--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/nabble/naml/compiler/InterpreterImpl.java	Thu Mar 21 19:15:52 2019 -0600
@@ -0,0 +1,141 @@
+package nabble.naml.compiler;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Map;
+
+
+class InterpreterImpl implements Interpreter {
+	private static final Logger logger = LoggerFactory.getLogger(Compiler.class);
+
+	final CommandSpec cmdSpec;
+	final RunState runState;
+	private final Map<Class,Integer> inStack;
+	private final Map<String,?> args;
+	private final Encoder oldEncoder;
+
+	InterpreterImpl(CommandSpec cmdSpec,RunState runState,Map<Class,Integer> inStack,Map<String,?> args) {
+		this.cmdSpec = cmdSpec;
+		this.runState = runState;
+		this.inStack = inStack;
+		this.args = args;
+		this.oldEncoder = runState.getEncoder();
+	}
+
+	public Object getArg(String param) {
+		return args.get(param);
+	}
+
+	public String getArgString(String param) {
+		return Template.stringValue( getArg(param) );
+	}
+
+	public Template template() {
+		return runState.template();
+	}
+
+	public <T> T getFromStack(Class<T> cls) {
+		Integer i = inStack.get(cls);
+		if( i == null )
+			throw new RuntimeException(""+cls+" not found in stack");
+		return cls.cast(runState.getFromStack(i));
+	}
+
+	public int callDepth() {
+		return runState.callDepth();
+	}
+
+	public final <T> T getArgAsNamespace(Class<T> cls,String param) {
+		String s = getArgString(param);
+		if( s == null )
+			return null;
+		return cls.cast(runState.getNamespace(s));
+	}
+
+	public boolean hasNamespace(String namespace) {
+		return runState.hasNamespace(namespace);
+	}
+
+	public boolean isInCommandStack(String commandName) {
+		return runState.isInCommandStack(commandName);
+	}
+
+
+	// from AbstractInterpreter
+
+	public final boolean hasModule(String moduleName) {
+		return runState.program().moduleNames().contains(moduleName);
+	}
+
+	public final boolean getArgAsBoolean(String param)
+		throws BooleanFormatException
+	{
+		try {
+			return Template.booleanValue( getArg(param) );
+		} catch(BooleanFormatException e) {
+			throw new BooleanFormatException( newMsg(param,e) );
+		}
+	}
+
+	public final boolean getArgAsBoolean(String param,boolean defaultValue)
+		throws BooleanFormatException
+	{
+		try {
+			return Template.booleanValue( getArg(param), defaultValue );
+		} catch(BooleanFormatException e) {
+			throw new BooleanFormatException( newMsg(param,e) );
+		}
+	}
+
+	public final int getArgAsInt(String param)
+		throws NumberFormatException
+	{
+		try {
+			return Template.intValue( getArg(param) );
+		} catch(NumberFormatException e) {
+			throw new NumberFormatException( newMsg(param,e) );
+		}
+	}
+
+	public int getArgAsInt(String param, int defaultValue)
+		throws NumberFormatException
+	{
+		try {
+			return Template.intValue( getArg(param), defaultValue );
+		} catch(NumberFormatException e) {
+			throw new NumberFormatException( newMsg(param,e) );
+		}
+	}
+
+	public final long getArgAsLong(String param)
+		throws NumberFormatException
+	{
+		try {
+			return Template.longValue( getArg(param) );
+		} catch(NumberFormatException e) {
+			throw new NumberFormatException( newMsg(param,e) );
+		}
+	}
+
+	private static String newMsg(String param,Exception e) {
+		return "For argument: \"" + param + "\" - " + e.getMessage();
+	}
+
+	public String encode(String s) {
+		return s==null ? null : getEncoder().encode(s);
+	}
+
+	public Encoder getEncoder() {
+		return runState.getEncoder();
+	}
+
+	public void setEncoder(Encoder encoder) {
+		runState.setEncoder(encoder);
+	}
+
+	void close() {
+		runState.setEncoder(oldEncoder);
+	}
+
+}