Package org.apache.calcite.adapter.enumerable

Class EnumUtils

java.lang.Object

org.apache.calcite.adapter.enumerable.EnumUtils

public class EnumUtils
extends Object

Utilities for generating programs in the Enumerable (functional) style.

Field Summary

Fields

Modifier and Type	Field	Description
static final List<String>	LEFT_RIGHT

Method Summary

Modifier and Type	Method	Description
static MethodCallExpression	call(@Nullable Expression targetExpression, Class clazz, String methodName, List<? extends Expression> arguments)	A more powerful version of Expressions.call(Type, String, Iterable).
static Expression	convert(Expression operand, Type toType)	Convert operand to target type toType.
static Expression	convert(Expression operand, Type fromType, Type toType)	Convert operand to target type toType.
static <T> @Nullable T	evaluate(Object o, Class<T> clazz)	Converts a value to a given class.
static @Nullable Expression	generateCollatorExpression(@Nullable SqlCollation collation)
static Enumerable<@Nullable Object[]>	hopping(Enumerator<@Nullable Object[]> inputEnumerator, int indexOfWatermarkedColumn, long emitFrequency, long windowSize, long offset)	Create enumerable implementation that applies hopping on each element from the input enumerator and produces at least one element for each input element.
static MethodDeclaration	overridingMethodDecl(Method method, Iterable<ParameterExpression> parameters, BlockStatement body)	Declares a method that overrides another method.
static Enumerable<@Nullable Object[]>	sessionize(Enumerator<@Nullable Object[]> inputEnumerator, int indexOfWatermarkedColumn, int indexOfKeyColumn, long gap)	Creates enumerable implementation that applies sessionization to elements from the input enumerator based on a specified key.
static Function<@Nullable Object[],List<@Nullable Object>>	toExternal(List<RelDataType> types, TimeZone timeZone)	Returns a function that converts an array of internal values to a list of external values.
static Function<Object,Object>	toExternal(RelDataType type, TimeZone timeZone)	Returns a function that converts an internal value to an external value.
static <TSource, TResult> Enumerable<TResult>	tumbling(Enumerable<TSource> inputEnumerable, Function1<TSource,TResult> outSelector)	Apply tumbling per row from the enumerable input.

Methods inherited from class java.lang.Object

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

Field Details

LEFT_RIGHT

public static final List<String> LEFT_RIGHT

Method Details

overridingMethodDecl

public static MethodDeclaration overridingMethodDecl(Method method,
 Iterable<ParameterExpression> parameters,
 BlockStatement body)

Declares a method that overrides another method.

convert

public static Expression convert(Expression operand,
 Type toType)

Convert operand to target type toType.

Parameters:

operand - The expression to convert

toType - Target type

Returns:

A new expression with type toType or original if there is no need to convert

convert

public static Expression convert(Expression operand,
 Type fromType,
 Type toType)

Convert operand to target type toType.

Parameters:

operand - The expression to convert

fromType - Field type

toType - Target type

Returns:

A new expression with type toType or original if there is no need to convert

evaluate

public static <T> @Nullable T evaluate(Object o,
 Class<T> clazz)

Converts a value to a given class.

call

public static MethodCallExpression call(@Nullable Expression targetExpression,
 Class clazz,
 String methodName,
 List<? extends Expression> arguments)

A more powerful version of Expressions.call(Type, String, Iterable). Tries best effort to convert the accepted arguments to match parameter type.

Parameters:

targetExpression - Target expression, or null if method is static

clazz - Class against which method is invoked

methodName - Name of method

arguments - Argument expressions

Returns:

MethodCallExpression that call the given name method

Throws:

RuntimeException - if no suitable method found

sessionize

public static Enumerable<@Nullable Object[]> sessionize(Enumerator<@Nullable Object[]> inputEnumerator,
 int indexOfWatermarkedColumn,
 int indexOfKeyColumn,
 long gap)

Creates enumerable implementation that applies sessionization to elements from the input enumerator based on a specified key. Elements are windowed into sessions separated by periods with no input for at least the duration specified by gap parameter.

hopping

public static Enumerable<@Nullable Object[]> hopping(Enumerator<@Nullable Object[]> inputEnumerator,
 int indexOfWatermarkedColumn,
 long emitFrequency,
 long windowSize,
 long offset)

Create enumerable implementation that applies hopping on each element from the input enumerator and produces at least one element for each input element.

tumbling

public static <TSource,
TResult> Enumerable<TResult> tumbling(Enumerable<TSource> inputEnumerable,
 Function1<TSource,TResult> outSelector)

Apply tumbling per row from the enumerable input.

generateCollatorExpression

public static @Nullable Expression generateCollatorExpression(@Nullable SqlCollation collation)

toExternal

public static Function<Object,Object> toExternal(RelDataType type,
 TimeZone timeZone)

Returns a function that converts an internal value to an external value.

Datetime values' internal representations have no time zone, and their external values are moments (relative to UTC epoch), so the timeZone parameter supplies the implicit time zone of the internal representation. If you specify the local time zone of the JVM, then Timestamp.toString(), Date.toString(), and Time.toString() on the external values will give a value consistent with the internal values.

toExternal

public static Function<@Nullable Object[],List<@Nullable Object>> toExternal(List<RelDataType> types,
 TimeZone timeZone)

Returns a function that converts an array of internal values to a list of external values.