The Definitive ANTLR4Reference 学习笔记

[3]The Definitive ANTLR 4 Reference

CHAPTER 2 Big Picture

Conceptions

CHAPTER 3-4 Demo

CHAPTER 5 Designing Grammars

Recognizing Common Language Patterns with ANTLR Grammars

dealing with Precedence, Left Recursion, and Associativity

Recognizing Common Lexical Structures

CHAPTER 6 Exploring Some Real Grammars󴖦

JSON

CHAPTER 7󴖦Decoupling Grammars from Application-Specific Code󴖦

Evolving from Embedded Actions to Listeners󴖦

Implementing Applications with Parse-Tree Listeners󴖦

Implementing Applications with Visitors󴖦

Labeling Rule Alternatives for Precise Event Methods󴖦

Listener和Visitor实现提供返回结果方式的区别

三种实现方法的示例

三种方法的对比和选取

CHAPTER 15󴖦Grammar Reference 可作为语法字典查询

CHAPTER 2 Big Picture

Conceptions

Language󴖦A language is a set of valid sentences; sentences are composed of phrases, which are composed of subphrases, and

so on.

Grammar A grammar formally defines the syntax rules of a language. Each rule in a grammar expresses the structure of a

subphrase.

Syntax tree or parse tree This represents the structure of the sentence where each subtree root gives an abstract name to

the elements beneath it. The subtree roots correspond to grammar rule names. The leaves of the tree are symbols or tokens

of the sentence.

input symbols to make decisions. Top- down parsers are goal-oriented and start matching at the rule associated with the

coarsest construct, such as program or inputFile.

Recursive-descent parser This is a specific kind of top-down parser implemented with a function for each rule in the

grammar.

Lookahead Parsers use lookahead to make decisions by comparing the symbols that begin each alternative.󴖦

Lexers process characters (short integers),

parsers process token types (integers).󴖦󴖦

1.

2.

3.

元素可以是关键字，字符串'RETR'，或标点符号

one or more elements, we use the + subrule operator, (INT)+ describes an arbitrarily long sequence of integers

zero-or-more * operator: INT*

zero-or-one sequence, specified with the ?

Pattern: Choice (Alternatives)

| as the “or” operator

例如choice of integers or strings.

field : INT | STRING ;

Pattern: Token Dependency

直接用(...), {...}, and [...].等符号表示token的一些附属

functionDecl

: type ID '(' formalParameters? ')' block // "void f(int x) {...}" ;

formalParameters

嵌套

stat: 'while' '(' expr ')' stat // match WHILE statement

| '{' stat* '}' // match block of statements in curlies

... // and other kinds of statements

dealing with Precedence, Left Recursion, and Associativity

优先级问题，坚持先定义高优先

例如：C语言中的指针优先级

󴖦

Recognizing Common Lexical Structures

lexer rule用大写字母

例如上面ID是包含FOR的但由于定义顺序，FOR可以匹配

【Tips】

【1】fragment

表示不作为token只在其他的lexcal中使用

󴖦

【2】字符串

用双引号包括

如字符串rule

STRING : .*? ; '"' '"' // match anything in "..."

【3】转义\或\\

STUFF : ~ + -> skip ; NL : ; '\n' '\n' // match and discard anything but a '\n'

CHAPTER 6 Exploring Some Real Grammars󴖦

给出5中解析的例子，可供学习些Grammars参考

CSV󴖦

JSON

Cymbol󴖦

R

JSON

其中JSON例子如下：