mp4ameta

https://docs.rs/mp4ameta/0.13.0/mp4ameta/
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mp4ameta is a Rust library for reading and writing iTunes-style MPEG-4 audio metadata, supporting...
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### Initialize WriteConfig

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.WriteConfig.html

Example showing how to initialize a custom WriteConfig by starting from the NONE constant.

```rust
use mp4ameta::WriteConfig;

let cfg = WriteConfig {
    write_meta_items: true,
    ..WriteConfig::NONE
};
```

--------------------------------

### Initialize ReadConfig

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.ReadConfig.html

Example of creating a custom ReadConfig instance by modifying the NONE default configuration.

```rust
use mp4ameta::ReadConfig;

let cfg = ReadConfig {
    read_meta_items: true,
    read_image_data: true,
    ..ReadConfig::NONE
};
```

--------------------------------

### Get Channel Configuration

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the channel configuration of the audio, if available.

```rust
pub fn channel_config(&self) -> Option<ChannelConfig>
```

--------------------------------

### Get Chapter List

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns a slice representing the chapter list.

```rust
pub fn chapter_list(&self) -> &[Chapter]
```

--------------------------------

### Get Sample Rate

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the sample rate of the audio, if available.

```rust
pub fn sample_rate(&self) -> Option<SampleRate>
```

--------------------------------

### Get Album

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the album metadata (`©alb`) if present.

```rust
pub fn album(&self) -> Option<&str>
```

--------------------------------

### Get Chapter Track

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns a slice representing the chapter track.

```rust
pub fn chapter_track(&self) -> &[Chapter]
```

--------------------------------

### Get Lyrics

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the lyrics (`©lyr`) if present.

```rust
pub fn lyrics(&self) -> Option<&str>
```

--------------------------------

### Get Duration

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the duration of the audio in seconds.

```rust
pub fn duration(&self) -> Duration
```

--------------------------------

### Set and Get String Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Shows how to set UTF-8 string data for an identifier and retrieve it using `strings_of`. Use this for text metadata.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Utf8("data".into()));
assert_eq!(tag.strings_of(&test).next().unwrap(), "data");
```

--------------------------------

### Set and Get Image Data (JPEG)

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Shows how to set JPEG image data for an identifier and retrieve it as an `ImgRef`. Use this for image metadata.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Jpeg(b"image".to_vec()));
let img = tag.images_of(&test).next().unwrap();
assert_eq!(img.data, b"image");
```

--------------------------------

### Get Audio Information

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Retrieves a reference to the audio information contained within the tag.

```rust
pub fn audio_info(&self) -> &AudioInfo
```

--------------------------------

### Get Chapters

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns a slice of chapters. This method prefers the chapter list but will return the chapter track if the list is not available.

```rust
pub fn chapters(&self) -> &[Chapter]
```

--------------------------------

### Get Copyright

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the copyright information (`cprt`) if present.

```rust
pub fn copyright(&self) -> Option<&str>
```

--------------------------------

### Get First Artwork Image

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns the first artwork image (`covr`) found in the metadata, if any.

```rust
pub fn artwork(&self) -> Option<ImgRef<'_>>
```

--------------------------------

### Get Average Bitrate

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the average bitrate of the audio, if available.

```rust
pub fn avg_bitrate(&self) -> Option<u32>
```

--------------------------------

### Get Filetype

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the filetype string (ftyp) from the tag.

```rust
pub fn filetype(&self) -> &str
```

--------------------------------

### Get Media Type

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns the media type (`stik`) of the audio file, if set.

```rust
pub fn media_type(&self) -> Option<MediaType>
```

--------------------------------

### Get All Artwork Images

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns an iterator over all artwork images (`covr`) associated with the metadata.

```rust
pub fn artworks(&self) -> impl Iterator<Item = ImgRef<'_>>
```

--------------------------------

### Mutably Iterate Over Userdata Bytes

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Shows how to get mutable references to byte data within Userdata, allowing in-place modification. The example modifies a byte vector and then verifies the change.

```rust
use mp4ameta::{Userdata, Data, DataIdent, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.add_data(test, Data::Reserved(b"data".to_vec()));
tag.add_data(test, Data::Utf8("string".into()));

let (ident, data) = tag.bytes_mut().next().unwrap();
data.push('1' as u8);

let test = DataIdent::Fourcc(test);
let mut bytes = tag.bytes();
assert_eq!(bytes.next().unwrap(), (&test, &b"data1"[..]));
assert_eq!(bytes.next(), None);
```

--------------------------------

### Implement CloneToUninit (Nightly)

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/enum.DataIdent.html

An experimental nightly-only API for cloning data into uninitialized memory. Use with caution.

```rust
unsafe fn clone_to_uninit(&self, dest: *mut u8)
```

--------------------------------

### Get Title

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the title (`©nam`) if present.

```rust
pub fn title(&self) -> Option<&str>
```

--------------------------------

### Img Implementations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/type.ImgBuf.html

Provides methods for creating `Img` instances, including constructors for BMP, JPEG, and PNG formats.

```APIDOC
## Implementations

### impl<T> Img<T>

#### pub const fn new(fmt: ImgFmt, data: T) -> Self
Constructor for creating a new Img instance.

#### pub const fn bmp(data: T) -> Self
Constructor for creating a BMP image.

#### pub const fn jpeg(data: T) -> Self
Constructor for creating a JPEG image.

#### pub const fn png(data: T) -> Self
Constructor for creating a PNG image.
```

--------------------------------

### Constructor for Img

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Img.html

Provides methods to create new `Img` instances.

```APIDOC
## Img Constructors

### `new(fmt: ImgFmt, data: T) -> Self`
Creates a new `Img` instance with the specified format and data.

### `bmp(data: T) -> Self`
Creates a new `Img` instance with BMP format.

### `jpeg(data: T) -> Self`
Creates a new `Img` instance with JPEG format.

### `png(data: T) -> Self`
Creates a new `Img` instance with PNG format.
```

--------------------------------

### Img Implementations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/type.ImgMut.html

Provides methods for creating and managing Img instances.

```APIDOC
## Implementations

### impl<T> Img<T>

#### `pub const fn new(fmt: ImgFmt, data: T) -> Self`
Creates a new Img instance.

#### `pub const fn bmp(data: T) -> Self`
Creates a new Img instance with BMP format.

#### `pub const fn jpeg(data: T) -> Self`
Creates a new Img instance with JPEG format.

#### `pub const fn png(data: T) -> Self`
Creates a new Img instance with PNG format.
```

--------------------------------

### Get Movement

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the movement name (`©mvn`) if present.

```rust
pub fn movement(&self) -> Option<&str>
```

--------------------------------

### Chapter Implementations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Chapter.html

Provides details on the implementations available for the Chapter struct, including constructor methods and trait implementations.

```APIDOC
### impl Chapter

#### pub fn new(start: Duration, title: impl Into<String>) -> Self

### impl Clone for Chapter

#### fn clone(&self) -> Chapter
Returns a duplicate of the value.

#### fn clone_from(&mut self, source: &Self)
Performs copy-assignment from `source`.

### impl Debug for Chapter

#### fn fmt(&self, f: &mut Formatter<'_>) -> Result
Formats the value using the given formatter.

### impl Default for Chapter

#### fn default() -> Chapter
Returns the “default value” for a type.

### impl PartialEq for Chapter

#### fn eq(&self, other: &Chapter) -> bool
Tests for `self` and `other` values to be equal, and is used by `==`.

#### fn ne(&self, other: &Rhs) -> bool
Tests for `!=`.

### impl Eq for Chapter

### impl StructuralPartialEq for Chapter
```

--------------------------------

### Get Encoder

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the encoder information (`©too`) if present.

```rust
pub fn encoder(&self) -> Option<&str>
```

--------------------------------

### Add and Iterate Over Userdata Images

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Demonstrates adding JPEG and UTF-8 data, then iterating over images to verify.

```rust
use std::rc::Rc;
use mp4ameta::{Userdata, Data, DataIdent, Fourcc, Img};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.add_data(test, Data::Jpeg(b"data".to_vec()));
tag.add_data(test, Data::Utf8("string".into()));

let test = DataIdent::Fourcc(test);
let (ident, image) = tag.into_images().next().unwrap();
assert_eq!(ident, test);
assert_eq!(image, Img::jpeg(b"data".to_vec()));
```

--------------------------------

### Implement PartialEq for AudioInfo

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.AudioInfo.html

Enables comparison for equality between two AudioInfo instances.

```rust
fn eq(&self, other: &AudioInfo) -> bool
```

--------------------------------

### Iterate Over Userdata Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Shows how to add reserved, UTF-8, and PNG data, then iterate through them using the `data()` method.

```rust
use mp4ameta::{Userdata, Data, DataIdent, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.add_data(test, Data::Reserved(b"data".to_vec()));
tag.add_data(test, Data::Utf8("string".into()));
tag.add_data(test, Data::Png(b"image".to_vec()));

let test = DataIdent::Fourcc(test);
let mut data = tag.data();
assert_eq!(data.next().unwrap(), (&test, &Data::Reserved(b"data".to_vec())));
assert_eq!(data.next().unwrap(), (&test, &Data::Utf8("string".into())));
assert_eq!(data.next().unwrap(), (&test, &Data::Png(b"image".to_vec())));
assert_eq!(data.next(), None);
```

--------------------------------

### CloneToUninit Trait Implementation

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Nightly-only experimental API for cloning to uninitialized memory.

```APIDOC
### impl<T> CloneToUninit for T
where T: Clone,

#### unsafe fn clone_to_uninit(&self, dest: *mut u8)
Performs copy-assignment from `self` to `dest`.
```

--------------------------------

### Get Maximum Bitrate

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the maximum bitrate of the audio, if available.

```rust
pub fn max_bitrate(&self) -> Option<u32>
```

--------------------------------

### Read Tag from Path with Configuration

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Attempts to read an MPEG-4 audio tag from a file at the specified path, using a given configuration. The path must implement `AsRef<Path>`.

```rust
pub fn read_with_path(path: impl AsRef<Path>, cfg: &ReadConfig) -> Result<Self>
```

--------------------------------

### Result Method Documentation

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/type.Result.html

Documentation for common Result methods including unwrap_or_default, expect_err, unwrap_err, into_ok, into_err, and, and and_then.

```APIDOC
## unwrap_or_default

### Description
Returns the contained Ok value or a default value if the result is Err.

### Parameters
- **self** (Result<T, E>) - Required - The result instance.

### Response
- **T** - The contained value or the default value for type T.

## expect_err

### Description
Returns the contained Err value, consuming the self value. Panics if the value is an Ok.

### Parameters
- **msg** (&str) - Required - The message to include in the panic if the result is Ok.

### Response
- **E** - The contained error value.

## unwrap_err

### Description
Returns the contained Err value, consuming the self value. Panics if the value is an Ok.

### Response
- **E** - The contained error value.

## into_ok

### Description
Returns the contained Ok value, but never panics. Used as a safeguard for infallible results.

### Response
- **T** - The contained value.

## into_err

### Description
Returns the contained Err value, but never panics. Used as a safeguard for infallible results.

### Response
- **E** - The contained error value.

## and

### Description
Returns res if the result is Ok, otherwise returns the Err value of self.

### Parameters
- **res** (Result<U, E>) - Required - The result to return if self is Ok.

### Response
- **Result<U, E>** - The result of the operation.

## and_then

### Description
Calls op if the result is Ok, otherwise returns the Err value of self.

### Parameters
- **op** (FnOnce(T) -> Result<U, E>) - Required - The function to call if self is Ok.

### Response
- **Result<U, E>** - The result of the operation.
```

--------------------------------

### Implement Default for AudioInfo

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.AudioInfo.html

Provides a default value for the AudioInfo type.

```rust
fn default() -> AudioInfo
```

--------------------------------

### Get Freeform Identifier from FreeformIdent

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/ident/struct.FreeformIdent.html

Retrieves the freeform identifier from a FreeformIdent.

```rust
fn freeform(&self) -> Option<FreeformIdentBorrowed<'a>>
```

--------------------------------

### Get TV Show Name

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the TV show name (`tvsh`) if present.

```rust
pub fn tv_show_name(&self) -> Option<&str>
```

--------------------------------

### Configure Read and Write Operations

Source: https://docs.rs/mp4ameta

Optimize performance by specifying which metadata sections to read or write using ReadConfig and WriteConfig.

```rust
use mp4ameta::{ChplTimescale, ReadConfig, Tag, WriteConfig};

// Only read the metadata item list, not chapters or audio information
let read_cfg = ReadConfig {
    read_meta_items: true,
    read_image_data: false,
    ..ReadConfig::NONE
};
let mut tag = Tag::read_with_path("music.m4a", &read_cfg).unwrap();

println!("{tag}");

tag.clear_meta_items();

// Only overwrite the metadata item list, leave chapters intact
let write_cfg = WriteConfig {
    write_meta_items: true,
    ..WriteConfig::NONE
};
tag.write_with_path("music.m4a", &write_cfg).unwrap();
```

--------------------------------

### Get TV Network Name

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the TV network name (`tvnn`) if present.

```rust
pub fn tv_network_name(&self) -> Option<&str>
```

--------------------------------

### Read Tag with Configuration

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Attempts to read an MPEG-4 audio tag from a reader with a specified configuration. Requires the reader to implement `Read` and `Seek` traits.

```rust
pub fn read_with( reader: &mut (impl Read + Seek), cfg: &ReadConfig, ) -> Result<Self>
```

--------------------------------

### Get TV Episode Name

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Returns the TV episode name (`tven`) if present.

```rust
pub fn tv_episode_name(&self) -> Option<&str>
```

--------------------------------

### Add and Iterate Userdata

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Demonstrates adding different data types (UTF-8 strings and PNG images) to Userdata and iterating through them. Note that duplicate keys can hold multiple values.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let tst1 = Fourcc(*b"tst1");
let tst2 = Fourcc(*b"tst2");

tag.add_data(tst1, Data::Utf8("data1".into()));
tag.add_data(tst2, Data::Png(b"data2".to_vec()));
tag.add_data(tst2, Data::Utf8("data3".into()));

let mut data = tag.data().map(|(i, d)| d);
assert_eq!(data.next(), Some(&Data::Utf8("data1".into())));
assert_eq!(data.next(), Some(&Data::Png(b"data2".to_vec())));
assert_eq!(data.next(), Some(&Data::Utf8("data3".into())));
assert_eq!(data.next(), None);
drop(data);
```

--------------------------------

### Get Mutable Chapter Track

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns a mutable slice representing the chapter track.

```rust
pub fn chapter_track_mut(&mut self) -> &mut Vec<Chapter>
```

--------------------------------

### Genre Management (Standard and Custom)

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Methods for managing both standard and custom genres.

```APIDOC
## GET /api/userdata/genres

### Description
Returns all genres, first the standard genres (`gnre`) then custom ones (`©gen`).

### Method
GET

### Endpoint
/api/userdata/genres

### Parameters
None

### Request Body
None

### Request Example
None

### Response
#### Success Response (200)
- **genres** (Iterator<String>) - An iterator over all genre strings.

#### Response Example
["rock", "pop", "electronic"]
```

```APIDOC
## GET /api/userdata/genre

### Description
Returns the first genre (`gnre` or `©gen`).

### Method
GET

### Endpoint
/api/userdata/genre

### Parameters
None

### Request Body
None

### Request Example
None

### Response
#### Success Response (200)
- **genre** (Option<String>) - The first genre string, or None if not present.

#### Response Example
"rock"
```

```APIDOC
## POST /api/userdata/take_genres

### Description
Removes all custom genres (`©gen`) and returns all genres, first standard genres (`gnre`) then custom ones (`©gen`).

### Method
POST

### Endpoint
/api/userdata/take_genres

### Parameters
None

### Request Body
None

### Request Example
None

### Response
#### Success Response (200)
- **genres** (Iterator<String>) - An iterator over all genre strings after removal of custom genres.

#### Response Example
["rock", "pop"]
```

```APIDOC
## POST /api/userdata/take_genre

### Description
Removes all custom genres (`©gen`) and returns the first genre (`gnre` or `©gen`).

### Method
POST

### Endpoint
/api/userdata/take_genre

### Parameters
None

### Request Body
None

### Request Example
None

### Response
#### Success Response (200)
- **genre** (Option<String>) - The first genre string after removal of custom genres, or None if not present.

#### Response Example
"rock"
```

```APIDOC
## POST /api/userdata/genre

### Description
Sets the custom genre (`©gen`). This will remove all other standard or custom genres.

### Method
POST

### Endpoint
/api/userdata/genre

### Parameters
None

### Request Body
- **genre** (String) - Required - The custom genre string to set.

### Request Example
{
  "genre": "jazz"
}

### Response
#### Success Response (200)
Indicates successful setting of the custom genre.

#### Response Example
{}
```

```APIDOC
## POST /api/userdata/genres

### Description
Sets the custom genre (`©gen`). This will remove all other standard or custom genres.

### Method
POST

### Endpoint
/api/userdata/genres

### Parameters
None

### Request Body
- **genres** (Array<String>) - Required - An iterable of custom genre strings to set.

### Request Example
{
  "genres": ["classical", "opera"]
}

### Response
#### Success Response (200)
Indicates successful setting of custom genres.

#### Response Example
{}
```

```APIDOC
## POST /api/userdata/add_genre

### Description
Adds a custom genre (`©gen`).

### Method
POST

### Endpoint
/api/userdata/add_genre

### Parameters
None

### Request Body
- **genre** (String) - Required - The custom genre string to add.

### Request Example
{
  "genre": "blues"
}

### Response
#### Success Response (200)
Indicates successful addition of the custom genre.

#### Response Example
{}
```

```APIDOC
## DELETE /api/userdata/genres

### Description
Removes the genre (`gnre` or `©gen`).

### Method
DELETE

### Endpoint
/api/userdata/genres

### Parameters
None

### Request Body
None

### Request Example
None

### Response
#### Success Response (200)
Indicates successful removal of genres.

#### Response Example
{}
```

--------------------------------

### Get Mutable Chapter List

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns a mutable slice representing the chapter list.

```rust
pub fn chapter_list_mut(&mut self) -> &mut Vec<Chapter>
```

--------------------------------

### Get Advisory Rating

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns the advisory rating (`rtng`) of the audio file, if set.

```rust
pub fn advisory_rating(&self) -> Option<AdvisoryRating>
```

--------------------------------

### PODCAST Constant

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/ident/constant.PODCAST.html

Documentation for the `PODCAST` constant within the mp4ameta crate.

```APIDOC
## Constant PODCAST

### Description
Represents the FourCC code for podcast metadata.

### Type
`FourCC`

### Value
`pcst`
```

--------------------------------

### Implement Clone for AudioInfo

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.AudioInfo.html

Provides functionality to create a duplicate of an AudioInfo value.

```rust
fn clone(&self) -> AudioInfo
```

--------------------------------

### TryInto<U> for T Implementation

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/enum.MediaType.html

Provides a convenient way to attempt conversion from one type to another, returning a Result. This is a blanket implementation.

```rust
type Error = <U as TryFrom<T>>::Error;
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
```

--------------------------------

### Set Media Type

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Sets the media type (`stik`) for the audio file.

```rust
pub fn set_media_type(&mut self, media_type: MediaType)
```

--------------------------------

### Userdata - Data Manipulation

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Methods for getting, setting, and taking string data associated with an identifier.

```APIDOC
## Userdata - Data Manipulation

### Description
Methods for getting, setting, and taking string data associated with an identifier.

### Methods

#### `set_data(ident: impl Ident, data: Data)`
Sets data for a given identifier. If data already exists, it will be overwritten.

#### `take_strings_of(ident: &impl Ident) -> impl Iterator<Item = &str>`
Returns an iterator over references to all strings corresponding to the identifier. This method consumes the data.

#### `strings_of(ident: &impl Ident) -> impl Iterator<Item = &str>`
Returns an iterator over references to all strings corresponding to the identifier.
```

--------------------------------

### Read and Write Metadata Simply

Source: https://docs.rs/mp4ameta

Use the Tag struct to read from and write to a file path with minimal boilerplate.

```rust
let mut tag = mp4ameta::Tag::read_from_path("music.m4a").unwrap();

println!("{}", tag.artist().unwrap());

tag.set_artist("artist");
tag.write_to_path("music.m4a").unwrap();
```

--------------------------------

### Userdata - Image Operations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Methods for getting, modifying, and taking image data associated with an identifier.

```APIDOC
## GET /images_of

### Description
Returns references to all images corresponding to the identifier.
See `Data::image`.

### Method
GET

### Endpoint
`/images_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the images.

### Response
#### Success Response (200)
- **Iterator<Item = ImgRef>** - An iterator over references to the images.

### Response Example
```json
{
  "example": "[ImgRef { data: b'image' }]"
}
```

## PUT /images_mut_of

### Description
Returns mutable references to all images corresponding to the identifier.
See `Data::image_mut`.

### Method
PUT

### Endpoint
`/images_mut_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the images.

### Response
#### Success Response (200)
- **Iterator<Item = ImgMut>** - An iterator over mutable references to the images.

### Response Example
```json
{
  "example": "[ImgMut { data: b'image1' }]"
}
```

## DELETE /take_images_of

### Description
Removes the atom corresponding to the identifier and returns all of its images.
See `Data::into_image`.

### Method
DELETE

### Endpoint
`/take_images_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the images.

### Response
#### Success Response (200)
- **Iterator<Item = ImgBuf>** - An iterator over the removed images.

### Response Example
```json
{
  "example": "[Img::png(b'image'.to_vec())]"
}
```
```

--------------------------------

### Userdata - String Operations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Methods for getting, modifying, and taking string data associated with an identifier.

```APIDOC
## GET /strings_of

### Description
Returns references to all strings corresponding to the identifier.
See `Data::string`.

### Method
GET

### Endpoint
`/strings_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the strings.

### Response
#### Success Response (200)
- **Iterator<Item = &str>** - An iterator over references to the strings.

### Response Example
```json
{
  "example": "[\"data\"]"
}
```

## PUT /strings_mut_of

### Description
Returns all mutable string references corresponding to the identifier.
See `Data::string_mut`.

### Method
PUT

### Endpoint
`/strings_mut_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the strings.

### Response
#### Success Response (200)
- **Iterator<Item = &mut String>** - An iterator over mutable references to the strings.

### Response Example
```json
{
  "example": "[\"string1\"]"
}
```

## DELETE /take_strings_of

### Description
Removes the atom corresponding to the identifier and returns all of its strings.
See `Data::into_string`.

### Method
DELETE

### Endpoint
`/take_strings_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the strings.

### Response
#### Success Response (200)
- **Iterator<Item = String>** - An iterator over the removed strings.

### Response Example
```json
{
  "example": "[\"string\"]"
}
```
```

--------------------------------

### Userdata - Data Operations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Methods for getting, modifying, and taking raw data associated with an identifier.

```APIDOC
## GET /data_of

### Description
Returns references to all data corresponding to the identifier.

### Method
GET

### Endpoint
`/data_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the data.

### Response
#### Success Response (200)
- **Iterator<Item = &Data>** - An iterator over references to the Data.

### Response Example
```json
{
  "example": "[Data::Utf8(\"data\".into())]"
}
```

## PUT /data_mut_of

### Description
Returns mutable references to all data corresponding to the identifier.

### Method
PUT

### Endpoint
`/data_mut_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the data.

### Response
#### Success Response (200)
- **Iterator<Item = &mut Data>** - An iterator over mutable references to the Data.

### Response Example
```json
{
  "example": "[Data::Utf8(\"data1\".into())]"
}
```

## DELETE /take_data_of

### Description
Removes the atom corresponding to the identifier and returns all of its data.

### Method
DELETE

### Endpoint
`/take_data_of`

### Parameters
#### Query Parameters
- **ident** (impl Ident) - Required - The identifier for the data.

### Response
#### Success Response (200)
- **Iterator<Item = Data>** - An iterator over the removed Data.

### Response Example
```json
{
  "example": "[Data::Utf8(\"data\".into())]"
}
```
```

--------------------------------

### Blanket Implementations for Chapter

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Chapter.html

Details blanket implementations applied to the Chapter struct, providing generic functionalities.

```APIDOC
### Blanket Implementations
- impl<T> Any for T
  - fn type_id(&self) -> TypeId
- impl<T> Borrow<T> for T
  - fn borrow(&self) -> &T
- impl<T> BorrowMut<T> for T
  - fn borrow_mut(&mut self) -> &mut T
- impl<T> CloneToUninit for T
  - unsafe fn clone_to_uninit(&self, dest: *mut u8)
- impl<T> From<T> for T
  - fn from(t: T) -> T
- impl<T, U> Into<U> for T
  - fn into(self) -> U
- impl<T> ToOwned for T
  - type Owned = T
  - fn to_owned(&self) -> T
  - fn clone_into(&self, target: &mut T)
- impl<T, U> TryFrom<U> for T
  - type Error = Infallible
  - fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
- impl<T, U> TryInto<U> for T
  - type Error = <U as TryFrom<T>>::Error
  - fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
```

--------------------------------

### Macro const_assert

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/macro.const_assert.html

Documentation for the `const_assert` macro, including its definition and usage.

```APIDOC
## Macro const_assert

### Description
A macro for compile-time assertions.

### Summary
```rust
macro_rules! const_assert {
    ($x:expr $(,)?) => { ... };
}
```

### Source
[Link to source code if available]
```

--------------------------------

### Remove and Get All Artwork Images

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Removes and returns an iterator over all artwork images (`covr`) from the metadata.

```rust
pub fn take_artworks(&mut self) -> impl Iterator<Item = ImgBuf> + '_ 
```

--------------------------------

### Read Tag from Path

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Attempts to read an MPEG-4 audio tag directly from a file at the specified path. The path must implement `AsRef<Path>`.

```rust
pub fn read_from_path(path: impl AsRef<Path>) -> Result<Self>
```

--------------------------------

### Chapter Struct Definition

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Chapter.html

The primary structure for defining a chapter, containing its start time and title.

```rust
pub struct Chapter {
    pub start: Duration,
    pub title: String,
}
```

--------------------------------

### Take Chapter List

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Removes and returns a vector representing the chapter list.

```rust
pub fn take_chapter_list(&mut self) -> Vec<Chapter>
```

--------------------------------

### Remove and Get First Artwork Image

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Removes and returns the first artwork image (`covr`) from the metadata, if any.

```rust
pub fn take_artwork(&mut self) -> Option<ImgBuf>
```

--------------------------------

### Add All Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Adds multiple data entries to an existing atom or creates a new atom.

```APIDOC
## POST /userdata/add_all_data

### Description
If an atom corresponding to the identifier exists, the new data will be added to it, otherwise a new metadata item atom containing the data will be created.

### Method
POST

### Endpoint
/userdata/add_all_data

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
- **ident** (impl Ident + Into<DataIdent>) - Required - The identifier for the metadata.
- **data** (impl IntoIterator<Item = Data>) - Required - An iterator of data items to add.

### Request Example
```json
{
  "ident": "test",
  "data": [
    {
      "type": "Utf8",
      "value": "data1"
    },
    {
      "type": "Utf8",
      "value": "data2"
    }
  ]
}
```

### Response
#### Success Response (200)
- **status** (string) - Indicates success.

#### Response Example
```json
{
  "status": "success"
}
```
```

--------------------------------

### Get Freeform from DataIdent

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/enum.DataIdent.html

Retrieves a borrowed FreeformIdent if the DataIdent is of the Freeform variant. Returns None otherwise.

```rust
fn freeform(&self) -> Option<FreeformIdentBorrowed<'_>>
```

--------------------------------

### Get FourCC from DataIdent

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/enum.DataIdent.html

Retrieves the FourCC identifier if the DataIdent is of the FourCC variant. Returns None otherwise.

```rust
fn fourcc(&self) -> Option<Fourcc>
```

--------------------------------

### WriteConfig Constants

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.WriteConfig.html

Provides predefined WriteConfig instances for common use cases.

```APIDOC
### `DEFAULT`: WriteConfig

The default configuration for writing tags.

### `NONE`: WriteConfig

A configuration that would write no data at all.

#### Example Usage
```rust
use mp4ameta::WriteConfig;

let cfg = WriteConfig {
    write_meta_items: true,
    ..WriteConfig::NONE
};
```
```

--------------------------------

### Write MP4AMeta with Config

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Attempts to write the MPEG-4 audio tag to a specified path using a given write configuration. This will overwrite existing metadata.

```rust
pub fn write_with_path( &self, path: impl AsRef<Path>, cfg: &WriteConfig, ) -> Result<()>
```

--------------------------------

### Modify Image Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Illustrates how to get a mutable reference to an image's data and modify it. This requires mutable access to the Userdata.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Jpeg(b"image".to_vec()));
let img = tag.images_mut_of(&test).next().unwrap();
img.data.push('1' as u8);

let img = tag.images_of(&test).next().unwrap();
assert_eq!(img.data, b"image1");
```

--------------------------------

### FreeformIdentStatic Constructor

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/ident/type.FreeformIdentStatic.html

Provides the implementation for creating a new FreeformIdentStatic instance.

```APIDOC
### impl FreeformIdentStatic

#### `pub const fn new_static(mean: &'static str, name: &'static str) -> Self`

Creates a new freeform (`----`) ident with a static lifetime. Using this type _will avoid_ allocating the `mean` and `name` strings when inserting data into the `Userdata` struct.
```

--------------------------------

### Modify String Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Illustrates how to get a mutable reference to a string and modify it in place. Note that this requires mutable access to the Userdata.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Utf8("string".into()));
tag.strings_mut_of(&test).next().unwrap().push('1');
assert_eq!(tag.strings_of(&test).next().unwrap(), "string1");
```

--------------------------------

### Send, Sync, Unpin, UnsafeUnpin, UnwindSafe Implementations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

These are standard blanket implementations for thread safety and memory safety traits.

```APIDOC
## Blanket Implementations for Tag

### impl Send for Tag

### impl Sync for Tag

### impl Unpin for Tag

### impl UnsafeUnpin for Tag

### impl UnwindSafe for Tag
```

--------------------------------

### Chapter Struct

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Chapter.html

Defines the structure for a chapter, including its start time and title. It also notes limitations on chapter title length.

```APIDOC
## Struct Chapter

### Description
A chapter.
Note that chapter titles have a relatively small maximum size. For chapter lists this limit is 255 (`u8::MAX`); For chapter tracks this limit is 65535 (`u16::MAX`); If this limit is exceeded the title is truncated.

### Fields
- **start** (Duration) - The start of the chapter.
- **title** (String) - The title of the chapter.
```

--------------------------------

### Gapless Playback API

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Manage the gapless playback flag (`pgap`) for MP4 metadata.

```APIDOC
## GET /api/mp4ameta/gapless_playback

### Description
Retrieves the gapless playback flag (`pgap`) from the MP4 metadata.

### Method
GET

### Endpoint
/api/mp4ameta/gapless_playback

### Response
#### Success Response (200)
- **gapless_playback** (boolean) - True if gapless playback is enabled, false otherwise.

#### Response Example
```json
{
  "gapless_playback": true
}
```
```

```APIDOC
## POST /api/mp4ameta/gapless_playback

### Description
Sets the gapless playback flag to true (`pgap`) in the MP4 metadata.

### Method
POST

### Endpoint
/api/mp4ameta/gapless_playback

### Response
#### Success Response (200)
- **message** (string) - Confirmation message.

#### Response Example
```json
{
  "message": "Gapless playback flag set to true."
}
```
```

```APIDOC
## DELETE /api/mp4ameta/gapless_playback

### Description
Removes the gapless playback flag (`pgap`) from the MP4 metadata.

### Method
DELETE

### Endpoint
/api/mp4ameta/gapless_playback

### Response
#### Success Response (200)
- **message** (string) - Confirmation message.

#### Response Example
```json
{
  "message": "Gapless playback flag removed."
}
```
```

--------------------------------

### mp4ameta::ident DESCRIPTION Constant

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/ident/constant.DESCRIPTION.html

Documentation for the DESCRIPTION constant within the mp4ameta crate.

```APIDOC
## Constant DESCRIPTION

### Description
Represents the FourCC identifier for description metadata.

### Source
```rust
pub const DESCRIPTION: Fourcc;
```

### Details
This constant is associated with the `desc` identifier.
```

--------------------------------

### Get Mutable Chapters

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Returns a mutable slice of chapters. This method prefers the chapter list but will return the chapter track if the list is not available.

```rust
pub fn chapters_mut(&mut self) -> &mut Vec<Chapter>
```

--------------------------------

### Get Raw Data References

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Retrieves references to all `Data` items associated with a specific identifier. This is useful for inspecting the raw data without consuming it.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Utf8("data".into()));
assert_eq!(tag.data_of(&test).next().unwrap().string(), Some("data"));
```

--------------------------------

### Trait Conversions and Ownership

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/enum.DataIdent.html

Documentation for standard Rust traits used for type conversion and ownership management.

```APIDOC
## Trait Implementations

### Into<U>
- **fn into(self) -> U**: Calls `U::from(self)` to perform conversion.

### ToOwned
- **type Owned = T**: The resulting type after obtaining ownership.
- **fn to_owned(&self) -> T**: Creates owned data from borrowed data.
- **fn clone_into(&self, target: &mut T)**: Uses borrowed data to replace owned data.

### ToString
- **fn to_string(&self) -> String**: Converts the given value to a `String`.

### TryFrom<U>
- **type Error = Infallible**: The type returned in the event of a conversion error.
- **fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>**: Performs the conversion.

### TryInto<U>
- **type Error = <U as TryFrom<T>>::Error**: The type returned in the event of a conversion error.
- **fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>**: Performs the conversion.
```

--------------------------------

### Get Mutable Data References

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Obtains mutable references to `Data` items for a given identifier, allowing in-place modification. This requires mutable access to the `Userdata`.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Utf8("data".into()));
let data = tag.data_mut_of(&test).next().unwrap();
data.string_mut().unwrap().push('1');
assert_eq!(tag.strings_of(&test).next().unwrap(), "data1");
```

--------------------------------

### Media Flag Management

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Methods to manage boolean flags for compilation, gapless playback, and show movement.

```APIDOC
## Media Flag Management

### Description
Manage boolean metadata flags including compilation (cpil), gapless playback (pgap), and show movement (shwm).

### Methods
- compilation(): Returns compilation flag.
- set_compilation(): Sets compilation flag to true.
- remove_compilation(): Removes compilation flag.
- gapless_playback(): Returns gapless playback flag.
- set_gapless_playback(): Sets gapless playback flag to true.
- remove_gapless_playback(): Removes gapless playback flag.
- show_movement(): Returns show movement flag.
- set_show_movement(): Sets show movement flag to true.
- remove_show_movement(): Removes show movement flag.
```

--------------------------------

### Set All Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Tag.html

Replaces existing data for an identifier or creates a new metadata item atom with multiple data entries.

```APIDOC
## POST /userdata/set_all_data

### Description
If an atom corresponding to the identifier exists, its data will be replaced by the new data, otherwise a new metadata item atom containing the data will be created.

### Method
POST

### Endpoint
/userdata/set_all_data

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
- **ident** (impl Ident + Into<DataIdent>) - Required - The identifier for the metadata.
- **data** (impl IntoIterator<Item = Data>) - Required - An iterator of data items to set.

### Request Example
```json
{
  "ident": "test",
  "data": [
    {
      "type": "Utf8",
      "value": "data1"
    },
    {
      "type": "Utf8",
      "value": "data2"
    }
  ]
}
```

### Response
#### Success Response (200)
- **status** (string) - Indicates success.

#### Response Example
```json
{
  "status": "success"
}
```
```

--------------------------------

### Set and Get Raw Bytes Data

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Demonstrates setting raw byte data for a given Fourcc identifier and retrieving it. Use this for arbitrary binary data.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.set_data(test, Data::Reserved(b"data".to_vec()));
assert_eq!(tag.take_bytes_of(&test).next().unwrap(), b"data");
assert_eq!(tag.bytes_of(&test).next(), None);
```

--------------------------------

### Retain Data based on Predicate

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Shows how to retain metadata items based on a custom predicate function that checks the identifier and data. This example retains data where the identifier is not 'tst1'.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let tst1 = Fourcc(*b"tst1");
let tst2 = Fourcc(*b"tst2");

tag.add_data(tst1, Data::Utf8("data1".into()));
tag.add_data(tst2, Data::Utf8("data2".into()));

let mut data = tag.data().map(|(i, d)| d);
assert_eq!(data.next(), Some(&Data::Utf8("data1".into())));
assert_eq!(data.next(), Some(&Data::Utf8("data2".into())));
assert_eq!(data.next(), None);
drop(data);

tag.retain_data(|i, d| &tst1 != i);

let mut data = tag.data().map(|(i, d)| d);
assert_eq!(data.next(), Some(&Data::Utf8("data2".into())));
assert_eq!(data.next(), None);
```

--------------------------------

### Set All Metadata Items for an Identifier

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Shows how to set multiple data items for a single identifier. Existing data for that identifier is replaced. Asserts that all provided data items are present.

```rust
use mp4ameta::{Userdata, Data, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

let data = vec![
    Data::Utf8("data1".into()),
    Data::Utf8("data2".into()),
];
tag.set_all_data(test, data);

let mut strings = tag.strings_of(&test);
assert_eq!(strings.next(), Some("data1"));
assert_eq!(strings.next(), Some("data2"));
assert_eq!(strings.next(), None);
```

--------------------------------

### Mutably Iterate Over Userdata Strings

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.Userdata.html

Demonstrates obtaining mutable references to strings within Userdata, allowing direct modification of string content. The example appends a character to a string.

```rust
use mp4ameta::{Userdata, Data, DataIdent, Fourcc};

let mut tag = Userdata::default();
let test = Fourcc(*b"test");

tag.add_data(test, Data::Reserved(b"data".to_vec()));
tag.add_data(test, Data::Utf8("string".into()));

let (ident, data) = tag.strings_mut().next().unwrap();
data.push('1');

let test = DataIdent::Fourcc(test);
let mut strings = tag.strings();
assert_eq!(strings.next().unwrap(), (&test, "string1"));
assert_eq!(strings.next(), None);
```

--------------------------------

### Implement Copy for FreeformIdent

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/ident/struct.FreeformIdent.html

Enables copying of FreeformIdent instances.

```rust
impl<'a, T: Copy> Copy for FreeformIdent<'a, T>
```

--------------------------------

### Memory and Cloning Operations

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/struct.FreeformIdent.html

Methods for handling uninitialized memory copies and ownership cloning.

```APIDOC
## unsafe fn clone_to_uninit(&self, dest: *mut u8)

### Description
Performs copy-assignment from self to a destination pointer. This is a nightly-only experimental API.

### Parameters
- **dest** (*mut u8) - Required - The destination pointer to copy data into.
```

--------------------------------

### Chain fallible operations with and_then

Source: https://docs.rs/mp4ameta/0.13.0/mp4ameta/type.Result.html

Use and_then to chain operations that return a Result. The first example demonstrates mapping a value, while the second shows file system metadata access.

```rust
fn sq_then_to_string(x: u32) -> Result<String, &'static str> {
    x.checked_mul(x).map(|sq| sq.to_string()).ok_or("overflowed")
}

assert_eq!(Ok(2).and_then(sq_then_to_string), Ok(4.to_string()));
assert_eq!(Ok(1_000_000).and_then(sq_then_to_string), Err("overflowed"));
assert_eq!(Err("not a number").and_then(sq_then_to_string), Err("not a number"));
```

```rust
use std::{io::ErrorKind, path::Path};

// Note: on Windows "/" maps to "C:\"
let root_modified_time = Path::new("/").metadata().and_then(|md| md.modified());
assert!(root_modified_time.is_ok());

let should_fail = Path::new("/bad/path").metadata().and_then(|md| md.modified());
assert!(should_fail.is_err());
assert_eq!(should_fail.unwrap_err().kind(), ErrorKind::NotFound);
```
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