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Google App Engine compliant variation of FreeMarker. FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
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/*
 * Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * 22 October 1999: This class added by Holger Arendt.
 */

package freemarker.core;

import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;

import freemarker.template.TemplateException;
import freemarker.template.TemplateMethodModel;
import freemarker.template.TemplateMethodModelEx;
import freemarker.template.TemplateModel;
import freemarker.template.utility.NullWriter;


/**
 * A unary operator that calls a TemplateMethodModel.  It associates with the
 * Identifier or Dot to its left.
 */
final class MethodCall extends Expression {

    private final Expression target;
    private final ListLiteral arguments;

    MethodCall(Expression target, ArrayList arguments) {
        this(target, new ListLiteral(arguments));
    }

    private MethodCall(Expression target, ListLiteral arguments) {
        this.target = target;
        this.arguments = arguments;
    }

    TemplateModel _eval(Environment env) throws TemplateException
    {
        TemplateModel targetModel = target.eval(env);
        if (targetModel instanceof TemplateMethodModel) {
            TemplateMethodModel targetMethod = (TemplateMethodModel)targetModel;
            List argumentStrings = 
            targetMethod instanceof TemplateMethodModelEx
            ? arguments.getModelList(env)
            : arguments.getValueList(env);
            Object result = targetMethod.exec(argumentStrings);
            return env.getObjectWrapper().wrap(result);
        }
        else if (targetModel instanceof Macro) {
            Macro func = (Macro) targetModel;
            env.setLastReturnValue(null);
            if (!func.isFunction) {
                throw new _MiscTemplateException(env, "A macro cannot be called in an expression.");
            }
            Writer prevOut = env.getOut();
            try {
                env.setOut(NullWriter.INSTANCE);
                env.visit(func, null, arguments.items, null, null);
            } catch (IOException ioe) {
                throw new InternalError("This should be impossible.");
            } finally {
                env.setOut(prevOut);
            }
            return env.getLastReturnValue();
        }
        else {
            throw new NonMethodException(target, targetModel, env);
        }
    }

    public String getCanonicalForm() {
        StringBuffer buf = new StringBuffer();
        buf.append(target.getCanonicalForm());
        buf.append("(");
        String list = arguments.getCanonicalForm();
        buf.append(list.substring(1, list.length() -1));
        buf.append(")");
        return buf.toString();
    }

    String getNodeTypeSymbol() {
        return "...(...)";
    }
    
    TemplateModel getConstantValue() {
        return null;
    }

    boolean isLiteral() {
        return false;
    }

    protected Expression deepCloneWithIdentifierReplaced_inner(
            String replacedIdentifier, Expression replacement, ReplacemenetState replacementState) {
        return new MethodCall(
                target.deepCloneWithIdentifierReplaced(replacedIdentifier, replacement, replacementState),
                (ListLiteral)arguments.deepCloneWithIdentifierReplaced(replacedIdentifier, replacement, replacementState));
    }

    int getParameterCount() {
        return 1 + arguments.items.size();
    }

    Object getParameterValue(int idx) {
        if (idx == 0) {
            return target;
        } else if (idx < getParameterCount()) {
            return arguments.items.get(idx - 1);
        } else {
            throw new IndexOutOfBoundsException();
        }
    }

    ParameterRole getParameterRole(int idx) {
        if (idx == 0) {
            return ParameterRole.CALLEE;
        } else if (idx < getParameterCount()) {
            return ParameterRole.ARGUMENT_VALUE;
        } else {
            throw new IndexOutOfBoundsException();
        }
    }

}