/// Configuration related to sparse indexes.#[derive(Debug, Default, Clone, Copy)]pub struct Options {    /// If true, certain entries in the index will be excluded / skipped for certain operations,    /// based on the ignore patterns in the `.git/info/sparse-checkout` file. These entries will    /// carry the [`SKIP_WORKTREE`][crate::entry::Flags::SKIP_WORKTREE] flag.    ///    /// This typically is the value of `core.sparseCheckout` in the git configuration.    pub sparse_checkout: bool,     /// Interpret the `.git/info/sparse-checkout` file using _cone mode_.    ///    /// If true, _cone mode_ is active and entire directories will be included in the checkout, as well as files in the root    /// of the repository.    /// If false, non-cone mode is active and entries to _include_ will be matched with patterns like those found in `.gitignore` files.    ///    /// This typically is the value of `core.sparseCheckoutCone` in the git configuration.    pub directory_patterns_only: bool,     /// If true, will attempt to write a sparse index file which only works in cone mode.    ///    /// A sparse index has [`DIR` entries][crate::entry::Mode::DIR] that represent entire directories to be skipped    /// during checkout and other operations due to the added presence of    /// the [`SKIP_WORKTREE`][crate::entry::Flags::SKIP_WORKTREE] flag.    ///    /// This is typically the value of `index.sparse` in the git configuration.    pub write_sparse_index: bool,} impl Options {    /// Derive a valid mode from all parameters that affect the 'sparseness' of the index.    ///    /// Some combinations of them degenerate to one particular mode.    pub fn sparse_mode(&self) -> Mode {        match (            self.sparse_checkout,            self.directory_patterns_only,            self.write_sparse_index,        ) {            (true, true, true) => Mode::IncludeDirectoriesStoreIncludedEntriesAndExcludedDirs,            (true, true, false) => Mode::IncludeDirectoriesStoreAllEntriesSkipUnmatched,            (true, false, _) => Mode::IncludeByIgnorePatternStoreAllEntriesSkipUnmatched,            (false, _, _) => Mode::Disabled,        }    }} /// Describes the configuration how a sparse index should be written, or if one should be written at all.#[derive(Debug)]pub enum Mode {    /// index with DIR entries for exclusion and included entries, directory-only include patterns in `.git/info/sparse-checkout` file.    IncludeDirectoriesStoreIncludedEntriesAndExcludedDirs,    /// index with all file entries and skip worktree flags for exclusion, directory-only include patterns in `.git/info/sparse-checkout` file.    IncludeDirectoriesStoreAllEntriesSkipUnmatched,    /// index with all file entries and skip-worktree flags for exclusion, `ignore` patterns to include entries in `.git/info/sparse-checkout` file.    IncludeByIgnorePatternStoreAllEntriesSkipUnmatched,    /// index with all entries, non is excluded, `.git/info/sparse-checkout` file is not considered, a regular index.    Disabled,}