MINIFICPP-474 Added getDelimitedField EL function

[achristianson]

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[phrocker]

Still getting a build failure.

/home/marc/dev/apache/nifi-minifi-cpp/extensions/expression-language/Scanner.cpp:932:25: error: expected constructor, destructor, or type conversion before ‘(’ token
yyFlexLexer::yyFlexLexer( FLEX_STD istream* arg_yyin, FLEX_STD ostream* arg_yyout ):
^

[achristianson]

@phrocker

Try deleting the following generated files & trying again:

/extensions/expression-language/Parser.*
/extensions/expression-language/Scanner.cpp
/extensions/expression-language/location.hh
/extensions/expression-language/position.hh
/extensions/expression-language/stack.hh

[achristianson]

@phrocker Also rm -rf thirdparty/flex. It might have some junk from another PR that is no longer in git.