Chapter 3. Lexical Structure

最新推荐文章于 2023-09-13 16:38:38 发布

转载最新推荐文章于 2023-09-13 16:38:38 发布 · 164 阅读

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原文链接：http://www.cnblogs.com/extjs4/p/9149586.html

本文深入探讨了Java中表达式的构成与语法，包括表达式的不同层级如Expression1、Expression2、Expression3，以及类型定义如Type1、Type2、Type3等。详细解析了前缀操作符、后缀操作符、选择器、后置操作符等功能，并阐述了基本类型、字面量、参数类型等关键概念。

/**
 *  Expression = Expression1 [ExpressionRest]
 *  ExpressionRest = [AssignmentOperator Expression1]
 *  AssignmentOperator = "=" | "+=" | "-=" | "*=" | "/=" |
 *                       "&=" | "|=" | "^=" |
 *                       "%=" | "<<=" | ">>=" | ">>>="
 *  Type = Type1
 *  TypeNoParams = TypeNoParams1
 *  StatementExpression = Expression
 *  ConstantExpression = Expression
 */

/** Expression1   = Expression2 [Expression1Rest]
 *  Type1         = Type2
 *  TypeNoParams1 = TypeNoParams2
 */

/** Expression3    = PrefixOp Expression3
 *                 | "(" Expr | TypeNoParams ")" Expression3
 *                 | Primary {Selector} {PostfixOp}
 *
 *  Primary        = "(" Expression ")"
 *                 | Literal
 *                 | [TypeArguments] THIS [Arguments]
 *                 | [TypeArguments] SUPER SuperSuffix
 *                 | NEW [TypeArguments] Creator
 *                 | Ident { "." Ident }
 *                   [
 *                     "[" ( "]" BracketsOpt "." class | Expression "]" )
 *                      | Arguments
 *                      | "." ( class | THIS | [TypeArguments] SUPER Arguments | NEW [TypeArguments] InnerCreator )
 *                   ]
 *                 | BasicType BracketsOpt "." class
 *
 *  PrefixOp       = "++" | "--" | "!" | "~" | "+" | "-"
 *
 *  PostfixOp      = "++" | "--"
 *
 *  Type3          = Ident { "." Ident } [TypeArguments] {TypeSelector} BracketsOpt
 *                 | BasicType
 *
 *  TypeNoParams3  = Ident { "." Ident } BracketsOpt 其中的bracketsOpt的是方括号
 *
 *  Selector       = "." [TypeArguments] Ident [Arguments]
 *                 | "." THIS
 *                 | "." [TypeArguments] SUPER SuperSuffix
 *                 | "." NEW [TypeArguments] InnerCreator
 *                 | "[" Expression "]"
 *
 *  TypeSelector   = "." Ident [TypeArguments]
 *
 *  SuperSuffix    = Arguments | "." Ident [Arguments]
 *
 *  弄清方括号与花括号所表示的文法的含义
 */

转载于:https://www.cnblogs.com/extjs4/p/9149586.html