while (<>) {
    if (/^#ERRORS/ .. /^CELLS/) {
        push(@errors, $_);
    } elsif (/^CELLS/ .. /^\s*$/) {
        push(@errors, $_);
    } else {
        ...; # other processing
    }
}
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Which doesn't work.

Occurs to me that it might be a useful enhancement to allow .. conditionX to be an additional stage to the preceding condition1 .. condition2, creating a linked cascade of flip-flops:

if    (/match1/ .. /match2/) { doStage1(); }
elsif (.. /match3/)          { doStage2(); }
elsif (.. /match4/)          { doStage3(); }
else                         { doOtherProcessing(); }
[download]

The semantics would be an extension of .. In the second example, match1 would trigger stage 1 (doStage1() will be called). Then match2 will end stage 1 and trigger stage 2 (doStage2() will be called). Then match3 ends stage 2 and triggers stage 3 (doStage3() will be called). Finally, match4 resets the cascade.

Thoughts?

Updated to mention the first example doesn't work.

Updated second example and the description of the semmantics.