- (next-token PREFIX-CHAR-LIST BREAK-CHAR-LIST [COMMENT-STRING] [PORT])procedure
Skips any number of the prefix characters (members of the PREFIX-CHAR-LIST), if any, and reads the sequence of characters up to (but not including) a break character, one of the BREAK-CHAR-LIST. The string of characters thus read is returned. The break character is left on the input stream. The list of break characters may include EOF, which is to be coded as a symbol *eof*. Otherwise, EOF is fatal, generating an error message including a specified {COMMENT-STRING (if any)
The optional argument PORT defaults to the current input port.
Note: since we can't tell offhand how large the token being read is going to be, we make a guess, pre-allocate a string, and grow it by quanta if necessary. The quantum is always the length of the string before it was extended the last time. Thus the algorithm does a Fibonacci-type extension, which has been proven optimal. Note, explicit port specification in read-char, peek-char helps.