由于Antlr4是Antlr的新版本，因此这是我第一次使用它。我已经从eclipse市场下载了Antlr4插件。
我做了一个新的ANTLR 4项目，我得到了Hello.g4
后来我看到了这个小语法:
/**
* Define a grammar called Hello
*/
grammar Hello;
r : 'hello' ID ; // match keyword hello followed by an identifier
ID : [a-z]+ ; // match lower-case identifiers
WS : [ \t\r\n]+ -> skip ; // skip spaces, tabs, newlines
一旦保存，就完成了，我从Antlr控制台中看到了它，我想测试该程序，但是我不知道如何，也不知道如何制作可以由新版本编译的新文件。语法？
在此先感谢您的帮助。
最佳答案
您需要创建一个生成的解析器的实例才能运行它。
A的
generated-sources/antlr4文件夹，并将此链接的文件夹作为源文件夹。出现编译错误。
解析器并向其提供文本。您可以从
ANTLR文档，为方便起见，粘贴在下面。
必须通过传递语法名称(在您的示例中为 Hello )和起始规则( r )来调用TestRig。
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.DefaultErrorStrategy;
import org.antlr.v4.runtime.DiagnosticErrorListener;
import org.antlr.v4.runtime.InputMismatchException;
import org.antlr.v4.runtime.Lexer;
import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.atn.PredictionMode;
import javax.print.PrintException;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
/** Run a lexer/parser combo, optionally printing tree string or generating
* postscript file. Optionally taking input file.
*
* $ java org.antlr.v4.runtime.misc.TestRig GrammarName startRuleName
* [-tree]
* [-tokens] [-gui] [-ps file.ps]
* [-trace]
* [-diagnostics]
* [-SLL]
* [input-filename(s)]
*/
public class Test {
public static final String LEXER_START_RULE_NAME = "tokens";
protected String grammarName;
protected String startRuleName;
protected final List<String> inputFiles = new ArrayList<String>();
protected boolean printTree = false;
protected boolean gui = false;
protected String psFile = null;
protected boolean showTokens = false;
protected boolean trace = false;
protected boolean diagnostics = false;
protected String encoding = null;
protected boolean SLL = false;
public Test(String[] args) throws Exception {
if ( args.length < 2 ) {
System.err.println("java org.antlr.v4.runtime.misc.TestRig GrammarName startRuleName\n" +
" [-tokens] [-tree] [-gui] [-ps file.ps] [-encoding encodingname]\n" +
" [-trace] [-diagnostics] [-SLL]\n"+
" [input-filename(s)]");
System.err.println("Use startRuleName='tokens' if GrammarName is a lexer grammar.");
System.err.println("Omitting input-filename makes rig read from stdin.");
return;
}
int i=0;
grammarName = args[i];
i++;
startRuleName = args[i];
i++;
while ( i<args.length ) {
String arg = args[i];
i++;
if ( arg.charAt(0)!='-' ) { // input file name
inputFiles.add(arg);
continue;
}
if ( arg.equals("-tree") ) {
printTree = true;
}
if ( arg.equals("-gui") ) {
gui = true;
}
if ( arg.equals("-tokens") ) {
showTokens = true;
}
else if ( arg.equals("-trace") ) {
trace = true;
}
else if ( arg.equals("-SLL") ) {
SLL = true;
}
else if ( arg.equals("-diagnostics") ) {
diagnostics = true;
}
else if ( arg.equals("-encoding") ) {
if ( i>=args.length ) {
System.err.println("missing encoding on -encoding");
return;
}
encoding = args[i];
i++;
}
else if ( arg.equals("-ps") ) {
if ( i>=args.length ) {
System.err.println("missing filename on -ps");
return;
}
psFile = args[i];
i++;
}
}
}
public static void main(String[] args) throws Exception {
Test test = new Test(args);
if(args.length >= 2) {
test.process();
}
}
public void process() throws Exception {
//System.out.println("exec "+grammarName+" "+startRuleName);
String lexerName = grammarName+"Lexer";
ClassLoader cl = Thread.currentThread().getContextClassLoader();
Class<? extends Lexer> lexerClass = null;
try {
lexerClass = cl.loadClass(lexerName).asSubclass(Lexer.class);
}
catch (java.lang.ClassNotFoundException cnfe) {
System.err.println("1: Can't load "+lexerName+" as lexer or parser");
return;
}
Constructor<? extends Lexer> lexerCtor = lexerClass.getConstructor(CharStream.class);
Lexer lexer = lexerCtor.newInstance((CharStream)null);
Class<? extends Parser> parserClass = null;
Parser parser = null;
if ( !startRuleName.equals(LEXER_START_RULE_NAME) ) {
String parserName = grammarName+"Parser";
parserClass = cl.loadClass(parserName).asSubclass(Parser.class);
if ( parserClass==null ) {
System.err.println("Can't load "+parserName);
}
Constructor<? extends Parser> parserCtor = parserClass.getConstructor(TokenStream.class);
parser = parserCtor.newInstance((TokenStream)null);
}
if ( inputFiles.size()==0 ) {
InputStream is = System.in;
Reader r;
if ( encoding!=null ) {
r = new InputStreamReader(is, encoding);
}
else {
r = new InputStreamReader(is);
}
process(lexer, parserClass, parser, is, r);
return;
}
for (String inputFile : inputFiles) {
InputStream is = System.in;
if ( inputFile!=null ) {
is = new FileInputStream(inputFile);
}
Reader r;
if ( encoding!=null ) {
r = new InputStreamReader(is, encoding);
}
else {
r = new InputStreamReader(is);
}
if ( inputFiles.size()>1 ) {
System.err.println(inputFile);
}
process(lexer, parserClass, parser, is, r);
}
}
protected void process(Lexer lexer, Class<? extends Parser> parserClass, Parser parser, InputStream is, Reader r) throws IOException, IllegalAccessException, InvocationTargetException, PrintException {
try {
ANTLRInputStream input = new ANTLRInputStream(r);
lexer.setInputStream(input);
CommonTokenStream tokens = new CommonTokenStream(lexer);
tokens.fill();
if ( showTokens ) {
for (Object tok : tokens.getTokens()) {
System.out.println(tok);
}
}
if ( startRuleName.equals(LEXER_START_RULE_NAME) ) return;
if ( diagnostics ) {
parser.addErrorListener(new DiagnosticErrorListener());
parser.getInterpreter().setPredictionMode(PredictionMode.LL_EXACT_AMBIG_DETECTION);
}
if ( printTree || gui || psFile!=null ) {
parser.setBuildParseTree(true);
}
if ( SLL ) { // overrides diagnostics
parser.getInterpreter().setPredictionMode(PredictionMode.SLL);
}
parser.setTokenStream(tokens);
parser.setTrace(trace);
//parser.setErrorHandler(new BailErrorStrategy());
try {
Method startRule = parserClass.getMethod(startRuleName);
ParserRuleContext tree = (ParserRuleContext)startRule.invoke(parser, (Object[])null);
if ( printTree ) {
System.out.println(tree.toStringTree(parser));
}
if ( gui ) {
tree.inspect(parser);
}
if ( psFile!=null ) {
tree.save(parser, psFile); // Generate postscript
}
}
catch (NoSuchMethodException nsme) {
System.err.println("No method for rule "+startRuleName+" or it has arguments");
}
}
finally {
if ( r!=null ) r.close();
if ( is!=null ) is.close();
}
}
@SuppressWarnings("unused")
private static class BailErrorStrategy extends DefaultErrorStrategy {
/** Instead of recovering from exception e, rethrow it wrapped
* in a generic RuntimeException so it is not caught by the
* rule function catches. Exception e is the "cause" of the
* RuntimeException.
*/
@Override
public void recover(Parser recognizer, RecognitionException e) {
throw new RuntimeException(e);
}
/** Make sure we don't attempt to recover inline; if the parser
* successfully recovers, it won't throw an exception.
*/
@Override
public Token recoverInline(Parser recognizer)
throws RecognitionException
{
throw new RuntimeException(new InputMismatchException(recognizer));
}
/** Make sure we don't attempt to recover from problems in subrules. */
@Override
public void sync(Parser recognizer) { }
}
}
'希望这可以帮助!
关于eclipse - 如何在Eclipse中使用antlr4？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/28352193/