Package nz.org.riskscape.rl.ast

Class Lambda

java.lang.Object

nz.org.riskscape.rl.ast.Lambda

All Implemented Interfaces:

Expression

public class Lambda
extends Object

A lambda expression in the RiskScape language is a self-contained expression that can be applied to a list of arguments. A lambda expression can be in the form: ( [ARG1[, ARGn]] ) -> EXPRESSION or ARG -> EXPRESSION for a one-arg lambda.

A classic example for the use of a lambda function is for applying a mapping operation to a list - this can be expressed with a lambda expression like so: map([1, 2, 3, 4], element -> element * 2).

Constructor Summary

Constructors

Constructor	Description
Lambda(Token left, List<Token> arguments, Expression expression)	Creates a new Lambda instance.

Method Summary

Modifier and Type	Method	Description
<T, R> R	accept(ExpressionVisitor<T,R> visitor, T data)
protected void	appendSource(StringBuilder appendTo)	Implementers extend this to append their source to the given string builder.
protected boolean	canEqual(Object other)
boolean	equals(Object o)
List<Token>	getArguments()	Names of the arguments as given in the source
Optional<Pair<Token,Token>>	getBoundary()
Expression	getExpression()	The expression to be evaluated, scoped to the list of arguments
Token	getLeft()
int	hashCode()
final String	toSource()
final String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface nz.org.riskscape.rl.ast.Expression

isA

Constructor Details

Lambda

public Lambda(Token left,
 List<Token> arguments,
 Expression expression)

Creates a new Lambda instance.

Parameters:

left -

arguments - Names of the arguments as given in the source

expression - The expression to be evaluated, scoped to the list of arguments

Method Details

getBoundary

public Optional<Pair<Token,Token>> getBoundary()

Returns:

a pair of tokens that represent the start and end of this expression, to be used when giving users information about where errors have occurred. If the expression has been rebuilt then the boundary may be empty or it may be from the original expression. Intended for use in problems to trace errors back to their source.

accept

public <T,
R> R accept(ExpressionVisitor<T,R> visitor,
 T data)

appendSource

protected void appendSource(StringBuilder appendTo)

Implementers extend this to append their source to the given string builder. Done via string builder to encourage a more efficient implementation than is possible with concatenating multiple toString calls that typically contruct a string builder anyway.

equals

public boolean equals(Object o)

canEqual

protected boolean canEqual(Object other)

hashCode

public int hashCode()

getLeft

public Token getLeft()

getArguments

public List<Token> getArguments()

Names of the arguments as given in the source

getExpression

public Expression getExpression()

The expression to be evaluated, scoped to the list of arguments

toString

public final String toString()

Overrides:

toString in class Object

Returns:

the source, surrounded by the class name to make it easier to discern from a plane string among other debug output

toSource

public final String toSource()

Specified by:

toSource in interface Expression

Returns:

a normalized version of the AST that can be parsed to be exactly the same AST as this