rust-dirstate: specify concrete return type of DirsMultiset::iter()

This allows us to put a returned iterator in a struct. We could implement
DirsMultisetIter(hash_map::Keys<..>) struct to hide the implementation
detail, but I think type alias is good enough for us.

rust/hg-core/src/dirstate/dirs_multiset.rs

@@ -1,319 +1,322
 // dirs_multiset.rs
 //
 // Copyright 2019 Raphaël Gomès <[e-mail]>
 //
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2 or any later version.
 
 //! A multiset of directory names.
 //!
 //! Used to counts the references to directories in a manifest or dirstate.
 use crate::{
     dirstate::EntryState, utils::files, DirstateEntry, DirstateMapError,
 };
-use std::collections::hash_map::Entry;
+use std::collections::hash_map::{self, Entry};
 use std::collections::HashMap;
 
+// could be encapsulated if we care API stability more seriously
+pub type DirsMultisetIter<'a> = hash_map::Keys<'a, Vec<u8>, u32>;
+
 #[derive(PartialEq, Debug)]
 pub struct DirsMultiset {
     inner: HashMap<Vec<u8>, u32>,
 }
 
 impl DirsMultiset {
     /// Initializes the multiset from a dirstate.
     ///
     /// If `skip_state` is provided, skips dirstate entries with equal state.
     pub fn from_dirstate(
         vec: &HashMap<Vec<u8>, DirstateEntry>,
         skip_state: Option<EntryState>,
     ) -> Self {
         let mut multiset = DirsMultiset {
             inner: HashMap::new(),
         };
 
         for (filename, DirstateEntry { state, .. }) in vec {
             // This `if` is optimized out of the loop
             if let Some(skip) = skip_state {
                 if skip != *state {
                     multiset.add_path(filename);
                 }
             } else {
                 multiset.add_path(filename);
             }
         }
 
         multiset
     }
 
     /// Initializes the multiset from a manifest.
     pub fn from_manifest(vec: &Vec<Vec<u8>>) -> Self {
         let mut multiset = DirsMultiset {
             inner: HashMap::new(),
         };
 
         for filename in vec {
             multiset.add_path(filename);
         }
 
         multiset
     }
 
     /// Increases the count of deepest directory contained in the path.
     ///
     /// If the directory is not yet in the map, adds its parents.
     pub fn add_path(&mut self, path: &[u8]) {
         for subpath in files::find_dirs(path) {
             if let Some(val) = self.inner.get_mut(subpath) {
                 *val += 1;
                 break;
             }
             self.inner.insert(subpath.to_owned(), 1);
         }
     }
 
     /// Decreases the count of deepest directory contained in the path.
     ///
     /// If it is the only reference, decreases all parents until one is
     /// removed.
     /// If the directory is not in the map, something horrible has happened.
     pub fn delete_path(
         &mut self,
         path: &[u8],
     ) -> Result<(), DirstateMapError> {
         for subpath in files::find_dirs(path) {
             match self.inner.entry(subpath.to_owned()) {
                 Entry::Occupied(mut entry) => {
                     let val = entry.get().clone();
                     if val > 1 {
                         entry.insert(val - 1);
                         break;
                     }
                     entry.remove();
                 }
                 Entry::Vacant(_) => {
                     return Err(DirstateMapError::PathNotFound(
                         path.to_owned(),
                     ))
                 }
             };
         }
 
         Ok(())
     }
 
     pub fn contains(&self, key: &[u8]) -> bool {
         self.inner.contains_key(key)
     }
 
-    pub fn iter(&self) -> impl Iterator<Item = &Vec<u8>> {
+    pub fn iter(&self) -> DirsMultisetIter {
         self.inner.keys()
     }
 
     pub fn len(&self) -> usize {
         self.inner.len()
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use std::collections::HashMap;
 
     #[test]
     fn test_delete_path_path_not_found() {
         let mut map = DirsMultiset::from_manifest(&vec![]);
         let path = b"doesnotexist/";
         assert_eq!(
             Err(DirstateMapError::PathNotFound(path.to_vec())),
             map.delete_path(path)
         );
     }
 
     #[test]
     fn test_delete_path_empty_path() {
         let mut map = DirsMultiset::from_manifest(&vec![vec![]]);
         let path = b"";
         assert_eq!(Ok(()), map.delete_path(path));
         assert_eq!(
             Err(DirstateMapError::PathNotFound(path.to_vec())),
             map.delete_path(path)
         );
     }
 
     #[test]
     fn test_delete_path_successful() {
         let mut map = DirsMultiset {
             inner: [("", 5), ("a", 3), ("a/b", 2), ("a/c", 1)]
                 .iter()
                 .map(|(k, v)| (k.as_bytes().to_vec(), *v))
                 .collect(),
         };
 
         assert_eq!(Ok(()), map.delete_path(b"a/b/"));
         assert_eq!(Ok(()), map.delete_path(b"a/b/"));
         assert_eq!(
             Err(DirstateMapError::PathNotFound(b"a/b/".to_vec())),
             map.delete_path(b"a/b/")
         );
 
         assert_eq!(2, *map.inner.get(&b"a".to_vec()).unwrap());
         assert_eq!(1, *map.inner.get(&b"a/c".to_vec()).unwrap());
         eprintln!("{:?}", map);
         assert_eq!(Ok(()), map.delete_path(b"a/"));
         eprintln!("{:?}", map);
 
         assert_eq!(Ok(()), map.delete_path(b"a/c/"));
         assert_eq!(
             Err(DirstateMapError::PathNotFound(b"a/c/".to_vec())),
             map.delete_path(b"a/c/")
         );
     }
 
     #[test]
     fn test_add_path_empty_path() {
         let mut map = DirsMultiset::from_manifest(&vec![]);
         let path = b"";
         map.add_path(path);
 
         assert_eq!(1, map.len());
     }
 
     #[test]
     fn test_add_path_successful() {
         let mut map = DirsMultiset::from_manifest(&vec![]);
 
         map.add_path(b"a/");
         assert_eq!(1, *map.inner.get(&b"a".to_vec()).unwrap());
         assert_eq!(1, *map.inner.get(&Vec::new()).unwrap());
         assert_eq!(2, map.len());
 
         // Non directory should be ignored
         map.add_path(b"a");
         assert_eq!(1, *map.inner.get(&b"a".to_vec()).unwrap());
         assert_eq!(2, map.len());
 
         // Non directory will still add its base
         map.add_path(b"a/b");
         assert_eq!(2, *map.inner.get(&b"a".to_vec()).unwrap());
         assert_eq!(2, map.len());
 
         // Duplicate path works
         map.add_path(b"a/");
         assert_eq!(3, *map.inner.get(&b"a".to_vec()).unwrap());
 
         // Nested dir adds to its base
         map.add_path(b"a/b/");
         assert_eq!(4, *map.inner.get(&b"a".to_vec()).unwrap());
         assert_eq!(1, *map.inner.get(&b"a/b".to_vec()).unwrap());
 
         // but not its base's base, because it already existed
         map.add_path(b"a/b/c/");
         assert_eq!(4, *map.inner.get(&b"a".to_vec()).unwrap());
         assert_eq!(2, *map.inner.get(&b"a/b".to_vec()).unwrap());
 
         map.add_path(b"a/c/");
         assert_eq!(1, *map.inner.get(&b"a/c".to_vec()).unwrap());
 
         let expected = DirsMultiset {
             inner: [("", 2), ("a", 5), ("a/b", 2), ("a/b/c", 1), ("a/c", 1)]
                 .iter()
                 .map(|(k, v)| (k.as_bytes().to_vec(), *v))
                 .collect(),
         };
         assert_eq!(map, expected);
     }
 
     #[test]
     fn test_dirsmultiset_new_empty() {
         let new = DirsMultiset::from_manifest(&vec![]);
         let expected = DirsMultiset {
             inner: HashMap::new(),
         };
         assert_eq!(expected, new);
 
         let new = DirsMultiset::from_dirstate(&HashMap::new(), None);
         let expected = DirsMultiset {
             inner: HashMap::new(),
         };
         assert_eq!(expected, new);
     }
 
     #[test]
     fn test_dirsmultiset_new_no_skip() {
         let input_vec = ["a/", "b/", "a/c", "a/d/"]
             .iter()
             .map(|e| e.as_bytes().to_vec())
             .collect();
         let expected_inner = [("", 2), ("a", 3), ("b", 1), ("a/d", 1)]
             .iter()
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
         let new = DirsMultiset::from_manifest(&input_vec);
         let expected = DirsMultiset {
             inner: expected_inner,
         };
         assert_eq!(expected, new);
 
         let input_map = ["a/", "b/", "a/c", "a/d/"]
             .iter()
             .map(|f| {
                 (
                     f.as_bytes().to_vec(),
                     DirstateEntry {
                         state: EntryState::Normal,
                         mode: 0,
                         mtime: 0,
                         size: 0,
                     },
                 )
             })
             .collect();
         let expected_inner = [("", 2), ("a", 3), ("b", 1), ("a/d", 1)]
             .iter()
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
         let new = DirsMultiset::from_dirstate(&input_map, None);
         let expected = DirsMultiset {
             inner: expected_inner,
         };
         assert_eq!(expected, new);
     }
 
     #[test]
     fn test_dirsmultiset_new_skip() {
         let input_map = [
             ("a/", EntryState::Normal),
             ("a/b/", EntryState::Normal),
             ("a/c", EntryState::Removed),
             ("a/d/", EntryState::Merged),
         ]
         .iter()
         .map(|(f, state)| {
             (
                 f.as_bytes().to_vec(),
                 DirstateEntry {
                     state: *state,
                     mode: 0,
                     mtime: 0,
                     size: 0,
                 },
             )
         })
         .collect();
 
         // "a" incremented with "a/c" and "a/d/"
         let expected_inner = [("", 1), ("a", 2), ("a/d", 1)]
             .iter()
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
         let new =
             DirsMultiset::from_dirstate(&input_map, Some(EntryState::Normal));
         let expected = DirsMultiset {
             inner: expected_inner,
         };
         assert_eq!(expected, new);
     }
 }

rust/hg-core/src/lib.rs

@@ -1,148 +1,148
 // Copyright 2018 Georges Racinet <[e-mail]>
 //
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2 or any later version.
 mod ancestors;
 pub mod dagops;
 pub use ancestors::{AncestorsIterator, LazyAncestors, MissingAncestors};
 mod dirstate;
 pub mod discovery;
 pub mod testing; // unconditionally built, for use from integration tests
 pub use dirstate::{
-    dirs_multiset::DirsMultiset,
+    dirs_multiset::{DirsMultiset, DirsMultisetIter},
     dirstate_map::DirstateMap,
     parsers::{pack_dirstate, parse_dirstate, PARENT_SIZE},
     CopyMap, DirstateEntry, DirstateParents, EntryState, StateMap,
 };
 mod filepatterns;
 pub mod utils;
 
 pub use filepatterns::{
     build_single_regex, read_pattern_file, PatternSyntax, PatternTuple,
 };
 
 /// Mercurial revision numbers
 ///
 /// As noted in revlog.c, revision numbers are actually encoded in
 /// 4 bytes, and are liberally converted to ints, whence the i32
 pub type Revision = i32;
 
 /// Marker expressing the absence of a parent
 ///
 /// Independently of the actual representation, `NULL_REVISION` is guaranteed
 /// to be smaller that all existing revisions.
 pub const NULL_REVISION: Revision = -1;
 
 /// Same as `mercurial.node.wdirrev`
 ///
 /// This is also equal to `i32::max_value()`, but it's better to spell
 /// it out explicitely, same as in `mercurial.node`
 pub const WORKING_DIRECTORY_REVISION: Revision = 0x7fffffff;
 
 /// The simplest expression of what we need of Mercurial DAGs.
 pub trait Graph {
     /// Return the two parents of the given `Revision`.
     ///
     /// Each of the parents can be independently `NULL_REVISION`
     fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError>;
 }
 
 pub type LineNumber = usize;
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum GraphError {
     ParentOutOfRange(Revision),
     WorkingDirectoryUnsupported,
 }
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum DirstateParseError {
     TooLittleData,
     Overflow,
     CorruptedEntry(String),
     Damaged,
 }
 
 impl From<std::io::Error> for DirstateParseError {
     fn from(e: std::io::Error) -> Self {
         DirstateParseError::CorruptedEntry(e.to_string())
     }
 }
 
 impl ToString for DirstateParseError {
     fn to_string(&self) -> String {
         use crate::DirstateParseError::*;
         match self {
             TooLittleData => "Too little data for dirstate.".to_string(),
             Overflow => "Overflow in dirstate.".to_string(),
             CorruptedEntry(e) => format!("Corrupted entry: {:?}.", e),
             Damaged => "Dirstate appears to be damaged.".to_string(),
         }
     }
 }
 
 #[derive(Debug, PartialEq)]
 pub enum DirstatePackError {
     CorruptedEntry(String),
     CorruptedParent,
     BadSize(usize, usize),
 }
 
 impl From<std::io::Error> for DirstatePackError {
     fn from(e: std::io::Error) -> Self {
         DirstatePackError::CorruptedEntry(e.to_string())
     }
 }
 #[derive(Debug, PartialEq)]
 pub enum DirstateMapError {
     PathNotFound(Vec<u8>),
     EmptyPath,
 }
 
 pub enum DirstateError {
     Parse(DirstateParseError),
     Pack(DirstatePackError),
     Map(DirstateMapError),
     IO(std::io::Error),
 }
 
 impl From<DirstateParseError> for DirstateError {
     fn from(e: DirstateParseError) -> Self {
         DirstateError::Parse(e)
     }
 }
 
 impl From<DirstatePackError> for DirstateError {
     fn from(e: DirstatePackError) -> Self {
         DirstateError::Pack(e)
     }
 }
 
 #[derive(Debug)]
 pub enum PatternError {
     UnsupportedSyntax(String),
 }
 
 #[derive(Debug)]
 pub enum PatternFileError {
     IO(std::io::Error),
     Pattern(PatternError, LineNumber),
 }
 
 impl From<std::io::Error> for PatternFileError {
     fn from(e: std::io::Error) -> Self {
         PatternFileError::IO(e)
     }
 }
 
 impl From<DirstateMapError> for DirstateError {
     fn from(e: DirstateMapError) -> Self {
         DirstateError::Map(e)
     }
 }
 
 impl From<std::io::Error> for DirstateError {
     fn from(e: std::io::Error) -> Self {
         DirstateError::IO(e)
     }
 }