#include <cfloat>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include "BLI_utildefines.h"
#include "BLT_translation.hh"
#include "DNA_anim_types.h"
#include "DNA_key_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "RNA_access.hh"
#include "RNA_define.hh"
#include "RNA_prototypes.hh"
#include "BKE_action.hh"
#include "BKE_context.hh"
#include "BKE_key.hh"
#include "BKE_lib_id.hh"
#include "BKE_nla.hh"
#include "BKE_report.hh"
#include "BKE_scene.hh"
#include "ANIM_action.hh"
#include "ED_anim_api.hh"
#include "ED_screen.hh"
#include "DEG_depsgraph.hh"
#include "WM_api.hh"
#include "WM_types.hh"
#include "UI_interface.hh"
#include "UI_interface_c.hh"
#include "action_intern.hh"

Functions
Utilities
AnimData *	ED_actedit_animdata_from_context (const bContext C, ID *r_adt_id_owner)

Create New Action
static bAction *	action_create_new (bContext C, bAction oldact)

static void	actedit_change_action (bContext C, bAction act)

New Action Operator
Criteria: 1) There must be an dope-sheet/action editor, and it must be in a mode which uses actions... OR The NLA Editor is active (i.e. Animation Data panel -> new action) 2) The associated AnimData block must not be in tweak-mode.
static bool	action_new_poll (bContext *C)

static int	action_new_exec (bContext C, wmOperator )

void	ACTION_OT_new (wmOperatorType *ot)

Action Push-Down Operator
Criteria: 1) There must be an dope-sheet/action editor, and it must be in a mode which uses actions. 2) There must be an action active. 3) The associated AnimData block must not be in tweak-mode.
static bool	action_pushdown_poll (bContext *C)

static int	action_pushdown_exec (bContext C, wmOperator op)

void	ACTION_OT_push_down (wmOperatorType *ot)

Action Stash Operator
static int	action_stash_exec (bContext C, wmOperator op)

void	ACTION_OT_stash (wmOperatorType *ot)

Action Stash & Create Operator
Criteria: 1) There must be an dope-sheet/action editor, and it must be in a mode which uses actions. 2) The associated AnimData block must not be in tweak-mode.
static bool	action_stash_create_poll (bContext *C)

static int	action_stash_create_exec (bContext C, wmOperator op)

void	ACTION_OT_stash_and_create (wmOperatorType *ot)

Action Unlink Operator
We use a custom unlink operator here, as there are some technicalities which need special care: 1) When in Tweak Mode, it shouldn't be possible to unlink the active action, or else, everything turns to custard. 2) If the Action doesn't have any other users, the user should at least get a warning that it is going to get lost. 3) We need a convenient way to exit Tweak Mode from the Action Editor
void	ED_animedit_unlink_action (bContext C, ID id, AnimData adt, bAction act, ReportList *reports, bool force_delete)

static bool	action_unlink_poll (bContext *C)

static int	action_unlink_exec (bContext C, wmOperator op)

static int	action_unlink_invoke (bContext C, wmOperator op, const wmEvent *event)

void	ACTION_OT_unlink (wmOperatorType *ot)

Action Browsing
static NlaStrip *	action_layer_get_nlastrip (ListBase *strips, float ctime)

static void	action_layer_switch_strip (const OwnedAnimData owned_adt, NlaTrack old_track, NlaStrip old_strip, NlaTrack nlt, NlaStrip strip)

One Layer Up Operator
static bool	action_layer_next_poll (bContext *C)

static int	action_layer_next_exec (bContext C, wmOperator op)

void	ACTION_OT_layer_next (wmOperatorType *ot)

One Layer Down Operator
static bool	action_layer_prev_poll (bContext *C)

static int	action_layer_prev_exec (bContext C, wmOperator op)

void	ACTION_OT_layer_prev (wmOperatorType *ot)