Introduce "sort specs" to allow fine-grained sorting of files in torr…

…ents

Sort specs are of the form `KEY:ORDER`, and allow sorting files in a
torrent by multiple criteria. Multiple sort specs can be passed with
`--sort-by` upon torrent creation.

type: added

src/common.rs

@@ -35,10 +35,7 @@ pub(crate) use serde_with::rust::unwrap_or_skip;
 pub(crate) use sha1::Sha1;
 pub(crate) use snafu::{ResultExt, Snafu};
 pub(crate) use static_assertions::const_assert;
-pub(crate) use structopt::{
-  clap::{AppSettings, ArgSettings},
-  StructOpt,
-};
+pub(crate) use structopt::{clap::AppSettings, StructOpt};
 pub(crate) use strum::VariantNames;
 pub(crate) use strum_macros::{EnumString, EnumVariantNames, IntoStaticStr};
 pub(crate) use unicode_width::UnicodeWidthStr;
@@ -61,15 +58,15 @@ pub(crate) use crate::{
 // structs and enums
 pub(crate) use crate::{
   arguments::Arguments, bytes::Bytes, env::Env, error::Error, file_error::FileError,
-  file_info::FileInfo, file_order::FileOrder, file_path::FilePath, file_status::FileStatus,
-  files::Files, hasher::Hasher, host_port::HostPort, host_port_parse_error::HostPortParseError,
-  info::Info, infohash::Infohash, input::Input, input_target::InputTarget, lint::Lint,
-  linter::Linter, magnet_link::MagnetLink, md5_digest::Md5Digest, metainfo::Metainfo,
-  metainfo_error::MetainfoError, mode::Mode, options::Options, output_stream::OutputStream,
-  output_target::OutputTarget, piece_length_picker::PieceLengthPicker, piece_list::PieceList,
-  platform::Platform, sha1_digest::Sha1Digest, status::Status, style::Style,
-  subcommand::Subcommand, table::Table, torrent_summary::TorrentSummary, use_color::UseColor,
-  verifier::Verifier, walker::Walker,
+  file_info::FileInfo, file_path::FilePath, file_status::FileStatus, files::Files, hasher::Hasher,
+  host_port::HostPort, host_port_parse_error::HostPortParseError, info::Info, infohash::Infohash,
+  input::Input, input_target::InputTarget, lint::Lint, linter::Linter, magnet_link::MagnetLink,
+  md5_digest::Md5Digest, metainfo::Metainfo, metainfo_error::MetainfoError, mode::Mode,
+  options::Options, output_stream::OutputStream, output_target::OutputTarget,
+  piece_length_picker::PieceLengthPicker, piece_list::PieceList, platform::Platform,
+  sha1_digest::Sha1Digest, sort_key::SortKey, sort_order::SortOrder, sort_spec::SortSpec,
+  status::Status, style::Style, subcommand::Subcommand, table::Table,
+  torrent_summary::TorrentSummary, use_color::UseColor, verifier::Verifier, walker::Walker,
 };
 
 // type aliases

src/main.rs

@@ -56,7 +56,6 @@ mod env;
 mod error;
 mod file_error;
 mod file_info;
-mod file_order;
 mod file_path;
 mod file_status;
 mod files;
@@ -87,6 +86,9 @@ mod platform_interface;
 mod print;
 mod reckoner;
 mod sha1_digest;
+mod sort_key;
+mod sort_order;
+mod sort_spec;
 mod status;
 mod step;
 mod style;

src/sort_key.rs

@@ -0,0 +1,14 @@
+use crate::common::*;
+
+#[derive(Clone, Copy, Debug, PartialEq, IntoStaticStr, EnumString)]
+#[strum(serialize_all = "kebab-case")]
+pub(crate) enum SortKey {
+  Path,
+  Size,
+}
+
+impl SortKey {
+  pub(crate) fn name(self) -> &'static str {
+    self.into()
+  }
+}

src/sort_order.rs

@@ -0,0 +1,20 @@
+use crate::common::*;
+
+#[derive(Clone, Copy, Debug, PartialEq, IntoStaticStr, EnumString)]
+#[strum(serialize_all = "kebab-case")]
+pub(crate) enum SortOrder {
+  Ascending,
+  Descending,
+}
+
+impl SortOrder {
+  pub(crate) fn name(self) -> &'static str {
+    self.into()
+  }
+}
+
+impl Default for SortOrder {
+  fn default() -> Self {
+    Self::Ascending
+  }
+}

src/sort_spec.rs

@@ -0,0 +1,95 @@
+use crate::common::*;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) struct SortSpec {
+  key: SortKey,
+  order: SortOrder,
+}
+
+impl SortSpec {
+  pub(crate) fn compare(specs: &[SortSpec], a: &FileInfo, b: &FileInfo) -> Ordering {
+    let mut specs = specs.to_vec();
+
+    specs.push(SortSpec::default());
+
+    Self::compare_specs(&specs, a, b)
+  }
+
+  fn compare_specs(specs: &[SortSpec], a: &FileInfo, b: &FileInfo) -> Ordering {
+    specs.iter().fold(Ordering::Equal, |ordering, spec| {
+      ordering.then_with(|| spec.compare_file_info(a, b))
+    })
+  }
+
+  fn compare_file_info(self, a: &FileInfo, b: &FileInfo) -> Ordering {
+    let ordering = match self.key {
+      SortKey::Path => a.path.cmp(&b.path),
+      SortKey::Size => a.length.cmp(&b.length),
+    };
+
+    match self.order {
+      SortOrder::Ascending => ordering,
+      SortOrder::Descending => ordering.reverse(),
+    }
+  }
+}
+
+impl Default for SortSpec {
+  fn default() -> Self {
+    Self {
+      key: SortKey::Path,
+      order: SortOrder::default(),
+    }
+  }
+}
+
+impl FromStr for SortSpec {
+  type Err = strum::ParseError;
+
+  fn from_str(text: &str) -> Result<Self, Self::Err> {
+    if let Some(index) = text.find(':') {
+      Ok(SortSpec {
+        key: text[..index].parse()?,
+        order: text[index + 1..].parse()?,
+      })
+    } else {
+      Ok(SortSpec {
+        key: text.parse()?,
+        order: SortOrder::default(),
+      })
+    }
+  }
+}
+
+impl Display for SortSpec {
+  fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+    write!(f, "{}:{}", self.key.name(), self.order.name())
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn default() {
+    assert_eq!(
+      SortSpec::default(),
+      SortSpec {
+        key: SortKey::Path,
+        order: SortOrder::Ascending
+      }
+    );
+  }
+
+  #[test]
+  fn parse() {
+    assert_eq!(
+      SortSpec {
+        key: SortKey::Path,
+        order: SortOrder::Ascending
+      },
+      "path:ascending".parse().unwrap()
+    );
+  }
+}