include/ruby/internal/glob.h: add doxygen

Must not be a bad idea to improve documents. [ci skip]

include/ruby/internal/glob.h

@@ -20,15 +20,93 @@
  *             extension libraries.  They could be written in C++98.
  * @brief      Declares ::rb_glob().
  */
+#include "ruby/internal/attr/nonnull.h"
 #include "ruby/internal/dllexport.h"
 #include "ruby/internal/value.h"
 
 RBIMPL_SYMBOL_EXPORT_BEGIN()
 
-typedef int ruby_glob_func(const char*,VALUE, void*);
-void rb_glob(const char*,void(*)(const char*,VALUE,void*),VALUE);
-int ruby_glob(const char*,int,ruby_glob_func*,VALUE);
-int ruby_brace_glob(const char*,int,ruby_glob_func*,VALUE);
+/**
+ * Type of a glob callback function.  Called every time glob scans a path.
+ *
+ * @param[in]  path       The path in question.
+ * @param[in]  arg        The argument passed to rb_glob().
+ * @param[in]  enc        Encoding of the path.
+ * @retval     -1         Not enough memory to do the operation.
+ * @retval     0          Operation successful.
+ * @retval     otherwise  Opaque exception state.
+ * @note       You can use rb_protect() to generate the return value.
+ *
+ * @internal
+ *
+ * This  is a  wrong design.   Type of  `enc` should  have been  `rb_encoding*`
+ * instead of just `void*`.  But we cannot change the API any longer.
+ *
+ * Though not a part of our public API, the "opaque exception state" is in fact
+ * an  enum ruby_tag_type.   You can  see the  potential "otherwise"  values by
+ * looking at vm_core.h.
+ */
+typedef int ruby_glob_func(const char *path, VALUE arg, void *enc);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * The "glob"  operator.  Expands  the given pattern  against the  actual local
+ * filesystem,  then  iterates  over  the expanded  filenames  by  calling  the
+ * callback function.
+ *
+ * @param[in]  pattern        A glob pattern.
+ * @param[in]  func           Identical to ruby_glob_func,  except it can raise
+ *                            exceptions instead of returning opaque state.
+ * @param[in]  arg            Extra argument passed to func.
+ * @exception  rb_eException  Can propagate what `func` raises.
+ * @note       The  language  accepted   as  the  pattern  is   not  a  regular
+ *             expression.  It resembles shell's glob.
+ */
+void rb_glob(const char *pattern, void (*func)(const char *path, VALUE arg, void *enc), VALUE arg);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Identical to rb_glob(), except it returns opaque exception states instead of
+ * raising exceptions.
+ *
+ * @param[in]  pattern  A glob pattern.
+ * @param[in]  flags    No, you are not allowed to use this.  Just pass 0.
+ * @param[in]  func     A callback function.
+ * @param[in]  arg      Extra argument passed to func.
+ * @return     Return value of `func`.
+ *
+ * @internal
+ *
+ * This function is  completely broken by design...  Not only  is there no sane
+ * way to pass flags, but there also is no sane way to know what a return value
+ * is meant to be.
+ *
+ * Though not a part of our public API, and @shyouhei thinks it's a failure not
+ * to be  a public  API, the  flags can  be `FNM_EXTGLOB`,  `FNM_DOTMATCH` etc.
+ * Look at dir.c for the list.
+ *
+ * Though  not a  part  of our  public  API, the  return value  is  in fact  an
+ * enum ruby_tag_type.   You  can  see  the  potential  values  by  looking  at
+ * vm_core.h.
+ */
+int ruby_glob(const char *pattern, int flags, ruby_glob_func *func, VALUE arg);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Identical to  ruby_glob(), @shyouhei  currently suspects.   Historically you
+ * had to  call this function  instead of  ruby_glob() if the  pattern included
+ * "{x,y,...}" syntax.  However since commit 0f63d961169989a7f6dcf7c0487fe29da,
+ * ruby_glob() also  supports that syntax.   It seems  as of writing  these two
+ * functions  provide   basically  the   same  functionality  in   a  different
+ * implementation.  Is this analysis right?  Correct me! :FIXME:
+ *
+ * @param[in]  pattern  A glob pattern.
+ * @param[in]  flags    No, you are not allowed to use this.  Just pass 0.
+ * @param[in]  func     A callback function.
+ * @param[in]  arg      Extra argument passed to func.
+ * @return     Return value of `func`.
+ */
+int ruby_brace_glob(const char *pattern, int flags, ruby_glob_func *func, VALUE arg);
 
 RBIMPL_SYMBOL_EXPORT_END()