Struct LuaStateMut 

pub struct LuaStateMut<'scope, 'template, 'env>(/* private fields */);

A mlua::UserData wrapper around a mutable minijinja::State. This is passed to the callback provided to LuaEnvironment.render_captured. It can only be initialized within an mlua::Lua::scope callback, as it is not 'static

Methods from Deref<Target = State<'template, 'env>>

pub fn env(&self) -> &'env Environment<'env>

Returns a reference to the current environment.

pub fn name(&self) -> &str

Returns the name of the current template.

pub fn auto_escape(&self) -> AutoEscape

Returns the current value of the auto escape flag.

pub fn undefined_behavior(&self) -> UndefinedBehavior

Returns the current undefined behavior.

pub fn current_block(&self) -> Option<&str>

Returns the name of the innermost block.

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

Looks up a variable by name in the context.

Note on Closures

Macros and call blocks analyze which variables are referenced and create closures for them. This means that unless a variable is defined as a global in the environment, was passed in the initial render context, or was referenced by a macro, this method won’t be able to find it.

pub fn call_macro(&self, name: &str, args: &[Value]) -> Result<String, Error>

Looks up a global macro and calls it.

This looks up a value as lookup does and calls it with the passed args.

pub fn render_block(&mut self, block: &str) -> Result<String, Error>

Renders a block with the given name into a string.

This method works like Template::render but it only renders a specific block in the template. The first argument is the name of the block.

This renders only the block hi in the template:

let tmpl = env.get_template("hello")?;
let mut rendered = tmpl
    .render_captured(context!(name => "John"))?;
let rv = rendered.with_state_mut(|state| state.render_block("hi"))?;
println!("{}", rv);

Note that rendering a block is a stateful operation. If an error is returned the module has to be re-created as the internal state can end up corrupted. This also means you can only render blocks if you have a mutable reference to the state which is not possible from within filters or similar.

pub fn render_block_to_write<W>( &mut self, block: &str, w: W, ) -> Result<(), Error>

where W: Write,

Renders a block with the given name into an io::Write.

For details see render_block.

pub fn exports(&self) -> Vec<&str>

Returns a list of the names of all exports (top-level variables).

pub fn known_variables(&self) -> Vec<Cow<'_, str>>

Returns a list of all known variables.

This list contains all variables that are currently known to the state. To retrieve the values you can use lookup. This will include all the globals of the environment. Note that if the context has been initialized with an object that lies about variables (eg: it does not correctly implement enumeration), the returned list might not be complete.

pub fn get_template(&self, name: &str) -> Result<Template<'env, 'env>, Error>

Fetches a template by name with path joining.

This works like Environment::get_template with the difference that the lookup undergoes path joining. If the environment has a configured path joining callback, it will be invoked with the name of the current template as parent template.

For more information see Environment::set_path_join_callback.

pub fn apply_filter(&self, filter: &str, args: &[Value]) -> Result<Value, Error>

Invokes a filter with some arguments.

let rv = state.apply_filter("upper", &["hello world".into()]).unwrap();
assert_eq!(rv.as_str(), Some("HELLO WORLD"));

pub fn perform_test(&self, test: &str, args: &[Value]) -> Result<bool, Error>

Invokes a test function on a value.

let rv = state.perform_test("even", &[42i32.into()]).unwrap();
assert!(rv);

pub fn format(&self, value: Value) -> Result<String, Error>

Formats a value to a string using the formatter on the environment.

let rv = state.format(Value::from(42)).unwrap();
assert_eq!(rv, "42");

pub fn fuel_levels(&self) -> Option<(u64, u64)>

Returns the fuel levels.

When the fuel feature is enabled, during evaluation the template will keep track of how much fuel it has consumed. If the fuel tracker is turned on the returned value will be Some((consumed, remaining)). If fuel tracking is not enabled, None is returned instead.

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

Looks up a temp and returns it.

Temps are similar to context values but the engine never looks them up on their own and they are not scoped. The lifetime of temps is limited to the rendering process of a template. Temps are useful so that filters and other things can temporarily stash away state without having to resort to thread locals which are hard to manage. Unlike context variables, temps can also be modified during evaluation by filters and functions.

Temps are values but if you want to hold complex state you can store a custom object there.

Example

use minijinja::{Value, State};

fn inc(state: &State) -> Value {
    let old = state
        .get_temp("my_counter")
        .unwrap_or_else(|| Value::from(0i64));
    let new = Value::from(i64::try_from(old).unwrap() + 1);
    state.set_temp("my_counter", new.clone());
    new
}

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

Inserts a temp and returns the old temp.

For more information see get_temp.

pub fn get_or_set_temp_object<O, F>(&self, name: &str, f: F) -> Arc<O>

where O: Object + 'static, F: FnOnce() -> O,

Shortcut for registering an object as a temp.

If the value is already there, it’s returned as an object. If it’s not there yet, the function is invoked to create it.

Example

use std::sync::atomic::{AtomicUsize, Ordering};
use minijinja::{Value, State};
use minijinja::value::Object;

#[derive(Debug, Default)]
struct MyObject(AtomicUsize);

impl Object for MyObject {}

fn inc(state: &State) -> Value {
    let obj = state.get_or_set_temp_object("my_counter", MyObject::default);
    let old = obj.0.fetch_add(1, Ordering::AcqRel);
    Value::from(old + 1)
}

Panics

This will panic if the value registered under that name is not the object expected.

Trait Implementations

impl<'scope, 'template, 'env> Debug for LuaStateMut<'scope, 'template, 'env>

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

Formats the value using the given formatter.

impl<'scope, 'template, 'env> Deref for LuaStateMut<'scope, 'template, 'env>

type Target = State<'template, 'env>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'scope, 'template, 'env> DerefMut for LuaStateMut<'scope, 'template, 'env>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'scope, 'template, 'env> Display for LuaStateMut<'scope, 'template, 'env>

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

Formats the value using the given formatter.

impl<'scope, 'template, 'env> From<&'scope mut State<'template, 'env>> for LuaStateMut<'scope, 'template, 'env>

fn from(value: &'scope mut State<'template, 'env>) -> Self

Converts to this type from the input type.

impl<'scope, 'template, 'env> From<LuaStateMut<'scope, 'template, 'env>> for &'scope mut State<'template, 'env>

fn from(value: LuaStateMut<'scope, 'template, 'env>) -> Self

Converts to this type from the input type.

impl<'scope, 'template, 'env> UserData for LuaStateMut<'scope, 'template, 'env>

fn add_fields<F: UserDataFields<Self>>(fields: &mut F)

Adds custom fields specific to this userdata.

fn add_methods<M: UserDataMethods<Self>>(methods: &mut M)

Adds custom methods and operators specific to this userdata.

fn register(registry: &mut UserDataRegistry<Self>)

Registers this type for use in Lua.