rpal20.java

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;

import rpal.AST;
import rpal.CSEMachine;

import rpal.Parser;
import rpal.LexicalAnalyzer;


public class rpal20 {

  public static String fileName;

  public static void main(String[] args){
    boolean listFlag = false;
    boolean astFlag = false;
    boolean stFlag = false;
    boolean noOutFlag = false;
    fileName = "";
    AST ast = null;
    
    for(String cmdOption: args){
      if(cmdOption.equals("-help")){
        printHelp();
        return;
      }
      else if(cmdOption.equals("-l"))
        listFlag = true;
      else if(cmdOption.equals("-ast"))
        astFlag = true;
      else if(cmdOption.equals("-st"))
        stFlag = true;
      else if(cmdOption.equals("-noout"))
        noOutFlag = true;
      else
        fileName = cmdOption;
    }
    
    //calling P2 without any switches should evaluate the program and print the result
    if(!listFlag && !astFlag && !stFlag && !noOutFlag){
      ast = buildAST(fileName, true);
      ast.standardize();
      evaluateST(ast);
      return;
    }
    
    if(listFlag){
      if(fileName.isEmpty())
        throw new RuntimeException("Please specify a file. Call P2 with -help to see examples");
      printInputListing(fileName);
    }
    
    if(astFlag){
      if(fileName.isEmpty())
        throw new RuntimeException("Please specify a file. Call P2 with -help to see examples");
      ast = buildAST(fileName, true);
      printAST(ast);
      if(noOutFlag)
        return;
      ast.standardize();
      evaluateST(ast);
    }
    
    if(stFlag){
      if(fileName.isEmpty())
        throw new RuntimeException("Please specify a file. Call P2 with -help to see examples");
      ast = buildAST(fileName, true);
      ast.standardize();
      printAST(ast);
      if(noOutFlag)
        return;
      evaluateST(ast);
    }
    
    //-noout without -ast or -st produces no output
    if(noOutFlag && (!astFlag || !stFlag)){
      if(fileName.isEmpty())
        throw new RuntimeException("Please specify a file. Call P2 with -help to see examples");
    }
   
  }

  private static void evaluateST(AST ast){
    CSEMachine csem = new CSEMachine(ast);
    csem.evaluateProgram();
    System.out.println();
  }

  private static void printInputListing(String fileName){
    BufferedReader buffer = null;
    try{
      buffer = new BufferedReader(new InputStreamReader(new FileInputStream(new File(fileName))));
      String s = "";
      while((s = buffer.readLine())!=null){
        System.out.println(s);
      }
    }catch(FileNotFoundException e){
      throw new RuntimeException("File "+fileName+" not found.");
    }catch(IOException e){
      throw new RuntimeException("Error reading from file "+fileName);
    }finally{
      try{
        if(buffer!=null) buffer.close();
      }catch(IOException e){
      }
    }
  }

  private static AST buildAST(String fileName, boolean printOutput){
    AST ast = null;
    try{
      LexicalAnalyzer scanner = new LexicalAnalyzer(fileName);
      Parser parser = new Parser(scanner);
      ast = parser.buildAST();
    }catch(IOException e){
      throw new RuntimeException("ERROR: Could not read from file: " + fileName);
    }
    return ast;
  }

  private static void printAST(AST ast){
    ast.printAST();
  }

  private static void printHelp(){
    System.out.println("Usage: java P2 [OPTIONS] FILE");
    System.out.println("Without any switches, prints only the result of evaluating the program");
    System.out.println("  -ast: prints the abstract syntax tree generated followed by the result");
    System.out.println("        of evaluating the program");
    System.out.println("        with -noout, prints only the abstract syntax tree generated");
    System.out.println("   -st: prints the standardized syntax tree generated followed by the result");
    System.out.println("        of evaluating the program");
    System.out.println("        with -noout, prints only the standardized syntax tree generated");
    System.out.println("    -l: prints the source code listing");
  }

}