// =============================================================================
// Project: Bracket-matching example of stack usage                File: token.c 
// =============================================================================
#include "token.h"

Token classify( char ch )
{
    static const string brackets = "[](){}<>";
    Token tok;
    tok.ch = ch;
    
    char* p = strchr( brackets, ch );  
    if (p==NULL) {
        tok.typ = BKT_NONE;
        tok.sense = SENSE_LEFT;          // arbitrary value
    }
    else {
        int pos = p-brackets;            // pointer difference gives subscript.
        tok.sense = (pos%2 == 0) ? SENSE_LEFT : SENSE_RIGHT;
        tok.typ = (pos/2);               // integer arithmetic, with truncation.
    }
    return tok;
}