Package com.mckoi.database
Class FunctionFactory
- java.lang.Object
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- com.mckoi.database.FunctionFactory
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- All Implemented Interfaces:
FunctionLookup
public abstract class FunctionFactory extends java.lang.Object implements FunctionLookup
A factory that generates Function objects given a function name and a set of expression's that represent parameters. A developer may create their own instance of this class and register the factory with the DatabaseSystem. When the SQL grammer comes across a function, it will try and resolve the function name against the registered function factories.- Author:
- Tobias Downer
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Nested Class Summary
Nested Classes Modifier and Type Class Description protected class
FunctionFactory.FF_FunctionInfo
An implementation of FunctionInfo.
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Field Summary
Fields Modifier and Type Field Description static Expression[]
GLOB_LIST
Represents a function argument * for glob's such as 'count(*)'
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Constructor Summary
Constructors Constructor Description FunctionFactory()
Constructs the FunctionFactory.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected void
addFunction(java.lang.String fun_name, java.lang.Class fun_class)
Adds a new static function to this factory.protected void
addFunction(java.lang.String fun_name, java.lang.Class fun_class, int fun_type)
Adds a new function to this factory.protected boolean
functionDefined(java.lang.String fun_name)
Returns true if the function name is defined in this factory.Function
generateFunction(FunctionDef function_def)
Creates a Function object for the function with the given name with the given arguments.FunctionInfo[]
getAllFunctionInfo()
Returns the list of all function names that this FunctionFactory manages.FunctionInfo
getFunctionInfo(java.lang.String fun_name)
Returns a FunctionInfo instance of the function with the given name that this FunctionFactory manages.abstract void
init()
Initializes this FunctionFactory.boolean
isAggregate(FunctionDef function_def)
Returns true if the function defined by FunctionDef is an aggregate function, or false otherwise.protected void
removeFunction(java.lang.String fun_name)
Removes a static function from this factory.
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Field Detail
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GLOB_LIST
public static final Expression[] GLOB_LIST
Represents a function argument * for glob's such as 'count(*)'
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Method Detail
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addFunction
protected void addFunction(java.lang.String fun_name, java.lang.Class fun_class, int fun_type)
Adds a new function to this factory. Takes a function name and a class that is the Function implementation. When the 'generateFunction' method is called, it looks up the class with the function name and returns a new instance of the function.- Parameters:
fun_name
- the name of the function (eg. 'sum', 'concat').fun_class
- the Function class that we instantiate for this function.fun_type
- that type of function (either FunctionInfo.STATIC, FunctionInfo.AGGREGATE, FunctionInfo.STATE_BASED).
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addFunction
protected void addFunction(java.lang.String fun_name, java.lang.Class fun_class)
Adds a new static function to this factory.
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removeFunction
protected void removeFunction(java.lang.String fun_name)
Removes a static function from this factory.
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functionDefined
protected boolean functionDefined(java.lang.String fun_name)
Returns true if the function name is defined in this factory.
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init
public abstract void init()
Initializes this FunctionFactory. This is an abstract method that needs to be implemented. (It doesn't need to do anything if a developer implements their own version of 'generateFunction').
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generateFunction
public Function generateFunction(FunctionDef function_def)
Creates a Function object for the function with the given name with the given arguments. If this factory does not handle a function with the given name then it returns null.- Specified by:
generateFunction
in interfaceFunctionLookup
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isAggregate
public boolean isAggregate(FunctionDef function_def)
Returns true if the function defined by FunctionDef is an aggregate function, or false otherwise.- Specified by:
isAggregate
in interfaceFunctionLookup
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getFunctionInfo
public FunctionInfo getFunctionInfo(java.lang.String fun_name)
Returns a FunctionInfo instance of the function with the given name that this FunctionFactory manages. If 'generateFunction' is reimplemented then this method should be rewritten also.
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getAllFunctionInfo
public FunctionInfo[] getAllFunctionInfo()
Returns the list of all function names that this FunctionFactory manages. This is used to compile information about the function factories. If 'generateFunction' is reimplemented then this method should be rewritten also.
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