Class IntersectsFunction

All Implemented Interfaces:
ADQLObject, ADQLOperand

public class IntersectsFunction extends GeometryFunction
It represents the INTERSECTS function of the ADQL language.

This function determines if two geometry values overlap. This is most commonly used to express a "shape-vs-shape" intersection test.

Example:

An expression to determine whether a circle of one degree radius centered on position (25.4, -20.0) degrees overlaps with a box of ten degrees centered on position (20.0, -15.0) degrees, could be written as follows:

INTERSECTS(CIRCLE(25.4, -20.0, 1), BOX(20.0, -15.0, 10, 10))

, where the INTERSECTS function returns the numeric value 1 if the two arguments overlap and 0 if they do not.

When used as a predicate in the WHERE clause of a query, the numeric return value should be compared to the numeric values 0 or 1 to form a SQL predicate.

Example:

WHERE 1 = INTERSECTS(CIRCLE(25.4, -20.0, 1), BOX(20.0, -15.0, 10, 10))

for "does intersect" and

WHERE 0 = INTERSECTS(CIRCLE(25.4, -20.0, 1), BOX(20.0, -15.0, 10, 10))

for "does not intersect".

The geometric arguments for INTERSECTS may be literal values, as above, or they may be column references, functions or expressions that return geometric values.

Example:

WHERE 0 = INTERSECTS(t1.target, t2.footprint)

, where t1.target and t2.footprint are references to database columns that contain geometric (BOX, CIRCLE, POLYGON or REGION) values.

The arguments to INTERSECTS SHOULD be geometric expressions evaluating to either BOX, CIRCLE, POLYGON or REGION. Previous versions of this specification (invalid input: '<' 2.1) also allowed POINT values and required server implementations to interpret the expression as a CONTAINS with the POINT moved into the first position. Server implementations SHOULD still implement that behaviour, but clients SHOULD NOT expect it. This behaviour MAY be dropped in the next major version of this specification (> 2.1).

If the geometric arguments are expressed in different coordinate systems, the INTERSECTS function is responsible for converting one, or both, of the arguments into a different coordinate system. If the INTERSECTS function cannot perform the required conversion then it SHOULD throw an error. Details of the mechanism for reporting the error condition are implementation dependent.

  • Field Details

    • FEATURE

      public static final LanguageFeature FEATURE
      Description of this ADQL Feature.
      Since:
      2.0
  • Constructor Details

  • Method Details

    • getFeatureDescription

      public final LanguageFeature getFeatureDescription()
      Description copied from interface: ADQLObject
      Get the description of this ADQL's Language Feature.

      Note: Getting this description is generally only useful when discovery optional features so that determining if they are allowed to be used in ADQL queries.

      Returns:
      Description of this ADQL object as an ADQL's feature.
    • getCopy

      public ADQLObject getCopy() throws Exception
      Description copied from interface: ADQLObject
      Gets a (deep) copy of this ADQL object.
      Returns:
      The copy of this ADQL object.
      Throws:
      Exception - If there is any error during the copy.
    • getName

      public String getName()
      Description copied from interface: ADQLObject
      Gets the name of this object in ADQL.
      Returns:
      The name of this ADQL object.
    • isNumeric

      public boolean isNumeric()
      Description copied from interface: ADQLOperand
      Tell whether this operand is numeric or not.
      Returns:
      true if this operand is numeric, false otherwise.
    • isString

      public boolean isString()
      Description copied from interface: ADQLOperand
      Tell whether this operand is a string or not.
      Returns:
      true if this operand is a string, false otherwise.
    • isGeometry

      public boolean isGeometry()
      Description copied from interface: ADQLOperand
      Tell whether this operand is a geometrical region or not.
      Returns:
      true if this operand is a geometry, false otherwise.
    • getLeftParam

      public final GeometryFunction.GeometryValue<GeometryFunction> getLeftParam()
      Returns:
      The leftParam.
    • setLeftParam

      public final void setLeftParam(GeometryFunction.GeometryValue<GeometryFunction> leftParam)
      Parameters:
      leftParam - The leftParam to set.
    • getRightParam

      public final GeometryFunction.GeometryValue<GeometryFunction> getRightParam()
      Returns:
      The rightParam.
    • setRightParam

      public final void setRightParam(GeometryFunction.GeometryValue<GeometryFunction> rightParam)
      Parameters:
      rightParam - The rightParam to set.
    • getParameters

      public ADQLOperand[] getParameters()
      Description copied from class: ADQLFunction
      Gets the list of all parameters of this function.
      Specified by:
      getParameters in class ADQLFunction
      Returns:
      Its parameters list.
    • getNbParameters

      public int getNbParameters()
      Description copied from class: ADQLFunction
      Gets the number of parameters this function has.
      Specified by:
      getNbParameters in class ADQLFunction
      Returns:
      Number of parameters.
    • getParameter

      public ADQLOperand getParameter(int index) throws ArrayIndexOutOfBoundsException
      Description copied from class: ADQLFunction
      Gets the index-th parameter.
      Specified by:
      getParameter in class ADQLFunction
      Parameters:
      index - Parameter number.
      Returns:
      The corresponding parameter.
      Throws:
      ArrayIndexOutOfBoundsException - If the index is incorrect (index invalid input: '<' 0 || index >= getNbParameters()).
    • setParameter

      public ADQLOperand setParameter(int index, ADQLOperand replacer) throws ArrayIndexOutOfBoundsException, NullPointerException, Exception
      Description copied from class: ADQLFunction
      Replaces the index-th parameter by the given one.
      Specified by:
      setParameter in class ADQLFunction
      Parameters:
      index - Index of the parameter to replace.
      replacer - The replacer.
      Returns:
      The replaced parameter.
      Throws:
      ArrayIndexOutOfBoundsException - If the index is incorrect (index invalid input: '<' 0 || index >= getNbParameters()).
      NullPointerException - If a required parameter must be replaced by a NULL object.
      Exception - If another error occurs.