Trait LuaHost 

pub trait LuaHost {
    // Required method
    fn run(
        &self,
        engine: &mut Engine,
        name: &str,
        code: &[u8],
    ) -> Result<(), String>;

    // Provided methods
    fn dump(&self, _engine: &mut Engine) -> Vec<u8>  { ... }
    fn undump(&self, _engine: &mut Engine, _data: &[u8]) -> Result<(), String> { ... }
    fn call_simple(
        &self,
        _engine: &mut Engine,
        _name: &str,
    ) -> Result<(), String> { ... }
    fn call_with_string(
        &self,
        _engine: &mut Engine,
        _name: &str,
        _arg: &str,
    ) -> Result<(), String> { ... }
    fn has_callback(&self, _name: &str) -> bool { ... }
    fn define_font(
        &self,
        _engine: &mut Engine,
        _name: &[u8],
        _size: i32,
    ) -> Option<u32> { ... }
    fn list_filter(
        &self,
        _engine: &mut Engine,
        _callback: &str,
        head: NodeRef,
        _group: &str,
    ) -> ListFilter { ... }
    fn pack_quality(
        &self,
        _engine: &mut Engine,
        _cb: &str,
        _incident: &str,
        _detail: i32,
        _b: NodeRef,
        _first: i32,
        _last: i32,
    ) -> NodeRef { ... }
    fn node_pass(&self, _engine: &mut Engine, _cb: &str, _head: NodeRef) -> bool { ... }
    fn linebreak_filter(
        &self,
        _engine: &mut Engine,
        _head: NodeRef,
        _display: bool,
    ) -> Option<NodeRef> { ... }
    fn mlist_to_hlist(
        &self,
        _engine: &mut Engine,
        _head: NodeRef,
        _style: i32,
        _penalties: bool,
    ) -> Option<NodeRef> { ... }
    fn pipe_read(&self, _engine: &mut Engine, _cmd: &[u8]) -> Option<Vec<u8>> { ... }
    fn input_level_string(
        &self,
        _engine: &mut Engine,
        _n: i64,
    ) -> Option<Vec<u8>> { ... }
    fn glyph_info(&self, _engine: &mut Engine, _p: NodeRef) -> Option<Vec<u8>> { ... }
}

Callbacks from the engine into an embedded Lua interpreter.

The engine does not depend on Lua. \directlua and related primitives call this trait, which retex-lua implements. The host is shared (Rc), so nested calls (Lua → TeX → Lua) reach it too.

Required Methods

fn run( &self, engine: &mut Engine, name: &str, code: &[u8], ) -> Result<(), String>

Runs a chunk of Lua code for \directlua (or \latelua, etc.). name is the chunk name. Text printed with tex.print must be pushed back into the engine’s input by the host.

Provided Methods

fn dump(&self, _engine: &mut Engine) -> Vec<u8>

Data to store in the format file (e.g. lua.bytecode).

fn undump(&self, _engine: &mut Engine, _data: &[u8]) -> Result<(), String>

Restores data stored by dump.

fn call_simple(&self, _engine: &mut Engine, _name: &str) -> Result<(), String>

Calls callback name without arguments, ignoring its results (pre_dump, stop_run, …). Does nothing if none is registered.

fn call_with_string( &self, _engine: &mut Engine, _name: &str, _arg: &str, ) -> Result<(), String>

Calls callback name with one string argument, ignoring its results (buildpage_filter, contribute_filter).

fn has_callback(&self, _name: &str) -> bool

Whether a Lua function is registered for callback name.

fn define_font( &self, _engine: &mut Engine, _name: &[u8], _size: i32, ) -> Option<u32>

Calls the define_font callback. Returns the id of the font it defined, or None if the font could not be loaded.

fn list_filter( &self, _engine: &mut Engine, _callback: &str, head: NodeRef, _group: &str, ) -> ListFilter

Calls a node-list filter callback (pre_linebreak_filter, hpack_filter, post_linebreak_filter, …) on the list starting at head. Returns the new head; ListFilter::Flush means the list must be discarded.

fn pack_quality( &self, _engine: &mut Engine, _cb: &str, _incident: &str, _detail: i32, _b: NodeRef, _first: i32, _last: i32, ) -> NodeRef

Calls the hpack_quality or vpack_quality callback cb for box b with incident (overfull, underfull, loose, tight) and its detail; returns the node the callback gave (null if none).

fn node_pass(&self, _engine: &mut Engine, _cb: &str, _head: NodeRef) -> bool

Runs the hyphenate, ligaturing or kerning callback cb on the list after head (a temporary node), with its last node: true if a function or false is registered, which replaces the built-in pass.

fn linebreak_filter( &self, _engine: &mut Engine, _head: NodeRef, _display: bool, ) -> Option<NodeRef>

Calls the linebreak_filter callback on paragraph head (display: a display follows): Some(list) if it returned a node list, which replaces line breaking; None otherwise.

fn mlist_to_hlist( &self, _engine: &mut Engine, _head: NodeRef, _style: i32, _penalties: bool, ) -> Option<NodeRef>

Calls the mlist_to_hlist callback on math list head in style style (0–7); None if the callback failed or none is set.

fn pipe_read(&self, _engine: &mut Engine, _cmd: &[u8]) -> Option<Vec<u8>>

Runs shell command cmd under the shell escape rules (as Lua’s io.popen does) and returns its output; None if it may not run.

fn input_level_string(&self, _engine: &mut Engine, _n: i64) -> Option<Vec<u8>>

Calls the input_level_string callback with input-stack depth n; None if it returned no string.

fn glyph_info(&self, _engine: &mut Engine, _p: NodeRef) -> Option<Vec<u8>>

Calls the glyph_info callback for glyph node p: Some(text) is what to print, None means the callback returned no string.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors