Package uk.ac.starlink.table.formats
Class AsciiStarTable
java.lang.Object
uk.ac.starlink.table.AbstractStarTable
uk.ac.starlink.table.formats.StreamStarTable
uk.ac.starlink.table.formats.AsciiStarTable
- All Implemented Interfaces:
Closeable
,AutoCloseable
,StarTable
Simple ASCII-format table. This reader attempts to make sensible
decisions about what is a table and what is not, but inevitably it
will not be able to read ASCII tables in any format.
Here are the rules:
- Bytes in the file are interpreted as ASCII characters
- Each table row is represented by a single line of text
- Lines are terminated by one or more contiguous line termination characters: line feed (0x0A) or carriage return (0x0D)
- Within a line, fields are separated by one or more whitespace characters: space (" ") or tab (0x09)
- A field is either an unquoted sequence of non-whitespace characters, or a sequence of non-newline characters between matching single (') or double (") quote characters - spaces are therefore allowed in quoted fields
- Within a quoted field, whitespace characters are permitted and are treated literally
- Within a quoted field, any character preceded by a backslash character ("\") is treated literally. This allows quote characters to appear within a quoted string.
- An empty quoted string (two adjacent quotes) or the string
"
null
" (unquoted) represents the null value - All data lines must contain the same number of fields (this is the number of columns in the table)
- The data type of a column is guessed according to the fields that
appear in the table. If all the fields in one column can be parsed
as integers (or null values), then that column will turn into an
integer-type column. The types that are tried, in order of
preference, are:
Boolean
,Short
Integer
,Long
,Float
,Double
,String
- Empty lines are ignored
- Anything after a hash character "#" (except one in a quoted string)
on a line is ignored as far as table data goes;
any line which starts with a "!" is also ignored.
However, lines which start with a "#" or "!" at the start of the table
(before any data lines) will be interpreted as metadata as follows:
- The last "#"/"!"-starting line before the first data line may contain the column names. If it has the same number of fields as there are columns in the table, each field will be taken to be the title of the corresponding column. Otherwise, it will be taken as a normal comment line.
- Any comment lines before the first data line not covered by the above will be concatenated to form the "description" parameter of the table.
- Author:
- Mark Taylor (Starlink)
-
Field Summary
Fields inherited from class uk.ac.starlink.table.formats.StreamStarTable
END
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Constructor Summary
ConstructorsConstructorDescriptionAsciiStarTable
(uk.ac.starlink.util.DataSource datsrc) Constructor with default options.AsciiStarTable
(uk.ac.starlink.util.DataSource datsrc, int maxSample) Constructor with configuration option. -
Method Summary
Modifier and TypeMethodDescriptionprotected RowEvaluator.Metadata
Obtains column metadata for this table, probably by reading through the rows once and using a RowEvaluator.Reads the next row of data from a given stream.Methods inherited from class uk.ac.starlink.table.formats.StreamStarTable
getColumnCount, getColumnInfo, getInputStream, getRowCount, getRowSequence, init
Methods inherited from class uk.ac.starlink.table.AbstractStarTable
checkedLongToInt, close, getCell, getColumnAuxDataInfos, getName, getParameters, getRow, getRowAccess, getRowSplittable, getURL, isRandom, setName, setParameters, setURL
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface uk.ac.starlink.table.StarTable
getParameterByName, setParameter
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Constructor Details
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AsciiStarTable
public AsciiStarTable(uk.ac.starlink.util.DataSource datsrc) throws TableFormatException, IOException Constructor with default options.- Parameters:
datsrc
- the data source containing the table text- Throws:
TableFormatException
- if the input stream doesn't appear to form a ASCII-format tableIOException
- if some I/O error occurs
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AsciiStarTable
public AsciiStarTable(uk.ac.starlink.util.DataSource datsrc, int maxSample) throws TableFormatException, IOException Constructor with configuration option.- Parameters:
datsrc
- the data source containing the table textmaxSample
- maximum number of rows sampled to determine column data types; if <=0, all rows are sampled- Throws:
TableFormatException
- if the input stream doesn't appear to form a ASCII-format tableIOException
- if some I/O error occurs
-
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Method Details
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obtainMetadata
Description copied from class:StreamStarTable
Obtains column metadata for this table, probably by reading through the rows once and using a RowEvaluator.- Specified by:
obtainMetadata
in classStreamStarTable
- Returns:
- information about the table represented by the character stream
- Throws:
TableFormatException
- if the data doesn't represent this kind of tableIOException
- if I/O error is encountered
-
readRow
Reads the next row of data from a given stream. Ignorable rows are skipped; comments may be stashed away.- Specified by:
readRow
in classStreamStarTable
- Parameters:
in
- input stream- Returns:
- list of Strings one for each cell in the row, or
null
for end of stream - Throws:
IOException
- if I/O error is encountered
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