org.protelis.vm.util

Class StackImpl

java.lang.Object

org.protelis.vm.util.StackImpl

All Implemented Interfaces:

Stack

public final class StackImpl
extends java.lang.Object
implements Stack

Basic implementation of a Stack.

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.Deque<java.util.Map<Reference,java.lang.Object>>	stack

Constructor Summary

Constructors

Constructor and Description
StackImpl(java.util.Map<Reference,?> gamma)

Method Summary

Modifier and Type	Method and Description
java.lang.Object	get(Reference var) Look up a variable in the stack.
void	pop() Exit the current most-nested lexical scope.
void	push() Enter a new nested lexical scope.
java.lang.Object	put(Reference var, java.lang.Object val, boolean canShadow) Assign a value to a variable, either overwriting or shadowing prior value.
void	putAll(java.util.Map<Reference,?> map) Bind a collection of variable/value pairs into the current lexical scope, e.g., the arguments of a function.
private java.lang.Object	stackOperation(java8.util.function.Function<java.util.Map<Reference,java.lang.Object>,java.lang.Object> op)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

stack

private final java.util.Deque<java.util.Map<Reference,java.lang.Object>> stack

Constructor Detail

StackImpl

public StackImpl(java.util.Map<Reference,?> gamma)

Parameters:

gamma - Initial set of variables

Method Detail

push

public void push()

Description copied from interface: Stack

Enter a new nested lexical scope.

Specified by:

push in interface Stack

pop

public void pop()

Description copied from interface: Stack

Exit the current most-nested lexical scope.

Specified by:

pop in interface Stack

put

public java.lang.Object put(Reference var,
                            java.lang.Object val,
                            boolean canShadow)

Description copied from interface: Stack

Assign a value to a variable, either overwriting or shadowing prior value.

Specified by:

put in interface Stack

Parameters:

var - Name of the variable to be bound

val - Value to be assigned

canShadow - If true, then only values in the same lexical scope are overwritten; others are shadowed. If false, then prior value is always overwritten.

Returns:

Value overwritten, or null if no value is overwritten

stackOperation

private java.lang.Object stackOperation(java8.util.function.Function<java.util.Map<Reference,java.lang.Object>,java.lang.Object> op)

get

public java.lang.Object get(Reference var)

Description copied from interface: Stack

Look up a variable in the stack.

Specified by:

get in interface Stack

Parameters:

var - The variable to be looked up

Returns:

Value of the variable in the innermost lexical scope where it exists, if bound; otherwise null.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

putAll

public void putAll(java.util.Map<Reference,?> map)

Description copied from interface: Stack

Bind a collection of variable/value pairs into the current lexical scope, e.g., the arguments of a function.

Specified by:

putAll in interface Stack

Parameters:

map - Collection of variable/value pairs to be bound