Move file-specific options under OutFile (#529)

This PR is addressing #220. It's not super important but it's a breaking
change, so if it's something we want to do then I thought I should get
it in now before the next release.

- [x] pretend can become another variant of OutFile, probably
OutFile::None, as that's what it essentially is - just another output
destination and not a separate option
- [x] ~~backup and~~ preserve_attrs should become properties of
OutFile::Path variant (so that it would contain Path { path, ~~backup,~~
preserve_attrs }) as they don't have any effect on any other output and
so semantically belong there best

Closes #220

src/lib.rs

@@ -76,15 +76,36 @@ pub mod internal_tests {
 
 #[derive(Clone, Debug)]
 pub enum OutFile {
-    /// Path(None) means same as input
-    Path(Option<PathBuf>),
+    /// Don't actually write any output, just calculate the best results.
+    None,
+    /// Write output to a file.
+    ///
+    /// * `path`: Path to write the output file. `None` means same as input.
+    /// * `preserve_attrs`: Ensure the output file has the same permissions & timestamps as the input file.
+    Path {
+        path: Option<PathBuf>,
+        preserve_attrs: bool,
+    },
+    /// Write to standard output.
     StdOut,
 }
 
 impl OutFile {
+    /// Construct a new `OutFile` with the given path.
+    ///
+    /// This is a convenience method for `OutFile::Path { path: Some(path), preserve_attrs: false }`.
+    pub fn from_path(path: PathBuf) -> Self {
+        OutFile::Path {
+            path: Some(path),
+            preserve_attrs: false,
+        }
+    }
+
     pub fn path(&self) -> Option<&Path> {
         match *self {
-            OutFile::Path(Some(ref p)) => Some(p.as_path()),
+            OutFile::Path {
+                path: Some(ref p), ..
+            } => Some(p.as_path()),
             _ => None,
         }
     }
@@ -138,18 +159,10 @@ pub struct Options {
     ///
     /// Default: `false`
     pub check: bool,
-    /// Don't actually write any output, just calculate the best results.
-    ///
-    /// Default: `false`
-    pub pretend: bool,
     /// Write to output even if there was no improvement in compression.
     ///
     /// Default: `false`
     pub force: bool,
-    /// Ensure the output file has the same permissions as the input file.
-    ///
-    /// Default: `false`
-    pub preserve_attrs: bool,
     /// Which RowFilters to try on the file
     ///
     /// Default: `None,Sub,Entropy,Bigrams`
@@ -296,10 +309,8 @@ impl Default for Options {
         Options {
             backup: false,
             check: false,
-            pretend: false,
             fix_errors: false,
             force: false,
-            preserve_attrs: false,
             filter: indexset! {RowFilter::None, RowFilter::Sub, RowFilter::Entropy, RowFilter::Bigrams},
             interlace: Some(Interlacing::None),
             optimize_alpha: false,
@@ -416,7 +427,13 @@ pub fn optimize(input: &InFile, output: &OutFile, opts: &Options) -> PngResult<(
     let opt_metadata_preserved;
     let in_data = match *input {
         InFile::Path(ref input_path) => {
-            if opts.preserve_attrs {
+            if matches!(
+                output,
+                OutFile::Path {
+                    preserve_attrs: true,
+                    ..
+                }
+            ) {
                 opt_metadata_preserved = input_path
                     .metadata()
                     .map_err(|err| {
@@ -458,8 +475,8 @@ pub fn optimize(input: &InFile, output: &OutFile, opts: &Options) -> PngResult<(
     if is_fully_optimized(in_data.len(), optimized_output.len(), opts) {
         match (output, input) {
             // if p is None, it also means same as the input path
-            (OutFile::Path(ref p), InFile::Path(ref input_path))
-                if p.as_ref().map_or(true, |p| p == input_path) =>
+            (OutFile::Path { path, .. }, InFile::Path(ref input_path))
+                if path.as_ref().map_or(true, |p| p == input_path) =>
             {
                 info!("{}: Could not optimize further, no change written", input);
                 return Ok(());
@@ -484,20 +501,18 @@ pub fn optimize(input: &InFile, output: &OutFile, opts: &Options) -> PngResult<(
         )
     };
 
-    if opts.pretend {
-        info!("{}: Running in pretend mode, no output", savings);
-        return Ok(());
-    }
-
     match (output, input) {
-        (&OutFile::StdOut, _) | (&OutFile::Path(None), &InFile::StdIn) => {
+        (OutFile::None, _) => {
+            info!("{}: Running in pretend mode, no output", savings);
+        }
+        (&OutFile::StdOut, _) | (&OutFile::Path { path: None, .. }, &InFile::StdIn) => {
             let mut buffer = BufWriter::new(stdout());
             buffer
                 .write_all(&optimized_output)
                 .map_err(|e| PngError::new(&format!("Unable to write to stdout: {}", e)))?;
         }
-        (OutFile::Path(ref output_path), _) => {
-            let output_path = output_path
+        (OutFile::Path { path, .. }, _) => {
+            let output_path = path
                 .as_ref()
                 .map(|p| p.as_path())
                 .unwrap_or_else(|| input.path().unwrap());

src/main.rs

@@ -376,12 +376,16 @@ fn collect_files(
             }
             continue;
         };
-        let out_file = if let Some(ref out_dir) = *out_dir {
-            let out_path = Some(out_dir.join(input.file_name().unwrap()));
-            OutFile::Path(out_path)
-        } else {
-            (*out_file).clone()
-        };
+        let out_file =
+            if let (Some(out_dir), &OutFile::Path { preserve_attrs, .. }) = (out_dir, out_file) {
+                let path = Some(out_dir.join(input.file_name().unwrap()));
+                OutFile::Path {
+                    path,
+                    preserve_attrs,
+                }
+            } else {
+                (*out_file).clone()
+            };
         let in_file = if using_stdin {
             InFile::StdIn
         } else {
@@ -459,10 +463,15 @@ fn parse_opts_into_struct(
         None
     };
 
-    let out_file = if matches.get_flag("stdout") {
+    let out_file = if matches.get_flag("pretend") {
+        OutFile::None
+    } else if matches.get_flag("stdout") {
         OutFile::StdOut
     } else {
-        OutFile::Path(matches.get_one::<PathBuf>("output_file").cloned())
+        OutFile::Path {
+            path: matches.get_one::<PathBuf>("output_file").cloned(),
+            preserve_attrs: matches.get_flag("preserve"),
+        }
     };
 
     opts.optimize_alpha = matches.get_flag("alpha");
@@ -482,10 +491,6 @@ fn parse_opts_into_struct(
 
     opts.check = matches.get_flag("check");
 
-    opts.pretend = matches.get_flag("pretend");
-
-    opts.preserve_attrs = matches.get_flag("preserve");
-
     opts.bit_depth_reduction = !matches.get_flag("no-bit-reduction");
 
     opts.color_type_reduction = !matches.get_flag("no-color-reduction");

tests/filters.rs

@@ -20,10 +20,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 fn test_it_converts(

tests/flags.rs

@@ -26,10 +26,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 /// Add callback to allow checks before the output file is deleted again
@@ -518,8 +515,10 @@ fn preserve_attrs() {
     #[cfg(feature = "filetime")]
     let mtime_canon = RefCell::new(filetime::FileTime::from_unix_time(0, 0));
 
-    let (output, mut opts) = get_opts(&input);
-    opts.preserve_attrs = true;
+    let (mut output, opts) = get_opts(&input);
+    if let OutFile::Path { preserve_attrs, .. } = &mut output {
+        *preserve_attrs = true;
+    }
 
     #[cfg(feature = "filetime")]
     let callback_pre = |path_in: &Path| {

tests/interlaced.rs

@@ -22,10 +22,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 fn test_it_converts(

tests/interlacing.rs

@@ -17,10 +17,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 fn test_it_converts(

tests/lib.rs

@@ -37,7 +37,7 @@ fn optimize_from_memory_apng() {
 fn optimize() {
     let result = oxipng::optimize(
         &"tests/files/fully_optimized.png".into(),
-        &OutFile::Path(None),
+        &OutFile::None,
         &Options::default(),
     );
     assert!(result.is_ok());
@@ -47,7 +47,7 @@ fn optimize() {
 fn optimize_corrupted() {
     let result = oxipng::optimize(
         &"tests/files/corrupted_header.png".into(),
-        &OutFile::Path(None),
+        &OutFile::None,
         &Options::default(),
     );
     assert!(result.is_err());
@@ -57,7 +57,7 @@ fn optimize_corrupted() {
 fn optimize_apng() {
     let result = oxipng::optimize(
         &"tests/files/apng_file.png".into(),
-        &OutFile::Path(None),
+        &OutFile::None,
         &Options::from_preset(0),
     );
     assert!(result.is_ok());

tests/reduction.rs

@@ -21,10 +21,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 fn test_it_converts(

tests/regression.rs

@@ -20,10 +20,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 fn test_it_converts(
@@ -295,7 +292,7 @@ fn issue_92_filter_5() {
     let input = "tests/files/issue-92.png";
     let (_, mut opts) = get_opts(Path::new(input));
     opts.filter = [RowFilter::MinSum].iter().cloned().collect();
-    let output = OutFile::Path(Some(Path::new(input).with_extension("-f5-out.png")));
+    let output = OutFile::from_path(Path::new(input).with_extension("-f5-out.png"));
 
     test_it_converts(
         input,

tests/strategies.rs

@@ -19,10 +19,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     filter.insert(RowFilter::None);
     options.filter = filter;
 
-    (
-        OutFile::Path(Some(input.with_extension("out.png"))),
-        options,
-    )
+    (OutFile::from_path(input.with_extension("out.png")), options)
 }
 
 fn test_it_converts(