Class ATokenList

DescriptionHierarchyFieldsMethodsProperties

Unit

Declaration

type ATokenList = class(ALinkedList)

Description

This class represents a list of tokens that can be used as a sequential list or a stack. It is designed to be used by instances of AParser and its descendants, wherein tokens read from a source stream are pushed onto the list and then popped off (and freed) as the source is parsed.

Hierarchy

  • ATokenList

Overview

Methods

Public function init: boolean; override;
Public procedure push(const ThisToken: AToken); virtual;
Public function Pop: AToken; virtual;
Public function TokenAt(const index: longint): AToken; virtual;
Public function FirstToken: AToken; virtual;
Public function LastToken: AToken; virtual;

Description

Methods

Public function init: boolean; override;

Initializer

Public procedure push(const ThisToken: AToken); virtual;

Push ThisToken onto the end of the list.

After calling this routine, ATokenList.LastToken will return a reference to ThisToken, while a call to ATokenList.Pop will remove ThisToken and return it to the caller.

Public function Pop: AToken; virtual;

Pop the last token from the list.

If there are no tokens on the list, this routine will return Nil. Otherwise, it returns the most recent token pushed onto the list by a call to ATokenList.push.

Public function TokenAt(const index: longint): AToken; virtual;

Retrieve the token at the specified index.

This method causes a sequential search of the list to be performed; for very large lists, therefore, it may be inefficient.

Index zero (0) represents the first token in the list, while the last token is always at index (ATokenList.census - 1). If index specifies a value that is greater than the number of items in the list, then this method returns the last item in the list.

Public function FirstToken: AToken; virtual;

Retrieve a reference to the first token in the list.

Public function LastToken: AToken; virtual;

Retrieve a reference to the last token in the list.


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