ECMAScript for XML Specification(Ecma-357)(5)

The InputElementDiv symbol is used in those syntactic grammar contexts where a division (/), division-assignment (/=), less than (<), less than or equals (<=), left shift (<<) or left shift-assignment (<<=) operator is permitted. The InputElementXMLTag is used in those syntactic contexts where the literal contents of an XML tag are permitted. The InputElementXMLContent is used in those syntactic contexts where the literal contents of an XML element are permitted. The InputElementRegExp symbol is used in all other syntactic grammar contexts.

The addition of the production InputElementRegExp :: XMLMarkup and extended use of the existing production InputElementRegExp :: Punctuator :: < allow the start of XML initialisers to be identified.

To better understand when these goal symbols apply, consider the following example:

order = <{x}>{item}</{x}>;

The input elements returned from the lexical grammar along with the goal symbol and productions used for this example are as follows:

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欧洲计算机制造商协会(ECMA)标准文档

Input Element order = < { x } > { item } </ { x } > ;

Syntax

E4X extends the InputElementRegExp goal symbol defined by ECMAScript with the following production:

InputElementRegExp :: XMLMarkup

E4X extends ECMAScript by adding the following goal symbols:

InputElementXMLTag ::

XMLTagCharacters XMLTagPunctuator XMLAttributeValue XMLWhitespace {

InputElementXMLContent :: XMLMarkup XMLText { < [ lookahead { ?, ! } ] </

Goal

InputElementRegExp InputElementDiv InputElementRegExp InputElementXMLTag InputElementRegExp InputElementDiv InputElementXMLTag

Productions Token::Identifer Punctuator Punctuator {

Token::Identifier Punctuator XMLTagPunctuator

InputElementXMLContent { InputElementRegExp InputElementDiv

Token::Identifier Punctuator

InputElementXMLContent </ InputElementXMLTag InputElementRegExp InputElementDiv InputElementXMLTag InputElementRegExp

{

Token::Identifier Punctuator XMLTagPunctuator Token::Punctuator

8.1 Context Keywords

E4X extends ECMAScript by adding a set of context keywords. Context keywords take on a specific meaning when

used in specified contexts where identifiers are not permitted by the syntactic grammar. However, they differ from ECMAScript Edition 3 keywords in that they may also be used as identifiers. E4X does not add any additional keywords to ECMAScript.

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