Merge pull request 'Add support for void types' (#2) from 31-void-type into master

Reviewed-on: #2

src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4

@@ -33,7 +33,7 @@ parameter
   ;
 
 braced_block
-  : OBRK statement+ CBRK
+  : OBRK (statement | functionCall SCOL)+ CBRK
   ;
 
 
@@ -73,7 +73,7 @@ field_assignment
   ;
 
 return_statement
-  : RETURN expression SCOL
+  : RETURN expression? SCOL
   ;
 
 destroy_statement
@@ -120,6 +120,7 @@ type
   | BOOLEAN
   | FLOAT
   | IDENT
+  | VOID
   ;
 
 functionCall
@@ -186,6 +187,7 @@ DIV: '/';
 BOOLEAN: 'bool';
 INTEGER: 'int';
 FLOAT: 'float';
+VOID: 'void';
 
 INTEGER_LITERAL
   : [0-9]+

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -68,13 +68,13 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitBraced_block(KlangParser.Braced_blockContext ctx) {
-    int actualStatementCount = 0;
-    int declaredStatementCount = ctx.statement().size();
-    boolean hasReturn = false;
-    Statement[] statements = new Statement[declaredStatementCount];
+    var actualStatementCount = 0;
+    var declaredStatementCount = ctx.statement().size();
+    var hasReturn = false;
+    var statements = new Statement[declaredStatementCount];
 
     for (int i = 0; i < declaredStatementCount; i++) {
-      Node currentStatement = this.visit(ctx.statement(i));
+      var currentStatement = visit(ctx.statement(i));
       statements[i] = (Statement) currentStatement;
       actualStatementCount += 1;
 
@@ -83,7 +83,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       if (currentStatement.type != null && !(currentStatement instanceof VariableDeclaration)) {
         // check whether the type matches
         try {
-          this.currentDeclaredReturnType.combine(currentStatement.type);
+          currentDeclaredReturnType.combine(currentStatement.type);
         } catch (Exception e) {
           throw new RuntimeException(
               Helper.getErrorPrefix(currentStatement.line, currentStatement.col) + e.getMessage());
@@ -99,14 +99,15 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     // If there was unreachable code in this block,
     // create a shorter statements array and copy the statements to there
     if (actualStatementCount < declaredStatementCount) {
-      Statement[] newStatements = new Statement[actualStatementCount];
+      var newStatements = new Statement[actualStatementCount];
       System.arraycopy(statements, 0, newStatements, 0, actualStatementCount);
       statements = newStatements;
     }
 
     // if this block contains at least one statement that guarantees a return value,
     // we indicate that this block guarantees a return value by setting result.type
-    Block result = new Block(statements);
+    var result = new Block(statements);
+
     if (hasReturn) {
       result.type = this.currentDeclaredReturnType;
     }
@@ -186,6 +187,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     var line = ctx.start.getLine();
     var col = ctx.start.getCharPositionInLine();
 
+    if (declaredType.equals(Type.getVoidType())) {
+      var error = "Type " + declaredType.getName() + " can not be used to declare variables.";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+
     if (!declaredType.isPrimitiveType() && !structDefs.containsKey(declaredType.getName()) && !enumDefs.containsKey(declaredType.getName())) {
       var error = "Type " + declaredType.getName() + " not defined.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
@@ -266,19 +272,31 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitReturn_statement(KlangParser.Return_statementContext ctx) {
-    Expression expression = (Expression) this.visit(ctx.expression());
-    ReturnStatement result = new ReturnStatement(expression);
+    if (currentDeclaredReturnType.equals(Type.getVoidType())) {
+      var result = new ReturnStatement();
+      result.type = Type.getVoidType();
+      result.line = ctx.start.getLine();
+      result.col = ctx.start.getCharPositionInLine();
+      if (ctx.expression() != null) {
+        var error = "Cannot return an expression from a void function.";
+        throw new RuntimeException(Helper.getErrorPrefix(result.line, result.col) + error);
+      }
+      return result;
+    }
+
+    var expression = (Expression) visit(ctx.expression());
 
     // Check if this expression is a tail recursion
     if (expression instanceof FunctionCall funCall) {
-      if (funCall.name.equals(this.currentFunctionDefinitionName)) {
+      if (funCall.name.equals(currentFunctionDefinitionName)) {
         // Flag this function call
         funCall.isTailRecursive = true;
       }
     }
 
-    result.type = expression.type;
+    var result = new ReturnStatement(expression);
     result.line = ctx.start.getLine();
+    result.type = expression.type;
     result.col = ctx.start.getCharPositionInLine();
     return result;
   }
@@ -749,6 +767,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     var line = ctx.start.getLine();
     var col = ctx.start.getCharPositionInLine();
 
+    if (structFieldType.equals(Type.getVoidType())) {
+      var error = "Type void can not be used as a struct field type.";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+
     if (!structFieldType.isPrimitiveType() && !structDefs.containsKey(structFieldType.getName()) && !enumDefs.containsKey(structFieldType.getName())) {
       var error = "Type " + structFieldType.getName() + " not defined.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
@@ -779,7 +802,8 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     currentDeclaredReturnType = returnType;
     currentFunctionDefinitionName = name;
 
-    if (!returnType.isPrimitiveType() && !structDefs.containsKey(returnType.getName()) && !enumDefs.containsKey(returnType.getName())) {
+    var typeNotDefined = !returnType.isPrimitiveType() && !structDefs.containsKey(returnType.getName()) && !enumDefs.containsKey(returnType.getName());
+    if (!returnType.equals(Type.getVoidType()) && typeNotDefined) {
       var line = ctx.returnType.start.getLine();
       var col = ctx.returnType.start.getCharPositionInLine();
       var error = "Type " + returnType.getName() + " not defined.";
@@ -807,7 +831,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
     // Visit the block, make sure that a return value is guaranteed
     var block = visit(ctx.braced_block());
-    if (block.type == null) {
+    if (block.type == null && !returnType.equals(Type.getVoidType())) {
       var line = ctx.braced_block().start.getLine();
       var col = ctx.braced_block().start.getCharPositionInLine();
       var error = "Function " + name + " has to return something of type " + returnType.getName() + ".";
@@ -826,26 +850,29 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
   public Node visitParameter(KlangParser.ParameterContext ctx) {
     var parameterName = ctx.IDENT().getText();
     var parameterType = Type.getByName(ctx.type_annotation().type().getText());
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
+
+    if (parameterType.equals(Type.getVoidType())) {
+      var error = "Type " + parameterType.getName() + " cannot be used to declare a parameter.";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
 
     if (structDefs.containsKey(parameterName)) {
-      var line = ctx.start.getLine();
-      var col = ctx.start.getCharPositionInLine();
       var error = "Parameter name " + parameterName + " duplicates a struct of the same name.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
     if (enumDefs.containsKey(parameterName)) {
-      var line = ctx.start.getLine();
-      var col = ctx.start.getCharPositionInLine();
       var error = "Parameter name " + parameterName + " duplicates an enum of the same name.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
     if (!parameterType.isPrimitiveType() && !structDefs.containsKey(parameterType.getName()) && !enumDefs.containsKey(parameterType.getName())) {
-      var line = ctx.type_annotation().start.getLine();
-      var col = ctx.type_annotation().start.getCharPositionInLine();
+      var typeLine = ctx.type_annotation().start.getLine();
+      var typeCol = ctx.type_annotation().start.getCharPositionInLine();
       var error = "Type " + parameterType.getName() + " not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+      throw new RuntimeException(Helper.getErrorPrefix(typeLine, typeCol) + error);
     }
 
     var parameter = new Parameter(parameterName);

src/main/java/de/hsrm/compiler/Klang/Klang.java

@@ -1,9 +1,11 @@
 package de.hsrm.compiler.Klang;
 
+import de.hsrm.compiler.Klang.helper.*;
 import de.hsrm.compiler.Klang.nodes.EnumDefinition;
 import de.hsrm.compiler.Klang.nodes.FunctionDefinition;
 import de.hsrm.compiler.Klang.nodes.Node;
 import de.hsrm.compiler.Klang.nodes.StructDefinition;
+import de.hsrm.compiler.Klang.types.Type;
 import de.hsrm.compiler.Klang.visitors.EvalVisitor;
 import de.hsrm.compiler.Klang.visitors.GenASM;
 import de.hsrm.compiler.Klang.visitors.PrettyPrintVisitor;
@@ -120,7 +122,11 @@ public class Klang {
       System.out.println("\nEvaluating the source code:");
       EvalVisitor evalVisitor = new EvalVisitor(structDefs);
       Value result = root.welcome(evalVisitor);
-      generateOutput(out, "Result was: " + result.asObject().toString());
+      if (result.type.equals(Type.getVoidType())) {
+        generateOutput(out, "Result was void");
+      } else {
+        generateOutput(out, "Result was: " + result.asObject().toString());
+      }
       return;
     }
 

src/main/java/de/hsrm/compiler/Klang/nodes/statements/ReturnStatement.java

@@ -11,6 +11,10 @@ public class ReturnStatement extends Statement {
         this.expression = expression;
     }
 
+    public ReturnStatement() {
+      this.expression = null;    
+    }
+
     @Override
     public <R> R welcome(Visitor<R> v) {
         return v.visit(this);

src/main/java/de/hsrm/compiler/Klang/types/BooleanType.java

@@ -32,7 +32,7 @@ public class BooleanType extends PrimitiveType {
     }
 
     // Every remaining type will throw a RuntimeException
-    throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
+    throw new RuntimeException("Type mismatch: cannot combine " + this.getName() + " and " + that.getName());
   }
 
   @Override

src/main/java/de/hsrm/compiler/Klang/types/FloatType.java

@@ -36,7 +36,7 @@ public class FloatType extends NumericType {
     }
 
     // Every remaining type will throw a RuntimeException
-    throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
+    throw new RuntimeException("Type mismatch: cannot combine " + this.getName() + " and " + that.getName());
   }
 
   @Override

src/main/java/de/hsrm/compiler/Klang/types/IntegerType.java

@@ -36,7 +36,7 @@ public class IntegerType extends NumericType {
     }
 
     // Every remaining type will throw a RuntimeException
-    throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
+    throw new RuntimeException("Type mismatch: cannot combine " + this.getName() + " and " + that.getName());
   }
 
   @Override

src/main/java/de/hsrm/compiler/Klang/types/NullType.java

@@ -23,7 +23,7 @@ public class NullType extends Type {
     public Type combine(Type that) {
         // You can not combine null with a primitive type
         if (that.isPrimitiveType()) {
-            throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
+            throw new RuntimeException("Type mismatch: cannot combine " + this.getName() + " and " + that.getName());
         }
 
         // Everything else combines with null to the type it was before

src/main/java/de/hsrm/compiler/Klang/types/Type.java

@@ -27,12 +27,17 @@ public abstract class Type {
     return NullType.getType();
   }
 
+  public static VoidType getVoidType() {
+    return VoidType.getType();
+  }
+
   public static Type getByName(String name) {
     switch (name) {
       case "bool": return getBooleanType();
       case "int": return getIntegerType();
       case "float": return getFloatType();
       case "null": return getNullType();
+      case "void": return getVoidType();
       default: return new NamedType(name);
     }
   }

src/main/java/de/hsrm/compiler/Klang/types/VoidType.java

@@ -0,0 +1,45 @@
+package de.hsrm.compiler.Klang.types;
+
+import de.hsrm.compiler.Klang.Value;
+
+public class VoidType extends Type {
+
+  private static VoidType instance;
+
+  public static VoidType getType() {
+    if (instance != null) {
+        return instance;
+    }
+    instance = new VoidType();
+    return instance;
+}
+
+  @Override
+  public String getName() {
+    return "void";
+  }
+
+  @Override
+  public Type combine(Type that) {
+    if (that.equals(this)) {
+      return this;
+    }
+    throw new RuntimeException("Type mismatch: cannot combine " + this.getName() + " and " + that.getName());
+  }
+
+  @Override
+  public boolean valuesEqual(Value a, Value b) {
+    throw new RuntimeException("Can not compare void types.");
+  }
+
+  @Override
+  public boolean isPrimitiveType() {
+    return false;
+  }
+
+  @Override
+  public boolean isNumericType() {
+    return false;
+  }
+
+}

src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java

@@ -396,6 +396,9 @@ public class EvalVisitor implements Visitor<Value> {
 
   @Override
   public Value visit(ReturnStatement e) {
+    if (e.expression == null) {
+      return new Value(null, Type.getVoidType());
+    }
     return e.expression.welcome(this);
   }
 

src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java

@@ -525,7 +525,9 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(ReturnStatement e) {
-    e.expression.welcome(this);
+    if (e.expression != null) {
+      e.expression.welcome(this);
+    }
 
     // The ReturnStatement visitor is kindly removing the
     // stack space that was allocated by the FunctionDefinition

src/main/java/de/hsrm/compiler/Klang/visitors/GetVars.java

@@ -194,7 +194,9 @@ class GetVars implements Visitor<Void> {
 
   @Override
   public Void visit(ReturnStatement e) {
-    e.expression.welcome(this);
+    if (e.expression != null) {
+      e.expression.welcome(this);
+    }
     return null;
   }
 

src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java

@@ -310,8 +310,11 @@ public class PrettyPrintVisitor implements Visitor<Void> {
 
   @Override
   public Void visit(ReturnStatement e) {
-    ex.write("return ");
-    e.expression.welcome(this);
+    ex.write("return");
+    if (e.expression != null) {
+      ex.write(" ");
+      e.expression.welcome(this);
+    }
     ex.write(";");
     return null;
   }

src/test/java/ConstructorCallTest.java

@@ -21,7 +21,7 @@ public class ConstructorCallTest {
     }
 
     @Test
-    void numConstructorParameterMissmatch() {
+    void numConstructorParametermismatch() {
         ParseTree tree = Helper.prepareParser("struct bar { a: int; } function foo(): bar { return create bar(1, false); } foo();");
         var funcs = Helper.getFuncs(tree);
         var structs = Helper.getStructs(tree);
@@ -41,6 +41,6 @@ public class ConstructorCallTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:63 argument 0 Type missmatch: cannot combine bool and int", e.getMessage());
+        assertEquals("Error in line 1:63 argument 0 Type mismatch: cannot combine bool and int", e.getMessage());
     }
 }

src/test/java/FunctionCallTest.java

@@ -33,7 +33,7 @@ public class FunctionCallTest {
     }
 
     @Test
-    void parameterTypeMissmatch() {
+    void parameterTypeMismatch() {
         ParseTree tree = Helper.prepareParser("function foo(x: int): int { return x; } foo(false);");
         var funcs = Helper.getFuncs(tree);
         var structs = Helper.getStructs(tree);

src/test/java/VoidTest.java

@@ -0,0 +1,101 @@
+import de.hsrm.compiler.Klang.ContextAnalysis;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class VoidTest {
+
+    @Test
+    void shouldNotThrowIfVoidIsUsedAsReturnType() {
+        // given
+        var tree = Helper.prepareParser("function foo(): void { let a: int = 0; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldNotThrowIfVoidFunctionIsCalled() {
+        // given
+        var tree = Helper.prepareParser("""
+                function foo(): void {
+                    let a: int = 0;
+                }
+                function bar(): int {
+                    foo();
+                    return 1;
+                }
+                bar();
+                """);
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldThrowIfVoidFunctionIsAssignedToVariable() {
+        // given
+        var tree = Helper.prepareParser("""
+                function foo(): void {
+                    let a: int = 0;
+                }
+                function bar(): int {
+                    let a: int = foo();
+                    return 1;
+                }
+                bar();
+                """);
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 5:4 Type mismatch: cannot combine int and void", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowIfValueIsReturnedFromVoidFunction() {
+        // given
+        var tree = Helper.prepareParser("function foo(): void { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:23 Cannot return an expression from a void function.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowIfVoidIsUsedAsParameterType() {
+        // given
+        var tree = Helper.prepareParser("function foo(a: void): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:13 Type void cannot be used to declare a parameter.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowIfVoidIsUsedAsVariableType() {
+        // given
+        var tree = Helper.prepareParser("function foo(): int { let a: void; return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:22 Type void can not be used to declare variables.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowIfVoidIsUsedAsStructFieldType() {
+        // given
+        var tree = Helper.prepareParser("struct bar { a: void; } function foo(): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:13 Type void can not be used as a struct field type.", e.getMessage());
+    }
+
+}