/**CFile****************************************************************

  FileNameIn  [parseEqn.c]

  PackageName [ABC: Logic synthesis and verification system.]

  Synopsis    [Boolean formula parser.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

  Date        [Ver. 1.0. Started - December 18, 2006.]

  Revision    [$Id: parseEqn.c,v 1.0 2006/12/18 00:00:00 alanmi Exp $]

***********************************************************************/

////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////

#include "parseInt.h"

ABC_NAMESPACE_IMPL_START


// the list of operation symbols to be used in expressions
#define PARSE_EQN_SYM_OPEN    '('   // opening parenthesis
#define PARSE_EQN_SYM_CLOSE   ')'   // closing parenthesis
#define PARSE_EQN_SYM_CONST0  '0'   // constant 0
#define PARSE_EQN_SYM_CONST1  '1'   // constant 1
#define PARSE_EQN_SYM_NEG     '!'   // negation before the variable
#define PARSE_EQN_SYM_AND     '*'   // logic AND
#define PARSE_EQN_SYM_OR      '+'   // logic OR

// the list of opcodes (also specifying operation precedence)
#define PARSE_EQN_OPER_NEG    10    // negation
#define PARSE_EQN_OPER_AND     9    // logic AND
#define PARSE_EQN_OPER_OR      7    // logic OR
#define PARSE_EQN_OPER_MARK    1    // OpStack token standing for an opening parenthesis

// these are values of the internal Flag
#define PARSE_EQN_FLAG_START   1    // after the opening parenthesis 
#define PARSE_EQN_FLAG_VAR     2    // after operation is received
#define PARSE_EQN_FLAG_OPER    3    // after operation symbol is received
#define PARSE_EQN_FLAG_ERROR   4    // when error is detected

#define PARSE_EQN_STACKSIZE 1000

static Hop_Obj_t * Parse_ParserPerformTopOp( Hop_Man_t * pMan, Parse_StackFn_t * pStackFn, int Oper );

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFINITIONS                         ///
////////////////////////////////////////////////////////////////////////

/**Function*************************************************************

  Synopsis    [Derives the AIG corresponding to the equation.]

  Description [Takes the stream to output messages, the formula, the vector
  of variable names and the AIG manager.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Hop_Obj_t * Parse_FormulaParserEqn( FILE * pOutput, char * pFormInit, Vec_Ptr_t * vVarNames, Hop_Man_t * pMan )
{
    char * pFormula;
    Parse_StackFn_t * pStackFn;
    Parse_StackOp_t * pStackOp;
    Hop_Obj_t * gFunc;
    char * pTemp, * pName;
    int nParans, fFound, Flag;
    int Oper, Oper1, Oper2;
    int i, v;

    // make sure that the number of opening and closing parentheses is the same
    nParans = 0;
    for ( pTemp = pFormInit; *pTemp; pTemp++ )
        if ( *pTemp == '(' )
            nParans++;
        else if ( *pTemp == ')' )
            nParans--;
    if ( nParans != 0 )
    {
        fprintf( pOutput, "Parse_FormulaParserEqn(): Different number of opening and closing parentheses ().\n" );
        return NULL;
    }

    // copy the formula
    pFormula = ABC_ALLOC( char, strlen(pFormInit) + 3 );
    sprintf( pFormula, "(%s)", pFormInit );

    // start the stacks
    pStackFn = Parse_StackFnStart( PARSE_EQN_STACKSIZE );
    pStackOp = Parse_StackOpStart( PARSE_EQN_STACKSIZE );

    Flag = PARSE_EQN_FLAG_START;
    for ( pTemp = pFormula; *pTemp; pTemp++ )
    {
        switch ( *pTemp )
        {
        // skip all spaces, tabs, and end-of-lines
        case ' ':
        case '\t':
        case '\r':
        case '\n':
            continue;
        case PARSE_EQN_SYM_CONST0:
            Parse_StackFnPush( pStackFn, Hop_ManConst0(pMan) );  // Cudd_Ref( b0 );
            if ( Flag == PARSE_EQN_FLAG_VAR )
            {
                fprintf( pOutput, "Parse_FormulaParserEqn(): No operation symbol before constant 0.\n" );
                Flag = PARSE_EQN_FLAG_ERROR; 
                break;
            }
            Flag = PARSE_EQN_FLAG_VAR; 
            break;
        case PARSE_EQN_SYM_CONST1:
            Parse_StackFnPush( pStackFn, Hop_ManConst1(pMan) );  //  Cudd_Ref( b1 );
            if ( Flag == PARSE_EQN_FLAG_VAR )
            {
                fprintf( pOutput, "Parse_FormulaParserEqn(): No operation symbol before constant 1.\n" );
                Flag = PARSE_EQN_FLAG_ERROR; 
                break;
            }
            Flag = PARSE_EQN_FLAG_VAR; 
            break;
        case PARSE_EQN_SYM_NEG:
            if ( Flag == PARSE_EQN_FLAG_VAR )
            {// if NEGBEF follows a variable, AND is assumed
                Parse_StackOpPush( pStackOp, PARSE_EQN_OPER_AND );
                Flag = PARSE_EQN_FLAG_OPER;
            }
            Parse_StackOpPush( pStackOp, PARSE_EQN_OPER_NEG );
            break;
        case PARSE_EQN_SYM_AND:
        case PARSE_EQN_SYM_OR:
            if ( Flag != PARSE_EQN_FLAG_VAR )
            {
                fprintf( pOutput, "Parse_FormulaParserEqn(): There is no variable before AND, EXOR, or OR.\n" );
                Flag = PARSE_EQN_FLAG_ERROR; 
                break;
            }
            if ( *pTemp == PARSE_EQN_SYM_AND )
                Parse_StackOpPush( pStackOp, PARSE_EQN_OPER_AND );
            else //if ( *pTemp == PARSE_EQN_SYM_OR )
                Parse_StackOpPush( pStackOp, PARSE_EQN_OPER_OR );
            Flag = PARSE_EQN_FLAG_OPER; 
            break;
        case PARSE_EQN_SYM_OPEN:
            if ( Flag == PARSE_EQN_FLAG_VAR )
            {
//                Parse_StackOpPush( pStackOp, PARSE_EQN_OPER_AND );
                fprintf( pOutput, "Parse_FormulaParserEqn(): An opening parenthesis follows a var without operation sign.\n" ); 
                Flag = PARSE_EQN_FLAG_ERROR; 
                break; 
            }
            Parse_StackOpPush( pStackOp, PARSE_EQN_OPER_MARK );
            // after an opening bracket, it feels like starting over again
            Flag = PARSE_EQN_FLAG_START; 
            break;
        case PARSE_EQN_SYM_CLOSE:
            if ( !Parse_StackOpIsEmpty( pStackOp ) )
            {
                while ( 1 )
                {
                    if ( Parse_StackOpIsEmpty( pStackOp ) )
                    {
                        fprintf( pOutput, "Parse_FormulaParserEqn(): There is no opening parenthesis\n" );
                        Flag = PARSE_EQN_FLAG_ERROR; 
                        break;
                    }
                    Oper = Parse_StackOpPop( pStackOp );
                    if ( Oper == PARSE_EQN_OPER_MARK )
                        break;

                    // perform the given operation
                    if ( Parse_ParserPerformTopOp( pMan, pStackFn, Oper ) == NULL )
                    {
                        Parse_StackFnFree( pStackFn );
                        Parse_StackOpFree( pStackOp );
                        fprintf( pOutput, "Parse_FormulaParserEqn(): Unknown operation\n" );
                        ABC_FREE( pFormula );
                        return NULL;
                    }
                }
            }
            else
            {
                fprintf( pOutput, "Parse_FormulaParserEqn(): There is no opening parenthesis\n" );
                Flag = PARSE_EQN_FLAG_ERROR; 
                break;
            }
            if ( Flag != PARSE_EQN_FLAG_ERROR )
                Flag = PARSE_EQN_FLAG_VAR; 
            break;


        default:
            // scan the next name
            for ( i = 0; pTemp[i] && 
                         pTemp[i] != ' ' && pTemp[i] != '\t' && pTemp[i] != '\r' && pTemp[i] != '\n' &&
                         pTemp[i] != PARSE_EQN_SYM_AND && pTemp[i] != PARSE_EQN_SYM_OR && pTemp[i] != PARSE_EQN_SYM_CLOSE; i++ )
              {
                    if ( pTemp[i] == PARSE_EQN_SYM_NEG || pTemp[i] == PARSE_EQN_SYM_OPEN )
                    {
                        fprintf( pOutput, "Parse_FormulaParserEqn(): The negation sign or an opening parenthesis inside the variable name.\n" );
                        Flag = PARSE_EQN_FLAG_ERROR; 
                        break;
                    }
              }
            // variable name is found
            fFound = 0;
            Vec_PtrForEachEntry( char *, vVarNames, pName, v )
                if ( strncmp(pTemp, pName, i) == 0 && strlen(pName) == (unsigned)i )
                {
                    pTemp += i-1;
                    fFound = 1;
                    break;
                }
            if ( !fFound )
            { 
                fprintf( pOutput, "Parse_FormulaParserEqn(): The parser cannot find var \"%s\" in the input var list.\n", pTemp ); 
                Flag = PARSE_EQN_FLAG_ERROR; 
                break; 
            }
            if ( Flag == PARSE_EQN_FLAG_VAR )
            {
                fprintf( pOutput, "Parse_FormulaParserEqn(): The variable name \"%s\" follows another var without operation sign.\n", pTemp ); 
                Flag = PARSE_EQN_FLAG_ERROR; 
                break; 
            }
            Parse_StackFnPush( pStackFn, Hop_IthVar( pMan, v ) ); // Cudd_Ref( pbVars[v] );
            Flag = PARSE_EQN_FLAG_VAR; 
            break;
        }

        if ( Flag == PARSE_EQN_FLAG_ERROR )
            break;      // error exit
        else if ( Flag == PARSE_EQN_FLAG_START )
            continue;  //  go on parsing
        else if ( Flag == PARSE_EQN_FLAG_VAR )
            while ( 1 )
            {  // check if there are negations in the OpStack     
                if ( Parse_StackOpIsEmpty(pStackOp) )
                    break;
                Oper = Parse_StackOpPop( pStackOp );
                if ( Oper != PARSE_EQN_OPER_NEG )
                {
                    Parse_StackOpPush( pStackOp, Oper );
                    break;
                }
                else
                {
                      Parse_StackFnPush( pStackFn, Hop_Not((Hop_Obj_t *)Parse_StackFnPop(pStackFn)) );
                }
            }
        else // if ( Flag == PARSE_EQN_FLAG_OPER )
            while ( 1 )
            {  // execute all the operations in the OpStack
               // with precedence higher or equal than the last one
                Oper1 = Parse_StackOpPop( pStackOp ); // the last operation
                if ( Parse_StackOpIsEmpty(pStackOp) ) 
                {  // if it is the only operation, push it back
                    Parse_StackOpPush( pStackOp, Oper1 );
                    break;
                }
                Oper2 = Parse_StackOpPop( pStackOp ); // the operation before the last one
                if ( Oper2 >= Oper1 )  
                {  // if Oper2 precedence is higher or equal, execute it
                    if ( Parse_ParserPerformTopOp( pMan, pStackFn, Oper2 ) == NULL )
                    {
                        fprintf( pOutput, "Parse_FormulaParserEqn(): Unknown operation\n" );
                        ABC_FREE( pFormula );
                        Parse_StackFnFree( pStackFn );
                        Parse_StackOpFree( pStackOp );
                        return NULL;
                    }
                    Parse_StackOpPush( pStackOp,  Oper1 );     // push the last operation back
                }
                else
                {  // if Oper2 precedence is lower, push them back and done
                    Parse_StackOpPush( pStackOp, Oper2 );
                    Parse_StackOpPush( pStackOp, Oper1 );
                    break;
                }
            }
    }

    if ( Flag != PARSE_EQN_FLAG_ERROR )
    {
        if ( !Parse_StackFnIsEmpty(pStackFn) )
        {    
            gFunc = (Hop_Obj_t *)Parse_StackFnPop(pStackFn);
            if ( Parse_StackFnIsEmpty(pStackFn) )
                if ( Parse_StackOpIsEmpty(pStackOp) )
                {
                    Parse_StackFnFree(pStackFn);
                    Parse_StackOpFree(pStackOp);
//                    Cudd_Deref( gFunc );
                    ABC_FREE( pFormula );
                    return gFunc;
                }
                else
                    fprintf( pOutput, "Parse_FormulaParserEqn(): Something is left in the operation stack\n" );
            else
                fprintf( pOutput, "Parse_FormulaParserEqn(): Something is left in the function stack\n" );
        }
        else
            fprintf( pOutput, "Parse_FormulaParserEqn(): The input string is empty\n" );
    }
    ABC_FREE( pFormula );
    return NULL;
}

/**Function*************************************************************

  Synopsis    [Performs the operation on the top entries in the stack.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Hop_Obj_t * Parse_ParserPerformTopOp( Hop_Man_t * pMan, Parse_StackFn_t * pStackFn, int Oper )
{
    Hop_Obj_t * gArg1, * gArg2, * gFunc;
    // perform the given operation
    gArg2 = (Hop_Obj_t *)Parse_StackFnPop( pStackFn );
    gArg1 = (Hop_Obj_t *)Parse_StackFnPop( pStackFn );
    if ( Oper == PARSE_EQN_OPER_AND )
        gFunc = Hop_And( pMan, gArg1, gArg2 );
    else if ( Oper == PARSE_EQN_OPER_OR )
        gFunc = Hop_Or( pMan, gArg1, gArg2 );
    else
        return NULL;
//    Cudd_Ref( gFunc );
//    Cudd_RecursiveDeref( dd, gArg1 );
//    Cudd_RecursiveDeref( dd, gArg2 );
    Parse_StackFnPush( pStackFn,  gFunc );
    return gFunc;
}


////////////////////////////////////////////////////////////////////////
///                       END OF FILE                                ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END

