org.apache.drill.exec.store.easy.text.compliant

Class HeaderBuilder

java.lang.Object

org.apache.drill.exec.store.easy.text.compliant.HeaderBuilder

public class HeaderBuilder
extends Object

Text output that implements a header reader/parser. The caller parses out the characters of each header; this class assembles UTF-8 bytes into Unicode characters, fixes invalid characters (those not legal for SQL symbols), and maps duplicate names to unique names.

That is, this class is as permissive as possible with file headers to avoid spurious query failures for trivial reasons.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	HeaderBuilder.HeaderError Exception that reports header errors.

Field Summary

Fields

Modifier and Type	Field and Description
static String	ANONYMOUS_COLUMN_PREFIX Prefix used to create numbered columns for missing headers.
static String	COLUMN_PREFIX Prefix used to replace non-alphabetic characters at the start of a column name.
ByteBuffer	currentField
List<String>	headers
static int	MAX_HEADER_LEN Maximum Drill symbol length, as enforced for headers.

Constructor Summary

Constructors

Constructor and Description
HeaderBuilder()

Method Summary

Methods

Modifier and Type	Method and Description
void	append(byte data) This function appends the byte to the output character data buffer
void	appendIgnoringWhitespace(byte data) Add the provided data but drop any whitespace.
boolean	endEmptyField() Shortcut that lets the output know that we are closing ending a field with no data.
boolean	endField() End processing a field within a record.
void	finishBatch() Does any final cleanup that is required for closing a batch.
void	finishRecord() Completes the processing of a given record.
String[]	getHeaders()
long	getRecordCount() Return the total number of records (across batches) processed
boolean	rowHasData() Helper method to check if the current record has any non-empty fields
void	startBatch() Informs output to setup for new record batch.
void	startField(int index) Start processing a new field within a record.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_HEADER_LEN

public static final int MAX_HEADER_LEN

Maximum Drill symbol length, as enforced for headers.

See Also:

identifier documentation, Constant Field Values

COLUMN_PREFIX

public static final String COLUMN_PREFIX

Prefix used to replace non-alphabetic characters at the start of a column name. For example, $foo becomes col_foo. Used because SQL does not allow _foo.

See Also:

Constant Field Values

ANONYMOUS_COLUMN_PREFIX

public static final String ANONYMOUS_COLUMN_PREFIX

Prefix used to create numbered columns for missing headers. Typical names: column_1, column_2, ...

See Also:

Constant Field Values

headers

public final List<String> headers

currentField

public final ByteBuffer currentField

Constructor Detail

HeaderBuilder

public HeaderBuilder()

Method Detail

startField

public void startField(int index)

Start processing a new field within a record.

Parameters:

index - index within the record

endField

public boolean endField()

End processing a field within a record.

Returns:

true if engine should continue processing record. false if rest of record can be skipped.

endEmptyField

public boolean endEmptyField()

Shortcut that lets the output know that we are closing ending a field with no data.

Returns:

true if engine should continue processing record. false if rest of record can be skipped.

append

public void append(byte data)

This function appends the byte to the output character data buffer

Parameters:

data - current byte read

finishRecord

public void finishRecord()

Completes the processing of a given record. Also completes the processing of the last field being read.

getRecordCount

public long getRecordCount()

Return the total number of records (across batches) processed

startBatch

public void startBatch()

Informs output to setup for new record batch.

finishBatch

public void finishBatch()

Does any final cleanup that is required for closing a batch. Example might include closing the last field.

rowHasData

public boolean rowHasData()

Helper method to check if the current record has any non-empty fields

getHeaders

public String[] getHeaders()

appendIgnoringWhitespace

public void appendIgnoringWhitespace(byte data)

Add the provided data but drop any whitespace.

Parameters:

data -