341 lines
9.1 KiB
Rust
341 lines
9.1 KiB
Rust
//! A wrapper around an object that ties it to a physical file
|
|
|
|
extern crate serde;
|
|
|
|
use std::fmt;
|
|
use std::fs;
|
|
use std::io::prelude::*;
|
|
use std::path;
|
|
|
|
use serde::de::DeserializeOwned;
|
|
use serde::Serialize;
|
|
|
|
/// A wrapper around an object `T` that ties the object to a physical file
|
|
pub struct FileLinked<T>
|
|
where
|
|
T: Serialize,
|
|
{
|
|
val: T,
|
|
path: path::PathBuf,
|
|
}
|
|
|
|
impl<T> FileLinked<T>
|
|
where
|
|
T: Serialize,
|
|
{
|
|
/// Returns a readonly reference of `T`
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// # use file_linked::*;
|
|
/// # use serde::{Deserialize, Serialize};
|
|
/// # use std::fmt;
|
|
/// # use std::string::ToString;
|
|
/// # use std::path;
|
|
/// #
|
|
/// # #[derive(Deserialize, Serialize)]
|
|
/// # struct Test {
|
|
/// # pub a: u32,
|
|
/// # pub b: String,
|
|
/// # pub c: f64
|
|
/// # }
|
|
/// #
|
|
/// # fn main() {
|
|
/// let test = Test {
|
|
/// a: 1,
|
|
/// b: String::from("two"),
|
|
/// c: 3.0
|
|
/// };
|
|
///
|
|
/// let linked_test = FileLinked::new(test, path::PathBuf::from("./temp"))
|
|
/// .expect("Unable to create file linked object");
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, 1);
|
|
/// assert_eq!(linked_test.readonly().b, String::from("two"));
|
|
/// assert_eq!(linked_test.readonly().c, 3.0);
|
|
/// #
|
|
/// # std::fs::remove_file("./temp").expect("Unable to remove file");
|
|
/// # }
|
|
/// ```
|
|
pub fn readonly(&self) -> &T {
|
|
&self.val
|
|
}
|
|
|
|
/// Creates a new [`FileLinked`] object of type `T` stored to the file given by `path`.
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// # use file_linked::*;
|
|
/// # use serde::{Deserialize, Serialize};
|
|
/// # use std::fmt;
|
|
/// # use std::string::ToString;
|
|
/// # use std::path;
|
|
/// #
|
|
/// #[derive(Deserialize, Serialize)]
|
|
/// struct Test {
|
|
/// pub a: u32,
|
|
/// pub b: String,
|
|
/// pub c: f64
|
|
/// }
|
|
///
|
|
/// # fn main() {
|
|
/// let test = Test {
|
|
/// a: 1,
|
|
/// b: String::from("two"),
|
|
/// c: 3.0
|
|
/// };
|
|
///
|
|
/// let linked_test = FileLinked::new(test, path::PathBuf::from("./temp"))
|
|
/// .expect("Unable to create file linked object");
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, 1);
|
|
/// assert_eq!(linked_test.readonly().b, String::from("two"));
|
|
/// assert_eq!(linked_test.readonly().c, 3.0);
|
|
/// #
|
|
/// # std::fs::remove_file("./temp").expect("Unable to remove file");
|
|
/// # }
|
|
/// ```
|
|
pub fn new(val: T, path: path::PathBuf) -> Result<FileLinked<T>, String> {
|
|
if path.is_file() {
|
|
return Err(format!("{} is not a valid file path", path.display()));
|
|
}
|
|
|
|
let result = FileLinked { val, path };
|
|
|
|
result.write_data()?;
|
|
|
|
Ok(result)
|
|
}
|
|
|
|
fn write_data(&self) -> Result<(), String> {
|
|
let mut file = fs::OpenOptions::new()
|
|
.write(true)
|
|
.create(true)
|
|
.truncate(true)
|
|
.open(&self.path)
|
|
.map_err(|_| format!("Unable to open path {}", self.path.display()))?;
|
|
|
|
write!(
|
|
file,
|
|
"{}",
|
|
serde_json::to_string(&self.val).map_err(|e| e.to_string())?
|
|
)
|
|
.or_else(|_| Err(String::from("Unable to write to file.")))?;
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Modifies the data contained in a `FileLinked` object using a callback `op` that has a mutable reference to the
|
|
/// underlying data. After the mutable operation is performed the data is written to a file to synchronize the state.
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// # use file_linked::*;
|
|
/// # use serde::{Deserialize, Serialize};
|
|
/// # use std::fmt;
|
|
/// # use std::string::ToString;
|
|
/// # use std::path;
|
|
/// #
|
|
/// # #[derive(Deserialize, Serialize)]
|
|
/// # struct Test {
|
|
/// # pub a: u32,
|
|
/// # pub b: String,
|
|
/// # pub c: f64
|
|
/// # }
|
|
/// #
|
|
/// # fn main() -> Result<(), String> {
|
|
/// let test = Test {
|
|
/// a: 1,
|
|
/// b: String::from(""),
|
|
/// c: 0.0
|
|
/// };
|
|
///
|
|
/// let mut linked_test = FileLinked::new(test, path::PathBuf::from("./temp"))
|
|
/// .expect("Unable to create file linked object");
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, 1);
|
|
///
|
|
/// linked_test.mutate(|t| t.a = 2)?;
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, 2);
|
|
/// #
|
|
/// # std::fs::remove_file("./temp").expect("Unable to remove file");
|
|
/// #
|
|
/// # Ok(())
|
|
/// # }
|
|
/// ```
|
|
pub fn mutate<U, F: FnOnce(&mut T) -> U>(&mut self, op: F) -> Result<U, String> {
|
|
let result = op(&mut self.val);
|
|
|
|
self.write_data()?;
|
|
|
|
Ok(result)
|
|
}
|
|
|
|
/// Replaces the value held by the `FileLinked` object with `val`. After replacing the object will be written to a file.
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// # use file_linked::*;
|
|
/// # use serde::{Deserialize, Serialize};
|
|
/// # use std::fmt;
|
|
/// # use std::string::ToString;
|
|
/// # use std::path;
|
|
/// #
|
|
/// # #[derive(Deserialize, Serialize)]
|
|
/// # struct Test {
|
|
/// # pub a: u32,
|
|
/// # pub b: String,
|
|
/// # pub c: f64
|
|
/// # }
|
|
/// #
|
|
/// # fn main() -> Result<(), String> {
|
|
/// let test = Test {
|
|
/// a: 1,
|
|
/// b: String::from(""),
|
|
/// c: 0.0
|
|
/// };
|
|
///
|
|
/// let mut linked_test = FileLinked::new(test, path::PathBuf::from("./temp"))
|
|
/// .expect("Unable to create file linked object");
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, 1);
|
|
///
|
|
/// linked_test.replace(Test {
|
|
/// a: 2,
|
|
/// b: String::from(""),
|
|
/// c: 0.0
|
|
/// })?;
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, 2);
|
|
/// #
|
|
/// # std::fs::remove_file("./temp").expect("Unable to remove file");
|
|
/// #
|
|
/// # Ok(())
|
|
/// # }
|
|
/// ```
|
|
pub fn replace(&mut self, val: T) -> Result<(), String> {
|
|
self.val = val;
|
|
|
|
self.write_data()
|
|
}
|
|
}
|
|
|
|
impl<T> FileLinked<T>
|
|
where
|
|
T: Serialize + DeserializeOwned,
|
|
{
|
|
/// Deserializes an object `T` from the file given by `path`
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// # use file_linked::*;
|
|
/// # use serde::{Deserialize, Serialize};
|
|
/// # use std::fmt;
|
|
/// # use std::string::ToString;
|
|
/// # use std::fs;
|
|
/// # use std::fs::OpenOptions;
|
|
/// # use std::io::Write;
|
|
/// # use std::path;
|
|
/// #
|
|
/// # #[derive(Deserialize, Serialize)]
|
|
/// # struct Test {
|
|
/// # pub a: u32,
|
|
/// # pub b: String,
|
|
/// # pub c: f64
|
|
/// # }
|
|
/// #
|
|
/// # fn main() -> Result<(), String> {
|
|
/// let test = Test {
|
|
/// a: 1,
|
|
/// b: String::from("2"),
|
|
/// c: 3.0
|
|
/// };
|
|
///
|
|
/// let path = path::PathBuf::from("./temp");
|
|
///
|
|
/// let mut file = OpenOptions::new()
|
|
/// .write(true)
|
|
/// .create(true)
|
|
/// .open(path.clone())
|
|
/// .expect("Unable to create file");
|
|
///
|
|
/// write!(file, "{}", serde_json::to_string(&test)
|
|
/// .expect("Unable to serialize object"))
|
|
/// .expect("Unable to write file");
|
|
///
|
|
/// drop(file);
|
|
///
|
|
/// let mut linked_test = FileLinked::<Test>::from_file(path)
|
|
/// .expect("Unable to create file linked object");
|
|
///
|
|
/// assert_eq!(linked_test.readonly().a, test.a);
|
|
/// assert_eq!(linked_test.readonly().b, test.b);
|
|
/// assert_eq!(linked_test.readonly().c, test.c);
|
|
/// #
|
|
/// # std::fs::remove_file("./temp").expect("Unable to remove file");
|
|
/// #
|
|
/// # Ok(())
|
|
/// # }
|
|
/// ```
|
|
pub fn from_file(path: path::PathBuf) -> Result<FileLinked<T>, String> {
|
|
let meta = fs::metadata(&path);
|
|
|
|
match &meta {
|
|
Ok(m) if m.is_file() && path.is_file()=> {
|
|
let file = fs::OpenOptions::new()
|
|
.read(true)
|
|
.open(&path)
|
|
.map_err(|_| format!("Unable to open file {}", path.display()))?;
|
|
|
|
let val = serde_json::from_reader(file)
|
|
.map_err(|_| String::from("Unable to parse value from file."))?;
|
|
|
|
Ok(FileLinked { val, path })
|
|
}
|
|
Ok(_) => Err(format!("{} is not a file.", path.display())),
|
|
_ => Err(format!("Error parsing file path {}", path.display())),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T> fmt::Debug for FileLinked<T>
|
|
where
|
|
T: fmt::Debug + Serialize,
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
write!(f, "{:?}", self.val)
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
use std::fs;
|
|
|
|
#[test]
|
|
fn test_mutate() -> Result<(), String> {
|
|
let list = vec![1, 2, 3, 4];
|
|
let mut file_linked_list = FileLinked::new(list, path::PathBuf::from("test.txt"))?;
|
|
|
|
assert_eq!(format!("{:?}", file_linked_list.readonly()), "[1, 2, 3, 4]");
|
|
|
|
file_linked_list.mutate(|v1| v1.push(5))?;
|
|
|
|
assert_eq!(
|
|
format!("{:?}", file_linked_list.readonly()),
|
|
"[1, 2, 3, 4, 5]"
|
|
);
|
|
|
|
file_linked_list.mutate(|v1| v1[1] = 1)?;
|
|
|
|
assert_eq!(
|
|
format!("{:?}", file_linked_list.readonly()),
|
|
"[1, 1, 3, 4, 5]"
|
|
);
|
|
|
|
fs::remove_file("test.txt").expect("Unable to remove file");
|
|
|
|
Ok(())
|
|
}
|
|
}
|