Package uk.ac.starlink.ttools.jel

Class StarTableJELRowReader

  • Direct Known Subclasses:
    DummyJELRowReader, RandomJELRowReader, SequentialJELRowReader
    public abstract class StarTableJELRowReader
extends JELRowReader
    JELRowReader subclass for access to StarTables.

    In addition to the syntax provided by the superclass, the following symbols are understood:

    "$0" or "$index" or (deprecated) "index" (case insensitive):
    the 1-based index of the current row.
    "$ncol"
    Number of columns in the table.
    "$nrow"
    Number of rows in the table. If this is not known, a null value is returned.
    Parameter names:
    The string "param$" followed by the name of a table parameter (case-insensitive) is a constant for the table (as a primitive, if applicable). This can only work if the parameter name is a legal java identifier.
    UCD specifiers:
    The string "ucd$" followed by the text of a UCD giving the required value. Any punctuation (such as ".", ";", "-") in the UCD should be replaced with a "_" (since these symbols cannot appear in identifiers). If the identifier has a trailing "_", then any UCD which starts as specified is considered to match. The first matching column, or if there is none the first matching parameter value is returned. UCD matching is case-insensitive.
    Utype specifiers:
    The string "utype$" followed by the text of a Utype identifying the required value. Any punctuation (such as ".", ":", "-") in the Utype should be replaced with a "_" (since these symbols cannot appear in identifiers). The first matching column, or if there is none the first matching parameter value is returned. UType matching is case-insensitive.
    "$random" (case insensitive) or (deprecated) "RANDOM":
    The special token "$random" evaluates to a double-precision random number 0<=x<1 which is constant for a given row within this reader. The quality of the random numbers may not be particularly good.
    Since:
    7 Dec 2007
    Author:
    Mark Taylor

    • Field Detail

      • PARAM_PREFIX

        public static final java.lang.String PARAM_PREFIX
        The string which should be prefixed to a table parameter (constant) name to result in substituting its value.
        See Also:
        Constant Field Values

      • UCD_PREFIX

        public static final java.lang.String UCD_PREFIX
        A string to prefix to a UCD string to indicate the column/parameter with that UCD. The first matching column, else the first matching parameter, is used. Punctuation in the UCD name is all mapped to "_". A trailing "_" corresponds to a wildcard.
        See Also:
        Constant Field Values

      • UTYPE_PREFIX

        public static final java.lang.String UTYPE_PREFIX
        A string to prefix to a Utype string to indicate the column/parameter with that Utype. The first matching column, else the first matching parameter, is used. Punctuation in the Utype name is all mapped to "_".
        See Also:
        Constant Field Values

    • Constructor Detail

      • StarTableJELRowReader

        public StarTableJELRowReader​(uk.ac.starlink.table.StarTable table)
        Constructs a new row reader for a given StarTable. Note that this reader cannot become aware of changes to the columns of the table; in the event of such changes this object should be dicarded and and a new one used for any new expressions.
        Parameters:
        table - the StarTable this reader will read from

    • Method Detail

      • getTable

        public uk.ac.starlink.table.StarTable getTable()
        Returns the table associated with this reader.
        Returns:
        table

      • getCell

        protected abstract java.lang.Object getCell​(int icol)
                                     throws java.io.IOException
        Returns the value for a given column in this reader's table at the current row.
        Parameters:
        icol - column index
        Returns:
        contents of column icol at the current row
        Throws:
        java.io.IOException

      • getCurrentRow

        public abstract long getCurrentRow()
        Returns the index of the row on which evaluations are currently taking place.
        Returns:
        row index (first row is 0)

      • isBlank

        protected boolean isBlank​(int icol)
        Description copied from class: JELRowReader
        Indicates whether the value in a given column is null.
        Specified by:
        isBlank in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        true if value at icol is null

      • getColumnClass

        protected java.lang.Class<?> getColumnClass​(int icol)
        Description copied from class: JELRowReader
        Returns the class of values returned by a given column. If no column with the given index exists, null should be returned.
        Specified by:
        getColumnClass in class JELRowReader
        Parameters:
        icol - non-negative column index
        Returns:
        value class, or null for non-existent column

      • getColumnIndexByName

        protected int getColumnIndexByName​(java.lang.String name)
        Description copied from class: JELRowReader
        Returns the column index of a column in the row given its name. If name does not refer to any known column, return -1.
        Specified by:
        getColumnIndexByName in class JELRowReader
        Parameters:
        name - column name
        Returns:
        column index, or -1

      • getConstantByName

        protected Constant getConstantByName​(java.lang.String name)
        Understands table parameters identified case-insensitively by name (using the PARAM_PREFIX prefix) or by UCD (using the UCD_PREFIX prefix) or by Utype (using the UTYPE_PREFIX prefix).
        Specified by:
        getConstantByName in class JELRowReader
        Parameters:
        name - constant name
        Returns:
        constant, or null

      • getSpecialByName

        protected Constant getSpecialByName​(java.lang.String name)
        Adds to the superclass implementation the following:
        • "$0", "index" or "$index" gives the (1-based) row number
        • "$ncol" gives the number of columns in the table
        • "$nrow" gives the number of rows in the table (null if unknown)
        • "$random" or "RANDOM" returns a double random number, always the same for a given row
        Overrides:
        getSpecialByName in class JELRowReader
        Parameters:
        name - special name
        Returns:
        special, or null

      • createDescribedValueConstant

        protected Constant createDescribedValueConstant​(uk.ac.starlink.table.DescribedValue dval)
        Returns a Constant object based on a DescribedValue. The supplied implementation evaluates the constant's class and value once when this method is called.
        Parameters:
        dval - described value object
        Returns:
        constant which evaluates to dval's value

      • getBooleanColumnValue

        protected boolean getBooleanColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a boolean value for a cell of the current row. Will only be called if the relevant column is declared boolean. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getBooleanColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getByteColumnValue

        protected byte getByteColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a byte value for a cell of the current row. Will only be called if the relevant column is declared byte. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getByteColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getCharColumnValue

        protected char getCharColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a char value for a cell of the current row. Will only be called if the relevant column is declared char. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getCharColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getShortColumnValue

        protected short getShortColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a short value for a cell of the current row. Will only be called if the relevant column is declared short. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getShortColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getIntColumnValue

        protected int getIntColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a int value for a cell of the current row. Will only be called if the relevant column is declared int. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getIntColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getLongColumnValue

        protected long getLongColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a long value for a cell of the current row. Will only be called if the relevant column is declared long. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getLongColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getFloatColumnValue

        protected float getFloatColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a float value for a cell of the current row. Will only be called if the relevant column is declared float. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getFloatColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getDoubleColumnValue

        protected double getDoubleColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns a double value for a cell of the current row. Will only be called if the relevant column is declared double. Must call JELRowReader.foundNull() (and return any value) if the result is null.
        Specified by:
        getDoubleColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getObjectColumnValue

        protected java.lang.Object getObjectColumnValue​(int icol)
        Description copied from class: JELRowReader
        Returns an Object value for a cell of the current row.
        Specified by:
        getObjectColumnValue in class JELRowReader
        Parameters:
        icol - column index
        Returns:
        value

      • getUcdRegex

        public static java.util.regex.Pattern getUcdRegex​(java.lang.String ucd)
        Takes a (non-prefixed) UCD specification and returns a Pattern actual UCDs should match if they represent the same thing. Punctuation is mapped to underscores, and the pattern is case-insensitive, which means that the same syntax can work for UCD1s and UCD1+s. If a trailing underscore (or other punctuation mark) is present in the input ucd it is considered as a trailing match-all wildcard.
        Parameters:
        ucd - UCD1 or UCD1+ specification/pattern
        Returns:
        regular expression pattern which matches actual UCD1s or UCD1+s

      • getUtypeRegex

        public static java.util.regex.Pattern getUtypeRegex​(java.lang.String utype)
        Takes a (non-prefixed) Utype specification and returns a Pattern actual Utypes should match if they represent the same thing. Punctuation is mapped to underscores, and the pattern is case-insensitive.
        Parameters:
        utype - utype specification
        Returns:
        regular expression pattern which matches actual Utypes