Get rid of left-recursion cached rule

schala-lang/language/src/parsing/new.rs

@@ -6,6 +6,12 @@ fn rc_string(s: &str) -> Rc<String> {
     Rc::new(s.to_string())
 }
 
+enum ExtendedPart<'a> {
+    Index(Vec<Expression>),
+    Accessor(&'a str),
+    Call(Vec<InvocationArgument>),
+}
+
 peg::parser! {
     pub grammar schala_parser() for str {
 
@@ -207,52 +213,33 @@ peg::parser! {
             quiet!{$( ['+' | '-' | '*' | '/' | '%' | '<' | '>' | '=' | '!' | '$' | '&' | '|' | '?' | '^' | '`']+ )} /
             expected!("operator")
 
-
         rule extended_expr(struct_ok: bool) -> ExpressionKind =
-            item:extended_expr_ok_struct() {? if struct_ok { Ok(item) } else { Err("no-struct-allowed") } } /
-            item:extended_expr_no_struct() {? if !struct_ok { Ok(item) } else { Err("!no-struct-allowed") } }
+            primary:primary(struct_ok) parts:(extended_expr_part()*) {
+                let mut expression = Expression::new(Default::default(), primary);
+                for part in parts.into_iter() {
+                    let kind = match part {
+                        ExtendedPart::Index(indexers) => {
+                            ExpressionKind::Index { indexee: Box::new(expression), indexers }
+                        },
+                        ExtendedPart::Accessor(name) => {
+                            let name = rc_string(name);
+                            ExpressionKind::Access { name, expr: Box::new(expression) }
+                        },
+                        ExtendedPart::Call(arguments) => {
+                            ExpressionKind::Call { f: Box::new(expression), arguments }
+                        }
+                    };
 
-        #[cache_left_rec]
-        rule extended_expr_ok_struct() -> ExpressionKind =
-            indexee:extended_expr_ok_struct() indexers:index_part() {
-                ExpressionKind::Index {
-                    indexee: Box::new(Expression::new(Default::default(), indexee)),
-                    indexers,
-                }
-            } /
-            f:extended_expr_ok_struct() arguments:call_part() {
-                ExpressionKind::Call {
-                    f: Box::new(Expression::new(Default::default(), f)),
-                    arguments,
+                    expression = Expression::new(Default::default(), kind);
                 }
 
-            } /
-            expr:extended_expr_ok_struct() "." name:identifier() { ExpressionKind::Access {
-                name: Rc::new(name.to_string()),
-                expr: Box::new(Expression::new(Default::default(),expr)),
-            } } /
-            primary(true)
+                expression.kind
+            }
 
-        #[cache_left_rec]
-        rule extended_expr_no_struct() -> ExpressionKind =
-            indexee:extended_expr_no_struct() indexers:index_part() {
-                ExpressionKind::Index {
-                    indexee: Box::new(Expression::new(Default::default(), indexee)),
-                    indexers,
-                }
-            } /
-            f:extended_expr_no_struct() arguments:call_part() {
-                ExpressionKind::Call {
-                    f: Box::new(Expression::new(Default::default(), f)),
-                    arguments,
-                }
-
-            } /
-            expr:extended_expr_no_struct() "." name:identifier() { ExpressionKind::Access {
-                name: Rc::new(name.to_string()),
-                expr: Box::new(Expression::new(Default::default(),expr)),
-            } } /
-            primary(false)
+        rule extended_expr_part() -> ExtendedPart<'input> =
+            indexers:index_part() { ExtendedPart::Index(indexers) } /
+            arguments:call_part() { ExtendedPart::Call(arguments) } /
+            "." name:identifier() { ExtendedPart::Accessor(name) }
 
         rule index_part() -> Vec<Expression> =
             "[" indexers:(expression() ++ ",") "]" { indexers }