Class MrtTableBuilder
- java.lang.Object
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- uk.ac.starlink.table.formats.DocumentedTableBuilder
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- uk.ac.starlink.table.formats.MrtTableBuilder
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- All Implemented Interfaces:
Documented
,DocumentedIOHandler
,TableBuilder
public class MrtTableBuilder extends DocumentedTableBuilder
Input handler for the so-called "Machine-Readable Table" format used by AAS journals. This is a horrid format, based on the VizieR readMe files, which are themselves underdocumented, but picking and leaving whatever bits and pieces they feel like, without any careful documentation of that process. This reader has mainly been put together by looking at given instances of files claimed to be in this format.- Since:
- 30 Apr 2021
- Author:
- Mark Taylor
- See Also:
- https://journals.aas.org/mrt-standards/
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
MAGIC_TXT
Should be present at the start of all MRT files.
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Constructor Summary
Constructors Constructor Description MrtTableBuilder()
Default constructor.MrtTableBuilder(ErrorMode errorMode, boolean checkMagic)
Constructor with configuration options.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
canImport(java.awt.datatransfer.DataFlavor flavor)
Indicates whether this builder is able to turn a resource of media type indicated by flavor into a table.boolean
canStream()
Indicates whether this handler can read tables from a stream.boolean
docIncludesExample()
Indicates whether the serialization of some (short) example table should be added to the user documentation for this handler.java.lang.String
getFormatName()
Returns "MRT".java.lang.String
getXmlDescription()
Returns user-directed documentation in XML format.static boolean
isMagic(byte[] intro)
Indicates whether the given buffer starts with the MRT magic number"Title: "
.StarTable
makeStarTable(uk.ac.starlink.util.DataSource datsrc, boolean wantRandom, StoragePolicy storage)
Constructs aStarTable
based on a given DataSource.void
setCheckMagic(boolean checkMagic)
Sets whether the handler will attempt to guess by looking at the file whether it appears to be an MRT file before attempting to parse it as one.void
setErrorMode(ErrorMode errorMode)
Sets the error handling mode.void
streamStarTable(java.io.InputStream in, TableSink sink, java.lang.String pos)
Reads a table from an input stream and writes it a row at a time to a sink.-
Methods inherited from class uk.ac.starlink.table.formats.DocumentedTableBuilder
getExtensions, looksLikeFile
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface uk.ac.starlink.table.formats.DocumentedIOHandler
readText
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Field Detail
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MAGIC_TXT
public static final java.lang.String MAGIC_TXT
Should be present at the start of all MRT files.- See Also:
- Constant Field Values
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Constructor Detail
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MrtTableBuilder
public MrtTableBuilder()
Default constructor.
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MrtTableBuilder
public MrtTableBuilder(ErrorMode errorMode, boolean checkMagic)
Constructor with configuration options.- Parameters:
errorMode
- error handling modecheckMagic
- whether to require finding the magic number before attempting to parse
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Method Detail
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getFormatName
public java.lang.String getFormatName()
Returns "MRT".- Returns:
- one-word description of this handler's format
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canImport
public boolean canImport(java.awt.datatransfer.DataFlavor flavor)
Description copied from interface:TableBuilder
Indicates whether this builder is able to turn a resource of media type indicated by flavor into a table. It should return true if it thinks that itsTableBuilder.streamStarTable(java.io.InputStream, uk.ac.starlink.table.TableSink, java.lang.String)
method stands a reasonable chance of successfully constructing a StarTable from a DataSource whose input stream is described by theDataFlavor
flavor. It will typically make this determination based on the flavor's MIME type.This method should only return true if the flavor looks like it is targeted at this builder; for instance a builder which uses a text-based format should return false for a flavor which indicates a MIME type of text/plain.
This method is used in supporting drag and drop functionality (see
StarTableFactory.canImport(java.awt.datatransfer.DataFlavor[])
).- Parameters:
flavor
- the DataFlavor whose suitability as stream input is to be assessed- Returns:
- true iff this builder reckons it stands a good chance of turning a stream of type flavor into a StarTable
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setErrorMode
@ConfigMethod(property="errmode", doc="<p>Indicates what action should be taken if formatting errors\nare detected in the file at read time.\n</p>", example="FAIL") public void setErrorMode(ErrorMode errorMode)
Sets the error handling mode.- Parameters:
errorMode
- error handling mode
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setCheckMagic
@ConfigMethod(property="checkmagic", doc="<p>Determines whether an initial test is made to see whether\nthe file looks like MRT before attempting to read it as one;\nthe test is that it starts with the string\n\"<code>Title: </code>\".\nSetting this true is generally a good idea\nto avoid attempting to parse non-MRT files,\nbut you can set it false to attempt to read an MRT file\nthat starts with the wrong sequence.\n</p>", example="false") public void setCheckMagic(boolean checkMagic)
Sets whether the handler will attempt to guess by looking at the file whether it appears to be an MRT file before attempting to parse it as one. This is generally a good idea, since otherwise it will attempt to make MRT sense of any old file, but you can set it false to try to parse MRT files with unexpected first few bytes.- Parameters:
checkMagic
- true to require magic number presence
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makeStarTable
public StarTable makeStarTable(uk.ac.starlink.util.DataSource datsrc, boolean wantRandom, StoragePolicy storage) throws java.io.IOException
Description copied from interface:TableBuilder
Constructs aStarTable
based on a given DataSource. If the source is not recognised or this builder does not know how to construct a table from it, then aTableFormatException
should be thrown. If this builder thinks it should be able to handle the source but an error occurs during processing, an IOException can be thrown.The wantRandom parameter is used to indicate whether, ideally, a random-access table should be returned. There is no requirement for the builder to honour this request, but if it knows how to make both random and non-random tables, it can use this flag to decide which to return.
Note: the presence of the
wantRandom
parameter is somewhat misleading. TableBuilder implementations usually should, and do, ignore it (it would be removed from the interface if it were not for backward compatibility issues). Regardless of the value of this parameter, implementations should return a random-access table only if it is easy for them to do so; in particular they should not use the suppliedstoragePolicy
, or any other resource-expensive measure, to randomise a sequential table just because thewantRandom
parameter is true.- Parameters:
datsrc
- the DataSource containing the table resourcewantRandom
- whether, preferentially, a random access table should be returnedstorage
- a StoragePolicy object which may be used to supply scratch storage if the builder needs it- Returns:
- a StarTable made out of datsrc
- Throws:
TableFormatException
- if the table is not of a kind that can be handled by this handlerjava.io.IOException
- if an unexpected I/O error occurs during processing
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streamStarTable
public void streamStarTable(java.io.InputStream in, TableSink sink, java.lang.String pos) throws java.io.IOException
Description copied from interface:TableBuilder
Reads a table from an input stream and writes it a row at a time to a sink. Not all implementations will be able to do this; for instance, extracting the table from the data may be a two-pass process. Implementations which are unable to perform this function should throw aTableFormatException
.The input stream should be prepared for use prior to calling this method, so implementations should not in general attempt to decompress or buffer istrm.
- Parameters:
in
- input stream containing table datasink
- destination of the tablepos
- position identifier describing the location of the table within the stream; seeDataSource.getPosition()
(may be null)- Throws:
TableFormatException
- if the table can't be streamed or the data is malformedjava.io.IOException
- if some other error occurs
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canStream
public boolean canStream()
Description copied from class:DocumentedTableBuilder
Indicates whether this handler can read tables from a stream.- Specified by:
canStream
in classDocumentedTableBuilder
- Returns:
- true iff this handler can read from streams
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docIncludesExample
public boolean docIncludesExample()
Description copied from interface:DocumentedIOHandler
Indicates whether the serialization of some (short) example table should be added to the user documentation for this handler. Binary formats, or instances for which theDocumented.getXmlDescription()
method already includes some example output, should return false.- Returns:
- true if the user documentation would benefit from the addition of an example serialization
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getXmlDescription
public java.lang.String getXmlDescription()
Description copied from interface:Documented
Returns user-directed documentation in XML format.The output should be a sequence of one or more <P> elements, using XHTML-like XML. Since rendering may be done in a number of contexts however, use of the full range of XHTML elements is discouraged. Where possible, the content should stick to simple markup such as the elements P, A, UL, OL, LI, DL, DT, DD EM, STRONG, I, B, CODE, TT, PRE.
- Returns:
- XML description of this object
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isMagic
public static boolean isMagic(byte[] intro)
Indicates whether the given buffer starts with the MRT magic number"Title: "
.- Parameters:
intro
- byte buffer- Returns:
- true iff magic number is present
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