Fix break and continue

StepLang.Tests/Examples/looping.step.out

@@ -95,15 +95,35 @@ c: 3
 4
 5
 5
+break out of a loop
+continue to the next iteration
 1
 2
 4
 5
-1
-2
-1
-2
-1
-2
-1
-2
+nested continue
+inner: 1
+inner: 2
+outer: 1
+inner: 1
+inner: 2
+outer: 2
+inner: 1
+inner: 2
+outer (skipped): 3
+inner: 1
+inner: 2
+outer (skipped): 4
+inner: 1
+inner: 2
+outer (skipped): 5
+nested break
+inner: 1
+inner: 2
+outer: 1
+inner: 1
+inner: 2
+outer: 2
+inner: 1
+inner: 2
+outer (skipped): 3

StepLang/Examples/looping.step

@@ -71,14 +71,14 @@ foreach (number x in nums) {
  println(x)
 }
 
-// break out of a loop
+println("break out of a loop")
 while (true) {
  break
 
  println("should not get printed")
 }
 
-// continue to the next iteration
+println("continue to the next iteration")
 foreach (number n in [1, 2, 3, 4, 5]) {
  if (n == 3) {
  continue
@@ -89,7 +89,7 @@ foreach (number n in [1, 2, 3, 4, 5]) {
  println(n)
 }
 
-// nested continue
+println("nested continue")
 foreach (number n in [1, 2, 3, 4, 5]) {
  foreach (number n2 in [1, 2, 3, 4, 5]) {
  if (n2 >= 3) {
@@ -98,19 +98,21 @@ foreach (number n in [1, 2, 3, 4, 5]) {
  println("should not get printed")
  }
 
- println(n2)
+ println("inner: ", n2)
  }
 
  if (n >= 3) {
+ println("outer (skipped): ", n)
+
  continue
 
  println("should not get printed")
  }
 
- println(n)
+ println("outer: ", n)
 }
 
-// nested break
+println("nested break")
 foreach (number n in [1, 2, 3, 4, 5]) {
  foreach (number n2 in [1, 2, 3, 4, 5]) {
  if (n2 == 3) {
@@ -119,14 +121,16 @@ foreach (number n in [1, 2, 3, 4, 5]) {
  println("should not get printed")
  }
 
- println(n2)
+ println("inner: ", n2)
  }
 
  if (n == 3) {
+ println("outer (skipped): ", n)
+
  break
 
  println("should not get printed")
  }
 
- println(n)
+ println("outer: ", n)
 }

StepLang/Interpreting/Interpreter.Branching.cs

@@ -33,4 +33,14 @@ public void Execute(IfElseIfStatementNode statementNode)
  if (elseResult.IsTruthy())
  Execute(statementNode.ElseBody);
  }
+
+ public void Execute(ContinueStatementNode statementNode)
+ {
+ CurrentScope.SetContinue();
+ }
+
+ public void Execute(BreakStatementNode statementNode)
+ {
+ CurrentScope.SetBreak();
+ }
 }

StepLang/Interpreting/Interpreter.Foreach.cs

@@ -140,30 +140,35 @@ private void RunForeachLoop(Action<ExpressionResult>? updateKey, Action<Expressi
 
  foreach (var (keyValue, valueValue) in pairs)
  {
- PushScope();
+ var loopScope = PushScope();
 
+ // update/initialize key and value in loop scope
  updateKey?.Invoke(keyValue);
  updateValue(valueValue);
 
- Execute(body);
-
- if (BreakDepth > 0)
+ foreach (var statement in body)
  {
- BreakDepth--;
-
- PopScope();
+ Execute(statement);
 
- break;
+ if (loopScope.ShouldReturn() || loopScope.ShouldBreak() || loopScope.ShouldContinue())
+ break;
  }
 
- if (CurrentScope.TryGetResult(out var resultValue, out var resultLocation))
- {
- PopScope();
+ _ = PopScope();
 
+ // handle returns to parent scope
+ if (loopScope.TryGetResult(out var resultValue, out var resultLocation))
+ {
  CurrentScope.SetResult(resultLocation, resultValue);
 
- break;
+ return;
  }
+
+ // break out of loop
+ if (loopScope.ShouldBreak())
+ return;
+
+ // continue is implicitly handled
  }
  }
 }

StepLang/Interpreting/Interpreter.While.cs

@@ -8,25 +8,31 @@ public void Execute(WhileStatementNode statementNode)
  {
  while (ShouldLoop())
  {
- PushScope();
+ var loopScope = PushScope();
 
- Execute(statementNode.Body);
-
- var loopScope = PopScope();
-
- if (BreakDepth > 0)
+ foreach (var statement in statementNode.Body)
  {
- BreakDepth--;
+ Execute(statement);
 
- break;
+ if (loopScope.ShouldReturn() || loopScope.ShouldBreak() || loopScope.ShouldContinue())
+ break;
  }
 
+ _ = PopScope();
+
+ // handle returns to parent scope
  if (loopScope.TryGetResult(out var resultValue, out var resultLocation))
  {
  CurrentScope.SetResult(resultLocation, resultValue);
 
  return;
  }
+
+ // break out of loop
+ if (loopScope.ShouldBreak())
+ return;
+
+ // continue is implicitly handled
  }
 
  return;

StepLang/Interpreting/Interpreter.cs

@@ -11,10 +11,6 @@ public partial class Interpreter : IRootNodeVisitor, IStatementVisitor, IExpress
  public TextWriter? DebugOut { get; }
  public int ExitCode { get; set; }
 
- public int BreakDepth { get; set; }
-
- public int ContinueDepth { get; set; }
-
  private readonly Stack<Scope> scopes = new();
 
  private Lazy<Random> random = new(() => new());
@@ -58,23 +54,28 @@ public void Execute(IEnumerable<StatementNode> statements)
  {
  foreach (var statement in statements)
  {
- if (ContinueDepth > 0)
- {
- ContinueDepth--;
+ Execute(statement);
 
- DebugOut?.WriteLine("Continuing");
+ if (CurrentScope.TryGetResult(out _, out _))
+ {
+ DebugOut?.WriteLine("Result found, continuing");
 
- break;
+ return;
  }
 
- Execute(statement);
+ if (CurrentScope.ShouldBreak())
+ {
+ DebugOut?.WriteLine("Break found, breaking");
 
- if (!CurrentScope.TryGetResult(out _, out _))
-  continue;
+  return;
+ }
 
- DebugOut?.WriteLine("Result found, continuing");
+ if (CurrentScope.ShouldContinue())
+ {
+ DebugOut?.WriteLine("Continue found, continuing");
 
- break;
+ return;
+ }
  }
  }
 

StepLang/Interpreting/Scope.cs

@@ -20,6 +20,9 @@ public class Scope
  private TokenLocation? scopeResultLocation;
  private ExpressionResult? scopeResult;
 
+ private bool shouldContinue;
+ private bool shouldBreak;
+
  public Scope(Scope parent) => parentScope = parent;
 
  private Scope()
@@ -150,6 +153,8 @@ public void SetResult(TokenLocation location, ExpressionResult result)
  scopeResult = result;
  }
 
+ public bool ShouldReturn() => scopeResult is not null;
+
  public bool TryGetResult([NotNullWhen(true)] out ExpressionResult? result, [NotNullWhen(true)] out TokenLocation? location)
  {
  location = scopeResultLocation;
@@ -158,6 +163,14 @@ public bool TryGetResult([NotNullWhen(true)] out ExpressionResult? result, [NotN
  return result is not null;
  }
 
+ public void SetContinue() => shouldContinue = true;
+
+ public void SetBreak() => shouldBreak = true;
+
+ public bool ShouldContinue() => shouldContinue;
+
+ public bool ShouldBreak() => shouldBreak;
+
  public override string ToString()
  {
  return $"Scope: {{{string.Join(", ", identifiers.Select(kvp => kvp.Value.ToString()))}}}";