yacc

I'm trying to write a lex/yacc grammar for C11 based off of N1570. Most of my grammar is copied verbatim from the informative syntax summary, but some yacc conflicts arose. I've managed to resolve all of them except for one: there seems to be some ambiguity between when '_Atomic' is used as a type specifier and when it's used as a type qualifier. In the specifier form, _Atomic is followed immediately by parentheses, so I'm assuming it has something to do with C's little-used syntax which allows declarators to be in parentheses, thus allowing parentheses to immediately follow a qualifier. But

I have flex code that copies a string lexeme using strdup() . %{ #include "json.tab.h" #define YY_DECL extern "C" int yylex() %} %option noyywrap %% [ \t\n]+ ; \"[a-zA-Z]+\" {yylval.sval = strdup(yytext); return STRING; } [0-9]+ {yylval.ival = atoi(yytext); return NUMBER; } . {return yytext[0];} ; %% strdup() allocates memory and copies the input string into it and return ( strdup() - what does it do in C? ), so I guess I need to free it up when I don't need it anymore. From this post: When is %destructor invoked in BISON? , I added %destructor { free($$); printf("free");} STRING in the yacc

I am storing the arguments passed to main in yacc in a file. Now I want the lex to read its input from this file rather than the terminal. I know I can point yyin to a file like yyin = fopen("fn","r"); but this works only when main is in lex. When I use this yyin declaration in main in yacc, it shows an error so please suggest something to overcome this problem. You probably just need to declare extern FILE * yyin; If that doesn't solve the problem, please give the error message you got. 来源： https://stackoverflow.com/questions/1796520/in-lex-how-to-make-yyin-point-to-a-file-with-the-main

If I forget to put an empty line at the end of any of my files my program gets a syntax error. The problem is my grammar expects a newline to end the current line. Since a newline doesn't exist bison generates a syntax error because it does not finish the rule. How do I solve this? I tried making <<EOF>> return MY_EOF BUT when I do that lex crashes a horrible death. I guess there's code in its default EOF that I am not calling. I have no idea what functions they may be. Using EOF create the error symbol EOF is used, but is not defined as a token and has no rules You could use a flex EOF rule

Is there a good parser generator (think lex/yacc or antlr) for .NET? Any that have a license that would not scare lawyers? Lot’s of LGPL but I am working on embedded components and some organizations are not comfortable with me taking an LGPL dependency. I've heard that Oslo may provide this functionality but I'm not sure if it's a build time dependency or also a runtime dependency. Can anyone clarify what Oslo will provide? UPDATE What I would really like is a parser generator that is a build time only dependency. It looks like ANTLR has a runtime component. I just discovered that F# ships

So this is kind of a trivial question, but it's bugging me that I can't answer it, and perhaps the answer will teach me some more details about how R works. The title says it all: how does R parse -> , the obscure right-side assignment function? My usual tricks to dive into this failed: `->` Error: object -> not found getAnywhere("->") no object named -> was found And we can't call it directly: `->`(3,x) Error: could not find function "->" But of course, it works: (3 -> x) #assigns the value 3 to the name x # [1] 3 It appears R knows how to simply reverse the arguments, but I thought the above