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#include "formula.h"
subExceptionDef( ParseException );
Formula::Formula()
{
}
Formula::~Formula()
{
}
double Formula::run( const char *sFormula )
{
sBuf.write( sFormula, strlen( sFormula ) );
sBuf.setPos( 0 );
nState = 0;
for(;;)
{
tLook = nextToken();
if( tLook.nSym == symEOS )
break;
state();
}
printf("\n");
return 0.0;
}
void Formula::state()
{
switch( nState )
{
case 0: // initial expr
switch( tLook.nSym )
{
case symNumber:
push();
nState = 1;
break;
}
break;
case 1: // binary operator
switch( tLook.nSym )
{
case symAdd:
case symSubtract:
push();
nState = 2;
break;
case symMultiply:
case symDivide:
push();
nState = 3;
break;
}
break;
case 2: // add/subtract
break;
}
}
void Formula::push()
{
printToken( tLook );
sToken.push( tLook );
}
Formula::Token Formula::nextToken()
{
char cbuf;
for(;;)
{
if( sBuf.isEOS() )
return Token( symEOS );
sBuf.read( &cbuf, 1 );
switch( cbuf )
{
case '+':
return Token( symAdd );
case '-':
return Token( symSubtract );
case '*':
return Token( symMultiply );
case '/':
return Token( symDivide );
case '(':
return Token( symOpenParen );
case ')':
return Token( symCloseParen );
case ' ':
case '\t':
case '\n':
case '\r':
break;
default:
if( cbuf == '.' || (cbuf >= '0' && cbuf <= '9') )
{
char num[50];
int nPos = 0;
bool bDot = false;
for(;;)
{
num[nPos++] = cbuf;
if( cbuf == '.' )
{
if( bDot == false )
bDot = true;
else
throw ParseException(
"Numbers cannot have more than one "
". in them."
);
}
sBuf.read( &cbuf, 1 );
if( (cbuf != '.' && (cbuf < '0' || cbuf > '9')) ||
sBuf.isEOS() )
{
if( !sBuf.isEOS() ) sBuf.seek( -1 );
num[nPos] = '\0';
return Token( symNumber, strtod( num, NULL ) );
}
}
}
break;
}
}
}
void Formula::printToken( Token &tok )
{
switch( tok.nSym )
{
case symEOS: printf("[EOS] "); break;
case symAdd: printf("+ "); break;
case symSubtract: printf("- "); break;
case symMultiply: printf("* "); break;
case symDivide: printf("/ "); break;
case symOpenParen: printf("( "); break;
case symCloseParen: printf(") "); break;
case symNumber: printf("%f ", tok.val.num ); break;
default: printf("??? "); break;
}
}
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