如何使用ANTLRInputStream从文件读取输入？

Question

我在web 中尝试了很多例子，但找不到任何工作示例。如何使用ANTLRInputStream

所以文件 读取输入，我可以很容易地理解

所以，请提供一个工作的例子。

在此先感谢。

Answer 1

实际上，将标准FileInputStream传递给ANTLRInputStream并不复杂。

从可以看出，ANTLRInputStrean是什么它将接受相当宽松的文件，所以如果你有传递一个字符串或字符[]数组，那么我怀疑有麻烦的是更大的问题：

ANTLRInputStream() 
ANTLRInputStream(char[] data, int numberOfActualCharsInArray) 
This is the preferred constructor for strings as no data is copied 
ANTLRInputStream(InputStream input) 
ANTLRInputStream(InputStream input, int initialSize) 
ANTLRInputStream(InputStream input, int initialSize, int readChunkSize) 
ANTLRInputStream(Reader r) 
ANTLRInputStream(Reader r, int initialSize) 
ANTLRInputStream(Reader r, int initialSize, int readChunkSize) 
ANTLRInputStream(String input) 
Copy data in string to a local char array 

你问例如所以这里是例子：

import java.io.File; 
import java.io.FileInputStream; 
import java.io.IOException; 

import org.antlr.v4.runtime.ANTLRInputStream; 
import org.antlr.v4.runtime.CommonTokenStream; 
import org.antlr.v4.runtime.tree.ParseTree; 
import org.antlr.v4.runtime.tree.ParseTreeWalker; 

// You're going to need to implement these based on the grammar you've created 
import your.package.here.MyLangListener; 
import your.package.here.MyLangTranslator; 

// These are generated by ANTLR 
import your.package.here.parser.LangLexer; 
import your.package.here.LangParser; 


public class App { 
    public static void main(String[] args) { 
     String fileName = "someInputBasedOnYourGrammarRules.lang"; 
     File file = new File(fileName); 
     FileInputStream fis = null; 

     try { 
      // Open the input file stream 
      fis = new FileInputStream(file); 

      // Create a CharStream that reads from standard input 
      ANTLRInputStream input = new ANTLRInputStream(fis); 

      // Create a lexer that feeds off of input CharStream 
      LangLexer lexer = new LangLexer(input); 

      // Create a buffer of tokens pulled from the lexer 
      CommonTokenStream tokens = new CommonTokenStream(lexer); 

      // Create a parser that feeds off the tokens buffer 
      LangParser parser = new LangParser(tokens); 

      // Begin parsing at rule prog 
      ParseTree tree = parser.prog(); 

      // Close the input file 
      fis.close(); 

      // Create a generic parse tree walker that can trigger callbacks 
      ParseTreeWalker walker = new ParseTreeWalker(); 
      // Walk the tree created during the parse, trigger callbacks 
      walker.walk(new MyLangListener(), tree); 
      System.out.println(); // print a \n after translation 

      // Walk the tree again to translate to java 
      walker.walk(new MyLangTranslator(), tree); 

      // Print LISP-style tree 
      //System.out.println(tree.toStringTree(parser)); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 
} 

另外，我建议你使用ANTLR Maven插件。