ANTLR4 version of Wrapper Generator

CFunction.g4

grammar CFunction;


function : retType name args ;

args :	 '(' arg (',' arg)* ')' ;

arg 	
  : 	'double' name 	# SCALAR_ARG
	|	'double' '*' name # ARRAY_ARG
	|	'int' name 	      # LENGTH_ARG
  ; 

retType	 
  :	'double' 	        # SCALAR_RET
	|	'double' '*' 	    # ARRAY_RET
	;

name : ID;

ID   : LETTER WORD*;

fragment
LETTER : 'a'..'z'|'A'..'Z';

fragment
DIGIT  : '0'..'9';

fragment
WORD   : LETTER | DIGIT | '_';

WS  : (' '|'\r'|'\t'|'\n')+ -> skip;

CFunctionWalker.java

// Generated from CFunction.g4 by ANTLR 4.0

import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.tree.TerminalNode;
import org.antlr.v4.runtime.tree.ErrorNode;
import org.antlr.stringtemplate.*;

import java.util.List;
import java.util.LinkedList;

public class CFunctionWalker extends CFunctionBaseListener {
  List<String> scalarArgs = new LinkedList<String>();
  List<String> arrayArgs = new LinkedList<String>();
  String functionName;
  List<String> lengthArgs = new LinkedList<String>();
  StringTemplate t;
  public String out;

  public CFunctionWalker( StringTemplate t_ ) {
    t = t_;
  }

	public void enterSCALAR_ARG(CFunctionParser.SCALAR_ARGContext ctx) { 
    scalarArgs.add( ctx.name().getText());  
  }

  public void enterARRAY_ARG(CFunctionParser.ARRAY_ARGContext ctx) { 
    arrayArgs.add( ctx.name().getText());  
  }

	@Override public void enterSCALAR_RET(CFunctionParser.SCALAR_RETContext ctx) { }
	@Override public void exitSCALAR_RET(CFunctionParser.SCALAR_RETContext ctx) { }

	@Override public void enterLENGTH_ARG(CFunctionParser.LENGTH_ARGContext ctx) { 
    lengthArgs.add( ctx.name().getText());  
  }

	@Override public void enterARRAY_RET(CFunctionParser.ARRAY_RETContext ctx) { }
	@Override public void exitARRAY_RET(CFunctionParser.ARRAY_RETContext ctx) { }

	public void enterFunction(CFunctionParser.FunctionContext ctx) { 
    functionName = ctx.name().getText();  
  }
	
  public void exitFunction(CFunctionParser.FunctionContext ctx) { 
    /*
    System.out.println( "Array arguments : " );
    for ( String array : arrayArgs ) System.out.println( array ); 
    System.out.println( "Scalar arguments : " );
    for ( String scalar : scalarArgs ) System.out.println( scalar ); 
    */

    t.setAttribute("name", functionName );
    t.setAttribute("len", lengthArgs );
    t.setAttribute("scalars", scalarArgs );
    t.setAttribute("arrays", arrayArgs );
    out = t.toString();
  }
}

MainV4.java

import org.antlr.v4.runtime.*;
import java.io.FileReader;

public class MainV4 {
  public static void main(String[] args) throws Exception {
    CharStream input = new ANTLRFileStream(args[0]);
    String templateFile;
    if ( args.length > 1 ) {
        templateFile = args[1];
    } else {
        templateFile = "PythonWrapper.stg";
    }
    String output = WrapperGenV4.generate( input, templateFile );
    System.out.println( output );
  }
}

WrapperGenV4.java

import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.tree.*;
import org.antlr.stringtemplate.*;
import java.io.FileReader;

public class WrapperGenV4 {

  public static String generate( String input, String templateFile ) 
  throws Exception {
      CharStream is = new ANTLRInputStream( input );
      return generate( is, templateFile );
  }

  public static String generate( String input ) 
  throws Exception {
      CharStream is = new ANTLRInputStream( input );
      return generate( is );
  }

  public static String generate( CharStream input ) throws Exception {
    return generate( input, "PythonWrapper.stg");
  }

  public static String generate( CharStream input, String templateFile ) throws Exception {
    CFunctionLexer lex = new CFunctionLexer(input);
    CommonTokenStream tokens = new CommonTokenStream(lex);
    CFunctionParser parser = new CFunctionParser(tokens);
    ParseTree tree = parser.function();

    FileReader groupFileR = new FileReader( templateFile );
    StringTemplateGroup templates = new StringTemplateGroup( groupFileR );
    groupFileR.close();
    StringTemplate t = templates.getInstanceOf( "function" );
    CFunctionWalker listener = new CFunctionWalker( t );
    
    ParseTreeWalker walker = new ParseTreeWalker( );
    walker.walk( listener, tree );

    return listener.out;
  }
}