Fix custom syntax bug.

CHANGELOG.md

@@ -14,6 +14,7 @@ Bug fixes
 * Expressions such as `(v[0].func()).prop` now parse correctly.
 * Shadowed variable exports are now handled correctly.
 * Shadowed constant definitions are now optimized correctly when propagated (e.g. `const X = 1; const X = 1 + 1 + 1; X` now evaluates to 3 instead of 0).
+* Identifiers and comma's in the middle of custom syntax now register correctly.
 
 New features
 ------------

src/api/custom_syntax.rs

@@ -232,11 +232,9 @@ impl Engine {
             }
 
             let token = Token::lookup_symbol_from_syntax(s).or_else(|| {
-                if is_reserved_keyword_or_symbol(s).0 {
-                    Some(Token::Reserved(Box::new(s.into())))
-                } else {
-                    None
-                }
+                is_reserved_keyword_or_symbol(s)
+                    .0
+                    .then(|| Token::Reserved(Box::new(s.into())))
             });
 
             let seg = match s {
@@ -256,6 +254,9 @@ impl Engine {
                 #[cfg(not(feature = "no_float"))]
                 CUSTOM_SYNTAX_MARKER_FLOAT if !segments.is_empty() => s.into(),
 
+                // Identifier not in first position
+                _ if !segments.is_empty() && is_valid_identifier(s) => s.into(),
+
                 // Keyword/symbol not in first position
                 _ if !segments.is_empty() && token.is_some() => {
                     // Make it a custom keyword/symbol if it is disabled or reserved
@@ -277,10 +278,7 @@ impl Engine {
                 {
                     return Err(LexError::ImproperSymbol(
                         s.to_string(),
-                        format!(
-                            "Improper symbol for custom syntax at position #{}: '{s}'",
-                            segments.len() + 1,
-                        ),
+                        format!("Improper symbol for custom syntax at position #0: '{s}'"),
                     )
                     .into_err(Position::NONE));
                 }

tests/custom_syntax.rs

@@ -251,6 +251,65 @@ fn test_custom_syntax() -> Result<(), Box<EvalAltResult>> {
     Ok(())
 }
 
+#[test]
+fn test_custom_syntax_scope() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+
+    engine.register_custom_syntax(
+        [
+            "with", "offset", "(", "$expr$", ",", "$expr$", ")", "$block$",
+        ],
+        true,
+        |context, inputs| {
+            let x = context
+                .eval_expression_tree(&inputs[0])?
+                .as_int()
+                .map_err(|typ| {
+                    Box::new(EvalAltResult::ErrorMismatchDataType(
+                        "integer".to_string(),
+                        typ.to_string(),
+                        inputs[0].position(),
+                    ))
+                })?;
+
+            let y = context
+                .eval_expression_tree(&inputs[1])?
+                .as_int()
+                .map_err(|typ| {
+                    Box::new(EvalAltResult::ErrorMismatchDataType(
+                        "integer".to_string(),
+                        typ.to_string(),
+                        inputs[1].position(),
+                    ))
+                })?;
+
+            let orig_len = context.scope().len();
+
+            context.scope_mut().push_constant("x", x);
+            context.scope_mut().push_constant("y", y);
+
+            let result = context.eval_expression_tree(&inputs[2]);
+
+            context.scope_mut().rewind(orig_len);
+
+            result
+        },
+    )?;
+
+    assert_eq!(
+        engine.eval::<INT>(
+            "
+                let y = 1;
+                let x = 0;
+                with offset(44, 2) { x - y }
+            "
+        )?,
+        42
+    );
+
+    Ok(())
+}
+
 #[test]
 fn test_custom_syntax_matrix() -> Result<(), Box<EvalAltResult>> {
     let mut engine = Engine::new();