Added ::= src/writing.rs

src/writing.rs

@@ -0,0 +1,123 @@
+/*********************** GNU General Public License 3.0 ***********************\
+|                                                                              |
+|  Copyright (C) 2024 Kevin Matthes                                            |
+|                                                                              |
+|  This program is free software: you can redistribute it and/or modify        |
+|  it under the terms of the GNU General Public License as published by        |
+|  the Free Software Foundation, either version 3 of the License, or           |
+|  (at your option) any later version.                                         |
+|                                                                              |
+|  This program is distributed in the hope that it will be useful,             |
+|  but WITHOUT ANY WARRANTY; without even the implied warranty of              |
+|  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               |
+|  GNU General Public License for more details.                                |
+|                                                                              |
+|  You should have received a copy of the GNU General Public License           |
+|  along with this program.  If not, see <https://www.gnu.org/licenses/>.      |
+|                                                                              |
+\******************************************************************************/
+
+use std::{io::Write, path::PathBuf};
+use sysexits::Result;
+
+/// Truncate files given as instances convertible to a [`std::path::PathBuf`].
+pub trait PathBufLikeTruncation<T>
+where
+    PathBuf: From<T>,
+{
+    /// Truncate the given file using the data this method is called on.
+    ///
+    /// This method behaves just like
+    /// [`crate::PathBufLikeTruncation::truncate_silently`] despite also
+    /// printing error messages to [`std::io::Stderr`].
+    ///
+    /// # Errors
+    ///
+    /// See [`sysexits::ExitCode`].
+    fn truncate_loudly(self, destination: T) -> Result<()>;
+
+    /// Truncate the given file using the data this method is called on.
+    ///
+    /// The data this method is called on will be converted to a [`String`] and
+    /// written to the given file.  The data therefore needs to implement
+    /// [`ToString`], the file needs to be convertible to a
+    /// [`std::path::PathBuf`].  The file will be truncated.
+    ///
+    /// The return value is either the unit type, in case of success, or a
+    /// [`sysexits::ExitCode`] to describe the error cause, otherwise.
+    ///
+    /// Error messages are not written to [`std::io::Stderr`].
+    ///
+    /// # Errors
+    ///
+    /// See [`sysexits::ExitCode`].
+    fn truncate_silently(self, destination: T) -> Result<()>;
+}
+
+impl<P, T: ToString> PathBufLikeTruncation<P> for T
+where
+    PathBuf: From<P>,
+{
+    fn truncate_loudly(self, destination: P) -> Result<()> {
+        match std::fs::File::options()
+            .append(false)
+            .create(true)
+            .truncate(true)
+            .write(true)
+            .open(PathBuf::from(destination))
+        {
+            Err(e) => {
+                eprintln!("{e}");
+                Err(e.into())
+            }
+            Ok(mut file) => {
+                let bytes = self.to_string().as_bytes().to_vec();
+
+                match file.write(&bytes) {
+                    Err(e) => {
+                        eprintln!("{e}");
+                        Err(e.into())
+                    }
+                    Ok(n) => {
+                        if n == bytes.len() {
+                            Ok(())
+                        } else {
+                            eprintln!(
+                                "Creating an exact copy was not possible."
+                            );
+                            Err(sysexits::ExitCode::IoErr)
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    fn truncate_silently(self, destination: P) -> Result<()> {
+        match std::fs::File::options()
+            .append(false)
+            .create(true)
+            .truncate(true)
+            .write(true)
+            .open(PathBuf::from(destination))
+        {
+            Err(e) => Err(e.into()),
+            Ok(mut file) => {
+                let bytes = self.to_string().as_bytes().to_vec();
+
+                match file.write(&bytes) {
+                    Err(e) => Err(e.into()),
+                    Ok(n) => {
+                        if n == bytes.len() {
+                            Ok(())
+                        } else {
+                            Err(sysexits::ExitCode::IoErr)
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+/******************************************************************************/