使用antlr4生成java src AST的setps是：
>安装antlr4你可以使用this链接来做到这一点.
>安装后下载JAVA grammar from here.
>现在使用以下命令生成Java8Lexer和Java8Parser：
antlr4 -visitor Java8.g4
>这将生成几个文件,如Java8BaseListener.java Java8BaseVisitor.java Java8Lexer.java Java8Lexer.tokens Java8Listener.java Java8Parser.java Java8.tokens Java8Visitor.java
使用此代码生成AST：
import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.RuleContext;
import org.antlr.v4.runtime.tree.ParseTree;
public class ASTGenerator {
public static String readFile() throws IOException {
File file = new File("path/to/the/test/file.java");
byte[] encoded = Files.readAllBytes(file.toPath());
return new String(encoded, Charset.forName("UTF-8"));
}
public static void main(String args[]) throws IOException {
String inputString = readFile();
ANTLRInputStream input = new ANTLRInputStream(inputString);
Java8Lexer lexer = new Java8Lexer(input);
CommonTokenStream tokens = new CommonTokenStream(lexer);
Java8Parser parser = new Java8Parser(tokens);
ParserRuleContext ctx = parser.classDeclaration();
printAST(ctx, false, 0);
}
private static void printAST(RuleContext ctx, boolean verbose, int indentation) {
boolean toBeIgnored = !verbose && ctx.getChildCount() == 1 && ctx.getChild(0) instanceof ParserRuleContext;
if (!toBeIgnored) {
String ruleName = Java8Parser.ruleNames[ctx.getRuleIndex()];
for (int i = 0; i < indentation; i++) {
System.out.print(" ");
}
System.out.println(ruleName + " -> " + ctx.getText());
}
for (int i = 0; i < ctx.getChildCount(); i++) {
ParseTree element = ctx.getChild(i);
if (element instanceof RuleContext) {
printAST((RuleContext) element, verbose, indentation + (toBeIgnored ? 0 : 1));
}
}
}
}
完成编码后,您可以使用gradle构建项目,也可以在项目目录中下载antlr-4.7.1-complete.jar并开始编译.
如果你想要一个DOT文件中的输出,以便你可以看到AST然后你可以参考this QnA帖子或直接参考我使用gradle来构建项目的repository.
希望这可以帮助. ?