Xgit v0.1.6 Xgit.Core.DirCache View Source

A directory cache records the current (intended) contents of a working tree when last scanned or created by git.

In Xgit, the DirCache structure is an abstract, in-memory data structure without any tie to a specific persistence mechanism. Persistence is implemented by a specific implementation of the Xgit.Repository behaviour.

This content is commonly persisted on disk as an index file at the root of the git tree. The module Xgit.Repository.WorkingTree.ParseIndexFile can parse that file format.

Changes in the working tree can be detected by comparing the modification times to the cached modification time within the dir cache.

Index files are also used during merges, where the merge happens within the index file first, and the working directory is updated as a post-merge step. Conflicts are stored in the index file to allow tool (and human) based resolutions to be easily performed.

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Types

Error reason codes returned by add_entries/2.

An entry for the remove option for remove_entries/2.

Error reason codes returned by remove_entries/2.

t()

This struct describes an entire working tree as understood by git.

Version number for an index file.

Functions

Returns a dir cache that has new directory entries added in.

Returns a dir cache that is the canonical "empty" dir cache (i.e. contains no entries).

Returns a dir cache that has some directory entries removed.

Return true if the value is a DirCache struct that is valid.

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add_entries_reason()

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add_entries_reason() ::
  :invalid_dir_cache | :invalid_entries | :duplicate_entries

Error reason codes returned by add_entries/2.

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entry_to_remove()

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entry_to_remove() :: {path :: [byte()], stage :: 0..3 | :all}

An entry for the remove option for remove_entries/2.

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remove_entries_reason()

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remove_entries_reason() :: :invalid_dir_cache | :invalid_entries

Error reason codes returned by remove_entries/2.

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t()

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t() :: %Xgit.Core.DirCache{
  entries: [Xgit.Core.DirCache.Entry.t()],
  entry_count: non_neg_integer(),
  version: version()
}

This struct describes an entire working tree as understood by git.

Struct Members

  • :version: the version number as read from disk (typically 2, 3, or 4)
  • :entry_count: the number of items in entries
  • :entries: a list of Entry structs in sorted order
  • :extensions: a list of Extension structs (not yet implemented)
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version()

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version() :: 2..4

Version number for an index file.

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add_entries(dir_cache, new_entries)

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add_entries(dir_cache :: t(), new_entries :: [Xgit.Core.DirCache.Entry.t()]) ::
  {:ok, t()} | {:error, add_entries_reason()}

Returns a dir cache that has new directory entries added in.

In the event of a collision between entries (same path and stage), the existing entry will be replaced by the new one.

Parameters

entries a list of entries to add to the existing dir cache

Return Value

{:ok, dir_cache} where dir_cache is the original dir_cache with the new entries added (and properly sorted).

{:error, :invalid_dir_cache} if the original dir_cache was invalid.

{:error, :invalid_entries} if one or more of the entries is invalid.

{:error, :duplicate_entries} if one or more of the entries in the new list are duplicates of other entries in the new list. (As stated earlier, duplicates from the original list are acceptable; in that event, the new entry will replace the old one.)

Returns a dir cache that is the canonical "empty" dir cache (i.e. contains no entries).

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remove_entries(dir_cache, entries_to_remove)

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remove_entries(dir_cache :: t(), entries_to_remove :: [entry_to_remove()]) ::
  {:ok, t()} | {:error, remove_entries_reason()}

Returns a dir cache that has some directory entries removed.

Parameters

entries_to_remove is a list of {path, stage} tuples identifying tuples to be removed.

  • path should be a byte list for the path.
  • stage should be 0..3 or :all, meaning any entry that matches the path, regardless of stage, should be removed.

Return Value

{:ok, dir_cache} where dir_cache is the original dir_cache with any matching entries removed.

{:error, :invalid_dir_cache} if the original dir_cache was invalid.

{:error, :invalid_entries} if one or more of the entries is invalid.

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valid?(dir_cache)

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valid?(dir_cache :: any()) :: boolean()

Return true if the value is a DirCache struct that is valid.

All of the following must be true for this to occur:

  • The value is a DirCache struct.
  • The version is supported by Xgit. (Currently, only version 2 is supported.)
  • The entry_count matches the actual number of entries.
  • The entries are properly sorted.
  • All entries are valid, as determined by Xgit.Core.DirCache.Entry.valid?/1.