ANTLR
Table of Contents
1. ANTLR 简介
ANTLR, or ANother Tool for Language Recognition, is a parser generator that uses LL(*) parsing.
1.1. Where is it used?
Here is a non-comprehensive list of software built using ANTLR:
- Groovy
- Jython
- Hibernate
- OpenJDK Compiler Grammar project experimental version of the javac compiler based upon a grammar written in ANTLR.
- Apex, Salesforce.com's programming language.
- The expression evaluator in Numbers, Apple's spreadsheet.
- Twitter's search query language.
- Weblogic server
- IntelliJ IDEA and Clion.
Reference: http://en.wikipedia.org/wiki/ANTLR
1.2. 安装 ANTLR
安装 ANTLR，测试环境：Ubuntu 14.04
$ sudo apt-get install antlr3
说明：生成的 parser 无法单独运行，它需要 antlr runtime 的支持。
2. ANTLR 简单实例
下面实例来自：The Definitive ANTLR Reference,2007, 1.4 节
第一步：准备 gammar 文件
$ cat T.g
grammar T;
/** Match things like "call foo;" */
r : 'call' ID ';' {System.out.println("invoke "+$ID.text);} ;
ID: 'a'..'z' + ;
WS: (' ' |'\n' |'\r' )+ {$channel=HIDDEN;} ; // ignore whitespace
第二步：生成词法和语法分析器
$ antlr3 T.g
运行成功后会生成三个文件：TLexer.java, TParser.java, T.tokens
第三步：准备测试类，入口函数 main
// file Test.java
import org.antlr.runtime.*;
public class Test {
public static void main(String[] args) throws Exception {
// create a CharStream that reads from standard input
ANTLRInputStream input = new ANTLRInputStream(System.in);
// create a lexer that feeds off of input CharStream
TLexer lexer = new TLexer(input);
// create a buffer of tokens pulled from the lexer
CommonTokenStream tokens = new CommonTokenStream(lexer);
// create a parser that feeds off the tokens buffer
TParser parser = new TParser(tokens);
// begin parsing at rule r
parser.r();
}
}
第四步：编译 java 文件
$ CLASSPATH=/usr/share/java/stringtemplate.jar:/usr/share/java/antlr3.jar:/usr/share/java/antlr3-runtime.jar javac *.java
第五步：运行程序
$ CLASSPATH=/usr/share/java/stringtemplate.jar:/usr/share/java/antlr3.jar:/usr/share/java/antlr3-runtime.jar:. java Test
启动后输入：
call abc;<EOF>
会输出：
invoke abc