#ifndef PROG_H
#define PROG_H
#include <iostream>
using namespace std;
#include "word.h"
#include "tree.t"
#include "lex.h"

class Prog{
private:
  Lex lex;
  int token;
  Tree<Word,int> tab;
public:
  Prog();
  void parse();
private:
  void input();
  void inc();
  void plus();
  void compute();
  void prog();
  void check(bool b, const char * mess);
  void next();
  void expect(int tok,const char *mess);
};
#endif

#include "prog.h"

Prog::Prog(){}

void Prog::parse(){
  Word line, linaux;
  cin>>line>>linaux;
  line+=' '; //white space to replace eoln
  //NOTE: I do not test whether all of "read" is on the
  //first line and the "write" starts the second line
  line+=linaux.str();
  lex.set(line);
  cout<<"Parse: "<<line<<endl;
  next();
  prog();
  check(token==Lex::EOLN," Junk at end of line");
  cout<<"Successful parse\n";
}

void Prog::prog(){
  input();
  expect(Lex::WRITE,"write");
  compute();
}

void Prog::input(){
  expect(Lex::READ,"read");
  check(token==Lex::IDENT," ident expected");
  while(token==Lex::IDENT){
    if(!tab.inTree(lex.str()))
      tab.add(lex.str());
    next();
  }
}
		  
void Prog::compute(){
  inc();
  while(token==Lex::SPLUS && lex.peek()==Lex::EQU){
    next();
    next();
    //    cout<<"in here\n";
    inc();
  }
}

void Prog::inc(){
  plus();
  //  cout<<"----->"<<lex.str()<<endl;
  while(token==Lex::SPLUS && lex.peek()==Lex::SPLUS){
    next();
    next();
    //  cout<<";===="<<endl;
  }
}

void Prog::plus(){
  switch(token){
  case Lex::IDENT:
    check(tab.inTree(lex.str()),"undeclared variable");
    // cout<<"----"<<lex.str()<<endl;
    next();
    break;
  case Lex::LT:
    next();
    compute();
    //    cout<<"HHH: '"<<lex.str()<<Lex::GT<<token<<"'\n";
    expect(Lex::GT,">");
    break;
  default:
    check(false," IDENT or '<' expected");
  }
}

void Prog::check(bool b, const char * mess){
  if(!b){
    //cerr<<"token="<<token<<" '"<<lex.str()<<"'\n";
    cerr.width(7+lex.count());
    cerr<<"^^"<<endl<<"ERROR: "<<mess<<endl;
    exit(1);
  }
}
  
void Prog::expect(int tok,const char * mess){
  Word temp('\'');
  temp+=mess;
  temp+="' expected";
  check(tok==token,temp.str());
  next();
}

void Prog::next(){
  token=lex.next();
}