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//! Working with memory.
use crate as rune;
use crate::alloc::fmt::TryWrite;
use crate::runtime::{self, Formatter, Value, VmResult};
use crate::{Any, ContextError, Module};
/// Working with memory.
#[rune::module(::std::mem)]
pub fn module() -> Result<Module, ContextError> {
let mut m = Module::from_meta(self::module_meta)?;
m.function_meta(drop)?;
m.function_meta(snapshot)?;
m.ty::<Snapshot>()?;
m.function_meta(Snapshot::display)?;
m.function_meta(Snapshot::debug)?;
m.function_meta(Snapshot::shared)?;
m.function_meta(Snapshot::is_exclusive)?;
m.function_meta(Snapshot::is_readable)?;
m.function_meta(Snapshot::is_writable)?;
Ok(m)
}
#[derive(Any)]
#[rune(item = ::std::mem)]
struct Snapshot {
inner: runtime::Snapshot,
}
impl Snapshot {
/// The number of shared references to the value.
///
/// # Examples
///
/// ```rune
/// use std::mem::snapshot;
///
/// let v = [1, 2, 3];
///
/// let s = snapshot(v)?;
/// assert_eq!(s.shared(), 0);
///
/// // An iterators takes a shared reference to the collection being iterated over.
/// let it = v.iter();
///
/// let s = snapshot(v)?;
/// assert_eq!(s.shared(), 1);
/// drop(it);
///
/// let s = snapshot(v)?;
/// assert_eq!(s.shared(), 0);
/// ```
#[rune::function]
fn shared(&self) -> usize {
self.inner.shared()
}
/// Test if the snapshot indicates that the value is exclusively held.
///
/// # Examples
///
/// ```rune
/// use std::mem::snapshot;
///
/// let v = [1, 2, 3];
///
/// let s = snapshot(v)?;
/// assert_eq!(s.shared(), 0);
/// assert!(!s.is_exclusive());
/// assert!(s.is_readable());
/// assert!(s.is_writable());
///
/// // Assign to a separate variable since the compiler will notice that `v` is moved.
/// let u = v;
///
/// // Move the value into a closure, causing the original reference to become exclusively held.
/// let closure = move || {
/// v
/// };
///
/// let s = snapshot(u)?;
/// assert!(s.is_exclusive());
/// assert!(!s.is_readable());
/// assert!(!s.is_writable());
/// ```
#[rune::function]
fn is_exclusive(&self) -> bool {
self.inner.is_exclusive()
}
/// Test if the snapshot indicates that the value is readable.
///
/// # Examples
///
/// ```rune
/// use std::mem::snapshot;
///
/// let v = [1, 2, 3];
///
/// let s = snapshot(v)?;
/// assert_eq!(s.shared(), 0);
/// assert!(!s.is_exclusive());
/// assert!(s.is_readable());
/// assert!(s.is_writable());
///
/// // Assign to a separate variable since the compiler will notice that `v` is moved.
/// let u = v;
///
/// // Move the value into a closure, causing the original reference to become exclusively held.
/// let closure = move || {
/// v
/// };
///
/// let s = snapshot(u)?;
/// assert!(s.is_exclusive());
/// assert!(!s.is_readable());
/// assert!(!s.is_writable());
/// ```
#[rune::function]
fn is_readable(&self) -> bool {
self.inner.is_readable()
}
/// Test if the snapshot indicates that the value is writable.
///
/// # Examples
///
/// ```rune
/// use std::mem::snapshot;
///
/// let v = [1, 2, 3];
///
/// let s = snapshot(v)?;
/// assert_eq!(s.shared(), 0);
/// assert!(!s.is_exclusive());
/// assert!(s.is_readable());
/// assert!(s.is_writable());
///
/// // Assign to a separate variable since the compiler will notice that `v` is moved.
/// let u = v;
///
/// // Move the value into a closure, causing the original reference to become exclusively held.
/// let closure = move || {
/// v
/// };
///
/// let s = snapshot(u)?;
/// assert!(s.is_exclusive());
/// assert!(!s.is_readable());
/// assert!(!s.is_writable());
/// ```
#[rune::function]
fn is_writable(&self) -> bool {
self.inner.is_writable()
}
#[rune::function(protocol = DISPLAY_FMT)]
fn display(&self, f: &mut Formatter) -> VmResult<()> {
vm_write!(f, "{}", self.inner)
}
#[rune::function(protocol = DEBUG_FMT)]
fn debug(&self, f: &mut Formatter) -> VmResult<()> {
vm_write!(f, "{:?}", self.inner)
}
}
/// Explicitly drop the given value, freeing up any memory associated with it.
///
/// Normally values are dropped as they go out of scope, but with this method it
/// can be explicitly controlled instead.
///
/// # Examples
///
/// Basic usage:
///
/// ```rune
/// let v = [1, 2, 3];
/// drop(v);
/// ```
#[rune::function]
fn drop(value: Value) -> VmResult<()> {
vm_try!(value.drop());
VmResult::Ok(())
}
/// Get the usage snapshot of a value.
///
/// A snapshot can be used to diagnose how many users a given value has.
///
/// # Examples
///
/// ```rune
/// use std::mem::snapshot;
///
/// let v1 = [1, 2, 3];
/// let a = snapshot(v1)?;
/// let v2 = [v1];
/// let b = snapshot(v1)?;
///
/// assert_eq!(a.shared(), 0);
/// assert_eq!(b.shared(), 0);
///
/// dbg!(a);
/// dbg!(b);
/// ```
#[rune::function]
fn snapshot(value: Value) -> Option<Snapshot> {
value
.snapshot()
.map(|snapshot| Snapshot { inner: snapshot })
}