Add --list flag

Related to #6

src/bin/main.rs

@@ -35,6 +35,13 @@ mod args {
         /// if set, no change will actually be made to the Cargo.toml file, simulating what would be done instead.
         pub dry_run: bool,
 
+        #[argh(option, short = 'l')]
+        /// provide any number N to limit the output to the N biggest files, ascending.
+        ///
+        /// if to 0, list all entries that would be in the crate with the current configuration.
+        /// Otherwise list the given amount of entries.
+        pub list: Option<usize>,
+
         #[argh(option, from_str_fn(parse_size))]
         /// if set, and the estimated compressed size of the package would exceed the given size, i.e. 40KB, the command
         /// will exit with a non-zero exit code.
@@ -75,6 +82,7 @@ fn main() -> anyhow::Result<()> {
         version,
         reset_manifest: reset,
         dry_run,
+        list,
         package_size_limit,
         #[cfg(feature = "dev-support")]
         save_package_for_unit_test,
@@ -88,6 +96,7 @@ fn main() -> anyhow::Result<()> {
             reset,
             dry_run,
             colored_output: atty::is(atty::Stream::Stdout),
+            list,
             package_size_limit,
             #[cfg(feature = "dev-support")]
             save_package_for_unit_test,

src/lib.rs

@@ -28,7 +28,7 @@ fn report_lean_crate(mut out: impl std::io::Write) -> std::io::Result<()> {
 fn report_savings(
     total_size_in_bytes: u64,
     total_files: u64,
-    mut wasted_files: Vec<WastedFile>,
+    wasted_files: Vec<WastedFile>,
     mut out: impl std::io::Write,
 ) -> std::io::Result<()> {
     if wasted_files.is_empty() {
@@ -38,6 +38,30 @@ fn report_savings(
         )?;
         return Ok(());
     }
+
+    let file_len = wasted_files.len();
+    let wasted_bytes = entries_to_table(wasted_files, &mut out, None)?;
+
+    writeln!(
+        out,
+        "Saved {:.0}% or {} in {} files (of {} and {} files in entire crate)",
+        (wasted_bytes as f32 / total_size_in_bytes as f32) * 100.0,
+        ByteSize(wasted_bytes),
+        file_len,
+        ByteSize(total_size_in_bytes),
+        total_files
+    )?;
+    Ok(())
+}
+
+fn entries_to_table(
+    mut entries: Vec<WastedFile>,
+    mut out: impl std::io::Write,
+    items: Option<usize>,
+) -> std::io::Result<u64> {
+    if entries.is_empty() {
+        return Ok(0);
+    }
     use ascii_table::{Align, AsciiTable, Column};
     use std::fmt::Display;
 
@@ -62,23 +86,21 @@ fn report_savings(
         },
     );
 
-    wasted_files.sort_by(|x, y| x.1.cmp(&y.1));
-    let wasted_bytes: u64 = wasted_files.iter().map(|(_, size)| size).sum();
-    let data: Vec<Vec<&dyn Display>> = wasted_files
+    entries.sort_by(|x, y| y.1.cmp(&x.1));
+    let bytes: u64 = entries
         .iter()
+        .take(items.unwrap_or(entries.len()))
+        .rev()
+        .map(|(_, size)| size)
+        .sum();
+    let data: Vec<Vec<&dyn Display>> = entries
+        .iter()
+        .take(items.unwrap_or(entries.len()))
+        .rev()
         .map(|(path, size)| vec![path as &dyn Display, size as &dyn Display])
         .collect();
-    ascii_table.print(data);
-    writeln!(
-        out,
-        "Saved {:.0}% or {} in {} files (of {} and {} files in entire crate)",
-        (wasted_bytes as f32 / total_size_in_bytes as f32) * 100.0,
-        ByteSize(wasted_bytes),
-        wasted_files.len(),
-        ByteSize(total_size_in_bytes),
-        total_files
-    )?;
-    Ok(())
+    out.write_all(ascii_table.format(data).as_bytes())?;
+    Ok(bytes)
 }
 
 fn edit(
@@ -290,6 +312,7 @@ pub struct Options {
     pub reset: bool,
     pub dry_run: bool,
     pub colored_output: bool,
+    pub list: Option<usize>,
     pub package_size_limit: Option<u64>,
     #[cfg(feature = "dev-support")]
     pub save_package_for_unit_test: Option<PathBuf>,
@@ -387,6 +410,9 @@ pub fn execute(options: Options, mut output: impl std::io::Write) -> Result<()>
     if options.reset && options.dry_run {
         std::fs::write(&manifest_path, &cargo_manifest_original_content)?;
     }
+    let list = options
+        .list
+        .map(|list| (list, package.entries_meta_data.clone()));
     let document = edit(document, package, &mut output)?;
     write_manifest(
         &manifest_path,
@@ -398,7 +424,42 @@ pub fn execute(options: Options, mut output: impl std::io::Write) -> Result<()>
     )?;
 
     if let Some((package, package_size_limit)) = package_size_limit {
-        check_package_size(package, package_size_limit, output, options.colored_output)?;
+        check_package_size(
+            package,
+            package_size_limit,
+            &mut output,
+            options.colored_output,
+        )?;
+    }
+    if let Some((list, entries)) = list {
+        list_entries(list, &mut output, entries)?;
     }
     Ok(())
 }
+
+fn list_entries(
+    num_entries: usize,
+    mut out: impl std::io::Write,
+    entries: Vec<TarHeader>,
+) -> Result<()> {
+    let num_entries = if num_entries == 0 {
+        entries.len()
+    } else {
+        num_entries.min(entries.len())
+    };
+    let bytes = entries_to_table(
+        entries
+            .into_iter()
+            .map(|tf| (tar_path_to_utf8_str(&tf.path).into(), tf.size))
+            .collect(),
+        &mut out,
+        Some(num_entries),
+    )?;
+    writeln!(
+        out,
+        "Crate contains a total of {} files and {}",
+        num_entries,
+        ByteSize(bytes)
+    )?;
+    Ok(())
+}

tests/snapshots/success-list-no-limit-with-zero

@@ -0,0 +1,10 @@
+Your crate is perfectly lean!
+There would be no change.
+┌─────────────┬─────────────┐
+│ File        │ Size (Byte) │
+├─────────────┼─────────────┤
+│ README.md   │           0 │
+│ src/main.rs │          45 │
+│ Cargo.toml  │         270 │
+└─────────────┴─────────────┘
+Crate contains a total of 3 files and <bytecount>

tests/snapshots/success-list-with-limit

@@ -0,0 +1,9 @@
+Your crate is perfectly lean!
+There would be no change.
+┌─────────────┬─────────────┐
+│ File        │ Size (Byte) │
+├─────────────┼─────────────┤
+│ src/main.rs │          45 │
+│ Cargo.toml  │         270 │
+└─────────────┴─────────────┘
+Crate contains a total of 2 files and <bytecount>

tests/stateless-journey.sh

@@ -231,6 +231,31 @@ function remove_bytecounts() {
             }
           )
         )
+
+        (with "the --list flag"
+          (when "a small amount is specified"
+            it "runs successfully and lists the given amount of entries entries in the package" && {
+              SNAPSHOT_FILTER=remove_bytecounts \
+              WITH_SNAPSHOT="$snapshot/success-list-with-limit" \
+              expect_run ${SUCCESSFULLY} "$exe" diet -n --list 2
+            }
+
+            it "does not put a file in target/package" && {
+              expect_run ${WITH_FAILURE} find target/package
+            }
+          )
+          (when "a 0 is specified as amount"
+            it "runs successfully and lists all entries entries in the package" && {
+              SNAPSHOT_FILTER=remove_bytecounts \
+              WITH_SNAPSHOT="$snapshot/success-list-no-limit-with-zero" \
+              expect_run ${SUCCESSFULLY} "$exe" diet -n --list 0
+            }
+
+            it "does not put a file in target/package" && {
+              expect_run ${WITH_FAILURE} find target/package
+            }
+          )
+        )
       )
     )
   )