com.tangosol.util.Extractors Maven / Gradle / Ivy
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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util;
import com.tangosol.io.pof.reflect.PofNavigator;
import com.tangosol.io.pof.reflect.SimplePofPath;
import com.tangosol.util.extractor.ChainedExtractor;
import com.tangosol.util.extractor.IdentityExtractor;
import com.tangosol.util.extractor.MultiExtractor;
import com.tangosol.util.extractor.PofExtractor;
import com.tangosol.util.extractor.ScriptValueExtractor;
import com.tangosol.util.extractor.UniversalExtractor;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
/**
* Simple Extractor DSL.
*
* The methods in this class are for the most part simple factory methods for
* various {@link ValueExtractor} classes, but in some cases provide additional type
* safety. They also tend to make the code more readable, especially if imported
* statically, so their use is strongly encouraged in lieu of direct construction
* of {@code Extractor} classes.
*
* @author lh, hr, as, mf 2018.06.14
*/
public class Extractors
{
/**
* Returns an extractor that always returns its input argument.
*
* @param the type of the input and output objects to the function
*
* @return an extractor that always returns its input argument
*/
public static ValueExtractor identity()
{
return IdentityExtractor.INSTANCE();
}
/**
* Returns an extractor that extracts the value of the specified field.
*
* @param from the name of the field or method to extract the value from
*
* @param the type of the object to extract from
* @param the type of the extracted value
*
* @return an extractor that extracts the value of the specified field
*
* @see UniversalExtractor
*/
public static ValueExtractor extract(String from)
{
return new UniversalExtractor<>(from);
}
/**
* Returns an extractor that extracts the value of the specified field.
*
* @param from the name of the method to extract the value from (which must be
* the full method name)
* @param aoParam the parameters to pass to the method
*
* @param the type of the object to extract from
* @param the type of the extracted value
*
* @return an extractor that extracts the value of the specified field
*
* @see UniversalExtractor
*/
public static ValueExtractor extract(String from, Object... aoParam)
{
if (!from.endsWith("()"))
{
from = from + "()";
}
return new UniversalExtractor<>(from, aoParam);
}
/**
* Returns an extractor that extracts the specified fields
* and returns the extracted values in a {@link List}.
*
* @param fields the field names to extract
*
* @param the type of the object to extract from
*
* @return an extractor that extracts the value(s) of the specified field(s)
*
* @throws IllegalArgumentException if the fields parameter is null or an
* empty array
*
* @see UniversalExtractor
*/
@SuppressWarnings("unchecked")
public static ValueExtractor> multi(String... fields)
{
if (fields == null || fields.length == 0)
{
throw new IllegalArgumentException("The fields parameter cannot be null or empty");
}
ValueExtractor[] aExtractor = Arrays.stream(fields)
.filter(Objects::nonNull)
.map(Extractors::chained)
.toArray(ValueExtractor[]::new);
if (aExtractor.length == 0)
{
throw new IllegalArgumentException("The fields parameter must contain at least one non-null element");
}
return multi(aExtractor);
}
/**
* Returns an extractor that extracts values using the specified
* {@link ValueExtractor}s and returns the extracted values in a {@link List}.
*
* @param extractors the {@link ValueExtractor}s to use to extract the list of values
*
* @param the type of the object to extract from
*
* @return an extractor that extracts the value(s) of the specified field(s)
*
* @throws IllegalArgumentException if the fields parameter is null or an
* empty array
*
* @see UniversalExtractor
*/
@SuppressWarnings("unchecked")
public static ValueExtractor> multi(ValueExtractor... extractors)
{
return new MultiExtractor(extractors);
}
/**
* Returns an extractor that extracts the specified fields
* where extraction occurs in a chain where the result of each
* field extraction is the input to the next extractor. The result
* returned is the result of the final extractor in the chain.
*
* @param fields the field names to extract (if any field name contains a dot '.'
* that field name is split into multiple field names delimiting on
* the dots.
*
* @param the type of the object to extract from
*
* @return an extractor that extracts the value(s) of the specified field(s)
*
* @throws IllegalArgumentException if the fields parameter is null or an
* empty array
*
* @see UniversalExtractor
*/
@SuppressWarnings("unchecked")
public static ValueExtractor chained(String... fields)
{
if (fields == null || fields.length == 0)
{
throw new IllegalArgumentException("The fields parameter cannot be null or empty");
}
ValueExtractor[] aExtractor = Arrays.stream(fields)
.filter(Objects::nonNull)
.map(s -> s.split("\\."))
.flatMap(Arrays::stream)
.map(Extractors::extract)
.toArray(ValueExtractor[]::new);
if (aExtractor.length == 0)
{
throw new IllegalArgumentException("The fields parameter must contain at least one non-null element");
}
if (aExtractor.length == 1)
{
return aExtractor[0];
}
return chained(aExtractor);
}
/**
* Returns an extractor that extracts the specified fields
* where extraction occurs in a chain where the result of each
* field extraction is the input to the next extractor. The result
* returned is the result of the final extractor in the chain.
*
* @param extractors the {@link ValueExtractor}s to use to extract the list of values
*
* @param the type of the object to extract from
*
* @return an extractor that extracts the value(s) of the specified field(s)
*
* @throws IllegalArgumentException if the extractors parameter is null or an
* empty array
*
* @see UniversalExtractor
*/
@SuppressWarnings("unchecked")
public static ValueExtractor chained(ValueExtractor... extractors)
{
if (extractors == null || extractors.length == 0)
{
throw new IllegalArgumentException("The extractors parameter cannot be null or empty");
}
if (extractors.length == 1)
{
return (ValueExtractor) extractors[0];
}
return new ChainedExtractor<>(extractors);
}
/**
* Returns an extractor that casts its input argument.
*
* @param the type of the input objects to the function
* @param the type of the output objects to the function
*
* @return an extractor that always returns its input argument
*/
@SuppressWarnings("unchecked")
public static ValueExtractor identityCast()
{
return IdentityExtractor.INSTANCE;
}
/**
* Returns an extractor that extracts the value of the specified index(es)
* from a POF encoded binary value.
*
* @param indexes the POF index(es) to extract
*
* @param the type of the object to extract from
*
* @return an extractor that extracts the value of the specified field
*/
public static ValueExtractor fromPof(int... indexes)
{
return fromPof(null, indexes);
}
/**
* Returns an extractor that extracts the value of the specified index(es)
* from a POF encoded binary value.
*
* @param indexes the POF index(es) to extract
*
* @param the type of the POF serialized object to extract from
* @param the type of the extracted value
*
* @return an extractor that extracts the value of the specified field
*
* @throws NullPointerException if the indexes parameter is null
*/
public static ValueExtractor fromPof(Class cls, int... indexes)
{
return fromPof(cls, new SimplePofPath(Objects.requireNonNull(indexes)));
}
/**
* Returns an extractor that extracts the value of the specified index(es)
* from a POF encoded binary value.
*
* @param navigator the {@link PofNavigator} to use to determine the POF path to extract
*
* @param the type of the POF serialized object to extract from
* @param the type of the extracted value
*
* @return an extractor that extracts the value of the specified field
*
* @throws NullPointerException if the indexes parameter is null
*/
public static ValueExtractor fromPof(Class cls, PofNavigator navigator)
{
return new PofExtractor<>(cls, navigator);
}
/**
* Instantiate a {@code ValueExtractor} that is implemented using the specified
* language.
*
* @param sLanguage the string specifying one of the supported languages
* @param sScriptPath the path where the script reside, relative to root
* @param aoArgs the arguments to be passed to the script
* @param the type of object to extract from
* @param the type of the extracted value
*
* @return An instance of {@link ValueExtractor}
*
* @throws ScriptException if the {@code script} cannot be loaded or
* any errors occur during its execution
* @throws IllegalArgumentException if the specified language is not supported
*
* @since 14.1.1.0
*/
public static ValueExtractor script(String sLanguage, String sScriptPath, Object... aoArgs)
{
return new ScriptValueExtractor<>(sLanguage, sScriptPath, aoArgs);
}
}