Struct File

pub struct File<T, F> { /* private fields */ }

An evaluator for files.

This evaluator reads modules from files of a specific format. It uses Module as the top-level format of the module and serde to parse the contents of the file.

• File is capable of detecting import-cycles between modules.

• Import paths are resolved relative to the path of the importer module.

Example

use module::Merge;
use serde::Deserialize;

#[derive(Deserialize, Merge)]
struct Config {
    key: String,
    items: Vec<i32>,
}

let mut file = File::json();

// `config.json`:
// --------------
// {
//   "key": "424242",
//   "items": [1]
// }
assert!(file.read("config.json").is_ok());

// `config-extra.json`:
// --------------------
// {
//   "items": [3, 6, 0]
// }
assert!(file.read("config-extra.json").is_ok());

let config: Config = file.finish().unwrap();
assert_eq!(config.key, "424242");
assert_eq!(config.items, &[1, 3, 6, 0]);

Implementations

impl<T, F> File<T, F>

pub fn new(format: F) -> Self

Create a new File that reads files according to format.

pub fn format(&self) -> &F

Get a reference to the Format used.

pub fn format_mut(&mut self) -> &mut F

Get a mutable reference to the Format used.

pub fn finish(self) -> Option<T>

Finish the evaluation and return the final value.

Returns None if no file has been read() successfully. Otherwise, it returns Some(value).

Example

let mut file = File::json();
assert_eq!(file.finish(), None);

let mut file = File::json();
assert!(file.read("non_existent.json").is_err());
assert_eq!(file.finish(), None);

let mut file = File::json();
assert!(file.read("exists.json").is_ok());
assert!(matches!(file.finish(), Some(_)));

impl<T, F> File<T, F>

where T: Merge + DeserializeOwned, F: Format,

pub fn read<P>(&mut self, path: P) -> Result<(), Error>

where P: AsRef<Path>,

Read the module at path.

See the type-level docs for more information

impl<T> File<T, Json>

pub fn json() -> Self

Available on crate feature json only.

Create a new File that reads Json files.

See: Json.

Equivalent to: File::new(Json::default())

impl<T> File<T, Toml>

pub fn toml() -> Self

Available on crate feature toml only.

Create a new File that reads Toml files.

See: Toml.

Equivalent to: File::new(Toml::default())

impl<T> File<T, Yaml>

pub fn yaml() -> Self

Available on crate feature yaml only.

Create a new File that reads Yaml files.

See: Yaml.

Equivalent to: File::new(Yaml::default())

Trait Implementations

impl<T: Debug, F: Debug> Debug for File<T, F>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T, F> Default for File<T, F>

where F: Default,

fn default() -> Self

Returns the “default value” for a type.