Use interned strings for AST nodes.

src/ast/expr.rs

@@ -60,7 +60,7 @@ pub struct CustomExpr {
     /// List of keywords.
     pub inputs: StaticVec<Expr>,
     /// List of tokens actually parsed.
-    pub tokens: StaticVec<Identifier>,
+    pub tokens: StaticVec<ImmutableString>,
     /// Is the current [`Scope`][crate::Scope] possibly modified by this custom statement
     /// (e.g. introducing a new variable)?
     pub scope_may_be_changed: bool,
@@ -183,7 +183,7 @@ pub struct FnCallExpr {
     #[cfg(not(feature = "no_module"))]
     pub namespace: super::Namespace,
     /// Function name.
-    pub name: Identifier,
+    pub name: ImmutableString,
     /// Pre-calculated hashes.
     pub hashes: FnCallHashes,
     /// List of function call argument expressions.
@@ -392,14 +392,18 @@ pub enum Expr {
     /// This is to avoid reading a pointer redirection during each variable access.
     Variable(
         #[cfg(not(feature = "no_module"))]
-        Box<(Option<NonZeroUsize>, super::Namespace, u64, Identifier)>,
-        #[cfg(feature = "no_module")] Box<(Option<NonZeroUsize>, (), u64, Identifier)>,
+        Box<(Option<NonZeroUsize>, super::Namespace, u64, ImmutableString)>,
+        #[cfg(feature = "no_module")] Box<(Option<NonZeroUsize>, (), u64, ImmutableString)>,
         Option<NonZeroU8>,
         Position,
     ),
     /// Property access - ((getter, hash), (setter, hash), prop)
     Property(
-        Box<((Identifier, u64), (Identifier, u64), ImmutableString)>,
+        Box<(
+            (ImmutableString, u64),
+            (ImmutableString, u64),
+            ImmutableString,
+        )>,
         Position,
     ),
     /// xxx `.` method `(` expr `,` ... `)`

src/ast/ident.rs

@@ -1,6 +1,6 @@
 //! Module defining script identifiers.
 
-use crate::{Identifier, Position};
+use crate::{ImmutableString, Position};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 use std::{
@@ -14,7 +14,7 @@ use std::{
 #[derive(Clone, Eq, PartialEq, Hash)]
 pub struct Ident {
     /// Identifier name.
-    pub name: Identifier,
+    pub name: ImmutableString,
     /// Position.
     pub pos: Position,
 }
@@ -34,7 +34,7 @@ impl AsRef<str> for Ident {
 }
 
 impl Deref for Ident {
-    type Target = Identifier;
+    type Target = ImmutableString;
 
     #[inline(always)]
     fn deref(&self) -> &Self::Target {
@@ -50,12 +50,6 @@ impl DerefMut for Ident {
 }
 
 impl Ident {
-    /// An empty [`Ident`].
-    pub const EMPTY: Self = Self {
-        name: Identifier::new_const(),
-        pos: Position::NONE,
-    };
-
     /// Get the name of the identifier as a string slice.
     #[inline(always)]
     #[must_use]

src/ast/script_fn.rs

@@ -2,7 +2,7 @@
 #![cfg(not(feature = "no_function"))]
 
 use super::{FnAccess, StmtBlock};
-use crate::{Identifier, SmartString, StaticVec};
+use crate::{Identifier, ImmutableString, StaticVec};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 use std::{fmt, hash::Hash};
@@ -38,11 +38,11 @@ pub struct ScriptFnDef {
     #[cfg(not(feature = "no_function"))]
     pub environ: Option<EncapsulatedEnviron>,
     /// Function name.
-    pub name: Identifier,
+    pub name: ImmutableString,
     /// Function access mode.
     pub access: FnAccess,
     /// Names of function parameters.
-    pub params: StaticVec<Identifier>,
+    pub params: StaticVec<ImmutableString>,
     /// _(metadata)_ Function doc-comments (if any).
     /// Exported under the `metadata` feature only.
     ///
@@ -71,7 +71,7 @@ impl fmt::Display for ScriptFnDef {
             self.name,
             self.params
                 .iter()
-                .map(SmartString::as_str)
+                .map(|s| s.as_str())
                 .collect::<StaticVec<_>>()
                 .join(", ")
         )
@@ -132,7 +132,7 @@ impl<'a> From<&'a ScriptFnDef> for ScriptFnMetadata<'a> {
     fn from(value: &'a ScriptFnDef) -> Self {
         Self {
             name: &value.name,
-            params: value.params.iter().map(SmartString::as_str).collect(),
+            params: value.params.iter().map(|s| s.as_str()).collect(),
             access: value.access,
             #[cfg(feature = "metadata")]
             comments: value.comments.iter().map(<_>::as_ref).collect(),

src/ast/stmt.rs

@@ -594,7 +594,7 @@ pub enum Stmt {
     /// This variant does not map to any language structure.  It is currently only used only to
     /// convert a normal variable into a shared variable when the variable is _captured_ by a closure.
     #[cfg(not(feature = "no_closure"))]
-    Share(Box<crate::Identifier>, Position),
+    Share(crate::ImmutableString, Position),
 }
 
 impl Default for Stmt {