104 lines
2.6 KiB
Rust
104 lines
2.6 KiB
Rust
use std::fs;
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use std::str::FromStr;
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use std::fmt;
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use std::string::String;
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use std::string::ToString;
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use std::io::Read;
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use std::io::Write;
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pub struct FileLinked<T> {
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val: T,
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path: String,
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}
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impl<T> FileLinked<T>
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where
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T: FromStr + ToString + Default,
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{
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pub fn from_file(path: &str) -> Result<FileLinked<T>, String>
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{
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let meta = fs::metadata(path);
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match &meta {
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Ok(m) if m.is_file() => {
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let mut file = fs::OpenOptions::new().read(true).open(path).or_else(|_| {
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Err(format!("Unable to open file {}", path))
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})?;
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let mut s = String::new();
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file.read_to_string(&mut s).or_else(|_| {
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Err(String::from("Unable to read from file."))
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})?;
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let val = T::from_str(&s).or_else(|_| {
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Err(String::from("Unable to parse value from file."))
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})?;
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Ok(FileLinked {
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val,
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path: String::from(path),
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})
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}
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Ok(_) => Err(format!("{} is not a file.", path)),
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_ => {
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let result = FileLinked {
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val: T::default(),
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path: String::from(path),
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};
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result.write_data()?;
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Ok(result)
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}
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}
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}
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pub fn new(val: T, path: &str) -> Result<FileLinked<T>, String> {
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let result = FileLinked {
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val,
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path: String::from(path),
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};
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result.write_data()?;
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Ok(result)
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}
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pub fn write_data(&self) -> Result<(), String> {
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let mut file = fs::OpenOptions::new()
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.write(true)
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.create(true)
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.truncate(true)
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.open(&self.path)
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.or_else(|_| Err(format!("Unable to open path {}", self.path)))?;
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write!(file, "{}", self.val.to_string()).or_else(|_| {
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Err(String::from("Unable to write to file."))
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})?;
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Ok(())
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}
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pub fn readonly(&self) -> &T {
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&self.val
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}
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pub fn mutate<U, F: FnOnce(&mut T) -> U>(&mut self, op: F) -> Result<U, String> {
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let result = op(&mut self.val);
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self.write_data()?;
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Ok(result)
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}
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pub fn replace(&mut self, val: T) -> Result<(), String> {
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self.val = val;
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self.write_data()
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}
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}
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impl<T: fmt::Display> fmt::Display for FileLinked<T> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "{}", self.val)
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}
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}
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