Struct StateStore 

pub struct StateStore { /* private fields */ }

Reads and writes the state file in one state directory.

Implementations

impl StateStore

pub fn new(dir: impl Into<PathBuf>) -> Self

A store for dir/state.json. Nothing is touched until a method is called.

pub fn dir(&self) -> &Path

The state directory.

pub fn path(&self) -> &Path

The state file.

pub fn exists(&self) -> bool

Whether a state file exists.

pub fn load(&self) -> Result<Option<State>, StateError>

Loads the state, migrating old versions.

Ok(None) means there is no state file yet. A file that exists but cannot be read, parsed or migrated is a StateError::Load, and it is left exactly as it was: the caller must not mistake it for a fresh start.

Errors

StateError::Load for I/O errors, malformed JSON, a root that is not an object, an unsupported version, and missing or invalid fields.

pub fn save(&self, state: &State) -> Result<(), StateError>

Writes the state atomically: the JSON goes into a private temporary file in the same directory, is flushed to disk, and then replaces state.json in one step. The directory is created if needed. On failure no temporary file stays behind and the previous state.json is untouched.

Errors

StateError::Save if the state cannot be serialized or the file cannot be written.

pub fn remove(&self) -> Result<(), StateError>

Deletes the state file. A missing file is fine.

Errors

StateError::Remove if the file exists but cannot be deleted.

Trait Implementations

impl Clone for StateStore

fn clone(&self) -> StateStore

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StateStore

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for StateStore

impl PartialEq for StateStore

fn eq(&self, other: &StateStore) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for StateStore