added first VHDLTemplate, not working yet

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

@@ -14,6 +14,7 @@ public class Context {
     private final Context parent;
     private final StringBuilder code;
     private HashMap<String, Object> map;
+    private int recordStart = 0;
 
     /**
      * Creates a new context
@@ -37,6 +38,23 @@ public class Context {
         map = new HashMap<>();
     }
 
+    /**
+     * Returns true if this context contains a mapping for the specified key.
+     *
+     * @param name the key
+     * @return true if value is present
+     */
+    public boolean contains(String name) {
+        if (map.containsKey(name))
+            return true;
+        else {
+            if (parent != null)
+                return parent.contains(name);
+            else
+                return false;
+        }
+    }
+
     /**
      * Get a variable
      *
@@ -47,6 +65,13 @@ public class Context {
     public Object getVar(String name) throws EvalException {
         Object v = map.get(name);
         if (v == null) {
+
+            if (name.equals("output"))
+                return code.toString();
+
+            if (name.equals("fraction"))
+                return code.subSequence(recordStart, code.length()).toString();
+
             if (parent == null)
                 throw new EvalException("variable not found: " + name);
             else
@@ -76,8 +101,9 @@ public class Context {
     public Context print(String str) {
         if (parent != null)
             parent.print(str);
-        else
+        else {
             code.append(str);
+        }
         return this;
     }
 
@@ -88,4 +114,11 @@ public class Context {
         else
             return map.toString();
     }
+
+    /**
+     * resets the record position
+     */
+    public void resetRecorder() {
+        recordStart = code.length();
+    }
 }

src/main/java/de/neemann/digital/hdl/vhdl/VHDLLibrary.java

@@ -127,7 +127,7 @@ public class VHDLLibrary {
 
             e.writeHeader(out, node);
 
-            if (e instanceof ExternalVHDL)
+            if (e instanceof ExternalVHDL || e instanceof VHDLTemplate)
                 return;
 
             out.println();

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

@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2017 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.vhdl.lib;
+
+import de.neemann.digital.hdl.hgs.*;
+import de.neemann.digital.hdl.model.HDLException;
+import de.neemann.digital.hdl.model.HDLNode;
+import de.neemann.digital.hdl.printer.CodePrinter;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.util.HashSet;
+
+/**
+ * Reads a file with the vhdl code to create the entity
+ */
+public class VHDLTemplate implements VHDLEntity {
+    private final static String ENTITY_PREFIX = "DIG_";
+    private final Context staticContext;
+    private final Statement statements;
+    private HashSet<String> entitiesWritten;
+    private String entityName;
+
+    /**
+     * Creates a new instance
+     *
+     * @param name the name of the entity
+     * @throws IOException IOException
+     */
+    public VHDLTemplate(String name) throws IOException {
+        entityName = ENTITY_PREFIX + name;
+        InputStream inputStream = getClass().getClassLoader().getResourceAsStream(createFileName(entityName));
+        if (inputStream == null)
+            throw new IOException("file not present: " + createFileName(entityName));
+        try (Reader in = new InputStreamReader(inputStream, "utf-8")) {
+            Parser p = new Parser(in);
+            statements = p.parse();
+            staticContext = p.getStaticContext();
+        } catch (ParserException e) {
+            throw new IOException("error parsing template", e);
+        }
+        entitiesWritten = new HashSet<>();
+    }
+
+    private static String createFileName(String name) {
+        return "vhdl/" + name + ".tem";
+    }
+
+    @Override
+    public void writeHeader(CodePrinter out, HDLNode node) throws IOException {
+        try {
+            statements.execute(new Context().setVar("elem", node.getAttributes()));
+            entitiesWritten.add(getEntityName(node));
+        } catch (EvalException e) {
+            throw new IOException("error evaluating the template", e);
+        }
+    }
+
+    private String getEntityName(HDLNode node) throws EvalException {
+        String name = entityName;
+        if (staticContext.contains("name")) {
+            Object funcObj = staticContext.getVar("name");
+            if (funcObj instanceof FirstClassFunction)
+                name = ((FirstClassFunction) funcObj).evaluate(node.getAttributes()).toString();
+        }
+        return name;
+    }
+
+    @Override
+    public String getName(HDLNode node) throws HDLException {
+        try {
+            return getEntityName(node);
+        } catch (EvalException e) {
+            throw new HDLException("error requesting the entities name", e);
+        }
+    }
+
+    @Override
+    public boolean needsOutput(HDLNode node) throws HDLException {
+        try {
+            return !entitiesWritten.contains(getEntityName(node));
+        } catch (EvalException e) {
+            throw new HDLException("error requesting the entities name", e);
+        }
+    }
+
+    @Override
+    public void writeDeclaration(CodePrinter out, HDLNode node) throws IOException, HDLException {
+
+    }
+
+    @Override
+    public void writeArchitecture(CodePrinter out, HDLNode node) throws IOException, HDLException {
+    }
+
+    @Override
+    public void writeGenericMap(CodePrinter out, HDLNode node) throws IOException, HDLException {
+
+    }
+
+    @Override
+    public String getDescription(HDLNode node) {
+        return null;
+    }
+}

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

@@ -255,6 +255,11 @@ public class ParserTest extends TestCase {
                 new Context().setVar("a", 3)).toString());
     }
 
+    public void testFirstClassFunctionOutput() throws IOException, ParserException, EvalException {
+        assertEquals("testtext12testtext15",
+                exec("<? f=func(a){  ?>testtext<? print(a*3); return=output; };  print(f(4),f(5));?>").toString());
+    }
+
 
 //    public void testCode() throws IOException, ParserException {
 //        File dir = new File("/home/hneemann/temp/Digital/ideras/Digital/src/main/resources/verilog");