added lambdas and a return statement

src/main/java/de/neemann/digital/hdl/hgs/Context.java

@@ -19,6 +19,7 @@ public class Context {
     private final Context parent;
     private final StringBuilder code;
     private HashMap<String, Object> map;
+    private boolean functionContext = false;
 
     /**
      * Creates a new context
@@ -156,6 +157,45 @@ public class Context {
             return parent.length();
     }
 
+    /**
+     * Flags this context as context belonging to a function call.
+     * This allows to use the return statement.
+     *
+     * @return this for chained calls
+     */
+    public Context isFunctionContext() {
+        functionContext = true;
+        return this;
+    }
+
+    /**
+     * Returns from a function call.
+     *
+     * @param returnValue the return value
+     * @throws HGSEvalException HGSEvalException
+     */
+    public void returnFromFunc(Object returnValue) throws HGSEvalException {
+        if (!functionContext)
+            throw new HGSEvalException("The return statement is allowed only in a function!");
+
+        throw new ReturnException(returnValue);
+    }
+
+    /**
+     * Returns a function from this context
+     *
+     * @param funcName the functions name
+     * @return the function
+     * @throws HGSEvalException HGSEvalException
+     */
+    public FuncAdapter getFunction(String funcName) throws HGSEvalException {
+        Object fObj = getVar(funcName);
+        if (fObj instanceof FuncAdapter)
+            return (FuncAdapter) fObj;
+        else
+            throw new HGSEvalException("Variable '" + funcName + "' is not a function");
+    }
+
     private static final class FunctionPrint extends Function {
 
         private FunctionPrint() {
@@ -163,7 +203,7 @@ public class Context {
         }
 
         @Override
-        public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+        public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
             for (Expression arg : args)
                 c.print(arg.value(c).toString());
             return null;
@@ -177,7 +217,7 @@ public class Context {
         }
 
         @Override
-        public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+        public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
             c.print(format(c, args));
             return null;
         }
@@ -190,7 +230,7 @@ public class Context {
         }
 
         @Override
-        public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+        public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
             return format(c, args);
         }
     }
@@ -213,7 +253,7 @@ public class Context {
         }
 
         @Override
-        public Object calcValue(Context c, ArrayList<Expression> args) {
+        public Object callWithExpressions(Context c, ArrayList<Expression> args) {
             try {
                 args.get(0).value(c);
                 return true;
@@ -233,4 +273,28 @@ public class Context {
             throw new HGSEvalException(args[0].toString());
         }
     }
+
+    /**
+     * Exception used to return a value from a function
+     */
+    public static final class ReturnException extends HGSEvalException {
+        private final Object returnValue;
+
+        /**
+         * Creates a new instance
+         *
+         * @param returnValue the return value
+         */
+        ReturnException(Object returnValue) {
+            super("return");
+            this.returnValue = returnValue;
+        }
+
+        /**
+         * @return the return value
+         */
+        public Object getReturnValue() {
+            return returnValue;
+        }
+    }
 }

src/main/java/de/neemann/digital/hdl/hgs/Parser.java

@@ -7,6 +7,7 @@ package de.neemann.digital.hdl.hgs;
 
 import de.neemann.digital.core.Bits;
 import de.neemann.digital.hdl.hgs.function.FirstClassFunction;
+import de.neemann.digital.hdl.hgs.function.FirstClassFunctionCall;
 import de.neemann.digital.hdl.hgs.refs.*;
 
 import java.io.IOException;
@@ -179,6 +180,10 @@ public class Parser {
                 while (!nextIs(CLOSEDBRACE))
                     s.add(parseStatement());
                 return s.optimize();
+            case RETURN:
+                Expression retExp = parseExpression();
+                expect(SEMICOLON);
+                return c -> c.returnFromFunc(retExp.value(c));
             default:
                 throw newUnexpectedToken(token);
         }
@@ -413,7 +418,7 @@ public class Parser {
                 return exp;
             case FUNC:
                 FirstClassFunction func = parseFunction();
-                return c -> func;
+                return c -> new FirstClassFunctionCall(func, c);
             default:
                 throw newUnexpectedToken(t);
         }

src/main/java/de/neemann/digital/hdl/hgs/Tokenizer.java

@@ -18,7 +18,7 @@ class Tokenizer {
         UNKNOWN, IDENT, AND, OR, XOR, NOT, OPEN, CLOSE, NUMBER, EOL, EOF, SHIFTLEFT, SHIFTRIGHT, COMMA, EQUAL,
         ADD, SUB, MUL, GREATER, LESS, DIV, MOD, END, IF, ELSE, FOR, WHILE, SEMICOLON, NOTEQUAL, STRING,
         OPENBRACE, CLOSEDBRACE, CODEEND, OPENSQUARE, CLOSEDSQUARE, DOT, STATIC, FUNC, GREATEREQUAL, LESSEQUAL,
-        REPEAT, UNTIL
+        REPEAT, RETURN, UNTIL
     }
 
     private static HashMap<String, Token> statementMap = new HashMap<>();
@@ -31,6 +31,7 @@ class Tokenizer {
         statementMap.put("func", Token.FUNC);
         statementMap.put("repeat", Token.REPEAT);
         statementMap.put("until", Token.UNTIL);
+        statementMap.put("return", Token.RETURN);
     }
 
     private final Reader in;

src/main/java/de/neemann/digital/hdl/hgs/function/FirstClassFunction.java

@@ -5,48 +5,33 @@
  */
 package de.neemann.digital.hdl.hgs.function;
 
-import de.neemann.digital.hdl.hgs.Context;
-import de.neemann.digital.hdl.hgs.HGSEvalException;
 import de.neemann.digital.hdl.hgs.Statement;
 
 import java.util.ArrayList;
 
 /**
- * callable first class function
+ * Description of a first class function.
  */
-public class FirstClassFunction extends FuncAdapter {
+public class FirstClassFunction {
     private final ArrayList<String> args;
-    private final Statement st;
+    private final Statement statement;
 
     /**
      * Creates a new instance
      *
      * @param args      the names of the arguments
-     * @param st   the function body
+     * @param statement the function body
      */
-    public FirstClassFunction(ArrayList<String> args, Statement st) {
+    public FirstClassFunction(ArrayList<String> args, Statement statement) {
-        super(args.size());
         this.args = args;
-        this.st = st;
+        this.statement = statement;
     }
 
-    /**
+    ArrayList<String> getArgs() {
-     * Evaluates this function
+        return args;
-     *
-     * @param args the arguments
-     * @return the result
-     * @throws HGSEvalException HGSEvalException
-     */
-    @Override
-    public Object f(Object... args) throws HGSEvalException {
-        Context c = new Context();
-        for (int i = 0; i < args.length; i++)
-            c.setVar(this.args.get(i), args[i]);
-        st.execute(c);
-        if (c.contains("return"))
-            return c.getVar("return");
-        else
-            throw new HGSEvalException("A function must define the variable 'return'!");
     }
 
+    Statement getStatement() {
+        return statement;
+    }
 }

src/main/java/de/neemann/digital/hdl/hgs/function/FirstClassFunctionCall.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2018 Helmut Neemann.
+ * Use of this source code is governed by the GPL v3 license
+ * that can be found in the LICENSE file.
+ */
+package de.neemann.digital.hdl.hgs.function;
+
+import de.neemann.digital.hdl.hgs.Context;
+import de.neemann.digital.hdl.hgs.HGSEvalException;
+
+/**
+ * A call to a first class function
+ */
+public final class FirstClassFunctionCall extends FuncAdapter {
+    private final FirstClassFunction func;
+    private final Context capturedContext;
+
+    /**
+     * Creates a new instance
+     *
+     * @param func    the function
+     * @param context the captured context
+     */
+    public FirstClassFunctionCall(FirstClassFunction func, Context context) {
+        super(func.getArgs().size());
+        this.func = func;
+        this.capturedContext = context;
+    }
+
+    @Override
+    protected Object f(Object... args) throws HGSEvalException {
+        Context c = new Context(capturedContext).isFunctionContext();
+        for (int i = 0; i < args.length; i++)
+            c.setVar(func.getArgs().get(i), args[i]);
+        try {
+            func.getStatement().execute(c);
+            return null;
+        } catch (Context.ReturnException e) {
+            return e.getReturnValue();
+        }
+    }
+}

src/main/java/de/neemann/digital/hdl/hgs/function/FuncAdapter.java

@@ -25,10 +25,7 @@ public abstract class FuncAdapter extends Function {
     }
 
     @Override
-    public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+    public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
-        if (getArgCount() != args.size())
-            throw new HGSEvalException("wrong number of arguments! found: " + args.size() + ", expected: " + getArgCount());
-
         Object[] data = new Object[args.size()];
         for (int i = 0; i < args.size(); i++)
             data[i] = args.get(i).value(c);
@@ -36,11 +33,25 @@ public abstract class FuncAdapter extends Function {
     }
 
     /**
-     * The function
+     * Evaluates this function.
      *
-     * @param args the evaluated arguments
+     * @param args the arguments
      * @return the result
      * @throws HGSEvalException HGSEvalException
      */
     protected abstract Object f(Object... args) throws HGSEvalException;
+
+    /**
+     * Use this method to call the function from your java code.
+     *
+     * @param args the arguments of this function
+     * @return the function result
+     * @throws HGSEvalException HGSEvalException
+     */
+    public Object call(Object... args) throws HGSEvalException {
+        if (getArgCount() >= 0 && getArgCount() != args.length)
+            throw new HGSEvalException("wrong number of arguments! found: " + args.length + ", expected: " + getArgCount());
+        return f(args);
+    }
+
 }

src/main/java/de/neemann/digital/hdl/hgs/function/Function.java

@@ -42,5 +42,5 @@ public abstract class Function {
      * @return the value
      * @throws HGSEvalException HGSEvalException
      */
-    public abstract Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException;
+    public abstract Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException;
 }

src/main/java/de/neemann/digital/hdl/hgs/refs/ReferenceToFunc.java

@@ -38,8 +38,12 @@ public class ReferenceToFunc implements Reference {
     @Override
     public Object get(Context context) throws HGSEvalException {
         Object funcObj = parent.get(context);
-        if (funcObj instanceof Function)
+        if (funcObj instanceof Function) {
-            return ((Function) funcObj).calcValue(context, args);
+            final Function func = (Function) funcObj;
+            if (func.getArgCount() >= 0 && func.getArgCount() != args.size())
+                throw new HGSEvalException("wrong number of arguments! found: " + args.size() + ", expected: " + func.getArgCount());
+            return func.callWithExpressions(context, args);
+        }
         throw new HGSEvalException("Value is not a function!");
     }
 }

src/main/java/de/neemann/digital/hdl/vhdl/lib/VHDLTemplate.java

@@ -36,14 +36,14 @@ public class VHDLTemplate implements VHDLEntity {
             .addFunc("value", new FunctionValue())
             .addFunc("beginGenericPort", new Function(0) {
                 @Override
-                public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+                public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
                     c.setVar("portStartPos", c.length());
                     return null;
                 }
             })
             .addFunc("endGenericPort", new Function(0) {
                 @Override
-                public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+                public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
                     int start = Value.toInt(c.getVar("portStartPos"));
                     String portDecl = c.toString().substring(start);
                     c.setVar("portDecl", portDecl);
@@ -52,7 +52,7 @@ public class VHDLTemplate implements VHDLEntity {
             })
             .addFunc("registerGeneric", new Function(-1) {
                 @Override
-                public Object calcValue(Context c, ArrayList<Expression> args) throws HGSEvalException {
+                public Object callWithExpressions(Context c, ArrayList<Expression> args) throws HGSEvalException {
                     List<Generic> generics;
                     if (c.contains("generics"))
                         generics = (List<Generic>) c.getVar("generics");

src/test/java/de/neemann/digital/hdl/hgs/ParserTest.java

@@ -300,25 +300,25 @@ public class ParserTest extends TestCase {
     }
 
     public void testFirstClassFunctionStatic() throws IOException, ParserException, HGSEvalException {
-        Parser p = new Parser("<? @f=func(a){return=a*a+2;};  print(f(4));?>");
+        Parser p = new Parser("<? @f=func(a){return a*a+2;};  print(f(4));?>");
         p.parse();
         Object fObj = p.getStaticContext().getVar("f");
-        assertTrue(fObj instanceof FirstClassFunction);
+        assertTrue(fObj instanceof FuncAdapter);
-        FirstClassFunction f = (FirstClassFunction) fObj;
+        FuncAdapter f = (FuncAdapter) fObj;
-        assertEquals(11L, f.f(3));
+        assertEquals(11L, f.call(3));
     }
 
     public void testFirstClassFunction() throws IOException, ParserException, HGSEvalException {
-        assertEquals("18", exec("<? f=func(a){return=a*a+2;};  print(f(4));?>").toString());
+        assertEquals("18", exec("<? f=func(a){return a*a+2;};  print(f(4));?>").toString());
-        assertEquals("5", exec("<? f=func(a,b){return=a+2*b;};  print(f(1,2));?>").toString());
+        assertEquals("5", exec("<? f=func(a,b){return a+2*b;};  print(f(1,2));?>").toString());
-        assertEquals("13", exec("<? f=func(a,b){return=a+2*b;};  print(f(1,a*2));?>",
+        assertEquals("13", exec("<? f=func(a,b){return a+2*b;};  print(f(1,a*2));?>",
                 new Context().setVar("a", 3)).toString());
 
-        assertEquals("18", exec("<? m=newMap(); m.f=func(a){return=newMap(); return.v=a*a+2;};  print(m.f(4).v);?>").toString());
+        assertEquals("18", exec("<? m=newMap(); m.f=func(a){m=newMap(); m.v=a*a+2; return m;};  print(m.f(4).v);?>").toString());
-        assertEquals("18", exec("<? m=newList(); m[0]=func(a){ l=newList(); l[0]=a*a+2; return=l;};  print(m[0](4)[0]);?>").toString());
+        assertEquals("18", exec("<? m=newList(); m[0]=func(a){ l=newList(); l[0]=a*a+2; return l;};  print(m[0](4)[0]);?>").toString());
 
         try {
-            assertEquals("18", exec("<? f=func(a){return=a;}; f(1)=5; ?>").toString());
+            assertEquals("18", exec("<? f=func(a){return a;}; f(1)=5; ?>").toString());
             fail();
         } catch (HGSEvalException e) {
         }
@@ -326,9 +326,25 @@ public class ParserTest extends TestCase {
 
     public void testFirstClassFunctionOutput() throws IOException, ParserException, HGSEvalException {
         assertEquals("testtext12testtext15",
-                exec("<? f=func(a){  ?>testtext<? print(a*3); return=output; };  print(f(4),f(5));?>").toString());
+                exec("<? f=func(a){  ?>testtext<? print(a*3); return output; };  print(f(4),f(5));?>").toString());
     }
 
+    public void testFirstClassFunctionLambda() throws IOException, ParserException, HGSEvalException {
+        Context c = exec("<? outer=5; f=func(x) {return x+outer;}; ?>");
+        FuncAdapter f = c.getFunction("f");
+        assertEquals(6L,f.call(1));
+        assertEquals(7L,f.call(2));
+
+        c = exec("<? f=func(x){ return func(u){return u*x;};}; a=f(2); b=f(5); ?>");
+        FuncAdapter a = c.getFunction("a");
+        FuncAdapter b = c.getFunction("b");
+        assertEquals(4L,a.call(2));
+        assertEquals(6L,a.call(3));
+        assertEquals(10L,b.call(2));
+        assertEquals(15L,b.call(3));
+    }
+
+
     public void testPanic() throws IOException, ParserException, HGSEvalException {
         Statement s = new Parser("<? if (i>1) panic(\"myError\"); ?>").parse();