break!

src/compile.rs

@@ -56,6 +56,11 @@ struct Compiler<'bc, 'gc> {
     /// the current local variables that are in scope, only needed for compiling
     env: Rc<RefCell<Env>>,
     rt: &'gc mut RtAlloc,
+
+    /// How nested the current loop is, required for break offsets
+    loop_nesting: usize,
+    /// All break instructions currently in need of an offset. K=loop_nesting, V=break_indices
+    breaks: HashMap<usize, std::vec::Vec<usize>>,
 }
 
 pub fn compile<'ast, 'bc, 'gc>(
@@ -69,6 +74,8 @@ pub fn compile<'ast, 'bc, 'gc>(
         bump: bytecode_bump,
         env: Rc::new(RefCell::new(Env::default())),
         rt,
+        loop_nesting: 0,
+        breaks: HashMap::default(),
     };
 
     compiler.compile(ast)?;
@@ -200,12 +207,17 @@ impl<'bc, 'gc> Compiler<'bc, 'gc> {
           */
 
         let first_stmt_idx = self.code_len();
+
+        self.loop_nesting += 1;
+
         self.compile_block(ast_block)?;
 
         let jmp_offset = self.back_jmp_offset(first_stmt_idx);
 
         self.push_instr(Instr::Jmp(jmp_offset), StackChange::None, span);
 
+        self.end_loop();
+
         Ok(())
     }
 
@@ -219,6 +231,9 @@ impl<'bc, 'gc> Compiler<'bc, 'gc> {
           */
 
         let cond_index = self.code_len();
+
+        self.loop_nesting += 1;
+
         self.compile_expr(&while_stmt.cond)?;
 
         let jmp_false_idx =
@@ -232,11 +247,18 @@ impl<'bc, 'gc> Compiler<'bc, 'gc> {
         let jmp_offset = self.forward_jmp_offset(jmp_false_idx as isize);
         self.change_instr(jmp_false_idx, Instr::JmpFalse(jmp_offset));
 
+        self.end_loop();
+
         Ok(())
     }
 
-    fn compile_break(&mut self, _: Span) -> CResult {
-        todo!()
+    fn compile_break(&mut self, span: Span) -> CResult {
+        let break_idx = self.push_instr(Instr::Jmp(0), StackChange::None, span);
+        self.breaks
+            .entry(self.loop_nesting)
+            .or_default()
+            .push(break_idx);
+        Ok(())
     }
 
     fn compile_return(&mut self, _: &Option<Expr>, _: Span) -> CResult {
@@ -337,6 +359,17 @@ impl<'bc, 'gc> Compiler<'bc, 'gc> {
         todo!()
     }
 
+    fn end_loop(&mut self) {
+        let breaks = self.breaks.remove(&self.loop_nesting);
+        if let Some(breaks) = breaks {
+            for brk in breaks {
+                let offset = self.forward_jmp_offset(brk as isize);
+                self.change_instr(brk, Instr::Jmp(offset));
+            }
+        }
+        self.loop_nesting -= 1;
+    }
+
     fn current_stack_top(&self) -> usize {
         let block = &self.blocks[self.current_block];
         // we want the stack position, not the size, so the `- 1`

src/vm.rs

@@ -65,7 +65,7 @@ impl<'bc> Vm<'bc, '_> {
             }
             self.pc += 1;
             // debug stack size assertion
-            todo!()
+            // todo!()
         }
     }
 

test.dil

@@ -1,7 +1,5 @@
-let i = 0;
-
-while i < 100000 {
-    i = i + 1;
+loop {
+break;
 }
 
-print "done";
+print "hi";

tests/control_flow.rs

@@ -140,3 +140,74 @@ while i < 100 {
 }
 "#
 );
+
+run_test!(
+    break_out_loop,
+    r#"
+print "Start";
+
+loop {
+    break;
+    print "WRONG";
+}  
+
+print "Good end";
+"#
+);
+
+run_test!(
+    break_out_while,
+    r#"
+print "Start";
+
+while true {
+    break;
+    print "WRONG";
+}  
+
+print "Good end";
+"#
+);
+
+run_test!(
+    fizzbuzz_with_loop,
+    r#"
+let i = 1;
+
+loop {
+    if i % 15 == 0 {
+        print "FizzBuzz";
+    } else if i % 5 == 0 {
+        print "Buzz";
+    } else if i % 3 == 0 {
+        print "Fizz";
+    } else {
+        print i;
+    }
+    i = i + 1;
+    
+    if i >= 100 {
+        break;
+    }
+}
+"#
+);
+
+run_test!(
+    nested_loop_break,
+    r#"
+print "Start";
+loop {
+    print "Start inner";
+    loop {
+        print "inside inner";
+        break;
+        print "WRONG";
+    }
+    print "Outside inner";
+    break;
+    print "WRONG";
+}
+print "End";
+"#
+);

tests/snapshots/control_flow__break_out.snap

@@ -0,0 +1,7 @@
+---
+source: tests/control_flow.rs
+assertion_line: 144
+expression: output
+
+---
+"Start\nGood end\n"

tests/snapshots/control_flow__break_out_loop.snap

@@ -0,0 +1,7 @@
+---
+source: tests/control_flow.rs
+assertion_line: 144
+expression: output
+
+---
+"Start\nGood end\n"

tests/snapshots/control_flow__break_out_while.snap

@@ -0,0 +1,7 @@
+---
+source: tests/control_flow.rs
+assertion_line: 158
+expression: output
+
+---
+"Start\nGood end\n"

tests/snapshots/control_flow__fizzbuzz_with_loop.snap

@@ -0,0 +1,7 @@
+---
+source: tests/control_flow.rs
+assertion_line: 158
+expression: output
+
+---
+"1\n2\nFizz\n4\nBuzz\nFizz\n7\n8\nFizz\nBuzz\n11\nFizz\n13\n14\nFizzBuzz\n16\n17\nFizz\n19\nBuzz\nFizz\n22\n23\nFizz\nBuzz\n26\nFizz\n28\n29\nFizzBuzz\n31\n32\nFizz\n34\nBuzz\nFizz\n37\n38\nFizz\nBuzz\n41\nFizz\n43\n44\nFizzBuzz\n46\n47\nFizz\n49\nBuzz\nFizz\n52\n53\nFizz\nBuzz\n56\nFizz\n58\n59\nFizzBuzz\n61\n62\nFizz\n64\nBuzz\nFizz\n67\n68\nFizz\nBuzz\n71\nFizz\n73\n74\nFizzBuzz\n76\n77\nFizz\n79\nBuzz\nFizz\n82\n83\nFizz\nBuzz\n86\nFizz\n88\n89\nFizzBuzz\n91\n92\nFizz\n94\nBuzz\nFizz\n97\n98\nFizz\n"

tests/snapshots/control_flow__nested_loop_break.snap

@@ -0,0 +1,7 @@
+---
+source: tests/control_flow.rs
+assertion_line: 196
+expression: output
+
+---
+"Start\nStart inner\ninside inner\nOutside inner\nEnd\n"