Application: gvSIG desktop

import java.util.logging.Level;

import org.gvsig.tools.visitor.FilteredVisitable;

    public static Code resolveHostExpressions0(Interpreter interpreter, Code statement) throws Exception {

        List<Code> hostExpressions = new ArrayList<>();

        statement.accept(

                (Object code) -> {

                    hostExpressions.add((Code) code);

                },

                (FilteredVisitable code) -> !(code instanceof Code.Callable

                    && StringUtils.equalsIgnoreCase(((Code.Callable) code).name(), ExpressionBuilder.FUNCTION_$HOSTEXPRESSION))

        );

        if (hostExpressions.isEmpty()) {

            return statement;

        }

        Code newstatement = (Code) statement.clone();

        hostExpressions.clear();

        newstatement.accept(

                (Object code) -> {

                    hostExpressions.add((Code) code);

                },

                (FilteredVisitable code) -> !(code instanceof Code.Callable

                    && StringUtils.equalsIgnoreCase(((Code.Callable) code).name(), ExpressionBuilder.FUNCTION_$HOSTEXPRESSION))

        );

        if (hostExpressions.isEmpty()) {

            return statement;

        }

        CodeBuilder codeBuilder = ((DefaultInterpreter)interpreter).getCodeBuilder();

        List<Code.Constant> constants = new ArrayList<>();

        for (Code hostExpression : hostExpressions) {

            Object v = interpreter.run(hostExpression);

            constants.add(codeBuilder.constant(v));

        }

        for (int i = 0; i < hostExpressions.size(); i++) {

            Code hostExpression = hostExpressions.get(i);

            Code value = constants.get(i);

            newstatement.replace(hostExpression, value);

        }

        return newstatement;

//        return statement;

    }

    public Code resolveHostExpressions(Interpreter interpreter, Code statement) {

        try {

            return resolveHostExpressions0(interpreter, statement);

        } catch (Exception ex) {

            throw new RuntimeException("Can't resolve host expressions", ex);

        }

    }

    public Expression resolveHostExpressions(Expression expression, SymbolTable symbolTable) {

        try {

            Interpreter interpreter = this.createInterpreter();

            interpreter.setSymbolTable(symbolTable);

            Code code0 = expression.getCode();

            Code code1 = resolveHostExpressions0(interpreter, code0);

            if( code0 == code1 ) {

                // No hay "hosts expressions", devolvemos la expresion original.

                return expression;

            }

            DefaultExpression exp = new DefaultExpression(this);

            exp.setPhrase(code1.toValue().toString());

            return exp;

        } catch (Exception ex) {

            throw new RuntimeException("Can't resolve host expressions", ex);

        }

    }