GenASM: Make GenASM quietly rewrite a user's function if it's called main.

We generate our own main function that executes the user's specified expression at the end of his file. This auto generated function has to be called "main" in order for it to be executed on startup. If the user chooses to call one of his own functions "main" our auto generated function would collide with the user's function. That's why we quietly rewrite the user's function to "main_by_user". This way we prevent a collision.

Note for the future: We should change our Syntax to allow for no expression as the last definition of a file. This way the user can choose if a particular source file needs to contain a main function or not (just like c does it). This is also one of the requirements for modules to work.

pom.xml

@@ -72,6 +72,11 @@
           <descriptorRefs>
             <descriptorRef>jar-with-dependencies</descriptorRef>
           </descriptorRefs>
+          <archive>
+            <manifest>
+              <mainClass>de.hsrm.compiler.Klang.Klang</mainClass>
+            </manifest>
+          </archive>
         </configuration>
         <executions>
           <execution>

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

@@ -355,12 +355,15 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       }
 
       var enumValueName = path.get(0);
-      if (Arrays.stream(enumDef.enums).noneMatch(e -> e.equals(enumValueName))) {
-        var error = "Unknown enum value " + enumValueName + " of enum " +  enumDef.name + ".";
-        throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-      }
+      var enumValue = Arrays.stream(enumDef.enums)
+              .filter(e -> e.value.equals(enumValueName))
+              .findFirst()
+              .orElseThrow(() -> {
+                var error = "Unknown enum value " + enumValueName + " of enum " +  enumDef.name + ".";
+                throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+              });
 
-      var enumAccessExpression = new EnumAccessExpression(baseName, enumValueName);
+      var enumAccessExpression = new EnumAccessExpression(baseName, enumValueName, enumValue);
       enumAccessExpression.type = enumDef.type;
       enumAccessExpression.line = line;
       enumAccessExpression.col = col;

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

@@ -107,20 +107,26 @@ public class GetDefinitions extends KlangBaseVisitor<Node> {
         }
 
         // IDENT() includes the enumName as the first entry, which we skip
-        var enumFields = new LinkedHashSet<String>();
+        var enumValues = new LinkedHashMap<String, EnumValue>();
         for (int i = 1; i < ctx.IDENT().size(); i++) {
             var currentEnumField = ctx.IDENT(i);
             var currentEnumFieldName = currentEnumField.getText();
-            if (enumFields.contains(currentEnumFieldName)) {
-                var line = currentEnumField.getSymbol().getLine();
-                var col = currentEnumField.getSymbol().getCharPositionInLine();
+            var line = currentEnumField.getSymbol().getLine();
+            var col = currentEnumField.getSymbol().getCharPositionInLine();
+
+            if (enumValues.containsKey(currentEnumFieldName)) {
                 var error = " Duplicate enum value " + currentEnumFieldName + " in enum " + enumName + ".";
                 throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
             }
-            enumFields.add(currentEnumFieldName);
+
+            var enumValue = new EnumValue(currentEnumFieldName, i - 1);
+            enumValue.line = line;
+            enumValue.col = col;
+
+            enumValues.put(currentEnumFieldName, enumValue);
         }
 
-        var enumDef = new EnumDefinition(enumName, enumFields.toArray(new String[0]));
+        var enumDef = new EnumDefinition(enumName, enumValues.values().toArray(new EnumValue[0]));
         enumDef.line = ctx.start.getLine();
         enumDef.col = ctx.start.getCharPositionInLine();
         enumDef.type = new NamedType(enumName);

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

@@ -5,9 +5,9 @@ import de.hsrm.compiler.Klang.visitors.Visitor;
 public class EnumDefinition extends Node {
 
     public String name;
-    public String[] enums;
+    public EnumValue[] enums;
 
-    public EnumDefinition(String name, String[] enums) {
+    public EnumDefinition(String name, EnumValue[] enums) {
         this.name = name;
         this.enums = enums;
     }

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

@@ -0,0 +1,18 @@
+package de.hsrm.compiler.Klang.nodes;
+
+import de.hsrm.compiler.Klang.visitors.Visitor;
+
+public class EnumValue  extends Node {
+    public String value;
+    public int index;
+
+    public EnumValue(String value, int index) {
+        this.value = value;
+        this.index = index;
+    }
+
+    @Override
+    public <R> R welcome(Visitor<R> v) {
+        return v.visit(this);
+    }
+}

src/main/java/de/hsrm/compiler/Klang/nodes/expressions/EnumAccessExpression.java

@@ -1,14 +1,22 @@
 package de.hsrm.compiler.Klang.nodes.expressions;
 
+import de.hsrm.compiler.Klang.nodes.EnumDefinition;
+import de.hsrm.compiler.Klang.nodes.EnumValue;
 import de.hsrm.compiler.Klang.visitors.Visitor;
 
 public class EnumAccessExpression extends Expression {
     public String enumName;
     public String enumValueName;
+    public EnumValue enumValue;
 
-    public EnumAccessExpression(String enumName, String enumValueName) {
+    public EnumAccessExpression(
+            String enumName,
+            String enumValueName,
+            EnumValue enumValue
+    ) {
         this.enumName = enumName;
         this.enumValueName = enumValueName;
+        this.enumValue = enumValue;
     }
 
     @Override

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

@@ -1,5 +1,7 @@
 package de.hsrm.compiler.Klang.types;
 
+import de.hsrm.compiler.Klang.Value;
+
 public class BooleanType extends PrimitiveType {
 
   private static BooleanType instance = null;
@@ -33,4 +35,8 @@ public class BooleanType extends PrimitiveType {
     throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
   }
 
+  @Override
+  public boolean valuesEqual(Value a, Value b) {
+    return a.asBoolean() == b.asBoolean();
+  }
 }

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

@@ -1,5 +1,7 @@
 package de.hsrm.compiler.Klang.types;
 
+import de.hsrm.compiler.Klang.Value;
+
 public class FloatType extends NumericType {
 
   private static FloatType instance = null;
@@ -37,4 +39,8 @@ public class FloatType extends NumericType {
     throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
   }
 
+  @Override
+  public boolean valuesEqual(Value a, Value b) {
+    return a.asFloat() == b.asFloat();
+  }
 }

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

@@ -1,5 +1,7 @@
 package de.hsrm.compiler.Klang.types;
 
+import de.hsrm.compiler.Klang.Value;
+
 public class IntegerType extends NumericType {
 
   private static IntegerType instance = null;
@@ -37,4 +39,9 @@ public class IntegerType extends NumericType {
     throw new RuntimeException("Type missmatch: cannot combine " + this.getName() + " and " + that.getName());
   }
 
+  @Override
+  public boolean valuesEqual(Value a, Value b) {
+    return a.asInteger() == b.asInteger();
+  }
+
 }

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

@@ -1,5 +1,12 @@
 package de.hsrm.compiler.Klang.types;
 
+import de.hsrm.compiler.Klang.Value;
+import de.hsrm.compiler.Klang.nodes.EnumDefinition;
+import de.hsrm.compiler.Klang.nodes.FunctionDefinition;
+import de.hsrm.compiler.Klang.nodes.StructDefinition;
+
+import java.util.Map;
+
 public class NamedType extends Type {
     public String name;
 
@@ -21,6 +28,11 @@ public class NamedType extends Type {
         throw new RuntimeException("Type mismatch: cannot combine " + getName() + " and " + that.getName());
     }
 
+    @Override
+    public boolean valuesEqual(Value a, Value b) {
+        return a.asObject().equals(b.asObject());
+    }
+
     @Override
     public boolean isPrimitiveType() {
         return false;

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

@@ -1,5 +1,7 @@
 package de.hsrm.compiler.Klang.types;
 
+import de.hsrm.compiler.Klang.Value;
+
 public class NullType extends Type {
 
     private static NullType instance = null;
@@ -28,6 +30,11 @@ public class NullType extends Type {
         return that;
     }
 
+    @Override
+    public boolean valuesEqual(Value a, Value b) {
+        return a.asObject() == b.asObject();
+    }
+
     @Override
     public boolean isPrimitiveType() {
         return false;

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

@@ -1,6 +1,11 @@
 package de.hsrm.compiler.Klang.types;
 
-import java.util.Set;
+import de.hsrm.compiler.Klang.Value;
+import de.hsrm.compiler.Klang.nodes.EnumDefinition;
+import de.hsrm.compiler.Klang.nodes.FunctionDefinition;
+import de.hsrm.compiler.Klang.nodes.StructDefinition;
+
+import java.util.Map;
 
 public abstract class Type {
 
@@ -34,6 +39,7 @@ public abstract class Type {
 
   public abstract String getName();
   public abstract Type combine(Type that);
+  public abstract boolean valuesEqual(Value a, Value b);
   public abstract boolean isPrimitiveType();
   public abstract boolean isNumericType();
 }

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

@@ -46,25 +46,11 @@ public class EvalVisitor implements Visitor<Value> {
 
   @Override
   public Value visit(EqualityExpression e) {
-    Value lhs = e.lhs.welcome(this);
-    Value rhs = e.rhs.welcome(this);
-    Type resultType = Type.getBooleanType();
-    Type combineType = lhs.type.combine(rhs.type);
+    var lhs = e.lhs.welcome(this);
+    var rhs = e.rhs.welcome(this);
+    var combinedType = lhs.type.combine(rhs.type);
 
-    switch(combineType.getName()) {
-      case "bool": {
-        return new Value(lhs.asBoolean() == rhs.asBoolean(), resultType);
-      }
-      case "int": {
-        return new Value(lhs.asInteger() == rhs.asInteger(), resultType);
-      }
-      case "float": {
-        return new Value(lhs.asFloat() == rhs.asFloat(), resultType);
-      }
-      default: {
-        return new Value(lhs.asObject() == rhs.asObject(), resultType);
-      }
-    }
+    return new Value(combinedType.valuesEqual(lhs, rhs), Type.getBooleanType());
   }
 
   @Override
@@ -471,6 +457,11 @@ public class EvalVisitor implements Visitor<Value> {
     return null;
   }
 
+  @Override
+  public Value visit(EnumValue e) {
+    return null;
+  }
+
   @Override
   public Value visit(StructDefinition e) {
     // We get these from a previous visitor
@@ -498,7 +489,7 @@ public class EvalVisitor implements Visitor<Value> {
 
   @Override
   public Value visit(EnumAccessExpression e) {
-    return null;
+    return new Value(e.enumValueName, e.type);
   }
 
   @Override

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

@@ -567,6 +567,13 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(FunctionDefinition e) {
+    // If the user chooses "main" as one of his function names then
+    // rename it and hope that they didn't use the renamed function name
+    // as well :D
+    if (e.name.equals("main")) {
+      e.name = "main_by_user";
+    }
+
     int lblStart = ++lCount;
     this.currentFunctionStartLabel = lblStart;
     this.currentFunctionParams = e.parameters;
@@ -744,7 +751,8 @@ public class GenASM implements Visitor<Void> {
       asm.add("q", stackStartOffset, "%rsp");
     }
 
-    asm.call(e.name);
+    // We rename a function name if it is "main"
+    asm.call(e.name.equals("main") ? "main_by_user": e.name);
     return null;
   }
 
@@ -769,7 +777,7 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(Parameter e) {
-    // The work for a paremeter node is implement
+    // The work for a parameter node is implement
     // in the function definition visitor
     return null;
   }
@@ -779,6 +787,11 @@ public class GenASM implements Visitor<Void> {
     return null;
   }
 
+  @Override
+  public Void visit(EnumValue e) {
+    return null;
+  }
+
   @Override
   public Void visit(StructDefinition e) {
     // We get these from a previous visitor
@@ -819,6 +832,9 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(EnumAccessExpression e) {
+    // Since the access to an enum simply results in an integer (i.e. the index
+    // of the enum value), we can just let IntegerExpression handle the expected behaviour.
+    new IntegerExpression(e.enumValue.index).welcome(this);
     return null;
   }
 

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

@@ -239,6 +239,11 @@ class GetVars implements Visitor<Void> {
     return null;
   }
 
+  @Override
+  public Void visit(EnumValue e) {
+    return null;
+  }
+
   @Override
   public Void visit(StructDefinition e) {
     return null;

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

@@ -387,18 +387,24 @@ public class PrettyPrintVisitor implements Visitor<Void> {
   public Void visit(EnumDefinition e) {
     ex.write("enum " + e.name + " { ");
     var first = true;
-    for(var enumName: e.enums) {
+    for(var enumValue: e.enums) {
       if (!first) {
         ex.write(", ");
       } else {
         first = false;
       }
-      ex.write(enumName);
+      enumValue.welcome(this);
     }
     ex.write(" }");
     return null;
   }
 
+  @Override
+  public Void visit(EnumValue e) {
+    ex.write(e.value);
+    return null;
+  }
+
   @Override
   public Void visit(StructDefinition e) {
     ex.write("struct " + e.name + " {");

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

@@ -38,6 +38,7 @@ public interface Visitor<R> {
     R visit(Program e);
     R visit(Parameter e);
     R visit(EnumDefinition e);
+    R visit(EnumValue e);
     R visit(StructDefinition e);
     R visit(StructField e);
     R visit(MemberAccessExpression e);