include/ruby/internal/intern/parse.h: add doxygen

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

include/ruby/internal/intern/parse.h

@@ -21,41 +21,172 @@
  * @brief      Public APIs related to ::rb_cSymbol.
  */
 #include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/nonnull.h"
 #include "ruby/internal/dllexport.h"
 #include "ruby/internal/value.h"
 
 RBIMPL_SYMBOL_EXPORT_BEGIN()
 
-/* parse.y */
-ID rb_id_attrset(ID);
+/* symbol.c */
+
+/**
+ * Calculates an ID of attribute writer.   For instance it returns `:foo=` when
+ * passed `:foo`.
+ *
+ * @param[in]  id             An id.
+ * @exception  rb_eNameError  `id` is not for attributes (e.g. operator).
+ * @return     Calculated name of attribute writer.
+ */
+ID rb_id_attrset(ID id);
 
 RBIMPL_ATTR_CONST()
-int rb_is_const_id(ID);
+/**
+ * Classifies the given ID, then sees if it is a constant.  In case an ID is in
+ * Unicode (likely), its  "constant"-ness is determined if  its first character
+ * is  either upper  case or  title case.   Otherwise it  is detected  if case-
+ * folding the first character changes its case or not.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is a constant.
+ * @retval     0   It isn't.
+ */
+int rb_is_const_id(ID id);
 
 RBIMPL_ATTR_CONST()
-int rb_is_global_id(ID);
+/**
+ * Classifies the  given ID, then  sees if it is  a global variable.   A global
+ * variable must start with `$`.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is a global variable.
+ * @retval     0   It isn't.
+ */
+int rb_is_global_id(ID id);
 
 RBIMPL_ATTR_CONST()
-int rb_is_instance_id(ID);
+/**
+ * Classifies  the given  ID, then  sees  if it  is an  instance variable.   An
+ * instance variable must start with `@`, but not `@@`.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is an instance variable.
+ * @retval     0   It isn't.
+ */
+int rb_is_instance_id(ID id);
 
 RBIMPL_ATTR_CONST()
-int rb_is_attrset_id(ID);
+/**
+ * Classifies  the given  ID,  then sees  if  it is  an  attribute writer.   An
+ * attribute writer is otherwise a local variable, except it ends with `=`.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is an attribute writer.
+ * @retval     0   It isn't.
+ */
+int rb_is_attrset_id(ID id);
 
 RBIMPL_ATTR_CONST()
-int rb_is_class_id(ID);
+/**
+ * Classifies the  given ID,  then sees  if it  is a  class variable.   A class
+ * variable is must start with `@@`.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is a class variable.
+ * @retval     0   It isn't.
+ */
+int rb_is_class_id(ID id);
 
 RBIMPL_ATTR_CONST()
-int rb_is_local_id(ID);
+/**
+ * Classifies the  given ID,  then sees  if it  is a  local variable.   A local
+ * variable starts  with a lowercase  character, followed by  some alphanumeric
+ * characters or `_`, then ends with anything other than `!`, `?`, or `=`.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is a local variable.
+ * @retval     0   It isn't.
+ */
+int rb_is_local_id(ID id);
 
 RBIMPL_ATTR_CONST()
+/**
+ * Classifies the  given ID,  then sees  if it  is a  junk ID.   An ID  with no
+ * special syntactic structure is considered  junk.  This category includes for
+ * instance punctuation.
+ *
+ * @param[in]  id  An id to classify.
+ * @retval     1   It is a junk.
+ * @retval     0   It isn't.
+ */
 int rb_is_junk_id(ID);
-int rb_symname_p(const char*);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Sees if  the passed C string  constructs a valid syntactic  symbol.  Invalid
+ * ones for instance includes whitespaces.
+ *
+ * @param[in]  str  A C string to check.
+ * @retval     1    It is a valid symbol name.
+ * @retval     0    It is invalid as a symbol name.
+ */
+int rb_symname_p(const char *str);
+
+/* vm.c */
+
+/**
+ * Queries the last match, or `Regexp.last_match`, or the `$~`.  You don't have
+ * to use it, because in reality you can get `$~` using rb_gv_get() as usual.
+ *
+ * @retval  RUBY_Qnil  The method has not ran a regular expression.
+ * @retval  otherwise  An instance of ::rb_cMatch.
+ */
 VALUE rb_backref_get(void);
-void rb_backref_set(VALUE);
+
+/**
+ * Updates `$~`.  You don't have to use it, because in reality you can set `$~`
+ * using rb_gv_set() as usual.
+ *
+ * @param[in]  md  Arbitrary Ruby object.
+ * @post       The passed object is assigned to `$~`.
+ *
+ * @internal
+ *
+ * Yes, this  function bypasses  the Check_Type()  that would  normally prevent
+ * evil souls from assigning  evil objects to `$~`.  Use of  this function is a
+ * really bad smell.
+ */
+void rb_backref_set(VALUE md);
+
+/**
+ * Queries the last  line, or the `$_`.   You don't have to use  it, because in
+ * reality you can get `$_` using rb_gv_get() as usual.
+ *
+ * @retval  RUBY_Qnil  There has never been a "line" yet.
+ * @retval  otherwise  The last set `$_` value.
+ */
 VALUE rb_lastline_get(void);
-void rb_lastline_set(VALUE);
+
+/**
+ * Updates `$_`.  You don't have to use it, because in reality you can set `$_`
+ * using rb_gv_set() as usual.
+ *
+ * @param[in]  str  Arbitrary Ruby object.
+ * @post       The passed object is assigned to `$_`.
+ *
+ * @internal
+ *
+ * Unlike `$~`, you can assign non-strings to `$_`, even from ruby scripts.
+ */
+void rb_lastline_set(VALUE str);
 
 /* symbol.c */
+
+/**
+ * Collects every single bits of symbols  that have ever interned in the entire
+ * history of the current process.
+ *
+ * @return  An array that contains all symbols that have ever existed.
+ */
 VALUE rb_sym_all_symbols(void);
 
 RBIMPL_SYMBOL_EXPORT_END()