presto-rcfile/src/main/java/io/prestosql/rcfile/text/BooleanEncoding.java/BooleanEncoding/decodeColumn
class BooleanEncoding:    @Override
    public Block decodeColumn(ColumnData columnData)
    {
        int size = columnData.rowCount();
        BlockBuilder builder = type.createBlockBuilder(null, size);

        Slice slice = columnData.getSlice();
        for (int i = 0; i < size; i++) {
            int offset = columnData.getOffset(i);
            int length = columnData.getLength(i);
            if (isTrue(slice, offset, length)) {
                type.writeBoolean(builder, true);
            }
            else if (isFalse(slice, offset, length)) {
                type.writeBoolean(builder, false);
            }
            else {
                builder.appendNull();
            }
        }
        return builder.build();
    }