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//! Type to hold a mutable reference to the target of an evaluation.
use crate::{Dynamic, Position, RhaiResultOf};
use std::borrow::{Borrow, BorrowMut};
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
/// Calculate an offset+len pair given an actual length of the underlying array.
///
/// Negative starting positions count from the end.
///
/// Values going over bounds are limited to the actual length.
#[cfg(not(feature = "no_index"))]
#[inline]
#[allow(
clippy::cast_sign_loss,
clippy::absurd_extreme_comparisons,
clippy::cast_possible_truncation
)]
pub fn calc_offset_len(length: usize, start: crate::INT, len: crate::INT) -> (usize, usize) {
let start = if start < 0 {
let abs_start = start.unsigned_abs();
#[allow(clippy::unnecessary_cast)]
if abs_start as u64 > crate::MAX_USIZE_INT as u64 {
0
} else {
length - usize::min(abs_start as usize, length)
}
} else if start > crate::MAX_USIZE_INT || start as usize >= length {
return (length, 0);
} else {
start as usize
};
let len = if len <= 0 {
0
} else if len > crate::MAX_USIZE_INT || len as usize > length - start {
length - start
} else {
len as usize
};
(start, len)
}
/// Calculate an offset+len pair given an actual length of the underlying array.
///
/// Negative starting positions count from the end.
///
/// Values going over bounds call the provided closure to return a default value or an error.
#[inline]
#[allow(dead_code)]
#[allow(
clippy::cast_sign_loss,
clippy::cast_possible_truncation,
clippy::absurd_extreme_comparisons
)]
pub fn calc_index<E>(
length: usize,
index: crate::INT,
negative_count_from_end: bool,
err_func: impl FnOnce() -> Result<usize, E>,
) -> Result<usize, E> {
if length == 0 {
// Empty array, do nothing
} else if index < 0 {
if negative_count_from_end {
let abs_index = index.unsigned_abs();
#[allow(clippy::unnecessary_cast)]
if abs_index as u64 <= crate::MAX_USIZE_INT as u64 && (abs_index as usize) <= length {
return Ok(length - (abs_index as usize));
}
}
} else if index <= crate::MAX_USIZE_INT && (index as usize) < length {
return Ok(index as usize);
}
err_func()
}
/// _(internals)_ A type that encapsulates a mutation target for an expression with side effects.
/// Exported under the `internals` feature only.
///
/// This type is typically used to hold a mutable reference to the target of an indexing or property
/// access operation.
///
/// # Example
///
/// ```
/// # #[cfg(feature = "internals")] {
/// # use rhai::{Dynamic, Target};
/// // Normal `Dynamic` value
/// let mut value = Dynamic::from(42_i64);
/// let target: Target = value.into();
///
/// // Mutable reference to a `Dynamic` value
/// let mut value = Dynamic::from(42_i64);
/// let value_ref = &mut value;
/// let target: Target = value.into();
/// # }
/// ```
#[derive(Debug)]
#[must_use]
pub enum Target<'a> {
/// The target is a mutable reference to a [`Dynamic`].
RefMut(&'a mut Dynamic),
/// The target is a mutable reference to a _shared_ [`Dynamic`].
#[cfg(not(feature = "no_closure"))]
SharedValue {
/// Lock guard to the shared [`Dynamic`].
guard: crate::types::dynamic::DynamicWriteLock<'a, Dynamic>,
/// Copy of the shared value.
shared_value: Dynamic,
},
/// The target is a temporary [`Dynamic`] value (i.e. its mutation can cause no side effects).
TempValue(Dynamic),
/// The target is a bit inside an [`INT`][crate::INT].
/// This is necessary because directly pointing to a bit inside an [`INT`][crate::INT] is impossible.
#[cfg(not(feature = "no_index"))]
Bit {
/// Mutable reference to the source [`Dynamic`].
source: &'a mut Dynamic,
/// Copy of the boolean bit, as a [`Dynamic`].
value: Dynamic,
/// Bit offset.
bit: u8,
},
/// The target is a range of bits inside an [`INT`][crate::INT].
/// This is necessary because directly pointing to a range of bits inside an [`INT`][crate::INT] is impossible.
#[cfg(not(feature = "no_index"))]
BitField {
/// Mutable reference to the source [`Dynamic`].
source: &'a mut Dynamic,
/// Copy of the integer value of the bits, as a [`Dynamic`].
value: Dynamic,
/// Bitmask to apply to the source value (i.e. shifted)
mask: crate::INT,
/// Number of bits to right-shift the source value.
shift: u8,
},
/// The target is a byte inside a [`Blob`][crate::Blob].
/// This is necessary because directly pointing to a [byte][u8] inside a BLOB is impossible.
#[cfg(not(feature = "no_index"))]
BlobByte {
/// Mutable reference to the source [`Dynamic`].
source: &'a mut Dynamic,
/// Copy of the byte at the index, as a [`Dynamic`].
value: Dynamic,
/// Offset index.
index: usize,
},
/// The target is a character inside a string.
/// This is necessary because directly pointing to a [`char`] inside a [`String`] is impossible.
#[cfg(not(feature = "no_index"))]
StringChar {
/// Mutable reference to the source [`Dynamic`].
source: &'a mut Dynamic,
/// Copy of the character at the offset, as a [`Dynamic`].
value: Dynamic,
/// Offset index.
index: usize,
},
/// The target is a slice of a string.
/// This is necessary because directly pointing to a [`char`] inside a [`String`] is impossible.
#[cfg(not(feature = "no_index"))]
StringSlice {
/// Mutable reference to the source [`Dynamic`].
source: &'a mut Dynamic,
/// Copy of the character at the offset, as a [`Dynamic`].
value: Dynamic,
/// Offset index.
start: usize,
/// End index.
end: usize,
/// Is exclusive?
exclusive: bool,
},
}
impl<'a> Target<'a> {
/// Is the [`Target`] a reference pointing to other data?
#[allow(dead_code)]
#[inline]
#[must_use]
pub const fn is_ref(&self) -> bool {
match self {
Self::RefMut(..) => true,
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { .. } => true,
Self::TempValue(..) => false,
#[cfg(not(feature = "no_index"))]
Self::Bit { .. }
| Self::BitField { .. }
| Self::BlobByte { .. }
| Self::StringChar { .. }
| Self::StringSlice { .. } => false,
}
}
/// Is the [`Target`] a temp value?
#[inline]
#[must_use]
pub const fn is_temp_value(&self) -> bool {
match self {
Self::RefMut(..) => false,
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { .. } => false,
Self::TempValue(..) => true,
#[cfg(not(feature = "no_index"))]
Self::Bit { .. }
| Self::BitField { .. }
| Self::BlobByte { .. }
| Self::StringChar { .. }
| Self::StringSlice { .. } => false,
}
}
/// Is the [`Target`] a shared value?
#[inline]
#[must_use]
pub fn is_shared(&self) -> bool {
#[cfg(not(feature = "no_closure"))]
return match self {
Self::RefMut(r) => r.is_shared(),
Self::SharedValue { .. } => true,
Self::TempValue(value) => value.is_shared(),
#[cfg(not(feature = "no_index"))]
Self::Bit { .. }
| Self::BitField { .. }
| Self::BlobByte { .. }
| Self::StringChar { .. }
| Self::StringSlice { .. } => false,
};
#[cfg(feature = "no_closure")]
return false;
}
/// Get the value of the [`Target`] as a [`Dynamic`], cloning a referenced value if necessary.
#[inline]
pub fn take_or_clone(self) -> Dynamic {
match self {
Self::RefMut(r) => r.clone(), // Referenced value is cloned
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { shared_value, .. } => shared_value, // Original shared value is simply taken
Self::TempValue(value) => value, // Owned value is simply taken
#[cfg(not(feature = "no_index"))]
Self::Bit { value, .. }
| Self::BitField { value, .. }
| Self::BlobByte { value, .. }
| Self::StringChar { value, .. }
| Self::StringSlice { value, .. } => value, // Intermediate value is simply taken
}
}
/// Take a `&mut Dynamic` reference from the `Target`.
#[inline(always)]
#[must_use]
pub fn take_ref(self) -> Option<&'a mut Dynamic> {
match self {
Self::RefMut(r) => Some(r),
_ => None,
}
}
/// Convert a shared or reference [`Target`] into a target with an owned value.
#[inline(always)]
pub fn into_owned(self) -> Self {
match self {
Self::RefMut(r) => Self::TempValue(r.clone()),
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { shared_value, .. } => Self::TempValue(shared_value),
_ => self,
}
}
/// Get the source [`Dynamic`] of the [`Target`].
#[allow(dead_code)]
#[inline]
pub fn source(&self) -> &Dynamic {
match self {
Self::RefMut(r) => r,
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { guard, .. } => guard,
Self::TempValue(value) => value,
#[cfg(not(feature = "no_index"))]
Self::Bit { source, .. }
| Self::BitField { source, .. }
| Self::BlobByte { source, .. }
| Self::StringChar { source, .. }
| Self::StringSlice { source, .. } => source,
}
}
/// Propagate a changed value back to the original source.
/// This has no effect for direct references.
#[inline]
pub fn propagate_changed_value(&mut self, _pos: Position) -> RhaiResultOf<()> {
match self {
Self::RefMut(..) | Self::TempValue(..) => (),
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { .. } => (),
#[cfg(not(feature = "no_index"))]
Self::Bit { source, value, bit } => {
// Replace the bit at the specified index position
let new_bit = value.as_bool().map_err(|err| {
Box::new(crate::ERR::ErrorMismatchDataType(
"bool".to_string(),
err.to_string(),
_pos,
))
})?;
let value = &mut *source.write_lock::<crate::INT>().unwrap();
let index = *bit;
let mask = 1 << index;
if new_bit {
*value |= mask;
} else {
*value &= !mask;
}
}
#[cfg(not(feature = "no_index"))]
Self::BitField {
source,
value,
mask,
shift,
} => {
let shift = *shift;
let mask = *mask;
// Replace the bit at the specified index position
let new_value = value.as_int().map_err(|err| {
Box::new(crate::ERR::ErrorMismatchDataType(
"integer".to_string(),
err.to_string(),
_pos,
))
})?;
let new_value = (new_value << shift) & mask;
let value = &mut *source.write_lock::<crate::INT>().unwrap();
*value &= !mask;
*value |= new_value;
}
#[cfg(not(feature = "no_index"))]
Self::BlobByte {
source,
value,
index,
} => {
// Replace the byte at the specified index position
let new_byte = value.as_int().map_err(|err| {
Box::new(crate::ERR::ErrorMismatchDataType(
"INT".to_string(),
err.to_string(),
_pos,
))
})?;
let value = &mut *source.write_lock::<crate::Blob>().unwrap();
#[allow(clippy::cast_sign_loss)]
{
value[*index] = (new_byte & 0x00ff) as u8;
}
}
#[cfg(not(feature = "no_index"))]
Self::StringChar {
source,
value,
index,
} => {
// Replace the character at the specified index position
let new_ch = value.as_char().map_err(|err| {
Box::new(crate::ERR::ErrorMismatchDataType(
"char".to_string(),
err.to_string(),
_pos,
))
})?;
let s = &mut *source.write_lock::<crate::ImmutableString>().unwrap();
*s = s
.chars()
.enumerate()
.map(|(i, ch)| if i == *index { new_ch } else { ch })
.collect();
}
#[cfg(not(feature = "no_index"))]
Self::StringSlice {
source,
ref start,
ref end,
ref value,
exclusive,
} => {
let s = &mut *source.write_lock::<crate::ImmutableString>().unwrap();
let n = s.chars().count();
let vs = s.chars().take(*start);
let ve = if *exclusive {
let end = if *end > n { n } else { *end };
s.chars().skip(end)
} else {
let end = if *end >= n { n - 1 } else { *end };
s.chars().skip(end + 1)
};
*s = vs.chain(value.to_string().chars()).chain(ve).collect();
}
}
Ok(())
}
}
impl<'a> From<&'a mut Dynamic> for Target<'a> {
#[inline]
fn from(value: &'a mut Dynamic) -> Self {
#[cfg(not(feature = "no_closure"))]
if value.is_shared() {
// Cloning is cheap for a shared value
let shared_value = value.clone();
let guard = value.write_lock::<Dynamic>().unwrap();
return Self::SharedValue {
guard,
shared_value,
};
}
Self::RefMut(value)
}
}
impl AsRef<Dynamic> for Target<'_> {
#[inline]
fn as_ref(&self) -> &Dynamic {
match self {
Self::RefMut(r) => r,
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { guard, .. } => guard,
Self::TempValue(ref value) => value,
#[cfg(not(feature = "no_index"))]
Self::StringSlice { ref value, .. } => value,
#[cfg(not(feature = "no_index"))]
Self::Bit { ref value, .. }
| Self::BitField { ref value, .. }
| Self::BlobByte { ref value, .. }
| Self::StringChar { ref value, .. } => value,
}
}
}
impl Borrow<Dynamic> for Target<'_> {
#[inline(always)]
fn borrow(&self) -> &Dynamic {
self.as_ref()
}
}
impl AsMut<Dynamic> for Target<'_> {
#[inline]
fn as_mut(&mut self) -> &mut Dynamic {
match self {
Self::RefMut(r) => r,
#[cfg(not(feature = "no_closure"))]
Self::SharedValue { guard, .. } => &mut *guard,
Self::TempValue(ref mut value) => value,
#[cfg(not(feature = "no_index"))]
Self::StringSlice { ref mut value, .. } => value,
#[cfg(not(feature = "no_index"))]
Self::Bit { ref mut value, .. }
| Self::BitField { ref mut value, .. }
| Self::BlobByte { ref mut value, .. }
| Self::StringChar { ref mut value, .. } => value,
}
}
}
impl BorrowMut<Dynamic> for Target<'_> {
#[inline(always)]
fn borrow_mut(&mut self) -> &mut Dynamic {
self.as_mut()
}
}
impl<T: Into<Dynamic>> From<T> for Target<'_> {
#[inline(always)]
fn from(value: T) -> Self {
Self::TempValue(value.into())
}
}