> On 24 Apr 2015, at 15:47, John R. Levine <jo...@iecc.com> wrote:
>> Then, when the lexer finds it cannot scan forward anymore, by a character or >> EOS, it takes the longest match according to some rules and puts the rest >> stuff back into the stream for rescanning. > > That's not how flex works, unless you use the uncommon '/' trailing context > operator. It turns all of the patterns into a DFA and uses that to match the > input, not normally looking more than one character ahead. The DFA that bison > creates to do shifting should be able to do anything that the flex DFA can do. The DFA can only tell whether a full string is a match or not. When scanning forwards for the longest match, one must continue until there is a mismatch while recording the position for the final states one finds. The match is the final state with the highest position number: what remains must be put back. _______________________________________________ help-bison@gnu.org https://lists.gnu.org/mailman/listinfo/help-bison
