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Refactor context so that parents are a Weak reference

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This commit is contained in:
Jeff 2024-09-03 00:42:39 -04:00
parent 0aebd81665
commit d6ab891d7f
1 changed files with 215 additions and 73 deletions
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288
dust-lang/src/context.rs
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@ -2,7 +2,7 @@
use std::{
collections::HashMap,
fmt::{self, Display, Formatter},
sync::{Arc, PoisonError, RwLock, RwLockReadGuard, RwLockWriteGuard},
sync::{Arc, PoisonError, RwLock, RwLockReadGuard, RwLockWriteGuard, Weak},
};
use crate::{Constructor, Identifier, StructType, Type, Value};
@ -12,8 +12,7 @@ pub type Associations = HashMap<Identifier, (ContextData, usize)>;
/// Garbage-collecting context for variables.
#[derive(Debug, Clone)]
pub struct Context {
associations: Arc<RwLock<Associations>>,
parent: Option<Box<Context>>,
inner: Arc<ContextInner>,
}
impl Context {
@ -23,33 +22,183 @@ impl Context {
pub fn with_data(data: Associations) -> Self {
Self {
associations: Arc::new(RwLock::new(data)),
parent: None,
inner: Arc::new(ContextInner {
associations: RwLock::new(data),
parent: None,
}),
}
}
/// Creates a deep copy of another context.
pub fn with_data_from(other: &Self) -> Result<Self, ContextError> {
Ok(Self::with_data(other.associations.read()?.clone()))
let mut associations = HashMap::new();
for (identifier, (context_data, position)) in other.inner.associations.read()?.iter() {
associations.insert(identifier.clone(), (context_data.clone(), *position));
}
Ok(Self::with_data(associations))
}
pub fn create_child(&self) -> Self {
Self {
associations: Arc::new(RwLock::new(HashMap::new())),
parent: Some(Box::new(self.clone())),
inner: Arc::new(ContextInner {
associations: RwLock::new(HashMap::new()),
parent: Some(Arc::downgrade(&self.inner)),
}),
}
}
/// Returns the number of associated identifiers in the context.
pub fn association_count(&self) -> Result<usize, ContextError> {
let own_count = self.associations.read()?.len();
let ancestor_count = if let Some(parent) = &self.parent {
parent.association_count()?
} else {
0
};
self.inner.association_count()
}
Ok(own_count + ancestor_count)
/// Returns a boolean indicating whether the identifier is in the context.
pub fn contains(&self, identifier: &Identifier) -> Result<bool, ContextError> {
self.inner.contains(identifier)
}
/// Returns the full ContextData and Span if the context contains the given identifier.
pub fn get(
&self,
identifier: &Identifier,
) -> Result<Option<(ContextData, usize)>, ContextError> {
self.inner.get(identifier)
}
/// Returns the type associated with the given identifier.
pub fn get_type(&self, identifier: &Identifier) -> Result<Option<Type>, ContextError> {
self.inner.get_type(identifier)
}
/// Returns the ContextData associated with the identifier.
pub fn get_data(&self, identifier: &Identifier) -> Result<Option<ContextData>, ContextError> {
self.inner.get_data(identifier)
}
/// Returns the value associated with the identifier.
pub fn get_variable_value(
&self,
identifier: &Identifier,
) -> Result<Option<Value>, ContextError> {
self.inner.get_variable_value(identifier)
}
/// Returns the constructor associated with the identifier.
pub fn get_constructor(
&self,
identifier: &Identifier,
) -> Result<Option<Constructor>, ContextError> {
self.inner.get_constructor(identifier)
}
/// Returns the constructor type associated with the identifier.
pub fn get_constructor_type(
&self,
identifier: &Identifier,
) -> Result<Option<StructType>, ContextError> {
self.inner.get_constructor_type(identifier)
}
/// Associates an identifier with a variable type, with a position given for garbage collection.
pub fn set_variable_type(
&self,
identifier: Identifier,
r#type: Type,
) -> Result<(), ContextError> {
self.inner.set_variable_type(identifier, r#type)
}
/// Associates an identifier with a variable value.
pub fn set_variable_value(
&self,
identifier: Identifier,
value: Value,
) -> Result<(), ContextError> {
self.inner.set_variable_value(identifier, value)
}
/// Associates an identifier with a constructor.
pub fn set_constructor(
&self,
identifier: Identifier,
constructor: Constructor,
) -> Result<(), ContextError> {
self.inner.set_constructor(identifier, constructor)
}
/// Associates an identifier with a constructor type, with a position given for garbage
/// collection.
pub fn set_constructor_type(
&self,
identifier: Identifier,
struct_type: StructType,
) -> Result<(), ContextError> {
self.inner.set_constructor_type(identifier, struct_type)
}
/// Collects garbage up to the given position, removing all variables with lesser positions.
pub fn collect_garbage(&self, position: usize) -> Result<(), ContextError> {
self.inner.collect_garbage(position)
}
/// Updates an associated identifier's last known position, allowing it to live longer in the
/// program. Returns a boolean indicating whether the identifier was found. If the identifier is
/// not found in the current context, the parent context is searched but parent context's
/// position is not updated.
pub fn update_last_position(
&self,
identifier: &Identifier,
position: usize,
) -> Result<bool, ContextError> {
self.inner.update_last_position(identifier, position)
}
/// Recovers the context from a poisoned state by recovering data from an error.
///
/// This method is not used.
pub fn _recover_from_poison(&mut self, error: &ContextError) {
log::debug!("Context is recovering from poison error");
let ContextError::PoisonErrorRecovered(recovered) = error;
let mut new_associations = HashMap::new();
for (identifier, (context_data, position)) in recovered.as_ref() {
new_associations.insert(identifier.clone(), (context_data.clone(), *position));
}
self.inner = Arc::new(ContextInner {
associations: RwLock::new(new_associations),
parent: None,
});
}
}
impl Default for Context {
fn default() -> Self {
Self::new()
}
}
#[derive(Debug)]
pub struct ContextInner {
pub associations: RwLock<Associations>,
pub parent: Option<Weak<ContextInner>>,
}
impl ContextInner {
pub fn new(associations: RwLock<Associations>, parent: Option<Weak<ContextInner>>) -> Self {
Self {
associations,
parent,
}
}
/// Returns the number of associated identifiers in the context.
pub fn association_count(&self) -> Result<usize, ContextError> {
Ok(self.associations.read()?.len())
}
/// Returns a boolean indicating whether the identifier is in the context.
@ -57,7 +206,11 @@ impl Context {
if self.associations.read()?.contains_key(identifier) {
Ok(true)
} else if let Some(parent) = &self.parent {
parent.contains(identifier)
if let Some(parent) = parent.upgrade() {
parent.contains(identifier)
} else {
Ok(false)
}
} else {
Ok(false)
}
@ -69,12 +222,14 @@ impl Context {
identifier: &Identifier,
) -> Result<Option<(ContextData, usize)>, ContextError> {
if let Some((variable_data, position)) = self.associations.read()?.get(identifier) {
Ok(Some((variable_data.clone(), *position)))
return Ok(Some((variable_data.clone(), *position)));
} else if let Some(parent) = &self.parent {
parent.get(identifier)
} else {
Ok(None)
if let Some(parent) = parent.upgrade() {
return parent.get(identifier);
}
}
Ok(None)
}
/// Returns the type associated with the given identifier.
@ -89,21 +244,25 @@ impl Context {
}
if let Some(parent) = &self.parent {
parent.get_type(identifier)
} else {
Ok(None)
if let Some(parent) = parent.upgrade() {
return parent.get_type(identifier);
}
}
Ok(None)
}
/// Returns the ContextData associated with the identifier.
pub fn get_data(&self, identifier: &Identifier) -> Result<Option<ContextData>, ContextError> {
if let Some((variable_data, _)) = self.associations.read()?.get(identifier) {
Ok(Some(variable_data.clone()))
return Ok(Some(variable_data.clone()));
} else if let Some(parent) = &self.parent {
parent.get_data(identifier)
} else {
Ok(None)
if let Some(parent) = parent.upgrade() {
return parent.get_data(identifier);
}
}
Ok(None)
}
/// Returns the value associated with the identifier.
@ -114,12 +273,14 @@ impl Context {
if let Some((ContextData::VariableValue(value), _)) =
self.associations.read()?.get(identifier)
{
Ok(Some(value.clone()))
return Ok(Some(value.clone()));
} else if let Some(parent) = &self.parent {
parent.get_variable_value(identifier)
} else {
Ok(None)
if let Some(parent) = parent.upgrade() {
return parent.get_variable_value(identifier);
}
}
Ok(None)
}
/// Returns the constructor associated with the identifier.
@ -130,12 +291,14 @@ impl Context {
if let Some((ContextData::Constructor(constructor), _)) =
self.associations.read()?.get(identifier)
{
Ok(Some(constructor.clone()))
return Ok(Some(constructor.clone()));
} else if let Some(parent) = &self.parent {
parent.get_constructor(identifier)
} else {
Ok(None)
if let Some(parent) = parent.upgrade() {
return parent.get_constructor(identifier);
}
}
Ok(None)
}
/// Returns the constructor type associated with the identifier.
@ -146,16 +309,18 @@ impl Context {
let read_associations = self.associations.read()?;
if let Some((context_data, _)) = read_associations.get(identifier) {
match context_data {
return match context_data {
ContextData::Constructor(constructor) => Ok(Some(constructor.struct_type.clone())),
ContextData::ConstructorType(struct_type) => Ok(Some(struct_type.clone())),
_ => Ok(None),
}
};
} else if let Some(parent) = &self.parent {
parent.get_constructor_type(identifier)
} else {
Ok(None)
if let Some(parent) = parent.upgrade() {
return parent.get_constructor_type(identifier);
}
}
Ok(None)
}
/// Associates an identifier with a variable type, with a position given for garbage collection.
@ -279,22 +444,22 @@ impl Context {
let found = self.update_position_if_found(identifier, position)?;
if found {
Ok(true)
return Ok(true);
} else if let Some(parent) = &self.parent {
let found_in_ancestor = parent.update_position_if_found(identifier, position)?;
if let Some(parent) = parent.upgrade() {
let found_in_ancestor = parent.update_position_if_found(identifier, position)?;
if !found_in_ancestor {
let mut associations = self.associations.write()?;
if !found_in_ancestor {
let mut associations = self.associations.write()?;
log::trace!("Updating {identifier}'s last position to {position:?}");
log::trace!("Updating {identifier}'s last position to {position:?}");
associations.insert(identifier.clone(), (ContextData::Reserved, position));
associations.insert(identifier.clone(), (ContextData::Reserved, position));
}
}
Ok(false)
} else {
Ok(false)
}
Ok(false)
}
fn update_position_if_found(
@ -314,29 +479,6 @@ impl Context {
Ok(false)
}
}
/// Recovers the context from a poisoned state by recovering data from an error.
///
/// This method is not used.
pub fn _recover_from_poison(&mut self, error: &ContextError) {
log::debug!("Context is recovering from poison error");
let ContextError::PoisonErrorRecovered(recovered) = error;
let mut new_associations = HashMap::new();
for (identifier, (context_data, position)) in recovered.as_ref() {
new_associations.insert(identifier.clone(), (context_data.clone(), *position));
}
self.associations = Arc::new(RwLock::new(new_associations));
}
}
impl Default for Context {
fn default() -> Self {
Self::new()
}
}
#[derive(Debug, Clone)]