Struct OptionHandler 

pub struct OptionHandler { /* private fields */ }

Centralized option handler with built-in defaults, config file parsing, CLI argument override support, and DownloadOptions conversion.

Priority Order (lowest to highest)

1. Built-in defaults (from [DEFAULTS])
2. Config file values (via [load_config_file])
3. Command-line arguments (via [apply_args])
4. Explicit [set] calls

Example

use aria2_core::option::{OptionHandler, OptionValue};

let mut h = OptionHandler::new();
assert_eq!(h.get("split").as_usize(), 5); // default

h.set("split", OptionValue::Usize(10));
assert_eq!(h.get("split").as_usize(), 10);

Implementations

impl OptionHandler

pub fn new() -> Self

Create a new OptionHandler pre-populated with all built-in defaults.

Every default from [built_in_defaults] is copied into both options and defaults. Subsequent mutations only affect options; defaults remains immutable so fallback lookups always work.

pub fn set(&mut self, key: &str, value: OptionValue)

Set an option value. Overwrites any existing value.

After calling set, subsequent calls to [get] will return the new value instead of the default.

pub fn get(&self, key: &str) -> &OptionValue

Get the current value for key.

Falls back to the built-in default if the key was never explicitly set (or was removed). Returns OptionValue::None for completely unknown keys.

pub fn apply_args(&mut self, args: &[String])

Override options from raw command-line arguments.

Parses common CLI patterns:

• --key=value / --key:value
• --key value (value in next arg)
• --no-key sets boolean to false
• -o key=value (GNU style)

CLI arguments take precedence over config file values but can be overridden by explicit [set] calls.

pub fn load_config_file(&mut self, path: &Path) -> Result<(), String>

Load options from a .aria2rc config file.

File format:

# Comment lines start with #
key=value
key="value with spaces"
key=['val1', 'val2']
bool-key=true
number-key=42
float-key=3.14

Parse Rules

• Lines starting with # are comments and skipped.
• Blank lines are skipped.
• key=value: auto-detect type (see [detect_value_type]).
• Invalid lines produce warnings via tracing::warn but do not cause an error return.

Errors

Returns an error only if the file cannot be read (IO failure).

pub fn to_download_options(&self) -> DownloadOptions

Convert current options to a DownloadOptions struct suitable for creating a download task.

Maps well-known option keys to their corresponding fields in DownloadOptions. Unknown or unmapped keys are silently ignored.

pub fn to_map(&self) -> HashMap<String, OptionValue>

Export all current options as a key-value map.

Useful for RPC responses and serialization. Returns a clone of the internal options map (including defaults for unset keys).

pub fn default_count(&self) -> usize

Return the number of built-in defaults.

pub fn is_explicitly_set(&self, key: &str) -> bool

Check whether a specific key has been explicitly set (vs using default).

pub fn reset_to_default(&mut self, key: &str)

Remove an explicitly-set option, reverting it to its default value.

After removal, [get] will return the built-in default again.

Trait Implementations

impl Default for OptionHandler

fn default() -> Self

Returns the “default value” for a type.