Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl.function.programming;

import java.util.Objects;

import org.apache.commons.lang3.Range;

import org.gvsig.expressionevaluator.Code;

import org.gvsig.expressionevaluator.Codes;

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

import org.gvsig.expressionevaluator.ExpressionRuntimeException;

import org.gvsig.expressionevaluator.Formatter;

import org.gvsig.expressionevaluator.MutableSymbolTable;

import org.gvsig.expressionevaluator.PrettyFormatter;

import org.gvsig.expressionevaluator.impl.function.programming.BreakFunction.BreakException;

import org.gvsig.expressionevaluator.impl.function.programming.ReturnFunction.ReturnException;

public class ForEachFunction extends AbstractFunction {

    public static final String NAME = "FOREACH";

    public ForEachFunction() {

        super(Function.GROUP_PROGRAMMING, 

                NAME, 

                Range.is(3),

                "The foreach() function evaluate body for every element of the iterable.",

                "FOR n IN {{expression}}\n  BEGIN\n  PASS;\nEND FOR\n",

                null,

                "Object",

                false

        );

    }

    @Override

    public boolean isHidden() {

      return true;

    }

    @Override

    public boolean useArgumentsInsteadObjects() {

        return true;

    }

    @Override

    public boolean allowConstantFolding() {

        return false;

    }

    @Override

    public Object call(Interpreter interpreter, Object[] args) throws Exception {

        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

    }

    @Override

    public Object call(Interpreter interpreter, Codes args) throws Exception {

        if ( getObject(interpreter, args, 1)==null) {

            return null;

        }

        if( !(interpreter.getSymbolTable() instanceof MutableSymbolTable) ) {

            throw new ExpressionRuntimeException("The use of forech loops require a mutable symbol table.");

        }

        MutableSymbolTable symbolTable = (MutableSymbolTable) interpreter.getSymbolTable();

        Object body = null;

        String varname = getObject(interpreter, args, 0).toString();

        int argn = 1;

        Iterable iterable = (Iterable) getObject(interpreter, args, 1);

        for (Object value : iterable) {

            symbolTable.setVar(varname, value);

            try {

                Object x = getObject(interpreter, args, 2);

                body = x;

            } catch(BreakException ex) {

                break;

            } catch(ReturnException ex) {

                throw ex;

            } catch(Exception ex) {

                String stmt = "unknown";

                try {

                    stmt = Objects.toString(args);

                } catch(Exception ex2) {

                }

                LOGGER.warn("Error in foreach function calling arg "+ argn + ", "+ stmt, ex);

                throw ex;

            }

            argn++;

        }

        return body;

    }

    @Override

    public String toString(Codes args, Formatter<Code> formatter) {

        Code codeVarname = args.get(0);

        Code codeList = args.get(1);

        Code codeLoopBody = args.get(2);

        PrettyFormatter builder = PrettyFormatter.get(formatter);

        try {

            builder.push();

            builder.append("FOR \"");

            builder.append(Objects.toString(((Code.Constant)codeVarname).value()));        

            builder.append("\" IN ");

            builder.append(codeList.toString(formatter));

            builder.append(" LOOP ");

            builder.indent();

            builder.nl();

            if( Code.isFunction(codeLoopBody,"BLOCK") ) {

                Code.Callable block = (Code.Callable)codeLoopBody;

                for (Code parameter : block.parameters()) {

                    builder.nl();

                    builder.append(parameter.toString(formatter));

                    builder.append("; ");

                }

            } else {

                builder.nl();

                builder.append(codeLoopBody.toString(formatter));

                builder.append(" ");

            }            

            builder.unindent();

            builder.nl();

            builder.append("END LOOP");

            return builder.build();

        } finally {

            builder.pop();

        }

    }

}