal. Path components are separated by
     `/`.
  1. Absolute file path as a string literal.

The `visit_folder` macro is optional. If missing, the outputs of the
`visit_file` calls are directly passed as an input to the `visit_base` call.
This is useful to generate flat structures such as arrays. Similarly, the
`visit_base` macro is optional.

You can configure multiple visitors. They are applied in order.

To plug in visitors, add this to your configuration for each visitor:

```toml
[[template]]
visit_base = 'visit_my_base'
visit_folder = 'visit_my_folder'
visit_file = 'visit_my_file'
```

`visit_my_…` are the names of your corresponding macros.

See examples:

- [Basic](https://github.com/evolutics/iftree/blob/main/examples/configuration_template_visitors.rs)
- [Nesting](https://github.com/evolutics/iftree/blob/main/examples/configuration_template_visitors_nesting.rs)
- [Emulation of default code generation](https://github.com/evolutics/iftree/blob/main/examples/configuration_template_visitors_emulation.rs)

## Further resources

- [Changelog](https://github.com/evolutics/iftree/blob/main/CHANGELOG.md)
- [Latest revision of this documentation](https://github.com/evolutics/iftree/blob/main/README.md)
