Package adql.db

Class FunctionDef

java.lang.Object
adql.db.FunctionDef
All Implemented Interfaces:
Comparable<FunctionDef>

public class FunctionDef extends Object implements Comparable<FunctionDef>
Definition of any function that could be used in ADQL queries.

A such definition can be built manually thanks to the different constructors of this class, or by parsing a string function definition form using the static function parse(String).

The syntax of the expression expected by parse(String) is the same as the one used to build the string returned by toString(). Here is this syntax:

{fctName}([{param1Name} {param1Type}, ...])[ -> {returnType}]

A description of this function may be set thanks to the public class attribute description.

Since:
1.3
Version:
2.0 (08/2020)
Author:
Grégory Mantelet (CDS;ARI)
  • Field Details

    • regularIdentifierRegExp

      protected static final String regularIdentifierRegExp
      Regular expression for what should be a function or parameter name - a regular identifier.
      See Also:
    • typeRegExp

      protected static final String typeRegExp
      Rough regular expression for a function return type or a parameter type. The exact type is not checked here ; just the type name syntax is tested, not its value. This regular expression allows a type to have exactly one parameter (which is generally the length of a character or binary string.
      See Also:
    • fctParamsRegExp

      protected static final String fctParamsRegExp
      Rough regular expression for a function parameters' list.
      See Also:
    • fctParamRegExp

      protected static final String fctParamRegExp
      Rough regular expression for a function parameter: a name (see regularIdentifierRegExp) and a type (see typeRegExp).
      See Also:
    • fctDefRegExp

      protected static final String fctDefRegExp
      Rough regular expression for a whole function definition.
      See Also:
    • fctPattern

      protected static final Pattern fctPattern
      Pattern of a function definition. This object has been compiled with fctDefRegExp.
    • paramPattern

      protected static final Pattern paramPattern
      Pattern of a single parameter definition. This object has been compiled with fctParamRegExp.
    • argRefRegExp

      protected static final String argRefRegExp
      Regular expression for a reference to a UDF argument inside a translation pattern.
      Since:
      2.0
      See Also:
    • argRefPattern

      public static final Pattern argRefPattern
      Pattern of a single argument reference in a translation pattern. This object has been compiled with argRefRegExp.
      Since:
      2.0
    • name

      public final String name
      Name of the function.
    • description

      public String description
      Description of this function.
    • returnType

      public final DBType returnType
      Type of the result returned by this function.
    • isString

      protected final boolean isString
      Indicate whether the return type is a string.
    • isNumeric

      protected final boolean isNumeric
      Indicate whether the return type is a numeric.
    • isGeometry

      protected final boolean isGeometry
      Indicate whether the return type is a geometry.
    • isUnknown

      protected final boolean isUnknown
      Indicate whether the return type is an unknown type.

      Note: If true, isString, isNumeric and isGeometry are false. Otherwise, at least one of these attributes is set to true.

      Since:
      1.4
    • nbParams

      public final int nbParams
      Total number of parameters.
    • params

      protected final FunctionDef.FunctionParam[] params
      List of all the parameters of this function.
  • Constructor Details

    • FunctionDef

      public FunctionDef(String fctName)
      Create a function definition.

      The created function will have no return type and no parameter.

      Parameters:
      fctName - Name of the function.
    • FunctionDef

      public FunctionDef(String fctName, DBType returnType)
      Create a function definition.

      The created function will have a return type (if the provided one is not null) and no parameter.

      Parameters:
      fctName - Name of the function.
      returnType - Return type of the function. If NULL, this function will have no return type.
    • FunctionDef

      public FunctionDef(String fctName, FunctionDef.FunctionParam[] params)
      Create a function definition.

      The created function will have no return type and some parameters (except if the given array is NULL or empty).

      Parameters:
      fctName - Name of the function.
      params - Parameters of this function. If NULL or empty, this function will have no parameter.
    • FunctionDef

      public FunctionDef(String fctName, DBType returnType, FunctionDef.FunctionParam[] params)
  • Method Details

    • isNumeric

      public final boolean isNumeric()
      Tell whether this function returns a numeric.
      Returns:
      true if this function returns a numeric, false otherwise.
    • isString

      public final boolean isString()
      Tell whether this function returns a string.
      Returns:
      true if this function returns a string, false otherwise.
    • isGeometry

      public final boolean isGeometry()
      Tell whether this function returns a geometry.
      Returns:
      true if this function returns a geometry, false otherwise.
    • isUnknown

      public final boolean isUnknown()
      Tell whether this function returns an unknown type.

      If this function returns true, isNumeric(), isString() and isGeometry() MUST ALL return false. Otherwise, one of these 3 last functions MUST return true.

      Returns:
      true if this function returns an unknown/unresolved /unsupported type, false otherwise.
    • getNbParams

      public final int getNbParams()
      Get the number of parameters required by this function.
      Returns:
      Number of required parameters.
    • getParam

      public final FunctionDef.FunctionParam getParam(int indParam) throws ArrayIndexOutOfBoundsException
      Get the definition of the indParam-th parameter of this function.
      Parameters:
      indParam - Index of the parameter whose the definition must be returned.
      Returns:
      Definition of the specified parameter.
      Throws:
      ArrayIndexOutOfBoundsException - If the given index is negative or bigger than the number of parameters.
    • getUDFClass

      public final Class<? extends UserDefinedFunction> getUDFClass()
      Get the class of the UserDefinedFunction able to represent the function defined here in an ADQL tree.

      Note: This getter should return always NULL if the function defined here is not a user defined function.
      However, if this FunctionDef is defining a user defined function and this function returns NULL, the library will create on the fly a DefaultUDF corresponding to this definition when needed. Indeed this UDF class is useful only if the translation from ADQL (to SQL for instance) of the defined function has a different signature (e.g. a different name) in the target language (e.g. SQL).

      Returns:
      The corresponding UserDefinedFunction. MAY BE NULL
    • setUDFClass

      public final <T extends UserDefinedFunction> void setUDFClass(Class<T> udfClass) throws IllegalArgumentException
      Set the class of the UserDefinedFunction able to represent the function defined here in an ADQL tree.

      Note: If this FunctionDef defines an ordinary ADQL function - and not a user defined function - no class should be set here.
      However, if it defines a user defined function, there is no obligation to set a UDF class. It is useful only if the translation from ADQL (to SQL for instance) of the function has a different signature (e.g. a different name) in the target language (e.g. SQL). If the signature is the same, there is no need to set a UDF class ; a DefaultUDF will be created on the fly by the library when needed if it turns out that no UDF class is set.

      WARNING: If successful, this operation will reset to NULL any translation pattern already set with setTranslationPattern(String).

      Parameters:
      udfClass - Class to use to represent in an ADQL tree the User Defined Function defined in this FunctionDef.
      Throws:
      IllegalArgumentException - If the given class does not provide any constructor with a single parameter of type ADQLOperand[].
    • getTranslationPattern

      public final String getTranslationPattern()
      Get the translation pattern to apply on any ADQL function implementing this UDF definition.
      Returns:
      The corresponding UserDefinedFunction. NULL if no translation pattern is defined.
      Since:
      2.0
    • setTranslationPattern

      public final void setTranslationPattern(String pattern) throws IllegalArgumentException
      Set the translation pattern to apply on any ADQL function implementing this UDF definition.

      The given pattern is expected to be the exact string (even an empty string) resulting from a translation operation. It is possible to insert somewhere in this string any input argument through the syntax $i (where i is an integer >0). For instance $1 will insert the value of the 1st argument, $2 of the 2nd, etc...

      Note: Double the $ character to escape it. For instance, $$1 won't be interpreted as an argument reference and will be translated as the literal $1.

      WARNING 1: If the given pattern references an out-of-bound argument (i.e. $i ≤ 0 or $i > number of arguments), an IllegalArgumentException will be thrown.

      WARNING 2: If successful, this operation will reset to NULL any UDF class already set with setUDFClass(Class).

      Parameters:
      pattern - Pattern to apply while translating the here-defined UDF. NULL to set no pattern.
      Throws:
      IllegalArgumentException - If an argument reference is out-of-bound.
      Since:
      2.0
    • parse

      public static FunctionDef parse(String strDefinition) throws ParseException
      Let parsing the serialized form of a function definition.

      The expected syntax is (items between brackets are optional):

      {fctName}([{param1Name} {param1Type}, ...])[ -> {returnType}]

      This function must be able to parse functions as defined by TAPRegExt (section 2.3). Hence, allowed parameter types and return types should be one of the types listed by the UPLOAD section of the TAP recommendation document. These types are listed in the enumeration object DBType.DBDatatype. However, other types should be accepted like the common database types ...but it should be better to not rely on that since the conversion of those types to TAP types should not be exactly what is expected (because depending from the used DBMS); a default interpretation of database types is nevertheless processed by this parser.

      Parameters:
      strDefinition - Serialized function definition to parse.
      Returns:
      The object representation of the given string definition.
      Throws:
      ParseException - If the given string has a wrong syntax or uses unknown types.
    • toString

      public String toString()
      Overrides:
      toString in class Object
    • compareTo

      public int compareTo(FunctionDef def)
      Specified by:
      compareTo in interface Comparable<FunctionDef>
    • compareTo

      public int compareTo(ADQLFunction fct)
      Compare this function definition with the given ADQL function item.

      The comparison is done only on the function name and on rough type of the parameters. "Rough type" means here that just the kind of type is tested: numeric, string or geometry. Anyway, the return type is never tested by this function, since such information is usually not part of a function signature.

      The notions of "greater" and "less" are defined here according to the three following test steps:

      1. Name test: if the name of both function are equals, next steps are evaluated, otherwise the standard string comparison (case insensitive) result is returned.
      2. Parameters test: parameters are compared individually. Each time parameters (at the same position in both functions) are equals the next parameter can be tested, and so on until two parameters are different or the end of the parameters' list is reached. Just the kind of type is used for parameter comparison. Each kind of type is tested in the following order: numeric, string and geometry. When a kind of type is not equal for both parameters, the function exits with the appropriate value (1 if the parameter of this function definition is of the kind of type, -1 otherwise).
      3. Number of parameters test: in the case where this function definition has N parameters and the given ADQL function has M parameters, and that the L (= min(N,M)) first parameters have the same type in both functions, the value returns by this function will be N-M. Thus, if this function definition has more parameters than the given function, a positive value will be returned. Otherwise a negative value will be returned, or 0 if the number of parameters is the same.

      Note: If one of the tested types (i.e. parameters types) is unknown, the match should return 0 (i.e. equality). The notion of "unknown" is different in function of the tested item. A DBType is unknown if its function DBType.isUnknown() returns true ; thus, its other functions such as DBType.isNumeric() will return false. On the contrary, an ADQLOperand does not have any isUnknown() function. However, when the type of a such is unknown, all its functions isNumeric(), isString() and isGeometry() return true.

      Parameters:
      fct - ADQL function item to compare with this function definition.
      Returns:
      A positive value if this function definition is "greater" than the given ADQLFunction, 0 if they are perfectly matching or one of the tested types (i.e. parameters types) is unknown, or a negative value if this function definition is "less" than the given ADQLFunction.