s/stringport.h

#define STRPORT_CHAR 0
#define STRPORT_FILE 1

typedef struct {
  int kind;

  // kind=STRPORT_CHAR
  char *text;
  int place;

  // kind=STRPORT_FILE
  FILE *fptr;
} string_port;

int port_peek(string_port *port);
int port_eof(string_port *port);
int port_getc(string_port *port);