73 lines
2.5 KiB
Rust
73 lines
2.5 KiB
Rust
//! Evaluation state.
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use crate::func::call::FnResolutionCache;
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use crate::StaticVec;
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#[cfg(feature = "no_std")]
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use std::prelude::v1::*;
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use std::{collections::BTreeMap, marker::PhantomData};
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/// _(internals)_ A type that holds all the current states of the [`Engine`][crate::Engine].
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/// Exported under the `internals` feature only.
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#[derive(Debug, Clone)]
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pub struct EvalState<'a> {
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/// Force a [`Scope`][crate::Scope] search by name.
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///
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/// Normally, access to variables are parsed with a relative offset into the
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/// [`Scope`][crate::Scope] to avoid a lookup.
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///
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/// In some situation, e.g. after running an `eval` statement, or after a custom syntax
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/// statement, subsequent offsets may become mis-aligned.
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///
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/// When that happens, this flag is turned on.
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pub always_search_scope: bool,
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/// Level of the current scope.
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///
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/// The global (root) level is zero, a new block (or function call) is one level higher, and so on.
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pub scope_level: usize,
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/// Stack of function resolution caches.
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fn_resolution_caches: StaticVec<FnResolutionCache>,
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/// Take care of the lifetime parameter
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dummy: PhantomData<&'a ()>,
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}
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impl EvalState<'_> {
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/// Create a new [`EvalState`].
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#[inline(always)]
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#[must_use]
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pub fn new() -> Self {
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Self {
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always_search_scope: false,
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scope_level: 0,
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fn_resolution_caches: StaticVec::new_const(),
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dummy: Default::default(),
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}
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}
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/// Get the number of function resolution cache(s) in the stack.
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#[inline(always)]
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#[must_use]
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pub fn fn_resolution_caches_len(&self) -> usize {
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self.fn_resolution_caches.len()
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}
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/// Get a mutable reference to the current function resolution cache.
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#[inline]
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#[must_use]
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pub fn fn_resolution_cache_mut(&mut self) -> &mut FnResolutionCache {
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if self.fn_resolution_caches.is_empty() {
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// Push a new function resolution cache if the stack is empty
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self.push_fn_resolution_cache();
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}
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self.fn_resolution_caches.last_mut().unwrap()
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}
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/// Push an empty function resolution cache onto the stack and make it current.
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#[allow(dead_code)]
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#[inline(always)]
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pub fn push_fn_resolution_cache(&mut self) {
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self.fn_resolution_caches.push(BTreeMap::new());
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}
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/// Rewind the function resolution caches stack to a particular size.
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#[inline(always)]
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pub fn rewind_fn_resolution_caches(&mut self, len: usize) {
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self.fn_resolution_caches.truncate(len);
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}
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}
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