de.flapdoodle.eval.core.parser

Class ASTNode

java.lang.Object

de.flapdoodle.eval.core.parser.ASTNode

Direct Known Subclasses:

ImmutableASTNode

@Value.Immutable
public abstract class ASTNode
extends Object

Expressions are parsed into an abstract syntax tree (AST). The tree has one root node and each node has zero or more children (parameters), depending on the operation. A leaf node is a numerical or string constant that has no more children (parameters). Other nodes define operators, functions and special operations like array index and structure separation.

The tree is evaluated from bottom (leafs) to top, in a recursive way, until the root node is evaluated, which then holds the result of the complete expression.

To be able to visualize the tree, a toJSON method is provided. The produced JSON string can be used to visualize the tree. OE.g. with this online tool:

Online JSON to Tree Diagram Converter

Constructor Summary

Constructors

Constructor and Description
ASTNode()

Method Summary

Modifier and Type	Method and Description
abstract List<ASTNode>	getParameters()
abstract Token	getToken()
static ASTNode	of(Token token, ASTNode... parameters)
String	toJSON() Produces a JSON string representation of this node ad all its children.

Methods inherited from class java.lang.Object

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

Constructor Detail

ASTNode

public ASTNode()

Method Detail

getParameters

public abstract List<ASTNode> getParameters()

getToken

public abstract Token getToken()

of

public static ASTNode of(Token token,
                         ASTNode... parameters)

toJSON

public String toJSON()

Produces a JSON string representation of this node ad all its children.

Returns:

A JSON string of the tree structure starting at this node.