ANTLR初探
ANTLR初探
1.下载ANTLR放在安装目录下
地址：https://www.antlr.org/download/index.html
D:\Dev\SrcCode\antlr\antlr-4.5.3-complete.jar
D:\Dev\SrcCode\antlr\antlr4.bat
2.编写bat脚本
java org.antlr.v4.Tool %*
3.添加环境变量到classpath
.;%JAVA_HOME%\lib;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\tools.jar;D:\Dev\SrcCode\antlr\antlr-4.5.3-complete.jar
添加变量路径到path
D:\Dev\SrcCode\antlr
4.添加依赖到项目
<dependency>
<groupId>org.antlr</groupId>
<artifactId>antlr4-runtime</artifactId>
<version>4.5.3</version>
</dependency>
5.编写ANTLR文件，LearnAntlr.g4
grammar LearnAntlr ; // grammer是规则文件的头，要和文件名一样
@header{ //header代表生成的代码放在哪个包里面
package com.antlr4;
}
r : 'hello' ID; //r代表的是语法树的根结点
ID : [a-z]+ ;
WS : [ \t\r\n]+ -> skip ; //ID代表未知的值
6.执行g4文件
D:\Dev\SrcCode\antlr> antlr4 ..\tech-climbing-common\basic-tech-bigdata\src\main\java\com\antlr4\LearnAntlr.g4
生成如下文件
7.新建ListenerRewrite继承LearnAntlrBaseListener
public class ListenerRewrite extends LearnAntlrBaseListener {
@Override
public void exitR(LearnAntlrParser.RContext ctx) {
final String a = ctx.getChild(0).getText().toLowerCase();
final String b = ctx.getChild(1).getText().toLowerCase();
System.out.println(a + " " + b);
}
}
8.词法语法解析测试
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.tree.ParseTreeWalker;
public class Antlr4Test {
public static void main(String[] args) throws IOException {
//输入文本hello world
ANTLRInputStream inputStream = new ANTLRInputStream(" hello world");
//词法分析器
LearnAntlrLexer lexer = new LearnAntlrLexer(inputStream);
//新建词法符号缓冲区，用于存储词法分析器生成的词法符号
CommonTokenStream tokenStream = new CommonTokenStream(lexer);
//新建语法分析器，处理词法符号缓冲区内容
LearnAntlrParser parser = new LearnAntlrParser(tokenStream);
//正对规则开始词法分析
LearnAntlrParser.RContext context = parser.r();
//构建监听器
ListenerRewrite listener = new ListenerRewrite();
//使用监听器初始化对词法分析树遍历
ParseTreeWalker.DEFAULT.walk(listener, context);
}
}
输出hello world
