org.bytedeco.arrow

Class FieldRef

java.lang.Object

org.bytedeco.javacpp.Pointer

org.bytedeco.arrow.FieldRef

All Implemented Interfaces:

AutoCloseable

@Namespace(value="arrow")
 @NoOffset
 @Properties(inherit=arrow.class)
public class FieldRef
extends Pointer

\class FieldRef \brief Descriptor of a (potentially nested) field within a schema. Unlike FieldPath (which exclusively uses indices of child fields), FieldRef may reference a field by name. It is intended to replace parameters like int field_index and const std::string& field_name; it can be implicitly constructed from either a field index or a name. Nested fields can be referenced as well. Given schema({field("a", struct_({field("n", null())})), field("b", int32())}) the following all indicate the nested field named "n": FieldRef ref1(0, 0); FieldRef ref2("a", 0); FieldRef ref3("a", "n"); FieldRef ref4(0, "n"); ARROW_ASSIGN_OR_RAISE(FieldRef ref5, FieldRef::FromDotPath(".a[0]")); FieldPaths matching a FieldRef are retrieved using the member function FindAll. Multiple matches are possible because field names may be duplicated within a schema. For example: Schema a_is_ambiguous({field("a", int32()), field("a", float32())}); auto matches = FieldRef("a").FindAll(a_is_ambiguous); assert(matches.size() == 2); assert(matches[0].Get(a_is_ambiguous)->Equals(a_is_ambiguous.field(0))); assert(matches[1].Get(a_is_ambiguous)->Equals(a_is_ambiguous.field(1))); Convenience accessors are available which raise a helpful error if the field is not found or ambiguous, and for immediately calling FieldPath::Get to retrieve any matching children: auto maybe_match = FieldRef("struct", "field_i32").FindOneOrNone(schema); auto maybe_column = FieldRef("struct", "field_i32").GetOne(some_table);

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FieldRef.Hash

Nested classes/interfaces inherited from class org.bytedeco.javacpp.Pointer

Pointer.CustomDeallocator, Pointer.Deallocator, Pointer.NativeDeallocator, Pointer.ReferenceCounter

Field Summary

Fields inherited from class org.bytedeco.javacpp.Pointer

address, capacity, limit, position

Constructor Summary

Constructors

Constructor and Description
FieldRef()
FieldRef(BytePointer name)
FieldRef(FieldPath indices) Construct a FieldRef using a string of indices.
FieldRef(int index) Equivalent to a single index string of indices.
FieldRef(Pointer p) Pointer cast constructor.
FieldRef(String name) Construct a by-name FieldRef.

Method Summary

Modifier and Type	Method and Description
boolean	asBoolean()
boolean	equals(FieldRef other)
boolean	Equals(FieldRef other)
FieldPath	field_path()
FieldPath	FindAll(Array array)
FieldPath	FindAll(ArrayData array) \brief Convenience function which applies FindAll to arg's type or schema.
FieldPath	FindAll(DataType type)
FieldPath	FindAll(Field field)
FieldPath	FindAll(FieldVector fields)
FieldPath	FindAll(RecordBatch batch)
FieldPath	FindAll(Schema schema) \brief Retrieve FieldPath of every child field which matches this FieldRef.
static FieldRefResult	FromDotPath(BytePointer dot_path)
static FieldRefResult	FromDotPath(String dot_path) Parse a dot path into a FieldRef.
long	hash()
boolean	IsFieldPath()
boolean	IsName()
boolean	IsNested()
BytePointer	name()
boolean	not()
String	ToString()

Methods inherited from class org.bytedeco.javacpp.Pointer

address, asBuffer, asByteBuffer, availablePhysicalBytes, calloc, capacity, capacity, close, deallocate, deallocate, deallocateReferences, deallocator, deallocator, equals, fill, formatBytes, free, getDirectBufferAddress, getPointer, getPointer, getPointer, getPointer, hashCode, interruptDeallocatorThread, isNull, isNull, limit, limit, malloc, maxBytes, maxPhysicalBytes, memchr, memcmp, memcpy, memmove, memset, offsetAddress, offsetof, offsetof, parseBytes, physicalBytes, physicalBytesInaccurate, position, position, put, realloc, referenceCount, releaseReference, retainReference, setNull, sizeof, sizeof, toString, totalBytes, totalCount, totalPhysicalBytes, withDeallocator, zero

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

FieldRef

public FieldRef(Pointer p)

Pointer cast constructor. Invokes Pointer(Pointer).

FieldRef

public FieldRef()

FieldRef

public FieldRef(@ByVal
                FieldPath indices)

Construct a FieldRef using a string of indices. The reference will be retrieved as: schema.fields[self.indices[0]].type.fields[self.indices[1]] ... Empty indices are not valid.

FieldRef

public FieldRef(@StdString
                String name)

Construct a by-name FieldRef. Multiple fields may match a by-name FieldRef: [f for f in schema.fields where f.name == self.name]

FieldRef

public FieldRef(@StdString
                BytePointer name)

FieldRef

public FieldRef(int index)

Equivalent to a single index string of indices.

Method Detail

FromDotPath

@ByVal
public static FieldRefResult FromDotPath(@StdString
                                                 String dot_path)

Parse a dot path into a FieldRef. dot_path = '.' name | '[' digit+ ']' | dot_path+ Examples: ".alpha" => FieldRef("alpha") "[2]" => FieldRef(2) ".beta[3]" => FieldRef("beta", 3) "[5].gamma.delta[7]" => FieldRef(5, "gamma", "delta", 7) ".hello world" => FieldRef("hello world") R"(.\[y\]\tho\.\)" => FieldRef(R"([y]\tho.\)") Note: When parsing a name, a '\' preceding any other character will be dropped from the resulting name. Therefore if a name must contain the characters '.', '\', or '[' those must be escaped with a preceding '\'.

FromDotPath

@ByVal
public static FieldRefResult FromDotPath(@StdString
                                                 BytePointer dot_path)

Equals

@Cast(value="bool")
public boolean Equals(@Const @ByRef
                                           FieldRef other)

equals

@Cast(value="bool")
 @Name(value="operator ==")
public boolean equals(@Const @ByRef
                                                                        FieldRef other)

ToString

@StdString
public String ToString()

hash

@Cast(value="size_t")
public long hash()

asBoolean

@Cast(value="bool")
 @Name(value="operator bool")
public boolean asBoolean()

not

@Cast(value="bool")
 @Name(value="operator !")
public boolean not()

IsFieldPath

@Cast(value="bool")
public boolean IsFieldPath()

IsName

@Cast(value="bool")
public boolean IsName()

IsNested

@Cast(value="bool")
public boolean IsNested()

field_path

@Const
public FieldPath field_path()

name

@StdString
 @Cast(value={"char*","std::string*"})
public BytePointer name()

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     Schema schema)

\brief Retrieve FieldPath of every child field which matches this FieldRef.

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     Field field)

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     DataType type)

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     FieldVector fields)

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     ArrayData array)

\brief Convenience function which applies FindAll to arg's type or schema.

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     Array array)

FindAll

@StdVector
public FieldPath FindAll(@Const @ByRef
                                     RecordBatch batch)