Class MappingRowSplittable
- java.lang.Object
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- uk.ac.starlink.table.WrapperRowSequence
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- uk.ac.starlink.table.MappingRowSplittable
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,RowData
,RowSequence
,RowSplittable
,uk.ac.starlink.util.Sequence
,uk.ac.starlink.util.Splittable<RowSplittable>
public class MappingRowSplittable extends WrapperRowSequence implements RowSplittable
RowSplittable which wraps another RowSplittable but presents different column contents as controlled by a supplied column data mapping function. The methods other than the data access are delegated to a supplied base RowSplittable, so that the row structure must be the same as for the base.Note: this cannot in general be extended by an anonymous class to change aspects of the behaviour other than the column mapping, since the
split()
method has to return an instance of the same class rather than of its superclass.- Since:
- 12 Oct 2020
- Author:
- Mark Taylor
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Field Summary
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Fields inherited from class uk.ac.starlink.table.WrapperRowSequence
baseSeq
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Constructor Summary
Constructors Constructor Description MappingRowSplittable(RowSplittable baseSplit, java.util.function.Function<RowSplittable,RowData> dataMapper)
Constructor.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Object
getCell(int icol)
Returns the contents of a cell in the current row.java.lang.Object[]
getRow()
Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table.java.util.function.LongSupplier
rowIndex()
Returns a supplier for the index of the row currently being processed, if possible.RowSplittable
split()
long
splittableSize()
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Methods inherited from class uk.ac.starlink.table.WrapperRowSequence
close, next, toString
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Methods inherited from interface uk.ac.starlink.table.RowSequence
close, next
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Constructor Detail
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MappingRowSplittable
public MappingRowSplittable(RowSplittable baseSplit, java.util.function.Function<RowSplittable,RowData> dataMapper)
Constructor.- Parameters:
baseSplit
- base splittabledataMapper
- used to acquire data access behaviour from newly split base instances
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Method Detail
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getCell
public java.lang.Object getCell(int icol) throws java.io.IOException
Description copied from interface:RowSequence
Returns the contents of a cell in the current row. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass(). An unchecked exception will be thrown if there is no current row (next has not yet been called).- Specified by:
getCell
in interfaceRowData
- Specified by:
getCell
in interfaceRowSequence
- Overrides:
getCell
in classWrapperRowSequence
- Parameters:
icol
- column index- Returns:
- the contents of cell icol in the current row
- Throws:
java.io.IOException
- if there is an error reading the data
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getRow
public java.lang.Object[] getRow() throws java.io.IOException
Description copied from interface:RowSequence
Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table. An unchecked exception will be thrown if there is no current row (next has not yet been called).- Specified by:
getRow
in interfaceRowData
- Specified by:
getRow
in interfaceRowSequence
- Overrides:
getRow
in classWrapperRowSequence
- Returns:
- an array of the objects in each cell in row irow
- Throws:
java.io.IOException
- if there is an error reading the data
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splittableSize
public long splittableSize()
- Specified by:
splittableSize
in interfaceuk.ac.starlink.util.Splittable<RowSplittable>
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rowIndex
public java.util.function.LongSupplier rowIndex()
Description copied from interface:RowSplittable
Returns a supplier for the index of the row currently being processed, if possible. The row index is a global value; when accessing the first row of a top-level RowSplittable, the value returned by this supplier should be the first index in the table. But for objects resulting from splitting a top-level instance into sub-instances, the return value should reflect the index in the original sequence of rows; each index should be returned from only one of the splittables resulting from splitting a top-level instance.Typically, the row index will start at 0 and increment for each row, but the numbering may be different depending on the requirements of the implementation or usage.
Before the
RowSequence.next()
method has been called, the return value will be one less than the first row index. AfterRowSequence.next
has returned false, the value is undefined.Depending on the implementation, it may not be possible to determine the row index (for instance if the sequence is split into sub-splittables of unknown size). In such cases, this method returns null. The null-ness of the return value must be the same for all instances of the splittable hierarchy for a given sequence, so don't return a non-null value for the first splittable and then null values for some or all of its children.
- Specified by:
rowIndex
in interfaceRowSplittable
- Returns:
- supplier for the globally-referenced row index value of the current row of this sequence, or null
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split
public RowSplittable split()
- Specified by:
split
in interfaceuk.ac.starlink.util.Splittable<RowSplittable>
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