Introduction
I'm abandoning this post mid-stream...seems that regular alternatives can match erroneous input just as easily as so-called error alternatives. Because of adaptive LL
, it shouldn't affect production speed at all once it gets warmed up.
ANTLR has a built-in mechanism to detect, report, and recover from syntax errors. It seems to do a pretty good job. Certainly it's better than PEG, which can't detect errors until EOF. It does single token insertion and deletion automatically to deal with lots of common cases where people forget a symbol or have an extra one like "f(x;" and "f((x);".
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