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From fhueske <...@git.apache.org>
Subject [GitHub] flink pull request #4612: [FLINK-7452] [types] Add helper methods for all bu...
Date Fri, 15 Sep 2017 13:38:53 GMT
Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4612#discussion_r139113352
  
    --- Diff: flink-core/src/main/java/org/apache/flink/api/common/typeinfo/Types.java ---
    @@ -19,56 +19,408 @@
     package org.apache.flink.api.common.typeinfo;
     
     import org.apache.flink.annotation.PublicEvolving;
    +import org.apache.flink.api.common.functions.InvalidTypesException;
    +import org.apache.flink.api.java.typeutils.EitherTypeInfo;
    +import org.apache.flink.api.java.typeutils.EnumTypeInfo;
    +import org.apache.flink.api.java.typeutils.GenericTypeInfo;
    +import org.apache.flink.api.java.typeutils.ListTypeInfo;
    +import org.apache.flink.api.java.typeutils.MapTypeInfo;
    +import org.apache.flink.api.java.typeutils.ObjectArrayTypeInfo;
    +import org.apache.flink.api.java.typeutils.PojoField;
    +import org.apache.flink.api.java.typeutils.PojoTypeInfo;
     import org.apache.flink.api.java.typeutils.RowTypeInfo;
    +import org.apache.flink.api.java.typeutils.TupleTypeInfo;
    +import org.apache.flink.api.java.typeutils.TypeExtractor;
    +import org.apache.flink.api.java.typeutils.ValueTypeInfo;
     
    -import java.math.BigDecimal;
    -import java.sql.Date;
    -import java.sql.Time;
    -import java.sql.Timestamp;
    +import java.lang.reflect.Field;
    +import java.util.ArrayList;
    +import java.util.List;
    +import java.util.Map;
     
     /**
    - * This class gives access to the type information of the most most common types.
    + * This class gives access to the type information of the most common types for which
Flink
    + * has built-in serializers and comparators.
    + *
    + * <p>In many cases, Flink tries to analyze generic signatures of functions to
determine return
    + * types automatically. This class is intended for cases where the extraction is not
possible
    + * (or inefficient) as well as cases where type information has to be supplied manually.
    + *
    + * <p>Depending on the API you are using (e.g. Scala API or Table API), there might
be a more
    + * specialized <code>Types</code> class.
    + *
    + * <p>A more convenient alternative might be a {@link TypeHint}.
    + *
    + * @see TypeInformation#of(Class) specify type information based on a class that will
be analyzed
    + * @see TypeInformation#of(TypeHint) specify type information based on a {@link TypeHint}
      */
     @PublicEvolving
     public class Types {
     
    -	public static final BasicTypeInfo<String> STRING = BasicTypeInfo.STRING_TYPE_INFO;
    -	public static final BasicTypeInfo<Boolean> BOOLEAN = BasicTypeInfo.BOOLEAN_TYPE_INFO;
    -	public static final BasicTypeInfo<Byte> BYTE = BasicTypeInfo.BYTE_TYPE_INFO;
    -	public static final BasicTypeInfo<Short> SHORT = BasicTypeInfo.SHORT_TYPE_INFO;
    -	public static final BasicTypeInfo<Integer> INT = BasicTypeInfo.INT_TYPE_INFO;
    -	public static final BasicTypeInfo<Long> LONG = BasicTypeInfo.LONG_TYPE_INFO;
    -	public static final BasicTypeInfo<Float> FLOAT = BasicTypeInfo.FLOAT_TYPE_INFO;
    -	public static final BasicTypeInfo<Double> DOUBLE = BasicTypeInfo.DOUBLE_TYPE_INFO;
    -	public static final BasicTypeInfo<BigDecimal> DECIMAL = BasicTypeInfo.BIG_DEC_TYPE_INFO;
    +	/**
    +	 * Returns type information for {@link java.lang.Void}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> VOID = BasicTypeInfo.VOID_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for {@link java.lang.String}. Supports a null value.
    +	 */
    +	public static final TypeInformation<?> STRING = BasicTypeInfo.STRING_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>byte</code> and a
    +	 * wrapped {@link java.lang.Byte}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> BYTE = BasicTypeInfo.BYTE_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>boolean</code> and
a
    +	 * wrapped {@link java.lang.Boolean}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> BOOLEAN = BasicTypeInfo.BOOLEAN_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>short</code> and
a
    +	 * wrapped {@link java.lang.Short}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> SHORT = BasicTypeInfo.SHORT_TYPE_INFO;
     
    -	public static final SqlTimeTypeInfo<Date> SQL_DATE = SqlTimeTypeInfo.DATE;
    -	public static final SqlTimeTypeInfo<Time> SQL_TIME = SqlTimeTypeInfo.TIME;
    -	public static final SqlTimeTypeInfo<Timestamp> SQL_TIMESTAMP = SqlTimeTypeInfo.TIMESTAMP;
    +	/**
    +	 * Returns type information for both a primitive <code>int</code> and a
    +	 * wrapped {@link java.lang.Integer}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> INT = BasicTypeInfo.INT_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>long</code> and a
    +	 * wrapped {@link java.lang.Long}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> LONG = BasicTypeInfo.LONG_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>float</code> and
a
    +	 * wrapped {@link java.lang.Float}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> FLOAT = BasicTypeInfo.FLOAT_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>double</code> and
a
    +	 * wrapped {@link java.lang.Double}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> DOUBLE = BasicTypeInfo.DOUBLE_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for both a primitive <code>char</code> and a
    +	 * wrapped {@link java.lang.Character}. Does not support a null value.
    +	 */
    +	public static final TypeInformation<?> CHAR = BasicTypeInfo.CHAR_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for {@link java.math.BigDecimal}. Supports a null value.
    +	 */
    +	public static final TypeInformation<?> BIG_DEC = BasicTypeInfo.BIG_DEC_TYPE_INFO;
     
     	/**
    -	 * Generates a RowTypeInfo with fields of the given types.
    -	 * The fields have the default names (f0, f1, f2 ..).
    +	 * Returns type information for {@link java.math.BigInteger}. Supports a null value.
    +	 */
    +	public static final TypeInformation<?> BIG_INT = BasicTypeInfo.BIG_INT_TYPE_INFO;
    +
    +	/**
    +	 * Returns type information for {@link java.sql.Date}. Supports a null value.
    +	 */
    +	public static final TypeInformation<?> SQL_DATE = SqlTimeTypeInfo.DATE;
    +
    +	/**
    +	 * Returns type information for {@link java.sql.Time}. Supports a null value.
    +	 */
    +	public static final TypeInformation<?> SQL_TIME = SqlTimeTypeInfo.TIME;
    +
    +	/**
    +	 * Returns type information for {@link java.sql.Timestamp}. Supports a null value.
    +	 */
    +	public static final TypeInformation<?> SQL_TIMESTAMP = SqlTimeTypeInfo.TIMESTAMP;
    +
    +	/**
    +	 * Returns type information for {@link org.apache.flink.types.Row} with fields of the
given types.
    +	 * A row itself must not be null.
    +	 *
    +	 * <p>A row is a variable-length, null-aware composite type for storing multiple
values in a
    +	 * deterministic field order. Every field can be null independent of the field's type.
    +	 * Fields of a row are untyped; therefore, it is required to pass type information whenever
a row is used.
     	 * 
    -	 * <p>This method is a shortcut to {@code new RowTypeInfo(types)}.
    +	 * <p>This method generates type information with fields of the given types; the
fields have
    +	 * the default names (f0, f1, f2 ..).
     	 *
     	 * @param types The types of the row fields, e.g., Types.STRING, Types.INT
     	 */
    -	public static RowTypeInfo ROW(TypeInformation<?>... types) {
    +	public static TypeInformation<?> ROW(TypeInformation<?>... types) {
     		return new RowTypeInfo(types);
     	}
     
     	/**
    -	 * Generates a RowTypeInfo with fields of the given types and with given names.
    -	 * 
    +	 * Returns type information for {@link org.apache.flink.types.Row} with fields of the
given types and
    +	 * with given names. A row must not be null.
    +	 *
    +	 * <p>A row is a variable-length, null-aware composite type for storing multiple
values in a
    +	 * deterministic field order. Every field can be null independent of the field's type.
    +	 * Fields of a row are untyped; therefore, it is required to pass type information whenever
a row is used.
    +	 *
     	 * <p>Example use: {@code ROW_NAMED(new String[]{"name", "number"}, Types.STRING,
Types.INT)}.
    -	 * 
    -	 * <p>This method is identical to {@code new RowTypeInfo(types, names)}.
     	 *
     	 * @param fieldNames array of field names
     	 * @param types array of field types
     	 */
    -	public static RowTypeInfo ROW_NAMED(String[] fieldNames, TypeInformation<?>...
types) {
    +	public static TypeInformation<?> ROW_NAMED(String[] fieldNames, TypeInformation<?>...
types) {
     		return new RowTypeInfo(types, fieldNames);
     	}
    +
    +	/**
    +	 * Returns type information for subclasses of Flink's {@link org.apache.flink.api.java.tuple.Tuple}
    +	 * (namely {@link org.apache.flink.api.java.tuple.Tuple0} till {@link org.apache.flink.api.java.tuple.Tuple25})
    +	 * with fields of the given types. A tuple must not be null.
    +	 *
    +	 * <p>A tuple is a fixed-length composite type for storing multiple values in
a
    +	 * deterministic field order. Fields of a tuple are typed. Tuples are the most efficient
composite
    +	 * type; therefore, a tuple does not support null values unless its field type supports
nullability.
    +	 *
    +	 * @param types The types of the tuple fields, e.g., Types.STRING, Types.INT
    +	 */
    +	public static TypeInformation<?> TUPLE(TypeInformation<?>... types) {
    +		return new TupleTypeInfo<>(types);
    +	}
    +
    +	/**
    +	 * Returns type information for typed subclasses of Flink's {@link org.apache.flink.api.java.tuple.Tuple}.
    +	 * Typed subclassed are classes that extend {@link org.apache.flink.api.java.tuple.Tuple0}
till
    +	 * {@link org.apache.flink.api.java.tuple.Tuple25} to provide types for all fields and
might add
    +	 * additional getters and setters for better readability. A tuple must not be null.
    +	 *
    +	 * <p>A tuple is a fixed-length composite type for storing multiple values in
a
    +	 * deterministic field order. Fields of a tuple are typed. Tuples are the most efficient
composite
    +	 * type; therefore, a tuple does not support null values unless a field type supports
nullability.
    +	 *
    +	 * <p>Types for all fields of the tuple can be defined in a hierarchy of subclasses.
    +	 *
    +	 * <p>If Flink's type analyzer is unable to extract a tuple type information with
    +	 * type information for all fields, an {@link org.apache.flink.api.common.functions.InvalidTypesException}
    +	 * is thrown.
    +	 *
    +	 * <p>Example use:
    +	 * <pre>
    +	 * {@code
    +	 *   class MyTuple extends Tuple2<Integer, String> {
    +	 *
    +	 *     public int getId() { return f0; }
    +	 *
    +	 *     public String getName() { return f1; }
    +	 *   }
    +	 * }
    +	 *
    +	 * Types.TUPLE(MyTuple.class)
    +	 * </pre>
    +	 *
    +	 * @param tupleSubclass A subclass of {@link org.apache.flink.api.java.tuple.Tuple0}
till
    +	 *                      {@link org.apache.flink.api.java.tuple.Tuple25} that defines
all field types and
    +	 *                      does not add any additional fields
    +	 */
    +	public static TypeInformation<?> TUPLE(Class<?> tupleSubclass) {
    +		final TypeInformation<?> ti = TypeExtractor.createTypeInfo(tupleSubclass);
    +		if (ti instanceof TupleTypeInfo) {
    +			return ti;
    +		}
    +		throw new InvalidTypesException("Tuple type expected but was: " + ti);
    +	}
    +
    +	/**
    +	 * Returns type information for a POJO (Plain Old Java Object).
    +	 *
    +	 * <p>A POJO class is public and standalone (no non-static inner class). It has
a public no-argument
    +	 * constructor. All non-static, non-transient fields in the class (and all superclasses)
are either public
    +	 * (and non-final) or have a public getter and a setter method that follows the Java
beans naming
    +	 * conventions for getters and setters.
    +	 *
    +	 * <p>A POJO is a fixed-length, null-aware composite type with non-deterministic
field order. Every field
    --- End diff --
    
    At which point is the field order important for users? Isn't it only relevant if you are
dealing with the serialization format or when you want to map fields to a different type (as
we do in the Table API)?


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