org.apache.calcite.util.mapping

Class Mappings

java.lang.Object

org.apache.calcite.util.mapping.Mappings

public abstract class Mappings
extends Object

Utility functions related to mappings.

See Also:

MappingType, Mapping, Permutation

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Mappings.AbstractMapping Abstract implementation of Mapping.
static interface	Mappings.CoreMapping Core interface of all mappings.
static class	Mappings.FiniteAbstractMapping Abstract implementation of mapping where both source and target domains are finite.
static interface	Mappings.FunctionMapping Mapping where every source has a target.
static class	Mappings.IdentityMapping The identity mapping, of a given size, or infinite.
static class	Mappings.NoElementException Thrown when a mapping is expected to return one element but returns none.
static class	Mappings.OverridingSourceMapping Source mapping that returns the same result as a parent Mappings.SourceMapping except for specific overriding elements.
static class	Mappings.OverridingTargetMapping Target mapping that returns the same result as a parent Mappings.TargetMapping except for specific overriding elements.
static class	Mappings.PartialMapping A mapping where a source has at most one target, and every target has at most one source.
static interface	Mappings.SourceMapping Mapping suitable for sourcing columns.
static interface	Mappings.TargetMapping Mapping suitable for mapping columns to a target.
static class	Mappings.TooManyElementsException Thrown when a mapping is expected to return one element but returns several.

Method Summary

Methods

Modifier and Type	Method and Description
static Mappings.TargetMapping	append(Mappings.TargetMapping mapping0, Mappings.TargetMapping mapping1) Creates a mapping by appending two mappings.
static BitSet	apply(Mapping mapping, BitSet bitSet) Applies a mapping to a BitSet.
static ImmutableBitSet	apply(Mapping mapping, ImmutableBitSet bitSet) Applies a mapping to an ImmutableBitSet.
static <T> List<T>	apply(Mapping mapping, List<T> list) Applies a mapping to a list.
static List<Integer>	apply2(Mapping mapping, List<Integer> list)
static <T> List<T>	apply3(Mapping mapping, List<T> list) Creates a view of a list, permuting according to a mapping.
static List<Integer>	asList(Mappings.TargetMapping mapping) Returns a mapping as a list such that list.get(source) is mapping.getTarget(source) and list.size() is mapping.getSourceCount().
static Mapping	bijection(List<Integer> targets) Creates a bijection.
static Mapping	create(MappingType mappingType, int sourceCount, int targetCount) Creates a mapping with required properties.
static Mappings.IdentityMapping	createIdentity(int fieldCount) Creates the identity mapping.
static Mappings.TargetMapping	createShiftMapping(int sourceCount, int... ints) Creates a mapping that consists of a set of contiguous ranges.
static Mapping	divide(Mapping mapping1, Mapping mapping2) Divides one mapping by another.
static Iterable<IntPair>	invert(Iterable<IntPair> pairs) Inverts an Iterable over IntPairs.
static Iterator<IntPair>	invert(Iterator<IntPair> pairs) Inverts an Iterator over IntPairs.
static Mapping	invert(Mapping mapping) Converts a mapping to its inverse.
static boolean	isIdentity(List<Integer> list, int count) Returns whether a list of integers is the identity mapping [0, ..., n - 1].
static boolean	isIdentity(Mappings.TargetMapping mapping) Returns whether a mapping is the identity.
static Mappings.TargetMapping	merge(Mappings.TargetMapping mapping0, Mappings.TargetMapping mapping1) Creates a mapping by merging two mappings.
static Mapping	multiply(Mapping mapping1, Mapping mapping2) Multiplies one mapping by another.
static Mappings.TargetMapping	offset(Mappings.TargetMapping mapping, int offset, int sourceCount) Returns a mapping that shifts a given mapping's source and target by a given offset.
static Mappings.TargetMapping	offsetSource(Mappings.TargetMapping mapping, int offset) Returns a mapping that shifts a given mapping's source by a given offset, incrementing the number of sources by the minimum possible.
static Mappings.TargetMapping	offsetSource(Mappings.TargetMapping mapping, int offset, int sourceCount) Returns a mapping that shifts a given mapping's source by a given offset.
static Mappings.TargetMapping	offsetTarget(Mappings.TargetMapping mapping, int offset) Returns a mapping that shifts a given mapping's target by a given offset, incrementing the number of targets by the minimum possible.
static Mappings.TargetMapping	offsetTarget(Mappings.TargetMapping mapping, int offset, int targetCount) Returns a mapping that shifts a given mapping's target by a given offset.
static <T> List<T>	permute(List<T> list, Mappings.TargetMapping mapping) Creates a view of a list, permuting according to a target mapping.
static Mapping	source(List<Integer> targets, int targetCount)
static Mappings.TargetMapping	target(com.google.common.base.Function<Integer,Integer> function, int sourceCount, int targetCount)
static Mapping	target(Iterable<IntPair> pairs, int sourceCount, int targetCount)
static Mapping	target(List<Integer> sources, int sourceCount)
static Mappings.TargetMapping	target(Map<Integer,Integer> map, int sourceCount, int targetCount) Converts a Map of integers to a Mappings.TargetMapping.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

create

public static Mapping create(MappingType mappingType,
             int sourceCount,
             int targetCount)

Creates a mapping with required properties.

createIdentity

public static Mappings.IdentityMapping createIdentity(int fieldCount)

Creates the identity mapping.

For example, createIdentity(2) returns the mapping {0:0, 1:1, 2:2}.

Parameters:

fieldCount - Number of sources/targets

Returns:

Identity mapping

invert

public static Mapping invert(Mapping mapping)

Converts a mapping to its inverse.

divide

public static Mapping divide(Mapping mapping1,
             Mapping mapping2)

Divides one mapping by another.

divide(A, B) returns a mapping C such that B . C (the mapping B followed by the mapping C) is equivalent to A.

Parameters:

mapping1 - First mapping

mapping2 - Second mapping

Returns:

Mapping mapping3 such that mapping1 = mapping2 . mapping3

multiply

public static Mapping multiply(Mapping mapping1,
               Mapping mapping2)

Multiplies one mapping by another.

divide(A, B) returns a mapping C such that B . C (the mapping B followed by the mapping C) is equivalent to A.

Parameters:

mapping1 - First mapping

mapping2 - Second mapping

Returns:

Mapping mapping3 such that mapping1 = mapping2 . mapping3

apply

public static BitSet apply(Mapping mapping,
           BitSet bitSet)

Applies a mapping to a BitSet.

If the mapping does not affect the bit set, returns the original. Never changes the original.

Parameters:

mapping - Mapping

bitSet - Bit set

Returns:

Bit set with mapping applied

apply

public static ImmutableBitSet apply(Mapping mapping,
                    ImmutableBitSet bitSet)

Applies a mapping to an ImmutableBitSet.

If the mapping does not affect the bit set, returns the original. Never changes the original.

Parameters:

mapping - Mapping

bitSet - Bit set

Returns:

Bit set with mapping applied

apply

public static <T> List<T> apply(Mapping mapping,
                List<T> list)

Applies a mapping to a list.

Type Parameters:

T - Element type

Parameters:

mapping - Mapping

list - List

Returns:

List with elements permuted according to mapping

apply2

public static List<Integer> apply2(Mapping mapping,
                   List<Integer> list)

apply3

public static <T> List<T> apply3(Mapping mapping,
                 List<T> list)

Creates a view of a list, permuting according to a mapping.

Type Parameters:

T - Element type

Parameters:

mapping - Mapping

list - List

Returns:

Permuted view of list

permute

public static <T> List<T> permute(List<T> list,
                  Mappings.TargetMapping mapping)

Creates a view of a list, permuting according to a target mapping.

Type Parameters:

T - Element type

Parameters:

mapping - Mapping

list - List

Returns:

Permuted view of list

asList

public static List<Integer> asList(Mappings.TargetMapping mapping)

Returns a mapping as a list such that list.get(source) is mapping.getTarget(source) and list.size() is mapping.getSourceCount().

Converse of target(List, int)

target

public static Mappings.TargetMapping target(Map<Integer,Integer> map,
                            int sourceCount,
                            int targetCount)

Converts a Map of integers to a Mappings.TargetMapping.

target

public static Mappings.TargetMapping target(com.google.common.base.Function<Integer,Integer> function,
                            int sourceCount,
                            int targetCount)

target

public static Mapping target(Iterable<IntPair> pairs,
             int sourceCount,
             int targetCount)

source

public static Mapping source(List<Integer> targets,
             int targetCount)

target

public static Mapping target(List<Integer> sources,
             int sourceCount)

bijection

public static Mapping bijection(List<Integer> targets)

Creates a bijection.

Throws if sources and targets are not one to one.

isIdentity

public static boolean isIdentity(Mappings.TargetMapping mapping)

Returns whether a mapping is the identity.

createShiftMapping

public static Mappings.TargetMapping createShiftMapping(int sourceCount,
                                        int... ints)

Creates a mapping that consists of a set of contiguous ranges.

For example,

createShiftMapping(60,
     100, 0, 3,
     200, 50, 5);
 

creates

Example mapping

Source	Target
0	100
1	101
2	102
3	-1
...	-1
50	200
51	201
52	202
53	203
54	204
55	-1
...	-1
59	-1

Parameters:

sourceCount - Maximum value of source

ints - Collection of ranges, each (target, source, count)

Returns:

Mapping that maps from source ranges to target ranges

append

public static Mappings.TargetMapping append(Mappings.TargetMapping mapping0,
                            Mappings.TargetMapping mapping1)

Creates a mapping by appending two mappings.

Sources and targets of the second mapping are shifted to the right.

For example,

append({0:0, 1:1}, {0:0, 1:1, 2:2})

yields

{0:0, 1:1, 2:2, 3:3, 4:4}

.

See Also:

merge(org.apache.calcite.util.mapping.Mappings.TargetMapping, org.apache.calcite.util.mapping.Mappings.TargetMapping)

merge

public static Mappings.TargetMapping merge(Mappings.TargetMapping mapping0,
                           Mappings.TargetMapping mapping1)

Creates a mapping by merging two mappings. There must be no clashes.

Unlike append(org.apache.calcite.util.mapping.Mappings.TargetMapping, org.apache.calcite.util.mapping.Mappings.TargetMapping), sources and targets are not shifted.

For example, merge({0:0, 1:1}, {2:2, 3:3, 4:4}) yields {0:0, 1:1, 2:2, 3:3, 4:4}. merge({0:0, 1:1}, {1:2, 2:3}) throws, because there are two entries with source=1.

offsetSource

public static Mappings.TargetMapping offsetSource(Mappings.TargetMapping mapping,
                                  int offset)

Returns a mapping that shifts a given mapping's source by a given offset, incrementing the number of sources by the minimum possible.

Parameters:

mapping - Input mapping

offset - Offset to be applied to each source

Returns:

Shifted mapping

offsetSource

public static Mappings.TargetMapping offsetSource(Mappings.TargetMapping mapping,
                                  int offset,
                                  int sourceCount)

Returns a mapping that shifts a given mapping's source by a given offset.

For example, given mapping with sourceCount=2, targetCount=8, and (source, target) entries {[0: 5], [1: 7]}, offsetSource(mapping, 3) returns a mapping with sourceCount=5, targetCount=8, and (source, target) entries {[3: 5], [4: 7]}.

Parameters:

mapping - Input mapping

offset - Offset to be applied to each source

sourceCount - New source count; must be at least mapping's source count plus offset

Returns:

Shifted mapping

offsetTarget

public static Mappings.TargetMapping offsetTarget(Mappings.TargetMapping mapping,
                                  int offset)

Returns a mapping that shifts a given mapping's target by a given offset, incrementing the number of targets by the minimum possible.

Parameters:

mapping - Input mapping

offset - Offset to be applied to each target

Returns:

Shifted mapping

offsetTarget

public static Mappings.TargetMapping offsetTarget(Mappings.TargetMapping mapping,
                                  int offset,
                                  int targetCount)

Returns a mapping that shifts a given mapping's target by a given offset.

For example, given mapping with sourceCount=2, targetCount=8, and (source, target) entries {[0: 5], [1: 7]}, offsetTarget(mapping, 3) returns a mapping with sourceCount=2, targetCount=11, and (source, target) entries {[0: 8], [1: 10]}.

Parameters:

mapping - Input mapping

offset - Offset to be applied to each target

targetCount - New target count; must be at least mapping's target count plus offset

Returns:

Shifted mapping

offset

public static Mappings.TargetMapping offset(Mappings.TargetMapping mapping,
                            int offset,
                            int sourceCount)

Returns a mapping that shifts a given mapping's source and target by a given offset.

For example, given mapping with sourceCount=2, targetCount=8, and (source, target) entries {[0: 5], [1: 7]}, offsetSource(mapping, 3) returns a mapping with sourceCount=5, targetCount=8, and (source, target) entries {[3: 8], [4: 10]}.

Parameters:

mapping - Input mapping

offset - Offset to be applied to each source

sourceCount - New source count; must be at least mapping's source count plus offset

Returns:

Shifted mapping

isIdentity

public static boolean isIdentity(List<Integer> list,
                 int count)

Returns whether a list of integers is the identity mapping [0, ..., n - 1].

invert

public static Iterable<IntPair> invert(Iterable<IntPair> pairs)

Inverts an Iterable over IntPairs.

invert

public static Iterator<IntPair> invert(Iterator<IntPair> pairs)

Inverts an Iterator over IntPairs.