Polymer 3 dom-bind event handling

Original intent

is to update the text when component.selection is changed

index-0.html

<textarea style="width: 100%;height: 9em" id="configtext"></textarea>
<button onclick=" navigator.clipboard.writeText(configtext.value) ">&boxbox; Copy</button>

<webcomponents-element visible="true" id="webcomponentsElement" ></webcomponents-element>
<script>
    window.addEventListener("load",()=>{
        webcomponentsElement.addEventListener("selection-changed",(ev)=>{
            configtext.value=webcomponentsElement.selection.replace( /,/g , ",\n");
        });
    });
</script>

using dom-bind

The change handler is still initialized in SCRIPT code:

index-1.html

<dom-bind id="configurator">
    <template>

        <textarea style="width: 100%;height: 9em" id="configtext"></textarea>
        <button onclick=" navigator.clipboard.writeText(configtext.value) ">&boxbox; Copy</button>

        <webcomponents-element visible="true" id="webcomponentsElement"
                               on-selection-changed="onSelectionChanged"
        ></webcomponents-element>
    </template>
</dom-bind>
<script>
    configurator.onSelectionChanged = function (e) {
        configtext.value = webcomponentsElement.selection.replace(/,/g, ",\n");
    };
</script>

Final version - The power of declarative programming!

No JavaScript, binding only via sel variable scoped in binding context of dom-bind.

index.html

<dom-bind>
    <template>
        <textarea style="width: 100%;height: 9em" id="configtext" value="{{sel::change}}"></textarea>
        <button onclick=" navigator.clipboard.writeText(configtext.value) ">&boxbox; Copy</button>

        <webcomponents-element visible="true" id="webcomponentsElement" selection="{{sel}}"></webcomponents-element>
    </template>
</dom-bind>

Java Lambda vs method performance is 2x slower

Going over algorithms exercises I found that inline functions with access to outer scope variables make code way cleaner.  In Java 8+ I know two ways of doing so:

1. wrap an outer scope variables in object and define a method
2. use Lambda functions

Surprisingly 1st method became almost 2x more performant:

member

    final public class
BinaryGap
{
    public BinaryGap( long value ){ val = value; }

        public final static int
    maxGapCount( final long value )
    {
        final BinaryGap vo = new BinaryGap(value);
        vo.skipBits(0 );

        for( int max0 = 0; vo.val !=0 ; )
        {
            vo.skipBits(1 );
            int z = vo.skipBits(0 );
            if( z == 0 )
                return max0;
            if( z > max0 )
                max0 = z;
        }
        return 0;
    }
    long val;

    final int skipBits( final int bit0 )
    {   int ret = 0;
        do
        {   if( val == 0 || (val&1) != bit0  )
                return ret;
            val = val >> 1;
            ret++;
        }while( val != 0 );
        return ret;
    }
}

Lambda

        public final static int
    maxGapCountLambda(  long value )
    {   class Wrap{ long v; }
        final Wrap w = new Wrap(); w.v = value;
        IntSupplier skip0 = ()->
        {   int count=0;
            long L = w.v;
            for( ; L!=0 && (L&1) == 0; count++ ) // skip 0
                L = L>>1;
            w.v = L;
            return count;
        };
        IntSupplier skip1 = ()->
        {   long L = w.v;
            while( L!=0 && (L&1) == 1 ) // skip 1
                L = L>>1;
            w.v = L;
            return 0;
        };

        skip0.getAsInt();
        int maxCount =0;
        while( w.v != 0 )
        {
            skip1.getAsInt();
            int count =skip0.getAsInt();
            if( count > maxCount )
                maxCount = count;
        }
        return maxCount;
    }

Tests

Test	Duration	Result
maxGapCount	0s	passed
maxGapCountInlineLoad	0.126s Of course inline is fastest, but not as much readable.	passed
maxGapCountLambdaLoad	0.226s	passed
maxGapCountLoad	0.141s	passed
skipBits	0s	passed

Full sources

BinaryGap.java

package codily.lesson1;

import java.util.function.IntSupplier;
import java.util.function.LongPredicate;
import java.util.function.LongToIntFunction;

/**
 * https://app.codility.com/programmers/lessons/1-iterations/binary_gap/
 */
    final public class
BinaryGap
{
    long val;
    public BinaryGap( long value ){ val = value; }

        public final static int
    maxGapCount( final long value )
    {
        final BinaryGap vo = new BinaryGap(value);
        vo.skipBits(0 );

        for( int max0 = 0; vo.val !=0 ; )
        {
            vo.skipBits(1 );
            int z = vo.skipBits(0 );
            if( z == 0 )
                return max0;
            if( z > max0 )
                max0 = z;
        }
        return 0;
    }
        public final static int
    maxGapCountInline(  long value )
    {
        while( value!=0 && (value&1) == 0 ) // skip 0
            value = value>>1;
        int maxCount =0;

        while( value !=0 )
        {
            while( value!=0 && (value&1) == 1 ) // skip 1
                value = value>>1;

            int count =0;
            while( value!=0 && (value&1) == 0 ) // skip 0
            {   count ++;
                value = value >> 1;
            }
            if( count > maxCount )
                maxCount = count;
        }
        return maxCount;
    }
        public final static int
    maxGapCountLambda(  long value )
    {   class Wrap{ long v; }
        final Wrap w = new Wrap(); w.v = value;
        IntSupplier skip0 = ()->
        {   int count=0;
            long L = w.v;
            for( ; L!=0 && (L&1) == 0; count++ ) // skip 0
                L = L>>1;
            w.v = L;
            return count;
        };
        IntSupplier skip1 = ()->
        {   long L = w.v;
            while( L!=0 && (L&1) == 1 ) // skip 1
                L = L>>1;
            w.v = L;
            return 0;
        };

        skip0.getAsInt();
        int maxCount =0;
        while( w.v != 0 )
        {
            skip1.getAsInt();
            int count =skip0.getAsInt();
            if( count > maxCount )
                maxCount = count;
        }
        return maxCount;
    }


        final int
    skipBits( final int bit0 )
    {   int ret = 0;
        do
        {   if( val == 0 || (val&1) != bit0  )
                return ret;
            val = val >> 1;
            ret++;
        }while( val != 0 );
        return ret;
    }
}

BinaryGapTest.java

package codily.lesson1;

import org.junit.Test;
import static org.junit.Assert.*;

    public class
BinaryGapTest
{
    public final long [] exp =  { 00, 00, 00, 00, 00, 00, 01, 02, 03, 30 };
    public final long [] inp =  { 0b0000_0000_0000_0000_0000_0000_0000_0000L
                                , 0b1111_1111_1111_1111_1111_1111_1111_1111L
                                , 0b0000_0000_0000_0000_0000_0000_0000_0001L
                                , 0b0000_0000_0000_0000_0000_0000_0000_0011L
                                , 0b0000_0000_0000_0000_0000_0000_0000_0010L
                                , 0b0000_0000_0000_0000_0000_0000_0000_0100L
                                , 0b0000_0000_0000_0000_0000_0000_0000_0101L
                                , 0b0000_0000_0000_0000_0000_0000_0000_1001L
                                , 0b0000_0000_0000_0000_0000_0000_1000_1001L
                                , 0b1000_0000_0000_0000_0000_0000_0000_0001L
                                };
    long [] act= new long[inp.length];

        @Test public void
    maxGapCount()
    {
        assertEquals(00, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_0000L ) );
        assertEquals(00, BinaryGap.maxGapCount( 0b1111_1111_1111_1111_1111_1111_1111_1111L ) );
        assertEquals(00, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_0001L ) );
        assertEquals(00, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_0011L ) );
        assertEquals(00, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_0010L ) );
        assertEquals(00, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_0100L ) );

        assertEquals(01, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_0101L ) );
        assertEquals(02, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_0000_1001L ) );
        assertEquals(03, BinaryGap.maxGapCount( 0b0000_0000_0000_0000_0000_0000_1000_1001L ) );
        assertEquals(30, BinaryGap.maxGapCount( 0b1000_0000_0000_0000_0000_0000_0000_0001L ) );
    }
    final int REPEAT_COUNT = 1000_000;

    @Test public void
    maxGapCountLoad()
    {
        for( int k=0; k < REPEAT_COUNT; k++ ) // timer count
            for( int i=0; i<exp.length; i++ )
                act[i] = BinaryGap.maxGapCount( inp[i] );
        assertArrayEquals( act, exp );
    }
        @Test public void
    maxGapCountInlineLoad()
    {
        for( int k=0; k < REPEAT_COUNT; k++ ) // timer count
            for( int i=0; i<exp.length; i++ )
                act[i] = BinaryGap.maxGapCountInline( inp[i] );
        assertArrayEquals( act, exp );
    }
        @Test public void
    maxGapCountLambdaLoad()
    {
        for( int k=0; k < REPEAT_COUNT; k++ ) // timer count
            for( int i=0; i<exp.length; i++ )
                act[i] = BinaryGap.maxGapCountLambda( inp[i] );
        assertArrayEquals( act, exp );
    }

        @Test public void
    skipBits()
    {
        BinaryGap bg = new BinaryGap( 0L );
        assertEquals( "zero", bg.skipBits(0), 0 );
        assertEquals( "zero", bg.skipBits(0), 0 );
        assertEquals( "zero", bg.skipBits(1), 0 );

        bg = new BinaryGap( 0b1111_1111_1111_1111_1111_1111_1111_1111L );
        assertEquals( "zero", bg.skipBits(0), 0 );
        assertEquals( "zero", bg.skipBits(1), 32 );
        assertEquals( "zero", bg.skipBits(1), 0 );
        assertEquals( "zero", bg.skipBits(0), 0 );
    }
}