More tail call optimizations

Jemtaly · Sep 10, 2023 · 7605dab · 7605dab
1 parent 24e1f64
commit 7605dab
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Showing 4 changed files with 42 additions and 20 deletions.
diff --git a/lambda_cbn.cpp b/lambda_cbn.cpp
@@ -245,14 +245,21 @@ class Tree {
             }
         } else if (auto parg = std::get_if<TokenIdx::Arg>(&token)) {
             auto &[shr, rec] = **parg;
-            if (not rec) {
-                shr.calc();
-                rec = true;
-            }
             if (parg->use_count() == 1) {
-                *this = Tree(std::move(shr));
+                if (not rec) {
+                    *this = Tree(std::move(shr));
+                    TAIL_CALL calc();
+                } else {
+                    *this = Tree(std::move(shr));
+                }
             } else {
-                *this = shr;
+                if (not rec) {
+                    shr.calc();
+                    rec = true;
+                    *this = shr;
+                } else {
+                    *this = shr;
+                }
             }
         } else if (auto ppar = std::get_if<TokenIdx::Par>(&token)) {
             throw std::runtime_error("unbound variable: $" + *ppar);

diff --git a/lambda_cbn.rs b/lambda_cbn.rs
@@ -165,11 +165,15 @@ impl Tree {
             },
             Tree::Arg(arg) => {
                 let (shr, rec) = &mut *arg.borrow_mut();
-                if !*rec {
-                    *shr = mem::replace(shr, Tree::Empty).calculate()?;
-                    *rec = true;
+                if Rc::strong_count(&arg) == 1 {
+                    if !*rec { mem::replace(shr, Tree::Empty).calculate() } else { Ok(mem::replace(shr, Tree::Empty)) }
+                } else {
+                    if !*rec {
+                        *shr = mem::replace(shr, Tree::Empty).calculate()?;
+                        *rec = true;
+                    }
+                    Ok(shr.clone())
                 }
-                Ok(if Rc::strong_count(&arg) == 1 { mem::replace(shr, Tree::Empty) } else { shr.clone() })
             }
             Tree::Par(par) => {
                 Err(format!("unbound variable: ${}", par))

diff --git a/lambda_cbv.cpp b/lambda_cbv.cpp
@@ -249,14 +249,21 @@ class Tree {
             }
         } else if (auto parg = std::get_if<TokenIdx::Arg>(&token)) {
             auto &[shr, rec] = **parg;
-            if (not rec) {
-                shr.calc();
-                rec = true;
-            }
             if (parg->use_count() == 1) {
-                *this = Tree(std::move(shr));
+                if (not rec) {
+                    *this = Tree(std::move(shr));
+                    TAIL_CALL calc();
+                } else {
+                    *this = Tree(std::move(shr));
+                }
             } else {
-                *this = shr;
+                if (not rec) {
+                    shr.calc();
+                    rec = true;
+                    *this = shr;
+                } else {
+                    *this = shr;
+                }
             }
         } else if (auto ppar = std::get_if<TokenIdx::Par>(&token)) {
             throw std::runtime_error("unbound variable: $" + *ppar);

diff --git a/lambda_cbv.rs b/lambda_cbv.rs
@@ -168,11 +168,15 @@ impl Tree {
             },
             Tree::Arg(arg) => {
                 let (shr, rec) = &mut *arg.borrow_mut();
-                if !*rec {
-                    *shr = mem::replace(shr, Tree::Empty).calculate(map)?;
-                    *rec = true;
+                if Rc::strong_count(&arg) == 1 {
+                    if !*rec { mem::replace(shr, Tree::Empty).calculate(map) } else { Ok(mem::replace(shr, Tree::Empty)) }
+                } else {
+                    if !*rec {
+                        *shr = mem::replace(shr, Tree::Empty).calculate(map)?;
+                        *rec = true;
+                    }
+                    Ok(shr.clone())
                 }
-                Ok(if Rc::strong_count(&arg) == 1 { mem::replace(shr, Tree::Empty) } else { shr.clone() })
             }
             Tree::Par(par) => {
                 Err(format!("unbound variable: ${}", par))