com.metamatrix.query.function
Class FunctionLibrary

java.lang.Object
  com.metamatrix.query.function.FunctionLibrary

public class FunctionLibrary
extends java.lang.Object

The function library is the primary way for the system to find out what functions are available, resolve function signatures, and invoke system and user-defined functions.

Field Summary

static java.lang.String	CAST
static java.lang.String	COALESCE
static java.lang.String	COMMAND_PAYLOAD
static java.lang.String	CONCAT
static java.lang.String	CONCAT_OPERATOR
static java.lang.String	CONCAT2
static java.lang.String	CONTEXT
static java.lang.String	CONVERT
static java.lang.String	DECODEINTEGER
static java.lang.String	DECODESTRING
static java.lang.String	ENV
static java.lang.String	FROM_UNIXTIME
static java.lang.String	IFNULL
static java.lang.String	LOOKUP
static java.lang.String	NULLIF
static java.lang.String	NVL
static java.lang.String	ROWLIMIT
static java.lang.String	ROWLIMITEXCEPTION
static java.lang.String	SPACE
static java.lang.String	SUBSTRING
static java.lang.String	TIMESTAMPADD
static java.lang.String	USER
static java.lang.String	XPATHVALUE

Method Summary

FunctionDescriptor	copyFunctionChangeReturnType(FunctionDescriptor fd, java.lang.Class returnType) Return a copy of the given FunctionDescriptor with the sepcified return type.
FunctionDescriptor[]	determineNecessaryConversions(java.lang.String name, java.lang.Class<?> returnType, java.lang.Class<?>[] types, boolean hasUnknownType) Get the conversions that are needed to call the named function with arguments of the given type.
FunctionDescriptor	findFunction(java.lang.String name, java.lang.Class[] types) Find a function descriptor given a name and the types of the arguments.
FunctionForm	findFunctionForm(java.lang.String name, int numArgs) Find function form based on function name and # of arguments.
FunctionDescriptor	findTypedConversionFunction(java.lang.Class sourceType, java.lang.Class targetType) Find conversion function and set return type to proper type.
java.util.List	getFunctionCategories() Get all function categories, sorted in alphabetical order
java.util.List	getFunctionForms(java.lang.String category) Get all function forms in a category, sorted by name, then # of args, then names of args.
java.lang.Object	invokeFunction(FunctionDescriptor fd, java.lang.Object[] values) Invoke the function described in the function descriptor, using the values provided.
static boolean	isConvert(Function function)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CONVERT

public static final java.lang.String CONVERT

See Also:

Constant Field Values

CAST

public static final java.lang.String CAST

See Also:

Constant Field Values

LOOKUP

public static final java.lang.String LOOKUP

See Also:

Constant Field Values

USER

public static final java.lang.String USER

See Also:

Constant Field Values

ENV

public static final java.lang.String ENV

See Also:

Constant Field Values

XPATHVALUE

public static final java.lang.String XPATHVALUE

See Also:

Constant Field Values

CONTEXT

public static final java.lang.String CONTEXT

See Also:

Constant Field Values

ROWLIMIT

public static final java.lang.String ROWLIMIT

See Also:

Constant Field Values

ROWLIMITEXCEPTION

public static final java.lang.String ROWLIMITEXCEPTION

See Also:

Constant Field Values

DECODESTRING

public static final java.lang.String DECODESTRING

See Also:

Constant Field Values

DECODEINTEGER

public static final java.lang.String DECODEINTEGER

See Also:

Constant Field Values

COMMAND_PAYLOAD

public static final java.lang.String COMMAND_PAYLOAD

See Also:

Constant Field Values

CONCAT

public static final java.lang.String CONCAT

See Also:

Constant Field Values

CONCAT2

public static final java.lang.String CONCAT2

See Also:

Constant Field Values

CONCAT_OPERATOR

public static final java.lang.String CONCAT_OPERATOR

See Also:

Constant Field Values

SUBSTRING

public static final java.lang.String SUBSTRING

See Also:

Constant Field Values

NVL

public static final java.lang.String NVL

See Also:

Constant Field Values

IFNULL

public static final java.lang.String IFNULL

See Also:

Constant Field Values

FROM_UNIXTIME

public static final java.lang.String FROM_UNIXTIME

See Also:

Constant Field Values

TIMESTAMPADD

public static final java.lang.String TIMESTAMPADD

See Also:

Constant Field Values

NULLIF

public static final java.lang.String NULLIF

See Also:

Constant Field Values

COALESCE

public static final java.lang.String COALESCE

See Also:

Constant Field Values

SPACE

public static final java.lang.String SPACE

See Also:

Constant Field Values

Method Detail

getFunctionCategories

public java.util.List getFunctionCategories()

Get all function categories, sorted in alphabetical order

Returns:

List of function category names, sorted in alphabetical order

getFunctionForms

public java.util.List getFunctionForms(java.lang.String category)

Get all function forms in a category, sorted by name, then # of args, then names of args.

Parameters:

category - Category name

Returns:

List of FunctionForms in a category

findFunctionForm

public FunctionForm findFunctionForm(java.lang.String name,
                                     int numArgs)

Find function form based on function name and # of arguments.

Parameters:

name - Function name

numArgs - Number of arguments

Returns:

Corresponding form or null if not found

findFunction

public FunctionDescriptor findFunction(java.lang.String name,
                                       java.lang.Class[] types)

Find a function descriptor given a name and the types of the arguments. This method matches based on case-insensitive function name and an exact match of the number and types of parameter arguments.

Parameters:

name - Name of the function to resolve

types - Array of classes representing the types

Returns:

Descriptor if found, null if not found

determineNecessaryConversions

public FunctionDescriptor[] determineNecessaryConversions(java.lang.String name,
                                                          java.lang.Class<?> returnType,
                                                          java.lang.Class<?>[] types,
                                                          boolean hasUnknownType)

Get the conversions that are needed to call the named function with arguments of the given type. In the case of an exact match, the list will contain all nulls. In other cases the list will contain one or more non-null values where the value is a conversion function that can be used to convert to the proper types for executing the function.

Parameters:

name - Name of function

returnType -

types - Existing types passed to the function

Returns:

Null if no conversion could be found, otherwise an array of conversions to apply to each argument. The list should match 1-to-1 with the parameters. Parameters that do not need a conversion are null; parameters that do are FunctionDescriptors.

Throws:

QueryResolverException

findTypedConversionFunction

public FunctionDescriptor findTypedConversionFunction(java.lang.Class sourceType,
                                                      java.lang.Class targetType)

Find conversion function and set return type to proper type.

Parameters:

sourceType - The source type class

targetType - The target type class

Returns:

A CONVERT function descriptor or null if not possible

invokeFunction

public java.lang.Object invokeFunction(FunctionDescriptor fd,
                                       java.lang.Object[] values)
                                throws InvalidFunctionException,
                                       FunctionExecutionException

Invoke the function described in the function descriptor, using the values provided. Return the result of the function.

Parameters:

fd - Function descriptor describing the name and types of the arguments

values - Values that should match 1-to-1 with the types described in the function descriptor

Returns:

Result of invoking the function

Throws:

InvalidFunctionException

FunctionExecutionException

copyFunctionChangeReturnType

public FunctionDescriptor copyFunctionChangeReturnType(FunctionDescriptor fd,
                                                       java.lang.Class returnType)

Return a copy of the given FunctionDescriptor with the sepcified return type.

Parameters:

fd - FunctionDescriptor to be copied.

returnType - The return type to apply to the copied FunctionDescriptor.

Returns:

The copy of FunctionDescriptor.

isConvert

public static boolean isConvert(Function function)