Change precedence to own type.

src/engine.rs

@@ -17,7 +17,7 @@ use crate::stdlib::{
     collections::{HashMap, HashSet},
     fmt, format,
     hash::{Hash, Hasher},
-    num::{NonZeroU64, NonZeroU8, NonZeroUsize},
+    num::{NonZeroU8, NonZeroUsize},
     ops::DerefMut,
     string::{String, ToString},
     vec::Vec,
@@ -41,6 +41,8 @@ use crate::Map;
 #[cfg(not(feature = "no_object"))]
 pub const TYPICAL_MAP_SIZE: usize = 8; // Small maps are typical
 
+pub type Precedence = NonZeroU8;
+
 /// _(INTERNALS)_ A stack of imported [modules][Module].
 /// Exported under the `internals` feature only.
 ///
@@ -590,7 +592,7 @@ pub struct Limits {
     #[cfg(not(feature = "no_function"))]
     pub max_function_expr_depth: Option<NonZeroUsize>,
     /// Maximum number of operations allowed to run.
-    pub max_operations: Option<NonZeroU64>,
+    pub max_operations: Option<crate::stdlib::num::NonZeroU64>,
     /// Maximum number of [modules][Module] allowed to load.
     ///
     /// Set to zero to effectively disable loading any [module][Module].
@@ -724,7 +726,7 @@ pub struct Engine {
     /// A hashset containing symbols to disable.
     pub(crate) disabled_symbols: HashSet<String>,
     /// A hashmap containing custom keywords and precedence to recognize.
-    pub(crate) custom_keywords: HashMap<String, Option<NonZeroU8>>,
+    pub(crate) custom_keywords: HashMap<String, Option<Precedence>>,
     /// Custom syntax.
     pub(crate) custom_syntax: HashMap<ImmutableString, CustomSyntax>,
     /// Callback closure for resolving variable access.

src/engine_settings.rs

@@ -1,6 +1,7 @@
 //! Configuration settings for [`Engine`].
 
-use crate::stdlib::{format, num::NonZeroU8, string::String};
+use crate::engine::Precedence;
+use crate::stdlib::{format, string::String};
 use crate::token::Token;
 use crate::Engine;
 
@@ -272,7 +273,7 @@ impl Engine {
         keyword: &str,
         precedence: u8,
     ) -> Result<&mut Self, String> {
-        let precedence = NonZeroU8::new(precedence);
+        let precedence = Precedence::new(precedence);
 
         if precedence.is_none() {
             return Err("precedence cannot be zero".into());

src/parser.rs

@@ -5,7 +5,7 @@ use crate::ast::{
     Stmt, StmtBlock,
 };
 use crate::dynamic::{AccessMode, Union};
-use crate::engine::{KEYWORD_THIS, OP_CONTAINS};
+use crate::engine::{Precedence, KEYWORD_THIS, OP_CONTAINS};
 use crate::module::NamespaceRef;
 use crate::optimize::optimize_into_ast;
 use crate::optimize::OptimizationLevel;
@@ -1611,7 +1611,7 @@ fn parse_binary_op(
     input: &mut TokenStream,
     state: &mut ParseState,
     lib: &mut FunctionsLib,
-    parent_precedence: u8,
+    parent_precedence: Option<Precedence>,
     lhs: Expr,
     mut settings: ParseSettings,
 ) -> Result<Expr, ParseError> {
@@ -1625,18 +1625,12 @@ fn parse_binary_op(
     loop {
         let (current_op, current_pos) = input.peek().unwrap();
         let precedence = match current_op {
-            Token::Custom(c) => {
-                if state
+            Token::Custom(c) => state
                 .engine
                 .custom_keywords
                 .get(c)
-                    .map_or(false, Option::is_some)
-                {
-                    state.engine.custom_keywords.get(c).unwrap().unwrap().get()
-                } else {
-                    return Err(PERR::Reserved(c.clone()).into_err(*current_pos));
-                }
-            }
+                .cloned()
+                .ok_or_else(|| PERR::Reserved(c.clone()).into_err(*current_pos))?,
             Token::Reserved(c) if !is_valid_identifier(c.chars()) => {
                 return Err(PERR::UnknownOperator(c.into()).into_err(*current_pos))
             }
@@ -1656,18 +1650,12 @@ fn parse_binary_op(
 
         let (next_op, next_pos) = input.peek().unwrap();
         let next_precedence = match next_op {
-            Token::Custom(c) => {
-                if state
+            Token::Custom(c) => state
                 .engine
                 .custom_keywords
                 .get(c)
-                    .map_or(false, Option::is_some)
-                {
-                    state.engine.custom_keywords.get(c).unwrap().unwrap().get()
-                } else {
-                    return Err(PERR::Reserved(c.clone()).into_err(*next_pos));
-                }
-            }
+                .cloned()
+                .ok_or_else(|| PERR::Reserved(c.clone()).into_err(*next_pos))?,
             Token::Reserved(c) if !is_valid_identifier(c.chars()) => {
                 return Err(PERR::UnknownOperator(c.into()).into_err(*next_pos))
             }
@@ -1937,7 +1925,14 @@ fn parse_expr(
 
     // Parse expression normally.
     let lhs = parse_unary(input, state, lib, settings.level_up())?;
-    parse_binary_op(input, state, lib, 1, lhs, settings.level_up())
+    parse_binary_op(
+        input,
+        state,
+        lib,
+        Precedence::new(1),
+        lhs,
+        settings.level_up(),
+    )
 }
 
 /// Make sure that the expression is not a statement expression (i.e. wrapped in `{}`).

src/token.rs

@@ -1,8 +1,8 @@
 //! Main module defining the lexer and parser.
 
 use crate::engine::{
-    KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL, KEYWORD_FN_PTR_CURRY,
-    KEYWORD_IS_DEF_VAR, KEYWORD_PRINT, KEYWORD_THIS, KEYWORD_TYPE_OF,
+    Precedence, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL,
+    KEYWORD_FN_PTR_CURRY, KEYWORD_IS_DEF_VAR, KEYWORD_PRINT, KEYWORD_THIS, KEYWORD_TYPE_OF,
 };
 use crate::stdlib::{
     borrow::Cow,
@@ -666,10 +666,10 @@ impl Token {
     }
 
     /// Get the precedence number of the token.
-    pub fn precedence(&self) -> u8 {
+    pub fn precedence(&self) -> Option<Precedence> {
         use Token::*;
 
-        match self {
+        Precedence::new(match self {
             // Assignments are not considered expressions - set to zero
             Equals | PlusAssign | MinusAssign | MultiplyAssign | DivideAssign | PowerOfAssign
             | LeftShiftAssign | RightShiftAssign | AndAssign | OrAssign | XOrAssign
@@ -696,7 +696,7 @@ impl Token {
             Period => 240,
 
             _ => 0,
-        }
+        })
     }
 
     /// Does an expression bind to the right (instead of left)?