Add --format flag to specify formats

src/cli.rs

@@ -10,7 +10,7 @@ use clap::Parser;
 use fs_err as fs;
 use once_cell::sync::OnceCell;
 
-use crate::{Opts, QuestionPolicy, Subcommand};
+use crate::{error::FinalError, Opts, QuestionPolicy, Subcommand};
 
 /// Whether to enable accessible output (removes info output and reduces other
 /// output, removes visual markers like '[' and ']').
@@ -26,6 +26,13 @@ impl Opts {
     pub fn parse_args() -> crate::Result<(Self, QuestionPolicy)> {
         let mut opts = Self::parse();
 
+        if opts.format.as_ref().map(String::is_empty).unwrap_or(false) {
+            let error = FinalError::with_title("Given --format flag is empty")
+                .hint("Try passing a supported extension, like --format tar.gz");
+
+            return Err(error.into());
+        }
+
         ACCESSIBLE.set(opts.accessible).unwrap();
 
         let (Subcommand::Compress { files, .. }

src/commands.rs

@@ -46,7 +46,8 @@ fn represents_several_files(files: &[PathBuf]) -> bool {
 pub fn run(args: Opts, question_policy: QuestionPolicy) -> crate::Result<()> {
     match args.cmd {
         Subcommand::Compress { mut files, output: output_path } => {
-            // If the output_path file exists and is the same as some of the input files, warn the user and skip those inputs (in order to avoid compression recursion)
+            // If the output_path file exists and is the same as some of the input files, warn the
+            // user and skip those inputs (in order to avoid compression recursion)
             if output_path.exists() {
                 clean_input_files_if_needed(&mut files, &fs::canonicalize(&output_path)?);
             }
@@ -56,7 +57,15 @@ pub fn run(args: Opts, question_policy: QuestionPolicy) -> crate::Result<()> {
             }
 
             // Formats from path extension, like "file.tar.gz.xz" -> vec![Tar, Gzip, Lzma]
-            let mut formats = extension::extensions_from_path(&output_path);
+            let mut formats = if let Some(format) = args.format {
+                extension::from_format_text(&format).ok_or_else(|| {
+                    FinalError::with_title(format!("Cannot compress to '{}'.", to_utf(&output_path)))
+                        .detail("Supplied compression format is not valid")
+                        .hint("Check --help for all supported formats")
+                })
+            } else {
+                Ok(extension::extensions_from_path(&output_path))
+            }?;
 
             if formats.is_empty() {
                 let error = FinalError::with_title(format!("Cannot compress to '{}'.", to_utf(&output_path)))

src/extension.rs

@@ -102,8 +102,54 @@ impl fmt::Display for CompressionFormat {
     }
 }
 
-// use crate::extension::CompressionFormat::*;
-//
+/// Returns the list of compression formats that correspond to the given extension text.
+///
+/// # Examples:
+/// - `"tar" => Some(&[Tar])`
+/// - `"tgz" => Some(&[Tar, Gzip])`
+///
+/// Note that the text given as input should not contain any dots, otherwise, None will be returned.
+pub fn compression_formats_from_text(extension: &str) -> Option<&'static [CompressionFormat]> {
+    match extension {
+        "tar" => Some(&[Tar]),
+        "tgz" => Some(&[Tar, Gzip]),
+        "tbz" | "tbz2" => Some(&[Tar, Bzip]),
+        "tlz4" => Some(&[Tar, Lz4]),
+        "txz" | "tlzma" => Some(&[Tar, Lzma]),
+        "tsz" => Some(&[Tar, Snappy]),
+        "tzst" => Some(&[Tar, Zstd]),
+        "zip" => Some(&[Zip]),
+        "bz" | "bz2" => Some(&[Bzip]),
+        "gz" => Some(&[Gzip]),
+        "lz4" => Some(&[Lz4]),
+        "xz" | "lzma" => Some(&[Lzma]),
+        "sz" => Some(&[Snappy]),
+        "zst" => Some(&[Zstd]),
+        _ => None,
+    }
+}
+
+/// Grab a user given format, and parse it.
+///
+/// # Examples:
+/// - `"tar.gz"  => Extension { ... [Tar, Gz] }`
+/// - `".tar.gz" => Extension { ... [Tar, Gz] }`
+pub fn from_format_text(format: &str) -> Option<Vec<Extension>> {
+    let mut extensions = vec![];
+
+    // Ignore all dots, use filter to ignore dots at first and last char leaving empty pieces
+    let extension_pieces = format.split('.').filter(|piece| !piece.is_empty());
+    for piece in extension_pieces {
+        let extension = match compression_formats_from_text(piece) {
+            Some(formats) => Extension::new(formats, piece),
+            None => return None,
+        };
+        extensions.push(extension);
+    }
+
+    extensions.reverse();
+    Some(extensions)
+}
 
 /// Extracts extensions from a path,
 /// return both the remaining path and the list of extension objects
@@ -120,25 +166,10 @@ pub fn separate_known_extensions_from_name(mut path: &Path) -> (&Path, Vec<Exten
 
     // While there is known extensions at the tail, grab them
     while let Some(extension) = path.extension().and_then(OsStr::to_str) {
-        let formats: &[CompressionFormat] = match extension {
-            "tar" => &[Tar],
-            "tgz" => &[Tar, Gzip],
-            "tbz" | "tbz2" => &[Tar, Bzip],
-            "tlz4" => &[Tar, Lz4],
-            "txz" | "tlzma" => &[Tar, Lzma],
-            "tsz" => &[Tar, Snappy],
-            "tzst" => &[Tar, Zstd],
-            "zip" => &[Zip],
-            "bz" | "bz2" => &[Bzip],
-            "gz" => &[Gzip],
-            "lz4" => &[Lz4],
-            "xz" | "lzma" => &[Lzma],
-            "sz" => &[Snappy],
-            "zst" => &[Zstd],
-            _ => break,
+        let extension = match compression_formats_from_text(extension) {
+            Some(formats) => Extension::new(formats, extension),
+            None => break,
         };
-
-        let extension = Extension::new(formats, extension);
         extensions.push(extension);
 
         // Update for the next iteration

src/opts.rs

@@ -20,6 +20,10 @@ pub struct Opts {
     pub no: bool,
 
     /// Activate accessibility mode, reducing visual noise
+    #[clap(short = 'f', long)]
+    pub format: Option<String>,
+
+    /// Ignore autodetection, specifying
     #[clap(short = 'A', long, env = "ACCESSIBLE")]
     pub accessible: bool,