自学教程：C++ yystrlen函数代码示例

/* Copy to YYRES the contents of YYSTR after stripping away unnecessary   quotes and backslashes, so that it's suitable for yyerror.  The   heuristic is that double-quoting is unnecessary unless the string   contains an apostrophe, a comma, or backslash (other than   backslash-backslash).  YYSTR is taken from yytname.  If YYRES is   null, do not copy; instead, return the length of what the result   would have been.  */static YYSIZE_Tyytnamerr (char *yyres, const char *yystr){    if (*yystr == '"')    {        YYSIZE_T yyn = 0;        char const *yyp = yystr;        for (;;)            switch (*++yyp)            {            case '/'':            case ',':                goto do_not_strip_quotes;            case '//':                if (*++yyp != '//')                    goto do_not_strip_quotes;            /* Fall through.  */            default:                if (yyres)                    yyres[yyn] = *yyp;                yyn++;                break;            case '"':                if (yyres)                    yyres[yyn] = '/0';                return yyn;            }do_not_strip_quotes:        ;    }    if (! yyres)        return yystrlen (yystr);    return yystpcpy (yyres, yystr) - yyres;}

/* Copy into *YYMSG, which is of size *YYMSG_ALLOC, an error message   about the unexpected token YYTOKEN for the state stack whose top is   YYSSP.   Return 0 if *YYMSG was successfully written.  Return 1 if *YYMSG is   not large enough to hold the message.  In that case, also set   *YYMSG_ALLOC to the required number of bytes.  Return 2 if the   required number of bytes is too large to store.  */static intyysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,                yytype_int16 *yyssp, int yytoken){  YYSIZE_T yysize0 = yytnamerr (YY_NULLPTR, yytname[yytoken]);  YYSIZE_T yysize = yysize0;  enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };  /* Internationalized format string. */  const char *yyformat = YY_NULLPTR;  /* Arguments of yyformat. */  char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];  /* Number of reported tokens (one for the "unexpected", one per     "expected"). */  int yycount = 0;  /* There are many possibilities here to consider:     - If this state is a consistent state with a default action, then       the only way this function was invoked is if the default action       is an error action.  In that case, don't check for expected       tokens because there are none.     - The only way there can be no lookahead present (in yychar) is if       this state is a consistent state with a default action.  Thus,       detecting the absence of a lookahead is sufficient to determine       that there is no unexpected or expected token to report.  In that       case, just report a simple "syntax error".     - Don't assume there isn't a lookahead just because this state is a       consistent state with a default action.  There might have been a       previous inconsistent state, consistent state with a non-default       action, or user semantic action that manipulated yychar.     - Of course, the expected token list depends on states to have       correct lookahead information, and it depends on the parser not       to perform extra reductions after fetching a lookahead from the       scanner and before detecting a syntax error.  Thus, state merging       (from LALR or IELR) and default reductions corrupt the expected       token list.  However, the list is correct for canonical LR with       one exception: it will still contain any token that will not be       accepted due to an error action in a later state.  */  if (yytoken != YYEMPTY)    {      int yyn = yypact[*yyssp];      yyarg[yycount++] = yytname[yytoken];      if (!yypact_value_is_default (yyn))        {          /* Start YYX at -YYN if negative to avoid negative indexes in             YYCHECK.  In other words, skip the first -YYN actions for             this state because they are default actions.  */          int yyxbegin = yyn < 0 ? -yyn : 0;          /* Stay within bounds of both yycheck and yytname.  */          int yychecklim = YYLAST - yyn + 1;          int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;          int yyx;          for (yyx = yyxbegin; yyx < yyxend; ++yyx)            if (yycheck[yyx + yyn] == yyx && yyx != YYTERROR                && !yytable_value_is_error (yytable[yyx + yyn]))              {                if (yycount == YYERROR_VERBOSE_ARGS_MAXIMUM)                  {                    yycount = 1;                    yysize = yysize0;                    break;                  }                yyarg[yycount++] = yytname[yyx];                {                  YYSIZE_T yysize1 = yysize + yytnamerr (YY_NULLPTR, yytname[yyx]);                  if (! (yysize <= yysize1                         && yysize1 <= YYSTACK_ALLOC_MAXIMUM))                    return 2;                  yysize = yysize1;                }              }        }    }  switch (yycount)    {# define YYCASE_(N, S)                      /      case N:                               /        yyformat = S;                       /      break      YYCASE_(0, YY_("syntax error"));      YYCASE_(1, YY_("syntax error, unexpected %s"));      YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));      YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));      YYCASE_(4, YY_("syntax error, unexpected %s, expecting %s or %s or %s"));      YYCASE_(5, YY_("syntax error, unexpected %s, expecting %s or %s or %s or %s"));# undef YYCASE_    }  {    YYSIZE_T yysize1 = yysize + yystrlen (yyformat);//.........这里部分代码省略.........