Class AST

java.lang.Object

com.hypixel.hytale.server.npc.util.expression.compile.ast.AST

Direct Known Subclasses:

ASTOperand, ASTOperator

public abstract class AST
extends Object

The AST (=Abstract Syntax Tree) is an intermediate form of the parsed expression suitable for high level optimisations and type checking. The AST represents a node in the expression tree and can have a variable amount of children as operands. Parser feeds the AST operators and operands in Reverse Polish Notation. Does simple optimisations like constant folding on direct child nodes.

Constructor Summary

Constructors

Constructor	Description
AST(ValueType valueType, Token token, int tokenPosition)

Method Summary

Modifier and Type	Method	Description
ExecutionContext.Operand	asOperand()
ValueType	genCode(List<ExecutionContext.Instruction> list, Scope scope)	Generate an instruction list from AST.
boolean	getBoolean()
Function<Scope, ExecutionContext.Instruction>	getCodeGen()
double	getNumber()
AST	getParent()
String	getString()
Token	getToken()
int	getTokenPosition()
ValueType	getValueType()
abstract boolean	isConstant()
ValueType	returnType()
void	setParent(AST parent)

Methods inherited from class Object

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

Constructor Details

AST

public AST(@Nonnull
 ValueType valueType,
 @Nonnull
 Token token,
 int tokenPosition)

Method Details

getParent

public AST getParent()

setParent

public void setParent(AST parent)

getValueType

@Nonnull
public ValueType getValueType()

getToken

@Nonnull
public Token getToken()

getTokenPosition

public int getTokenPosition()

getCodeGen

@Nullable
public Function<Scope, ExecutionContext.Instruction> getCodeGen()

isConstant

public abstract boolean isConstant()

asOperand

public ExecutionContext.Operand asOperand()

getString

public String getString()

getBoolean

public boolean getBoolean()

getNumber

public double getNumber()

returnType

@Nonnull
public ValueType returnType()

genCode

public ValueType genCode(@Nonnull
 List<ExecutionContext.Instruction> list,
 Scope scope)

Generate an instruction list from AST.

If provided a scope as argument any references to function and variables are resolved to suppliers/functions from this scope, making the instructions only run with the same scope/context. This makes it possible to bind instructions to a specific object and eliminates the need to update the symbol table, as values can be read directly from the bound objects(s) using the suppliers.

If the provided scope is null then variables and functions are looked up in the scope passed as argument when executing the instructions.

Parameters:

list - List to append instructions to

scope - if not null does deep resolve of variables and functions

Returns:

Result type of expression