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Encapsulate index values into StaticVec type.

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This commit is contained in:
Stephen Chung 2020-04-27 20:25:20 +08:00
parent 0d5a36edc8
commit b3e4659790
1 changed files with 103 additions and 99 deletions
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188
src/engine.rs
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@ -60,6 +60,13 @@ pub const MAX_CALL_STACK_DEPTH: usize = 28;
#[cfg(not(debug_assertions))]
pub const MAX_CALL_STACK_DEPTH: usize = 256;
#[cfg(not(feature = "only_i32"))]
#[cfg(not(feature = "only_i64"))]
const FUNCTIONS_COUNT: usize = 512;
#[cfg(any(feature = "only_i32", feature = "only_i64"))]
const FUNCTIONS_COUNT: usize = 256;
pub const KEYWORD_PRINT: &str = "print";
pub const KEYWORD_DEBUG: &str = "debug";
pub const KEYWORD_TYPE_OF: &str = "type_of";
@ -68,13 +75,6 @@ pub const FUNC_TO_STRING: &str = "to_string";
pub const FUNC_GETTER: &str = "get$";
pub const FUNC_SETTER: &str = "set$";
#[cfg(not(feature = "only_i32"))]
#[cfg(not(feature = "only_i64"))]
const FUNCTIONS_COUNT: usize = 512;
#[cfg(any(feature = "only_i32", feature = "only_i64"))]
const FUNCTIONS_COUNT: usize = 256;
/// A type that encapsulates a mutation target for an expression with side effects.
enum Target<'a> {
/// The target is a mutable reference to a `Dynamic` value somewhere.
@ -82,6 +82,7 @@ enum Target<'a> {
/// The target is a temporary `Dynamic` value (i.e. the mutation can cause no side effects).
Value(Box<Dynamic>),
/// The target is a character inside a String.
/// This is necessary because directly pointing to a char inside a String is impossible.
StringChar(Box<(&'a mut Dynamic, usize, Dynamic)>),
}
@ -138,6 +139,55 @@ impl<T: Into<Dynamic>> From<T> for Target<'_> {
}
}
/// A type to hold a number of `Dynamic` values in static storage for speed,
/// and any spill-overs in a `Vec`.
struct StaticVec {
/// Total number of values held.
len: usize,
/// Static storage.
list: [Dynamic; 4],
/// Dynamic storage.
more: Vec<Dynamic>,
}
impl StaticVec {
/// Create a new `StaticVec`.
pub fn new() -> Self {
Self {
len: 0,
list: [().into(), ().into(), ().into(), ().into()],
more: Vec::new(),
}
}
/// Push a new value to the end of this `StaticVec`.
pub fn push<T: Into<Dynamic>>(&mut self, value: T) {
if self.len >= self.list.len() {
self.more.push(value.into());
} else {
self.list[self.len] = value.into();
}
self.len += 1;
}
/// Pop a value from the end of this `StaticVec`.
///
/// # Panics
///
/// Panics if the `StaticVec` is empty.
pub fn pop(&mut self) -> Dynamic {
let result = if self.len <= 0 {
panic!("nothing to pop!")
} else if self.len <= self.list.len() {
mem::replace(self.list.get_mut(self.len - 1).unwrap(), ().into())
} else {
self.more.pop().unwrap()
};
self.len -= 1;
result
}
}
/// A type that holds a library (`HashMap`) of script-defined functions.
///
/// Since script-defined functions have `Dynamic` parameters, functions with the same name
@ -393,7 +443,14 @@ fn search_scope<'a>(
.get(id)
.ok_or_else(|| Box::new(EvalAltResult::ErrorVariableNotFound(id.into(), begin)))?;
Ok((scope.get_mut(ScopeSource { name: id, typ, index }), typ))
Ok((
scope.get_mut(ScopeSource {
name: id,
typ,
index,
}),
typ,
))
}
impl Engine {
@ -536,8 +593,7 @@ impl Engine {
// Raise error
let types_list: Vec<_> = args
.iter()
.map(|x| x.type_name())
.map(|name| self.map_type_name(name))
.map(|name| self.map_type_name(name.type_name()))
.collect();
Err(Box::new(EvalAltResult::ErrorFunctionNotFound(
@ -611,12 +667,12 @@ impl Engine {
// Has a system function an override?
fn has_override(&self, fn_lib: Option<&FunctionsLib>, name: &str) -> bool {
let hash = &calc_fn_hash(name, once(TypeId::of::<String>()));
let hash = calc_fn_hash(name, once(TypeId::of::<String>()));
// First check registered functions
self.functions.contains_key(hash)
self.functions.contains_key(&hash)
// Then check packages
|| self.packages.iter().any(|p| p.functions.contains_key(hash))
|| self.packages.iter().any(|p| p.functions.contains_key(&hash))
// Then check script-defined functions
|| fn_lib.map_or(false, |lib| lib.has_function(name, 1))
}
@ -693,15 +749,12 @@ impl Engine {
}
/// Chain-evaluate a dot/index chain.
/// Index values are pre-calculated and stored in `idx_list`.
/// Any spill-overs are stored in `idx_more`.
fn eval_dot_index_chain_helper(
&self,
fn_lib: Option<&FunctionsLib>,
mut target: Target,
rhs: &Expr,
idx_list: &mut [Dynamic],
idx_more: &mut Vec<Dynamic>,
idx_values: &mut StaticVec,
is_index: bool,
op_pos: Position,
level: usize,
@ -715,20 +768,7 @@ impl Engine {
};
// Pop the last index value
let mut idx_val;
let mut idx_list = idx_list;
if let Some(val) = idx_more.pop() {
// Values in variable list
idx_val = val;
} else {
// No more value in variable list, pop from fixed list
let len = idx_list.len();
let splits = idx_list.split_at_mut(len - 1);
idx_val = mem::replace(splits.1.get_mut(0).unwrap(), ().into());
idx_list = splits.0;
}
let mut idx_val = idx_values.pop();
if is_index {
match rhs {
@ -740,7 +780,7 @@ impl Engine {
let indexed_val = self.get_indexed_mut(obj, idx_val, idx.position(), op_pos, false)?;
self.eval_dot_index_chain_helper(
fn_lib, indexed_val, idx_rhs.as_ref(), idx_list, idx_more, is_index, *pos, level, new_val
fn_lib, indexed_val, idx_rhs.as_ref(), idx_values, is_index, *pos, level, new_val
)
}
// xxx[rhs] = new_val
@ -758,9 +798,9 @@ impl Engine {
match rhs {
// xxx.fn_name(arg_expr_list)
Expr::FunctionCall(fn_name, _, def_val, pos) => {
let mut args = once(obj)
let mut args: Vec<_> = once(obj)
.chain(idx_val.downcast_mut::<Array>().unwrap().iter_mut())
.collect::<Vec<_>>();
.collect();
let def_val = def_val.as_ref();
// A function call is assumed to have side effects, so the value is changed
// TODO - Remove assumption of side effects by checking whether the first parameter is &mut
@ -807,7 +847,7 @@ impl Engine {
)));
};
self.eval_dot_index_chain_helper(
fn_lib, indexed_val, dot_rhs, idx_list, idx_more, is_index, *pos, level, new_val
fn_lib, indexed_val, dot_rhs, idx_values, is_index, *pos, level, new_val
)
}
// xxx.idx_lhs[idx_expr]
@ -829,7 +869,7 @@ impl Engine {
)));
});
let (result, changed) = self.eval_dot_index_chain_helper(
fn_lib, indexed_val.into(), dot_rhs, idx_list, idx_more, is_index, *pos, level, new_val
fn_lib, indexed_val.into(), dot_rhs, idx_values, is_index, *pos, level, new_val
)?;
// Feed the value back via a setter just in case it has been updated
@ -864,19 +904,9 @@ impl Engine {
level: usize,
new_val: Option<Dynamic>,
) -> Result<Dynamic, Box<EvalAltResult>> {
// Keep four levels of index values in fixed array to reduce allocations
let mut idx_list: [Dynamic; 4] = [().into(), ().into(), ().into(), ().into()];
// Spill over additional levels into a variable list
let idx_more: &mut Vec<Dynamic> = &mut Vec::new();
let idx_values = &mut StaticVec::new();
let size =
self.eval_indexed_chain(scope, fn_lib, dot_rhs, &mut idx_list, idx_more, 0, level)?;
let idx_list = if size < idx_list.len() {
&mut idx_list[0..size]
} else {
&mut idx_list
};
self.eval_indexed_chain(scope, fn_lib, dot_rhs, idx_values, 0, level)?;
match dot_lhs {
// id.??? or id[???]
@ -898,8 +928,7 @@ impl Engine {
fn_lib,
target.into(),
dot_rhs,
idx_list,
idx_more,
idx_values,
is_index,
op_pos,
level,
@ -921,8 +950,7 @@ impl Engine {
fn_lib,
val.into(),
dot_rhs,
idx_list,
idx_more,
idx_values,
is_index,
op_pos,
level,
@ -943,11 +971,10 @@ impl Engine {
scope: &mut Scope,
fn_lib: Option<&FunctionsLib>,
expr: &Expr,
list: &mut [Dynamic],
more: &mut Vec<Dynamic>,
idx_values: &mut StaticVec,
size: usize,
level: usize,
) -> Result<usize, Box<EvalAltResult>> {
) -> Result<(), Box<EvalAltResult>> {
match expr {
Expr::FunctionCall(_, arg_exprs, _, _) => {
let arg_values = arg_exprs
@ -955,22 +982,10 @@ impl Engine {
.map(|arg_expr| self.eval_expr(scope, fn_lib, arg_expr, level))
.collect::<Result<Vec<_>, _>>()?;
if size < list.len() {
list[size] = arg_values.into();
} else {
more.push(arg_values.into());
idx_values.push(arg_values)
}
Ok(size + 1)
}
Expr::Property(_, _) => {
// Store a placeholder - no need to copy the property name
if size < list.len() {
list[size] = ().into();
} else {
more.push(().into());
}
Ok(size + 1)
}
Expr::Property(_, _) => idx_values.push(()),
Expr::Index(lhs, rhs, _) | Expr::Dot(lhs, rhs, _) => {
// Evaluate in left-to-right order
let lhs_val = match lhs.as_ref() {
@ -979,25 +994,14 @@ impl Engine {
};
// Push in reverse order
let size = self.eval_indexed_chain(scope, fn_lib, rhs, list, more, size, level)?;
self.eval_indexed_chain(scope, fn_lib, rhs, idx_values, size, level)?;
if size < list.len() {
list[size] = lhs_val;
} else {
more.push(lhs_val);
}
Ok(size + 1)
}
_ => {
let val = self.eval_expr(scope, fn_lib, expr, level)?;
if size < list.len() {
list[size] = val;
} else {
more.push(val);
}
Ok(size + 1)
idx_values.push(lhs_val);
}
_ => idx_values.push(self.eval_expr(scope, fn_lib, expr, level)?),
}
Ok(())
}
/// Get the value at the indexed position of a base type
@ -1042,7 +1046,9 @@ impl Engine {
Ok(if create {
map.entry(index).or_insert(().into()).into()
} else {
map.get_mut(&index).map(Target::from).unwrap_or_else(|| Target::from(()))
map.get_mut(&index)
.map(Target::from)
.unwrap_or_else(|| Target::from(()))
})
}
@ -1140,9 +1146,7 @@ impl Engine {
Expr::FloatConstant(f, _) => Ok((*f).into()),
Expr::StringConstant(s, _) => Ok(s.to_string().into()),
Expr::CharConstant(c, _) => Ok((*c).into()),
Expr::Variable(id, pos) => {
search_scope(scope, id, *pos).map(|(v, _)| v.clone())
}
Expr::Variable(id, pos) => search_scope(scope, id, *pos).map(|(v, _)| v.clone()),
Expr::Property(_, _) => panic!("unexpected property."),
// Statement block
@ -1168,15 +1172,15 @@ impl Engine {
ScopeSource {
typ: ScopeEntryType::Normal,
..
}) => {
},
) => {
// Avoid referencing scope which is used below as mut
let entry = ScopeSource { name, ..entry };
*scope.get_mut(entry) = rhs_val.clone();
Ok(rhs_val)
}
Some(
ScopeSource {
Some(ScopeSource {
typ: ScopeEntryType::Constant,
..
}) => Err(Box::new(EvalAltResult::ErrorAssignmentToConstant(