com.pervasive.datarush.util

Class ColumnSelector

java.lang.Object

com.pervasive.datarush.util.ColumnSelector

public final class ColumnSelector
extends Object

Utility class to select a number of column fields based on field name and type criteria.

Constructor Summary

Constructors

Constructor and Description
ColumnSelector() Create a column selector.

Method Summary

Modifier and Type	Method and Description
ColumnSelector	addExcludes(Collection<String> excludes) Adds columns to exclude.
ColumnSelector	addExcludes(String... excludes) Adds columns to exclude.
ColumnSelector	addIncludes(Collection<String> includes) Adds columns to include.
ColumnSelector	addIncludes(String... includes) Adds columns to include.
RecordTokenType	filter(RecordTokenType type) Returns a type consisting of a subset of the given type that matches this column selector's criteria.
String[]	filterNames(RecordTokenType type) Returns the names of the fields of given type that match this column selector's criteria.
ColumnSelector	setMaxDistinctValues(int value) Sets the maximum number of distinct values to allow.
ColumnSelector	setType(ScalarTokenType type) Sets the type of columns to include.

Methods inherited from class java.lang.Object

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

Constructor Detail

ColumnSelector

public ColumnSelector()

Create a column selector. By default we select all columns

Method Detail

addIncludes

public ColumnSelector addIncludes(String... includes)

Adds columns to include. If set, we will only return columns in this list

Parameters:

includes - the set of columns to include

Returns:

a "this" reference to allow method chaining

addIncludes

public ColumnSelector addIncludes(Collection<String> includes)

Adds columns to include. If set, we will only return columns in this list

Parameters:

includes - the set of columns to include

Returns:

a "this" reference to allow method chaining

addExcludes

public ColumnSelector addExcludes(String... excludes)

Adds columns to exclude. If set, we will exclude those columns specified

Parameters:

excludes - the set of columns to exclude

Returns:

a "this" reference to allow method chaining

addExcludes

public ColumnSelector addExcludes(Collection<String> excludes)

Adds columns to exclude. If set, we will exclude those columns specified

Parameters:

excludes - the set of columns to exclude

Returns:

a "this" reference to allow method chaining

setType

public ColumnSelector setType(ScalarTokenType type)

Sets the type of columns to include. If set, will only return those columns that are assignable to the given type.

Parameters:

type - the type of columns to include

Returns:

a "this" reference to allow method chaining

setMaxDistinctValues

public ColumnSelector setMaxDistinctValues(int value)

Sets the maximum number of distinct values to allow. Columns having more distinct values than that specified or that have an unspecified domain will be filtered. Note that this should only be used by operators that have already discovered domain information since, in general, domain information will not be available.

Parameters:

value - the max distinct values

filter

public RecordTokenType filter(RecordTokenType type)

Returns a type consisting of a subset of the given type that matches this column selector's criteria. The set of fields returned is as follows

1. If includes are specified, include only those specified
2. If excludes are specified, exclude those specified
3. If type is specified, include only those columns matching the given type

Parameters:

type - the input type

Returns:

a subset of the input type that matches this column selector's criteria

filterNames

public String[] filterNames(RecordTokenType type)

Returns the names of the fields of given type that match this column selector's criteria. The set of fields returned is as follows

1. If includes are specified, include only those specified
2. If excludes are specified, exclude those specified
3. If type is specified, include only those columns matching the given type

Parameters:

type - the input type

Returns:

a subset of the names of the fields of given type type that match this column selector's criteria