pub struct Scope<'a> { /* private fields */ }
Expand description
Type containing information about the current scope. Useful for keeping state between
Engine
evaluation runs.
Lifetime
Currently the lifetime parameter is not used, but it is not guaranteed to remain unused for
future versions. Until then, 'static
can be used.
Thread Safety
Currently, Scope
is neither Send
nor Sync
. Turn on the sync
feature to make it
Send
+
Sync
.
Example
use rhai::{Engine, Scope};
let engine = Engine::new();
let mut my_scope = Scope::new();
my_scope.push("z", 40_i64);
engine.run_with_scope(&mut my_scope, "let x = z + 1; z = 0;")?;
let result: i64 = engine.eval_with_scope(&mut my_scope, "x + 1")?;
assert_eq!(result, 42);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 41);
assert_eq!(my_scope.get_value::<i64>("z").expect("z should exist"), 0);
When searching for entries, newly-added entries are found before similarly-named but older entries, allowing for automatic shadowing.
Implementations
sourceimpl Scope<'_>
impl Scope<'_>
sourcepub fn clear(&mut self) -> &mut Self
pub fn clear(&mut self) -> &mut Self
Empty the Scope
.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
assert!(my_scope.contains("x"));
assert_eq!(my_scope.len(), 1);
assert!(!my_scope.is_empty());
my_scope.clear();
assert!(!my_scope.contains("x"));
assert_eq!(my_scope.len(), 0);
assert!(my_scope.is_empty());
sourcepub fn push(
&mut self,
name: impl Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
pub fn push(
&mut self,
name: impl Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
sourcepub fn push_dynamic(
&mut self,
name: impl Into<Identifier>,
value: Dynamic
) -> &mut Self
pub fn push_dynamic(
&mut self,
name: impl Into<Identifier>,
value: Dynamic
) -> &mut Self
sourcepub fn push_constant(
&mut self,
name: impl Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
pub fn push_constant(
&mut self,
name: impl Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
Add (push) a new constant to the Scope
.
Constants are immutable and cannot be assigned to. Their values never change.
Constants propagation is a technique used to optimize an AST
.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push_constant("x", 42_i64);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 42);
sourcepub fn push_constant_dynamic(
&mut self,
name: impl Into<Identifier>,
value: Dynamic
) -> &mut Self
pub fn push_constant_dynamic(
&mut self,
name: impl Into<Identifier>,
value: Dynamic
) -> &mut Self
Add (push) a new constant with a Dynamic
value to the Scope.
Constants are immutable and cannot be assigned to. Their values never change.
Constants propagation is a technique used to optimize an AST
.
Example
use rhai::{Dynamic, Scope};
let mut my_scope = Scope::new();
my_scope.push_constant_dynamic("x", Dynamic::from(42_i64));
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 42);
sourcepub fn rewind(&mut self, size: usize) -> &mut Self
pub fn rewind(&mut self, size: usize) -> &mut Self
Truncate (rewind) the Scope
to a previous size.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
my_scope.push("y", 123_i64);
assert!(my_scope.contains("x"));
assert!(my_scope.contains("y"));
assert_eq!(my_scope.len(), 2);
my_scope.rewind(1);
assert!(my_scope.contains("x"));
assert!(!my_scope.contains("y"));
assert_eq!(my_scope.len(), 1);
my_scope.rewind(0);
assert!(!my_scope.contains("x"));
assert!(!my_scope.contains("y"));
assert_eq!(my_scope.len(), 0);
assert!(my_scope.is_empty());
sourcepub fn is_constant(&self, name: &str) -> Option<bool>
pub fn is_constant(&self, name: &str) -> Option<bool>
Check if the named entry in the Scope
is constant.
Search starts backwards from the last, stopping at the first entry matching the specified name.
Returns None
if no entry matching the specified name is found.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push_constant("x", 42_i64);
assert_eq!(my_scope.is_constant("x"), Some(true));
assert_eq!(my_scope.is_constant("y"), None);
sourcepub fn set_or_push(
&mut self,
name: impl AsRef<str> + Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
pub fn set_or_push(
&mut self,
name: impl AsRef<str> + Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
Update the value of the named entry in the Scope
if it already exists and is not constant.
Push a new entry with the value into the Scope
if the name doesn’t exist or if the
existing entry is constant.
Search starts backwards from the last, and only the first entry matching the specified name is updated.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.set_or_push("x", 42_i64);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 42);
assert_eq!(my_scope.len(), 1);
my_scope.set_or_push("x", 0_i64);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 0);
assert_eq!(my_scope.len(), 1);
my_scope.set_or_push("y", 123_i64);
assert_eq!(my_scope.get_value::<i64>("y").expect("y should exist"), 123);
assert_eq!(my_scope.len(), 2);
sourcepub fn set_value(
&mut self,
name: impl AsRef<str> + Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
pub fn set_value(
&mut self,
name: impl AsRef<str> + Into<Identifier>,
value: impl Variant + Clone
) -> &mut Self
Update the value of the named entry in the Scope
.
Search starts backwards from the last, and only the first entry matching the specified name is updated. If no entry matching the specified name is found, a new one is added.
Panics
Panics when trying to update the value of a constant.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 42);
my_scope.set_value("x", 0_i64);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 0);
sourcepub fn get_mut(&mut self, name: &str) -> Option<&mut Dynamic>
pub fn get_mut(&mut self, name: &str) -> Option<&mut Dynamic>
Get a mutable reference to an entry in the Scope
.
If the entry by the specified name is not found, of if it is read-only,
None
is returned.
Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 42);
let ptr = my_scope.get_mut("x").expect("x should exist");
*ptr = 123_i64.into();
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 123);
my_scope.push_constant("Z", 1_i64);
assert!(my_scope.get_mut("Z").is_none());
sourcepub fn set_alias(
&mut self,
name: impl AsRef<str> + Into<Identifier>,
alias: impl Into<Identifier>
)
pub fn set_alias(
&mut self,
name: impl AsRef<str> + Into<Identifier>,
alias: impl Into<Identifier>
)
Add an alias to a variable in the Scope
so that it is exported under that name.
This is an advanced API.
If the alias is empty, then the variable is exported under its original name.
Multiple aliases can be added to any variable.
Only the last variable matching the name (and not other shadowed versions) is aliased by this call.
sourcepub fn clone_visible(&self) -> Self
pub fn clone_visible(&self) -> Self
Clone the Scope
, keeping only the last instances of each variable name.
Shadowed variables are omitted in the copy.
sourcepub fn iter(&self) -> impl Iterator<Item = (&str, bool, Dynamic)>
pub fn iter(&self) -> impl Iterator<Item = (&str, bool, Dynamic)>
Get an iterator to entries in the Scope
.
Shared values are flatten-cloned.
Example
use rhai::{Dynamic, Scope};
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
my_scope.push_constant("foo", "hello");
let mut iter = my_scope.iter();
let (name, is_constant, value) = iter.next().expect("value should exist");
assert_eq!(name, "x");
assert!(!is_constant);
assert_eq!(value.cast::<i64>(), 42);
let (name, is_constant, value) = iter.next().expect("value should exist");
assert_eq!(name, "foo");
assert!(is_constant);
assert_eq!(value.cast::<String>(), "hello");
Trait Implementations
sourceimpl<K: Into<Identifier>> Extend<(K, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> Extend<(K, Dynamic)> for Scope<'_>
sourcefn extend<T: IntoIterator<Item = (K, Dynamic)>>(&mut self, iter: T)
fn extend<T: IntoIterator<Item = (K, Dynamic)>>(&mut self, iter: T)
Extends a collection with the contents of an iterator. Read more
sourcefn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)Reserves capacity in a collection for the given number of additional elements. Read more
sourceimpl<K: Into<Identifier>> Extend<(K, bool, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> Extend<(K, bool, Dynamic)> for Scope<'_>
sourcefn extend<T: IntoIterator<Item = (K, bool, Dynamic)>>(&mut self, iter: T)
fn extend<T: IntoIterator<Item = (K, bool, Dynamic)>>(&mut self, iter: T)
Extends a collection with the contents of an iterator. Read more
sourcefn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)Reserves capacity in a collection for the given number of additional elements. Read more
sourceimpl<K: Into<Identifier>> FromIterator<(K, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> FromIterator<(K, Dynamic)> for Scope<'_>
sourceimpl<K: Into<Identifier>> FromIterator<(K, bool, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> FromIterator<(K, bool, Dynamic)> for Scope<'_>
sourceimpl IntoIterator for Scope<'_>
impl IntoIterator for Scope<'_>
Auto Trait Implementations
impl<'a> !RefUnwindSafe for Scope<'a>
impl<'a> !Send for Scope<'a>
impl<'a> !Sync for Scope<'a>
impl<'a> Unpin for Scope<'a>
impl<'a> !UnwindSafe for Scope<'a>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> CallHasher for T where
T: Hash + ?Sized,
impl<T> CallHasher for T where
T: Hash + ?Sized,
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more