YACC에서 SKELETON.C???

이게 어디다 쓰는 파일인지??? 설명 보면 이걸루 Yacc를

만들라구 하는데 -_-;;;

제가 파일을 하나 다운 받았는데 밑에 처럼 되어 있네요.

다른건 대충 이해 하겠는데 도무지 3번 4번 8번이

이해가 잘 안가네요 많은 도움 부탁 드립니다.

FREEGRM5.TXT This introductory file
GRAMMAR5.TXT Parsing ambiguities in C++, and in my grammar
CPP5.Y My YACC compatible C++ grammar
C5.Y My YACC compatible, ANSI C conformant grammar
CPP5.L Flex input file defining a C++ lexical analyzer
SKELGRPH.C A hacked file from the Berkeley YACC distribution
AUTODOC5.TXT Documentation for my machine generated analysis
Y.OUTPUT Machine generated analysis of the C++ grammar.

1) Get the entire source for Berkeley YACC 1.8 1/2/91
2) Verify that you can make the YACC
3) Rename SKELETON.C to SKELOLD.C, and implant SKELGRPH.C in that directory as SKELETON.C
4) Make the yacc using this new SKELETON.C
5) Using the above yacc, process my CPP5.Y file
yacc -dvl cpp5.y
The result should be a file y.tab.c, and y.tab.h
6) Using Flex (replacement for lex) to process my CPP5.L file
flex cpp5.l
the result should be yy.lex.c
7) Compile the two files
cc -o cpp5 y.tab.c yy.lex.c
the result should be an executable called cpp5
8) Set the environment variable YYDEBUG to 6
setenv YYDEBUG 6
If you don't do this, the graphical output will not appear!
9) Run the program cpp5
cpp5
10) Try the input
int a;
11) You should see a nice parse tree. Enjoy. Note that
the lexer DOES NOT INCLUDE A SYMBOL TABLE, and does
NOT KEEP TRACK OF CURRENT SCOPES. The hack (see the
CPP5.L file for details) is to assume that any identifier
that begins with a capital letter is a typedef name
Send complaints about code that doesn't parse "correctly".