Struct History 

pub struct History { /* private fields */ }

Calculator history manager

Tracks past calculations for display and recall. Implements a bounded queue to prevent unbounded memory growth.

Implementations

impl History

pub const DEFAULT_MAX_ENTRIES: usize = 100

Default maximum history size

pub fn new() -> Self

Creates a new history with default capacity

pub fn with_capacity(max_entries: usize) -> Self

Creates a history with custom maximum size

pub fn push(&mut self, entry: HistoryEntry)

Adds an entry to the history

pub fn record(&mut self, expression: &str, result: f64)

Adds a calculation result to the history

pub fn len(&self) -> usize

Returns the number of entries

pub fn is_empty(&self) -> bool

Returns true if the history is empty

pub fn max_entries(&self) -> usize

Returns the maximum number of entries

pub fn clear(&mut self)

Clears all history entries

pub fn iter(&self) -> impl Iterator<Item = &HistoryEntry>

Returns an iterator over the entries (oldest first)

pub fn iter_rev(&self) -> impl Iterator<Item = &HistoryEntry>

Returns an iterator over the entries (newest first)

pub fn last(&self) -> Option<&HistoryEntry>

Returns the most recent entry

pub fn first(&self) -> Option<&HistoryEntry>

Returns the oldest entry

pub fn get(&self, index: usize) -> Option<&HistoryEntry>

Returns the entry at the given index (0 = oldest)

pub fn last_n(&self, n: usize) -> Vec<&HistoryEntry>

Returns the last n entries (newest first)

pub fn to_json(&self) -> Result<String, Error>

Serializes the history to JSON

pub fn from_json(json: &str) -> Result<Self, Error>

Deserializes history from JSON

pub fn export_formatted(&self) -> String

Exports history to a formatted string

Trait Implementations

impl Clone for History

fn clone(&self) -> History

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for History

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

Formats the value using the given formatter.

impl Default for History

fn default() -> Self

Returns the “default value” for a type.