io.burt.jmespath.function

Class BaseFunction

java.lang.Object

io.burt.jmespath.function.BaseFunction

All Implemented Interfaces:

Function

Direct Known Subclasses:

ArrayMathFunction, ContainsFunction, EndsWithFunction, JoinFunction, KeysFunction, LengthFunction, MapFunction, MathFunction, MergeFunction, NotNullFunction, ReverseFunction, SortFunction, StartsWithFunction, ToArrayFunction, ToNumberFunction, ToStringFunction, TransformByFunction, TypeFunction, ValuesFunction

public abstract class BaseFunction
extends Object
implements Function

Base class of all functions.

Subclasses must either use the constructor that specifies a name, or be called something that ends with "Function" – in which case the name will automatically be generated from the class name. "MyAwesomeFunction" will get the name "my_awesome", i.e. the camel cased name will be converted to snake case, minus the "Function" suffix.

Subclasses must override the callFunction(io.burt.jmespath.Adapter<T>, java.util.List<io.burt.jmespath.function.FunctionArgument<T>>) method, and not call(io.burt.jmespath.Adapter<T>, java.util.List<io.burt.jmespath.function.FunctionArgument<T>>). The latter does type checking on the arguments and then calls callFunction(io.burt.jmespath.Adapter<T>, java.util.List<io.burt.jmespath.function.FunctionArgument<T>>).

Subclasses must also provide argument constraints for checking arguments. This is done by using the ArgumentConstraints DSL and passing the result in a super call in the constructor.

Constructor Summary

Constructors

Constructor and Description
BaseFunction(ArgumentConstraint... argumentConstraints) Constructor used by subclasses whose name ends with "Function" and that accept a fixed number of argument.
BaseFunction(ArgumentConstraint argumentConstraints) Constructor used by subclasses whose name ends with "Function" and that accept a single, or a variable number of arguments.
BaseFunction(String name, ArgumentConstraint... argumentConstraints) Constructor used by subclasses that provide a custom name (not based on the class name) and that accept a fixed number of arguments.
BaseFunction(String name, ArgumentConstraint argumentConstraints) Constructor used by subclasses that provide a custom name (not based on the class name) and that accept a single, or a variable number of arguments.

Method Summary

Modifier and Type	Method and Description
ArgumentConstraint	argumentConstraints() Returns the constraints to use when checking the list of arguments before the function is called.
<T> T	call(Adapter<T> runtime, List<FunctionArgument<T>> arguments) Call this function with a list of arguments.
protected abstract <T> T	callFunction(Adapter<T> runtime, List<FunctionArgument<T>> arguments) Called from call(io.burt.jmespath.Adapter<T>, java.util.List<io.burt.jmespath.function.FunctionArgument<T>>) after the argument constraints have been checked against the arguments.
String	name() Returns the name of the function.

Methods inherited from class java.lang.Object

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

Constructor Detail

BaseFunction

public BaseFunction(ArgumentConstraint argumentConstraints)

Constructor used by subclasses whose name ends with "Function" and that accept a single, or a variable number of arguments.

Throws:

FunctionConfigurationException - when the function name cannot be produced from the class name

BaseFunction

public BaseFunction(ArgumentConstraint... argumentConstraints)

Constructor used by subclasses whose name ends with "Function" and that accept a fixed number of argument.

Throws:

FunctionConfigurationException - when the function name cannot be produced from the class name

BaseFunction

public BaseFunction(String name,
                    ArgumentConstraint... argumentConstraints)

Constructor used by subclasses that provide a custom name (not based on the class name) and that accept a fixed number of arguments.

BaseFunction

public BaseFunction(String name,
                    ArgumentConstraint argumentConstraints)

Constructor used by subclasses that provide a custom name (not based on the class name) and that accept a single, or a variable number of arguments.

Method Detail

name

public String name()

Description copied from interface: Function

Returns the name of the function.

The name is either automatically generated from the class name, or explicitly specified in the constructor.

Specified by:

name in interface Function

argumentConstraints

public ArgumentConstraint argumentConstraints()

Description copied from interface: Function

Returns the constraints to use when checking the list of arguments before the function is called.

Specified by:

argumentConstraints in interface Function

call

public <T> T call(Adapter<T> runtime,
                  List<FunctionArgument<T>> arguments)

Call this function with a list of arguments. The arguments can be either values or expressions, and will be checked by the function's argument constraints before the function runs.

Specified by:

call in interface Function

callFunction

protected abstract <T> T callFunction(Adapter<T> runtime,
                                      List<FunctionArgument<T>> arguments)

Called from call(io.burt.jmespath.Adapter<T>, java.util.List<io.burt.jmespath.function.FunctionArgument<T>>) after the argument constraints have been checked against the arguments.

May perform additional type checking and throw ArgumentTypeException. For example when using expressions there is currently no way to check the types produced by those expressions without running the function. Functions that accept expressions are responsible for checking the types of the values produced by those expressions.