Merge remote-tracking branch 'cryshado/tuple-popn'

libs/src/Fift.fif

@@ -124,6 +124,9 @@ variable base
 { "" swap { 0 word 2dup $cmp } { rot swap $+ +cr swap } while 2drop } : scan-until-word
 { 0 word -trailing scan-until-word 1 'nop } ::_ $<<
 
+{ count } : []len
+{ tpop } : []pop
+
 /* UNIMPLEMENTED
 { 0x40 runvmx } : runvmcode
 { 0x48 runvmx } : gasrunvmcode

src/core/stack.rs

@@ -83,6 +83,18 @@ impl Stack {
         Ok(())
     }
 
+    pub fn extend_raw<T>(&mut self, items: T) -> Result<()>
+    where
+        T: IntoIterator,
+        T::Item: Into<Rc<dyn StackValue>>,
+    {
+        for item in items {
+            self.push_raw(item.into())?;
+        }
+
+        Ok(())
+    }
+
     pub fn push_null(&mut self) -> Result<()> {
         self.push_raw(Self::make_null())
     }

src/modules/mod.rs

@@ -148,6 +148,22 @@ impl FiftModule for BaseModule {
         stack.push_raw(last)
     }
 
+    #[cmd(name = "[]popn", stack)]
+    fn interpret_tuple_popn(stack: &mut Stack) -> Result<()> {
+        let n = stack.pop_usize()?;
+        let mut tuple = stack.pop_tuple()?;
+
+        let moved: Vec<_> = {
+            let tuple = Rc::make_mut(&mut tuple);
+            (0..n)
+                .map(|_| tuple.pop().context("Tuple underflow"))
+                .collect::<Result<_>>()?
+        };
+
+        stack.push_raw(tuple)?;
+        stack.extend_raw(moved.iter().rev().cloned())
+    }
+
     #[cmd(name = "[]", stack)]
     fn interpret_tuple_index(stack: &mut Stack) -> Result<()> {
         let idx = stack.pop_usize()?;