Application: gvSIG desktop

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

import org.apache.commons.lang3.Range;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

public class InstrFunction extends AbstractFunction {

    public InstrFunction() {

        super(

                "String", "INSTR", Range.is(2),

                "The functions search string for substring. The function returns "

                        + "an integer indicating the position of the character "

                        + "in string that is the first character of this occurrence.\n"

                        + "The function returns a numeric value. The first position "

                        + "in the string is 1. If substring is not found in string, "

                        + "then the function will return 0",

                "INSTR"+"({{string}}, substring)",

                new String[]{

                    "string - String in which to perform the search.  ",

                    "substring - String to search"

                },

                "Integer",

                true

        );        

        // Nota: 

        // En SQL Server: CHARINDEX(substring, string)

        // En PostgreSQL: STRPOS(string,substring) o POSITION(substring in string)

        // En Oracle: INSTR(string,substring)

        // En H2: INSTR(string,substring)

    }

    @Override

    public boolean allowConstantFolding() {

        return true;

    }

    @Override

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

        String str = getStr(args, 0);

        String search = getStr(args, 1);

        if( str==null || search==null ) {

            return null;

        }

        int n = str.indexOf(search);

        if( n<0 ) {

            return 0;

        }

        return n+1;

    }

}