SQL: vers_current_time refactoring [closes #117]

* session sysvars;
* moved value parsing to set variable phase;
* renamed 'temporal_current_timestamp' to 'vers_current_time'.

1 files changed, 162 insertions, 0 deletions

diff --git a/sql/sys_vars.ic b/sql/sys_vars.ic
index 780450b484b..76bf8631630 100644
--- a/sql/sys_vars.ic
+++ b/sql/sys_vars.ic
@@ -2485,3 +2485,165 @@ public:
   bool global_update(THD *thd, set_var *var);
   uchar *global_value_ptr(THD *thd, const LEX_STRING *base);
 };
+
+
+class Sys_var_vers_asof: public sys_var
+{
+public:
+  Sys_var_vers_asof(
+    const char *name_arg,
+    const char *comment,
+    int flag_args,
+    ptrdiff_t off,
+    size_t size,
+    CMD_LINE getopt,
+    enum charset_enum is_os_charset_arg,
+    const char *def_val,
+    on_check_function on_check_func=0,
+    on_update_function on_update_func=0) :
+  sys_var(
+    &all_sys_vars,
+    name_arg,
+    comment,
+    flag_args,
+    off,
+    getopt.id,
+    getopt.arg_type,
+    SHOW_CHAR,
+    (intptr) def_val,
+    0,
+    VARIABLE_NOT_IN_BINLOG,
+    on_check_func,
+    on_update_func,
+    0)
+  {
+    option.var_type|= GET_STR;
+    if (global_update(def_val))
+    {
+      DBUG_ASSERT(false);
+    }
+  }
+
+  bool do_check(THD *thd, set_var *var)
+  { return false; }
+
+  bool update(String &in, st_vers_current_time &out)
+  {
+    if (in.length() == 3 &&
+      0 == my_strcasecmp(
+        in.charset(),
+        "ALL",
+        in.ptr()))
+    {
+      out.type= FOR_SYSTEM_TIME_ALL;
+    }
+    else if (in.length() == 3 &&
+      0 == my_strcasecmp(
+        in.charset(),
+        "NOW",
+        in.ptr()))
+    {
+      out.type= FOR_SYSTEM_TIME_UNSPECIFIED;
+    }
+    else
+    {
+      MYSQL_TIME_STATUS status;
+      if (str_to_datetime(
+            in.ptr(),
+            in.length(),
+            &out.ltime,
+            flags,
+            &status) ||
+          out.ltime.time_type != MYSQL_TIMESTAMP_DATETIME ||
+          (status.warnings & ~MYSQL_TIME_NOTE_TRUNCATED) != 0)
+      {
+        return true;
+      }
+      out.type= FOR_SYSTEM_TIME_AS_OF;
+    }
+    return false;
+  }
+  bool update(THD *thd, set_var *var, st_vers_current_time &out)
+  {
+    Item *item= var->value;
+
+    switch (item->result_type())
+    {
+    case TIME_RESULT:
+      {
+        if (item->get_date(&out.ltime, 0))
+          break;
+        out.type= FOR_SYSTEM_TIME_AS_OF;
+        return false;
+      }
+
+    case STRING_RESULT:
+      {
+        String *str= item->val_str();
+        if (!str || update(*str, out))
+          break;
+        return false;
+      }
+    default:
+      break;
+    }
+    String *str= item->val_str();
+    const char *cstr= str ? str->c_ptr_safe() : "NULL";
+    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), var->var->name.str, cstr);
+    return true;
+  }
+  bool global_update(const char *in)
+  {
+    String s(in, &my_charset_utf8_general_ci);
+    return update(s, global_var(st_vers_current_time));
+  }
+  bool option_updated()
+  {
+    return global_update(global_var(st_vers_current_time).str_value);
+  }
+  bool global_update(THD *thd, set_var *var)
+  {
+    return update(thd, var, global_var(st_vers_current_time));
+  }
+  bool session_update(THD *thd, set_var *var)
+  {
+    return update(thd, var, session_var(thd, st_vers_current_time));
+  }
+  uchar *valptr(THD *thd, st_vers_current_time &val)
+  {
+    switch (val.type)
+    {
+    case FOR_SYSTEM_TIME_UNSPECIFIED:
+      return (uchar*) thd->strdup("NOW");
+    case FOR_SYSTEM_TIME_ALL:
+      return (uchar*) thd->strdup("ALL");
+    case FOR_SYSTEM_TIME_AS_OF:
+      {
+        uchar *buf= (uchar*) thd->alloc(MAX_DATE_STRING_REP_LENGTH);
+        if (buf)
+        {
+          if (!my_datetime_to_str(&val.ltime, (char*) buf, 6))
+          {
+            my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), "vers_current_time", "NULL (wrong datetime)");
+            return (uchar*) thd->strdup("Error: wrong datetime");
+          }
+        }
+        return buf;
+      }
+    default:
+      break;
+    }
+    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), "vers_current_time", "NULL (wrong range type)");
+    return (uchar*) thd->strdup("Error: wrong range type");
+  }
+  void session_save_default(THD *thd, set_var *var)
+  { DBUG_ASSERT(false);  }
+  void global_save_default(THD *thd, set_var *var)
+  { DBUG_ASSERT(false); }
+  uchar *session_value_ptr(THD *thd, const LEX_STRING *base)
+  { return valptr(thd, session_var(thd, st_vers_current_time)); }
+  uchar *global_value_ptr(THD *thd, const LEX_STRING *base)
+  { return valptr(thd, global_var(st_vers_current_time)); }
+  uchar *default_value_ptr(THD *thd)
+  { return (uchar *)option.def_value; }
+};