pub struct EngineState {
Show 14 fields pub scope: ScopeFrame, pub ctrlc: Option<Arc<AtomicBool>>, pub env_vars: EnvVars, pub previous_env_vars: HashMap<String, Value>, pub config: Config, pub pipeline_externals_state: Arc<(AtomicU32, AtomicU32)>, pub repl_state: Arc<Mutex<ReplState>>, pub table_decl_id: Option<usize>, pub plugin_signatures: Option<PathBuf>, pub history_enabled: bool, pub history_session_id: i64, pub regex_cache: Arc<Mutex<LruCache<String, Regex>>>, pub is_interactive: bool, pub is_login: bool, /* private fields */
}
Expand description

The core global engine state. This includes all global definitions as well as any global state that will persist for the whole session.

Declarations, variables, blocks, and other forms of data are held in the global state and referenced elsewhere using their IDs. These IDs are simply their index into the global state. This allows us to more easily handle creating blocks, binding variables and callsites, and more, because each of these will refer to the corresponding IDs rather than their definitions directly. At runtime, this means less copying and smaller structures.

Note that the runtime stack is not part of this global state. Runtime stacks are handled differently, but they also rely on using IDs rather than full definitions.

A note on implementation:

Much of the global definitions are built on the Bodil’s ‘im’ crate. This gives us a way of working with lists of definitions in a way that is very cheap to access, while also allowing us to update them at key points in time (often, the transition between parsing and evaluation).

Over the last two years we tried a few different approaches to global state like this. I’ll list them here for posterity, so we can more easily know how we got here:

  • Rc - Rc is cheap, but not thread-safe. The moment we wanted to work with external processes, we needed a way send to stdin/stdout. In Rust, the current practice is to spawn a thread to handle both. These threads would need access to the global state, as they’ll need to process data as it streams out of the data pipeline. Because Rc isn’t thread-safe, this breaks.

  • Arc - Arc is the thread-safe version of the above. Often Arc is used in combination with a Mutex or RwLock, but you can use Arc by itself. We did this a few places in the original Nushell. This can work but because of Arc’s nature of not allowing mutation if there’s a second copy of the Arc around, this ultimately becomes limiting.

  • Arc + Mutex/RwLock - the standard practice for thread-safe containers. Unfortunately, this would have meant we would incur a lock penalty every time we needed to access any declaration or block. As we would be reading far more often than writing, it made sense to explore solutions that favor large amounts of reads.

  • im - the im crate was ultimately chosen because it has some very nice properties: it gives the ability to cheaply clone these structures, which is nice as EngineState may need to be cloned a fair bit to follow ownership rules for closures and iterators. It also is cheap to access. Favoring reads here fits more closely to what we need with Nushell. And, of course, it’s still thread-safe, so we get the same benefits as above.

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§scope: ScopeFrame§ctrlc: Option<Arc<AtomicBool>>§env_vars: EnvVars§previous_env_vars: HashMap<String, Value>§config: Config§pipeline_externals_state: Arc<(AtomicU32, AtomicU32)>§repl_state: Arc<Mutex<ReplState>>§table_decl_id: Option<usize>§plugin_signatures: Option<PathBuf>§history_enabled: bool§history_session_id: i64§regex_cache: Arc<Mutex<LruCache<String, Regex>>>§is_interactive: bool§is_login: bool

Implementations§

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impl EngineState

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pub fn new() -> Self

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pub fn merge_delta(&mut self, delta: StateDelta) -> Result<(), ShellError>

Merges a StateDelta onto the current state. These deltas come from a system, like the parser, that creates a new set of definitions and visible symbols in the current scope. We make this transactional as there are times when we want to run the parser and immediately throw away the results (namely: syntax highlighting and completions).

When we want to preserve what the parser has created, we can take its output (the StateDelta) and use this function to merge it into the global state.

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pub fn merge_env( &mut self, stack: &mut Stack, cwd: impl AsRef<Path> ) -> Result<(), ShellError>

Merge the environment from the runtime Stack into the engine state

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pub fn start_in_file(&mut self, file_path: Option<&str>)

Mark a starting point if it is a script (e.g., nu spam.nu)

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pub fn has_overlay(&self, name: &[u8]) -> bool

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pub fn active_overlay_ids<'a, 'b>( &'b self, removed_overlays: &'a [Vec<u8>] ) -> impl DoubleEndedIterator<Item = &OverlayId> + 'a
where 'b: 'a,

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pub fn active_overlays<'a, 'b>( &'b self, removed_overlays: &'a [Vec<u8>] ) -> impl DoubleEndedIterator<Item = &OverlayFrame> + 'a
where 'b: 'a,

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pub fn active_overlay_names<'a, 'b>( &'b self, removed_overlays: &'a [Vec<u8>] ) -> impl DoubleEndedIterator<Item = &[u8]> + 'a
where 'b: 'a,

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pub fn translate_overlay_ids(&self, other: &ScopeFrame) -> Vec<OverlayId>

Translate overlay IDs from other to IDs in self

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pub fn last_overlay_name(&self, removed_overlays: &[Vec<u8>]) -> &[u8]

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pub fn last_overlay(&self, removed_overlays: &[Vec<u8>]) -> &OverlayFrame

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pub fn get_overlay_name(&self, overlay_id: OverlayId) -> &[u8]

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pub fn get_overlay(&self, overlay_id: OverlayId) -> &OverlayFrame

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pub fn render_env_vars(&self) -> HashMap<&String, &Value>

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pub fn add_env_var(&mut self, name: String, val: Value)

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pub fn get_env_var(&self, name: &str) -> Option<&Value>

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pub fn get_path_env_var(&self) -> Option<&Value>

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pub fn update_plugin_file(&self) -> Result<(), ShellError>

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pub fn num_files(&self) -> usize

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pub fn num_virtual_paths(&self) -> usize

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pub fn num_vars(&self) -> usize

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pub fn num_decls(&self) -> usize

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pub fn num_blocks(&self) -> usize

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pub fn num_modules(&self) -> usize

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pub fn print_vars(&self)

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pub fn print_decls(&self)

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pub fn print_blocks(&self)

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pub fn print_contents(&self)

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pub fn find_decl( &self, name: &[u8], removed_overlays: &[Vec<u8>] ) -> Option<DeclId>

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pub fn find_decl_name( &self, decl_id: DeclId, removed_overlays: &[Vec<u8>] ) -> Option<&[u8]>

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pub fn get_module_comments(&self, module_id: ModuleId) -> Option<&[Span]>

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pub fn plugin_decls(&self) -> impl Iterator<Item = &Box<dyn Command + 'static>>

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pub fn find_module( &self, name: &[u8], removed_overlays: &[Vec<u8>] ) -> Option<ModuleId>

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pub fn which_module_has_decl( &self, decl_name: &[u8], removed_overlays: &[Vec<u8>] ) -> Option<&[u8]>

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pub fn find_overlay(&self, name: &[u8]) -> Option<OverlayId>

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pub fn find_active_overlay(&self, name: &[u8]) -> Option<OverlayId>

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pub fn find_commands_by_predicate( &self, predicate: impl Fn(&[u8]) -> bool, ignore_deprecated: bool ) -> Vec<(Vec<u8>, Option<String>)>

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pub fn get_span_contents(&self, span: Span) -> &[u8]

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pub fn get_config(&self) -> &Config

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pub fn set_config(&mut self, conf: Config)

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pub fn get_plugin_config(&self, plugin: &str) -> Option<&Value>

Fetch the configuration for a plugin

The plugin must match the registered name of a plugin. For register nu_plugin_example the plugin name to use will be "example"

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pub fn history_config(&self) -> Option<HistoryConfig>

Returns the configuration settings for command history or None if history is disabled

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pub fn get_var(&self, var_id: VarId) -> &Variable

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pub fn get_constant(&self, var_id: VarId) -> Option<&Value>

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pub fn set_variable_const_val(&mut self, var_id: VarId, val: Value)

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pub fn get_decl(&self, decl_id: DeclId) -> &Box<dyn Command>

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pub fn get_decls_sorted( &self, include_hidden: bool ) -> impl Iterator<Item = (Vec<u8>, DeclId)>

Get all commands within scope, sorted by the commands’ names

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pub fn get_signature(&self, decl: &Box<dyn Command>) -> Signature

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pub fn get_signatures(&self, include_hidden: bool) -> Vec<Signature>

Get signatures of all commands within scope.

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pub fn get_signatures_with_examples( &self, include_hidden: bool ) -> Vec<(Signature, Vec<Example<'_>>, bool, bool, bool)>

Get signatures of all commands within scope.

In addition to signatures, it returns whether each command is: a) a plugin b) custom

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pub fn get_block(&self, block_id: BlockId) -> &Block

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pub fn get_module(&self, module_id: ModuleId) -> &Module

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pub fn get_virtual_path( &self, virtual_path_id: VirtualPathId ) -> &(String, VirtualPath)

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pub fn next_span_start(&self) -> usize

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pub fn files(&self) -> impl Iterator<Item = &(String, usize, usize)>

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pub fn add_file(&mut self, filename: String, contents: Vec<u8>) -> usize

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pub fn get_cwd(&self) -> Option<String>

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pub fn set_config_path(&mut self, key: &str, val: PathBuf)

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pub fn get_config_path(&self, key: &str) -> Option<&PathBuf>

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pub fn build_usage(&self, spans: &[Span]) -> (String, String)

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pub fn build_module_usage( &self, module_id: ModuleId ) -> Option<(String, String)>

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pub fn current_work_dir(&self) -> String

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pub fn get_file_contents(&self) -> &[(Vec<u8>, usize, usize)]

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pub fn get_startup_time(&self) -> i64

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pub fn set_startup_time(&mut self, startup_time: i64)

Trait Implementations§

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impl Clone for EngineState

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fn clone(&self) -> EngineState

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Default for EngineState

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fn default() -> Self

Returns the “default value” for a type. Read more

Auto Trait Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<D> OwoColorize for D

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fn fg<C>(&self) -> FgColorDisplay<'_, C, Self>
where C: Color,

Set the foreground color generically Read more
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fn bg<C>(&self) -> BgColorDisplay<'_, C, Self>
where C: Color,

Set the background color generically. Read more
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fn black<'a>(&'a self) -> FgColorDisplay<'a, Black, Self>

Change the foreground color to black
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fn on_black<'a>(&'a self) -> BgColorDisplay<'a, Black, Self>

Change the background color to black
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fn red<'a>(&'a self) -> FgColorDisplay<'a, Red, Self>

Change the foreground color to red
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fn on_red<'a>(&'a self) -> BgColorDisplay<'a, Red, Self>

Change the background color to red
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fn green<'a>(&'a self) -> FgColorDisplay<'a, Green, Self>

Change the foreground color to green
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fn on_green<'a>(&'a self) -> BgColorDisplay<'a, Green, Self>

Change the background color to green
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fn yellow<'a>(&'a self) -> FgColorDisplay<'a, Yellow, Self>

Change the foreground color to yellow
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fn on_yellow<'a>(&'a self) -> BgColorDisplay<'a, Yellow, Self>

Change the background color to yellow
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fn blue<'a>(&'a self) -> FgColorDisplay<'a, Blue, Self>

Change the foreground color to blue
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fn on_blue<'a>(&'a self) -> BgColorDisplay<'a, Blue, Self>

Change the background color to blue
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fn magenta<'a>(&'a self) -> FgColorDisplay<'a, Magenta, Self>

Change the foreground color to magenta
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fn on_magenta<'a>(&'a self) -> BgColorDisplay<'a, Magenta, Self>

Change the background color to magenta
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fn purple<'a>(&'a self) -> FgColorDisplay<'a, Magenta, Self>

Change the foreground color to purple
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fn on_purple<'a>(&'a self) -> BgColorDisplay<'a, Magenta, Self>

Change the background color to purple
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fn cyan<'a>(&'a self) -> FgColorDisplay<'a, Cyan, Self>

Change the foreground color to cyan
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fn on_cyan<'a>(&'a self) -> BgColorDisplay<'a, Cyan, Self>

Change the background color to cyan
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fn white<'a>(&'a self) -> FgColorDisplay<'a, White, Self>

Change the foreground color to white
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fn on_white<'a>(&'a self) -> BgColorDisplay<'a, White, Self>

Change the background color to white
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fn default_color<'a>(&'a self) -> FgColorDisplay<'a, Default, Self>

Change the foreground color to the terminal default
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fn on_default_color<'a>(&'a self) -> BgColorDisplay<'a, Default, Self>

Change the background color to the terminal default
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fn bright_black<'a>(&'a self) -> FgColorDisplay<'a, BrightBlack, Self>

Change the foreground color to bright black
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fn on_bright_black<'a>(&'a self) -> BgColorDisplay<'a, BrightBlack, Self>

Change the background color to bright black
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fn bright_red<'a>(&'a self) -> FgColorDisplay<'a, BrightRed, Self>

Change the foreground color to bright red
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fn on_bright_red<'a>(&'a self) -> BgColorDisplay<'a, BrightRed, Self>

Change the background color to bright red
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fn bright_green<'a>(&'a self) -> FgColorDisplay<'a, BrightGreen, Self>

Change the foreground color to bright green
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fn on_bright_green<'a>(&'a self) -> BgColorDisplay<'a, BrightGreen, Self>

Change the background color to bright green
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fn bright_yellow<'a>(&'a self) -> FgColorDisplay<'a, BrightYellow, Self>

Change the foreground color to bright yellow
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fn on_bright_yellow<'a>(&'a self) -> BgColorDisplay<'a, BrightYellow, Self>

Change the background color to bright yellow
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fn bright_blue<'a>(&'a self) -> FgColorDisplay<'a, BrightBlue, Self>

Change the foreground color to bright blue
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fn on_bright_blue<'a>(&'a self) -> BgColorDisplay<'a, BrightBlue, Self>

Change the background color to bright blue
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fn bright_magenta<'a>(&'a self) -> FgColorDisplay<'a, BrightMagenta, Self>

Change the foreground color to bright magenta
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fn on_bright_magenta<'a>(&'a self) -> BgColorDisplay<'a, BrightMagenta, Self>

Change the background color to bright magenta
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fn bright_purple<'a>(&'a self) -> FgColorDisplay<'a, BrightMagenta, Self>

Change the foreground color to bright purple
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fn on_bright_purple<'a>(&'a self) -> BgColorDisplay<'a, BrightMagenta, Self>

Change the background color to bright purple
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fn bright_cyan<'a>(&'a self) -> FgColorDisplay<'a, BrightCyan, Self>

Change the foreground color to bright cyan
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fn on_bright_cyan<'a>(&'a self) -> BgColorDisplay<'a, BrightCyan, Self>

Change the background color to bright cyan
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fn bright_white<'a>(&'a self) -> FgColorDisplay<'a, BrightWhite, Self>

Change the foreground color to bright white
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fn on_bright_white<'a>(&'a self) -> BgColorDisplay<'a, BrightWhite, Self>

Change the background color to bright white
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fn bold<'a>(&'a self) -> BoldDisplay<'a, Self>

Make the text bold
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fn dimmed<'a>(&'a self) -> DimDisplay<'a, Self>

Make the text dim
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fn italic<'a>(&'a self) -> ItalicDisplay<'a, Self>

Make the text italicized
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fn underline<'a>(&'a self) -> UnderlineDisplay<'a, Self>

Make the text italicized
Make the text blink
Make the text blink (but fast!)
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fn reversed<'a>(&'a self) -> ReversedDisplay<'a, Self>

Swap the foreground and background colors
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fn hidden<'a>(&'a self) -> HiddenDisplay<'a, Self>

Hide the text
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fn strikethrough<'a>(&'a self) -> StrikeThroughDisplay<'a, Self>

Cross out the text
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fn color<Color>(&self, color: Color) -> FgDynColorDisplay<'_, Color, Self>
where Color: DynColor,

Set the foreground color at runtime. Only use if you do not know which color will be used at compile-time. If the color is constant, use either OwoColorize::fg or a color-specific method, such as OwoColorize::green, Read more
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fn on_color<Color>(&self, color: Color) -> BgDynColorDisplay<'_, Color, Self>
where Color: DynColor,

Set the background color at runtime. Only use if you do not know what color to use at compile-time. If the color is constant, use either OwoColorize::bg or a color-specific method, such as OwoColorize::on_yellow, Read more
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fn fg_rgb<const R: u8, const G: u8, const B: u8>( &self ) -> FgColorDisplay<'_, CustomColor<R, G, B>, Self>

Set the foreground color to a specific RGB value.
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fn bg_rgb<const R: u8, const G: u8, const B: u8>( &self ) -> BgColorDisplay<'_, CustomColor<R, G, B>, Self>

Set the background color to a specific RGB value.
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fn truecolor(&self, r: u8, g: u8, b: u8) -> FgDynColorDisplay<'_, Rgb, Self>

Sets the foreground color to an RGB value.
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fn on_truecolor(&self, r: u8, g: u8, b: u8) -> BgDynColorDisplay<'_, Rgb, Self>

Sets the background color to an RGB value.
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fn style(&self, style: Style) -> Styled<&Self>

Apply a runtime-determined style
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impl<T> Pointable for T

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const ALIGN: usize = _

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type Init = T

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type Error = <U as TryFrom<T>>::Error

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Performs the conversion.