Bison Syntax Error
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An action in the grammar can also explicitly proclaim an error, using the macro YYERROR (see Special Features for Use in Actions). The Bison parser expects to report the error by calling an error reporting function bison syntax error unexpected identifier named yyerror, which you must supply. It is called by yyparse whenever a syntax bison syntax error unexpected $end error is found, and it receives one argument. For a syntax error, the string is normally "syntaxerror". If you invoke ‘%define parse.error
Bison Syntax Error Unexpected End Of File
verbose’ in the Bison declarations section (see The Bison Declarations Section), then Bison provides a more verbose and specific error message string instead of just plain "syntaxerror". However, that message sometimes contains incorrect information if
Bison Syntax Error Line Number
LAC is not enabled (see LAC). The parser can detect one other kind of error: memory exhaustion. This can happen when the input contains constructions that are very deeply nested. It isn’t likely you will encounter this, since the Bison parser normally extends its stack automatically up to a very large limit. But if memory is exhausted, yyparse calls yyerror in the usual fashion, except that the argument string is "memoryexhausted". In syntax error yyparse some cases diagnostics like "syntaxerror" are translated automatically from English to some other language before they are passed to yyerror. See Internationalization. The following definition suffices in simple programs: void yyerror (char const *s) { fprintf (stderr, "%s\n", s); } After yyerror returns to yyparse, the latter will attempt error recovery if you have written suitable error recovery grammar rules (see Error Recovery). If recovery is impossible, yyparse will immediately return 1. Obviously, in location tracking pure parsers, yyerror should have an access to the current location. With %define api.pure, this is indeed the case for the GLR parsers, but not for the Yacc parser, for historical reasons, and this is the why %define api.pure full should be prefered over %define api.pure. When %locations %define api.pure full is used, yyerror has the following signature: void yyerror (YYLTYPE *locp, char const *msg); The prototypes are only indications of how the code produced by Bison uses yyerror. Bison-generated code always ignores the returned value, so yyerror can return any type, including void. Also, yyerror can be a variadic function; that is why the message is always passed last. Traditionally yyerror returns an int that is always ignored, but this is purely for historical reasons, and void is preferable since it more accurately describes
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Yacc Syntax Error End Of File
Learn more about Stack Overflow the company Business Learn more about hiring developers or bison yacc posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow yyerror Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Syntax error in Bison after one token is https://www.gnu.org/s/bison/manual/html_node/Error-Reporting.html processed up vote 2 down vote favorite 1 I am trying to come up to speed on Flex and Bison. I can parse one token with a very simple "language" but it fails on the second, even though the token is legitimate. test.l: %{ #include
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more http://stackoverflow.com/questions/12114673/bison-unexpected-indentifier-error about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each http://dinosaur.compilertools.net/bison/bison_7.html other. Join them; it only takes a minute: Sign up Bison unexpected indentifier error up vote 0 down vote favorite %{ #include
needs to use. Keep in mind that the parser uses many C identifiers starting with `yy' and `YY' for internal purposes. If you use such an identifier (aside from those in this manual) in an action or in additional C code in the grammar file, you are likely to run into trouble. The Parser Function yyparse You call the function yyparse to cause parsing to occur. This function reads tokens, executes actions, and ultimately returns when it encounters end-of-input or an unrecoverable syntax error. You can also write an action which directs yyparse to return immediately without reading further. The value returned by yyparse is 0 if parsing was successful (return is due to end-of-input). The value is 1 if parsing failed (return is due to a syntax error). In an action, you can cause immediate return from yyparse by using these macros: YYACCEPT Return immediately with value 0 (to report success). YYABORT Return immediately with value 1 (to report failure). The Lexical Analyzer Function yylex The lexical analyzer function, yylex, recognizes tokens from the input stream and returns them to the parser. Bison does not create this function automatically; you must write it so that yyparse can call it. The function is sometimes referred to as a lexical scanner. In simple programs, yylex is often defined at the end of the Bison grammar file. If yylex is defined in a separate source file, you need to arrange for the token-type macro definitions to be available there. To do this, use the `-d' option when you run Bison, so that it will write these macro definitions into a separate header file `name.tab.h' which you can include in the other source files that need it. See section Invoking Bison. Calling Convention for yylex The value that yylex returns must be the numeric code for the type of token it has just found, or 0 for end-of-input. When a token is referred to in the grammar rules by a name, that name in the parser file becomes a C macro whose definition is the proper numeric code for