Package uk.ac.starlink.table.formats
Class AsciiStarTable
- java.lang.Object
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- uk.ac.starlink.table.AbstractStarTable
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- uk.ac.starlink.table.formats.StreamStarTable
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- uk.ac.starlink.table.formats.AsciiStarTable
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- All Implemented Interfaces:
StarTable
public class AsciiStarTable extends StreamStarTable
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)
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Field Summary
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Fields inherited from class uk.ac.starlink.table.formats.StreamStarTable
END
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Constructor Summary
Constructors Constructor Description AsciiStarTable(uk.ac.starlink.util.DataSource datsrc)
Constructs a new AsciiStarTable from a datasource.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected RowEvaluator.Metadata
obtainMetadata()
Obtains column metadata for this table, probably by reading through the rows once and using a RowEvaluator.protected java.util.List
readRow(java.io.PushbackInputStream in)
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
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Methods inherited from class uk.ac.starlink.table.AbstractStarTable
checkedLongToInt, getCell, getColumnAuxDataInfos, getName, getParameterByName, getParameters, getRow, getURL, isRandom, setName, setParameter, setParameters, setURL
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Constructor Detail
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AsciiStarTable
public AsciiStarTable(uk.ac.starlink.util.DataSource datsrc) throws TableFormatException, java.io.IOException
Constructs a new AsciiStarTable from a datasource.- Parameters:
datsrc
- the data source containing the table text- Throws:
TableFormatException
- if the input stream doesn't appear to form a ASCII-format tablejava.io.IOException
- if some I/O error occurs
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Method Detail
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obtainMetadata
protected RowEvaluator.Metadata obtainMetadata() throws TableFormatException, java.io.IOException
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 tablejava.io.IOException
- if I/O error is encountered
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readRow
protected java.util.List readRow(java.io.PushbackInputStream in) throws java.io.IOException
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:
TableFormatException
- if the data doesn't represent this kind of tablejava.io.IOException
- if I/O error is encountered
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