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§
source§impl Scope<'_>
impl Scope<'_>
sourcepub fn with_capacity(capacity: usize) -> Self
pub fn with_capacity(capacity: usize) -> Self
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 pop(&mut self) -> &mut Self
pub fn pop(&mut self) -> &mut Self
Remove the last entry from the Scope
.
§Panics
Panics is the Scope
is empty.
§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.pop();
assert!(my_scope.contains("x"));
assert!(!my_scope.contains("y"));
assert_eq!(my_scope.len(), 1);
my_scope.pop();
assert!(!my_scope.contains("x"));
assert!(!my_scope.contains("y"));
assert_eq!(my_scope.len(), 0);
assert!(my_scope.is_empty());
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 get_value_mut<T: Variant + Clone>(
&mut self,
name: &str
) -> Option<&mut T>
pub fn get_value_mut<T: Variant + Clone>( &mut self, name: &str ) -> Option<&mut T>
Get a mutable reference the value of an entry in the Scope
, starting from the last.
§Panics
Panics if the value is shared.
§Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
let ptr = my_scope.get_value_mut::<i64>("x").expect("x should exist");
*ptr = 0;
assert_eq!(my_scope.get_value::<i64>("x").expect("x should exist"), 0);
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(&self, name: &str) -> Option<&Dynamic>
pub fn get(&self, name: &str) -> Option<&Dynamic>
Get a reference to an entry in the Scope
.
If the entry by the specified name is not found, None
is returned.
§Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 42_i64);
let value = my_scope.get("x").expect("x should exist");
assert_eq!(value.as_int().unwrap(), 42);
assert!(my_scope.get("z").is_none());
sourcepub fn remove<T: Variant + Clone>(&mut self, name: &str) -> Option<T>
pub fn remove<T: Variant + Clone>(&mut self, name: &str) -> Option<T>
Remove the last entry in the Scope
by the specified name and return its value.
If the entry by the specified name is not found, None
is returned.
§Example
use rhai::Scope;
let mut my_scope = Scope::new();
my_scope.push("x", 123_i64); // first 'x'
my_scope.push("x", 42_i64); // second 'x', shadows first
assert_eq!(my_scope.len(), 2);
let value = my_scope.remove::<i64>("x").expect("x should exist");
assert_eq!(value, 42);
assert_eq!(my_scope.len(), 1);
let value = my_scope.get_value::<i64>("x").expect("x should still exist");
assert_eq!(value, 123);
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 the value of an entry in the Scope
.
If the entry by the specified name is not found, or 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<ImmutableString>
)
pub fn set_alias( &mut self, name: impl AsRef<str> + Into<Identifier>, alias: impl Into<ImmutableString> )
Add an alias to a variable in the Scope
so that it is exported under that name.
This is an advanced API.
Variable aliases are used, for example, in Module::eval_ast_as_new
to create a new module with exported variables under different names.
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§
source§impl<'de> Deserialize<'de> for Scope<'de>
impl<'de> Deserialize<'de> for Scope<'de>
source§fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error>
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error>
source§impl<K: Into<Identifier>> Extend<(K, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> Extend<(K, Dynamic)> for Scope<'_>
source§fn extend<T: IntoIterator<Item = (K, Dynamic)>>(&mut self, iter: T)
fn extend<T: IntoIterator<Item = (K, Dynamic)>>(&mut self, iter: T)
source§fn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)source§fn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)source§impl<K: Into<Identifier>> Extend<(K, bool, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> Extend<(K, bool, Dynamic)> for Scope<'_>
source§fn extend<T: IntoIterator<Item = (K, bool, Dynamic)>>(&mut self, iter: T)
fn extend<T: IntoIterator<Item = (K, bool, Dynamic)>>(&mut self, iter: T)
source§fn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)source§fn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)source§impl<K: Into<Identifier>> FromIterator<(K, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> FromIterator<(K, Dynamic)> for Scope<'_>
source§impl<K: Into<Identifier>> FromIterator<(K, bool, Dynamic)> for Scope<'_>
impl<K: Into<Identifier>> FromIterator<(K, bool, Dynamic)> for Scope<'_>
source§impl<'a> IntoIterator for &'a Scope<'_>
impl<'a> IntoIterator for &'a Scope<'_>
Auto Trait Implementations§
impl<'a> Freeze for Scope<'a>
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§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> Variant for T
impl<T> Variant for T
source§fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Variant
trait object to &mut dyn Any
.source§fn as_boxed_any(self: Box<T>) -> Box<dyn Any>
fn as_boxed_any(self: Box<T>) -> Box<dyn Any>
Variant
trait object to Box<dyn Any>
.