rustpp: Try to fix for loop semantics

src/include/keywords.hh

@@ -27,14 +27,16 @@
 // clang-format on
 
 #define rustpp_for(value, iter)                                                                                   \
-    auto RUSTPP_UNIQ (iterator) = iter.into_iter (); \
-    for (auto value = RUSTPP_UNIQ (iterator).next (); value.is_some (); value = RUSTPP_UNIQ (iterator).next ())
+    if (auto RUSTPP_UNIQ (iterator) = iter.into_iter (); auto RUSTPP_UNIQ (opt) = RUSTPP_UNIQ (iterator).next ()) \
+        for (auto value = RUSTPP_UNIQ (opt).unwrap_unchecked ();                                                  \
+            RUSTPP_UNIQ (opt).is_some ();                                                                         \
+            RUSTPP_UNIQ (opt) = RUSTPP_UNIQ (iterator).next (), value = RUSTPP_UNIQ (opt).unwrap_unchecked ())
 
 
 #ifndef I_AM_RUSTPP_RUNTIME
 
 #define main rustpp__main
-#define new __rustpp__new
+#define new rustpp__new
 
 #ifndef NO_RUSTPP_FOR
 #define for(...) rustpp_for (__VA_ARGS__)

src/include/primitives.hh

@@ -1,3 +1,5 @@
+//! Rusty primitive types
+
 #pragma once
 #include <stdint.h>
 #include <sys/types.h>

src/include/rust.hh

@@ -1,12 +1,12 @@
 #pragma once
 
+// all C/++ headers must be imported first
 #include <cstdlib>
-#include <print>   // IWYU pragma: export
 
 #include "panic.hh"      // IWYU pragma: export
 #include "primitives.hh" // IWYU pragma: export
 
-// no reorder
+// keywords.hh must come last; changes language semantics with macros
 #include "keywords.hh" // IWYU pragma: export
 
 type Cstr = char *;
@@ -37,37 +37,41 @@ mod option {
        public:
         makeSelf (Option<T>);
 
-        pub static fn Some (T value) -> Self {
+        static fn Some (T value) -> Self {
             Self op;
             op.value.Some = value;
             op.variant = variant::Some;
             return op;
         }
 
-        pub static fn None (T *_type = (T *) (0)) -> Self {
+        static fn None (T *_type = (T *) (0)) -> Self {
             Self op;
             op.value.None = 0;
             op.variant = variant::None;
             return op;
         }
 
-        pub fn return_value () -> int {
+        fn return_value () -> int {
             return self.is_some ();
         }
 
-        pub fn is_some () -> bool {
+        fn is_some () -> bool {
             return variant == variant::Some;
         }
 
-        pub fn is_none () -> bool {
+        fn is_none () -> bool {
             return variant == variant::None;
         }
 
-        pub operator bool () {
+        operator bool () {
             return this->is_some ();
         }
 
-        pub fn unwrap () -> T {
+        fn unwrap_unchecked () -> T {
+            return value.Some;
+        }
+
+        fn unwrap () -> T {
             match (variant) {
                 arm (variant::Some, return value.Some);
                 arm (variant::None, panic ("Called Option::unwrap() on a None value"));
@@ -75,7 +79,7 @@ mod option {
         }
 
         template <typename U>
-        pub fn map (U (f) (T)) -> Option<U> {
+        fn map (U (f) (T)) -> Option<U> {
             match (variant) {
                 arm (variant::Some, return Some (f (value.Some)));
                 arm (variant::None, return None<U> ());
@@ -115,42 +119,68 @@ mod result {
 
         // TODO: destructor for Result
 
-        pub static fn Ok (T value) -> Self {
+        static fn Ok (T value) -> Self {
             Self result;
             result.value.Ok = value;
             result.variant = variant::Ok;
             return result;
         }
 
-        pub static fn Err (E error) -> Self {
+        static fn Err (E error) -> Self {
             Self result;
             result.value.Err = error;
             result.variant = variant::Err;
             return result;
         }
 
-        pub fn is_ok () -> bool {
+        fn is_ok () -> bool {
             return variant == variant::Ok;
         }
 
-        pub fn is_err () -> bool {
+        fn is_err () -> bool {
             return variant == variant::Err;
         }
 
-        pub fn unwrap () -> T {
+        fn ok () -> option::Option<T> {
+            match (variant) {
+                arm (variant::Ok, return option::Some (value.Ok));
+                arm (variant::Err, return option::None<T> ());
+            }
+        }
+
+        fn err () -> option::Option<E> {
+            match (variant) {
+                arm (variant::Err, return option::Some (value.Err));
+                arm (variant::Ok, return option::None<T> ());
+            }
+        }
+
+        fn unwrap () -> T {
             match (variant) {
                 arm (variant::Ok, return value.Ok);
                 arm (variant::Err, panic ("Called Result::unwrap() on Err value"));
             }
         }
 
-        pub fn unwrap_err () -> E {
+        fn unwrap_err () -> E {
             match (variant) {
                 arm (variant::Ok, panic ("Called Result::unwrap_err() on Ok value"));
                 arm (variant::Err, return value.Err);
             }
         }
     };
+
+    /// Constructs a Result with variant Err and value `Err(value)`
+    template <typename T, typename E>
+    fn Err (E error) -> Result<T, E> {
+        return Result<T, E>::Err (error);
+    }
+
+    /// Constructs a Result with variant Ok and value `Ok(value)`
+    template <typename T, typename E>
+    fn Ok (T value) -> Result<T, E> {
+        return Result<T, E>::Ok (value);
+    }
 }
 
 mod ptr {
@@ -159,12 +189,11 @@ mod ptr {
         T *value;
         makeSelf (Nonnull<T>);
 
-        pub static fn __rustpp__new (T *value) -> option::Option<Self> {
-            switch (value) {
-                case nullptr:
-                    return option::Some ({ value });
-                default:
-                    return option::None (&value);
+        static fn rustpp__new (T *value) -> option::Option<Self> {
+            if (value) {
+                return option::Some ((Self) { value });
+            } else {
+                return option::None<Self> ();
             }
         }
 
@@ -200,7 +229,7 @@ mod iter {
 
 mod slice {
     template <typename T>
-    class Iter: public iter::Iterator<T *> {
+    class Iter: public iter::Iterator<ptr::Nonnull<T>> {
         T *head;
         T *tail;
 
@@ -209,15 +238,15 @@ mod slice {
        public:
         makeSelf (Iter<T>);
 
-        static fn __rustpp__new (T *head, usize len) -> Self {
+        static fn rustpp__new (T *head, usize len) -> Self {
             return { head, head + len };
         }
 
-        fn next () -> option::Option<T *> override {
+        fn next () -> option::Option<ptr::Nonnull<T>> override {
             if (head < tail)
-                return option::Some (head++);
+                return ptr::Nonnull<T>::rustpp__new (head++);
             else
-                return option::None<T *> ();
+                return option::None<ptr::Nonnull<T>> ();
         }
 
         fn into_iter () -> Self & {
@@ -232,7 +261,7 @@ mod slice {
 
         makeSelf (Slice<T>);
         fn into_iter () -> Iter<T> {
-            return Iter<T>::__rustpp__new (self.ptr, self.len);
+            return Iter<T>::rustpp__new (self.ptr, self.len);
         }
     };
 }
@@ -276,7 +305,7 @@ mod vec {
 
         makeSelf (Vec<T>);
 
-        static fn __rustpp__new () -> Self {
+        static fn rustpp__new () -> Self {
             return {};
         }
 
@@ -347,4 +376,4 @@ mod prelude {
 }
 
 
-using mod prelude;
+use mod prelude;

src/main.cc

@@ -1,5 +1,6 @@
 #include <print>
 
+// rust.hh changes language semantics, so must be included last!
 #include "rust.hh"
 
 fn main () -> i32 {
@@ -9,16 +10,15 @@ fn main () -> i32 {
     v.push (20);
     v.push (30);
 
-    std::println("Printing contents of v");
-    for (x, v) {
-        std::println ("{}", x.unwrap ());
+    std::println ("Printing contents of v by reference");
+    for (x, v.iter ()) {
+        std::println ("{}", *x);
     }
 
-    // This is okay, because the previous for loop moved out of v
-    // leaving it default-initialized.
-    std::println("Printing contents of v");
+    // This is okay, because the previous for loop borrowed v
+    std::println ("Printing contents of v by value");
     for (x, v) {
-        std::println ("{}", x.unwrap ());
+        std::println ("{}", x);
     }
 
     return 0;