An forward-iterable range that traverses a subtree of prims rooted at a given prim in depth-first order. More...

Classes
class	EndSentinel
	This class lets us represent past-the-end without the full weight of an iterator. More...

class	iterator
	A forward iterator into a UsdPrimRange. More...

Public Types
using	const_iterator = iterator

Public Member Functions
	UsdPrimRange (const UsdPrim &start)
	Construct a PrimRange that traverses the subtree rooted at `start` in depth-first order, visiting prims that pass the default predicate (as defined by UsdPrimDefaultPredicate). More...

	UsdPrimRange (const UsdPrim &start, const Usd_PrimFlagsPredicate &predicate)
	Construct a PrimRange that traverses the subtree rooted at `start` in depth-first order, visiting prims that pass `predicate`. More...

iterator	begin () const
	Return an iterator to the start of this range. More...

const_iterator	cbegin () const
	Return a const_iterator to the start of this range. More...

UsdPrim	front () const
	Return the first element of this range. The range must not be empty(). More...

iterator	end () const
	Return the past-the-end iterator for this range. More...

const_iterator	cend () const
	Return the past-the-end const_iterator for this range. More...

void	increment_begin ()
	Modify this range by advancing the beginning by one. More...

void	set_begin (iterator const &newBegin)
	Set the start of this range to `newBegin`. More...

bool	empty () const
	Return true if this range contains no prims, false otherwise. More...

	operator bool () const
	Return true if this range contains one or more prims, false otherwise. More...

bool	operator== (UsdPrimRange const &other) const
	Return true if this range is equivalent to `other`. More...

bool	operator!= (UsdPrimRange const &other) const
	Return true if this range is not equivalent to `other`. More...

Static Public Member Functions
static UsdPrimRange	PreAndPostVisit (const UsdPrim &start)
	Create a PrimRange that traverses the subtree rooted at `start` in depth-first order, visiting prims that pass the default predicate (as defined by UsdPrimDefaultPredicate) with pre- and post-order visitation. More...

static UsdPrimRange	PreAndPostVisit (const UsdPrim &start, const Usd_PrimFlagsPredicate &predicate)
	Create a PrimRange that traverses the subtree rooted at `start` in depth-first order, visiting prims that pass `predicate` with pre- and post-order visitation. More...

static UsdPrimRange	AllPrims (const UsdPrim &start)
	Construct a PrimRange that traverses the subtree rooted at `start` in depth-first order, visiting all prims (including deactivated, undefined, and abstract prims). More...

static UsdPrimRange	AllPrimsPreAndPostVisit (const UsdPrim &start)
	Construct a PrimRange that traverses the subtree rooted at `start` in depth-first order, visiting all prims (including deactivated, undefined, and abstract prims) with pre- and post-order visitation. More...

static USD_API UsdPrimRange	Stage (const UsdStagePtr &stage, const Usd_PrimFlagsPredicate &predicate=UsdPrimDefaultPredicate)
	Create a PrimRange that traverses all the prims on `stage`, and visits those that pass the default predicate (as defined by UsdPrimDefaultPredicate). More...

Detailed Description

An forward-iterable range that traverses a subtree of prims rooted at a given prim in depth-first order.

In addition to depth-first order, UsdPrimRange provides the optional ability to traverse in depth-first pre- and post-order wher prims appear twice in the range; first before all descendants and then again immediately after all descendants. This is useful for maintaining state associated with subtrees, in a stack-like fashion. See UsdPrimRange::iterator::IsPostVisit() to detect when an iterator is visiting a prim for the second time.

There are several constructors providing different levels of configurability; ultimately, one can provide a prim predicate for a custom iteration, just as one would use UsdPrim::GetFilteredChildren() in a custom recursion.

Why would one want to use a UsdPrimRange rather than just iterating over the results of UsdPrim::GetFilteredDescendants() ? Primarily, if one of the following applies:

You need to perform pre-and-post-order processing
You may want to prune sub-trees from processing (see UsdPrimRange::iterator::PruneChildren())
You want to treat the root prim itself uniformly with its descendents (GetFilteredDescendants() will not return the root prim itself, while UsdPrimRange will - see UsdPrimRange::Stage for an exception).

Using UsdPrimRange in C++

UsdPrimRange provides standard container-like semantics. For example:

*  // simple range-for iteration
*  for (UsdPrim prim: UsdPrimRange(rootPrim)) {
*      ProcessPrim(prim);
*  }
* 
*  // using stl algorithms
*  std::vector<UsdPrim> meshes;
*  auto range = stage->Traverse();
*  std::copy_if(range.begin(), range.end(), std::back_inserter(meshes),
*               [](UsdPrim const &) { return prim.IsA<UsdGeomMesh>(); });
* 
*  // iterator-based iterating, with subtree pruning
*  UsdPrimRange range(rootPrim);
*  for (auto iter = range.begin(); iter != range.end(); ++iter) {
*      if (UsdModelAPI(*iter).GetKind() == KindTokens->component) {
*          iter.PruneChildren();
*      }
*      else {
*          nonComponents.push_back(*iter);
*      }
*  }
*  

Using Usd.PrimRange in python

The python wrapping for PrimRange is python-iterable, so it can used directly as the object of a "for x in..." clause; however in that usage one loses access to PrimRange methods such as PruneChildren() and IsPostVisit(). Simply create the iterator outside the loop to overcome this limitation. Finally, in python, prim predicates must be combined with bit-wise operators rather than logical operators because the latter are not overridable.

 *  # simple iteration
 *  for prim in Usd.PrimRange(rootPrim):
 *      ProcessPrim(prim)
 * 
 *  # filtered range using iterator to invoke iterator methods
 *  it = iter(Usd.PrimRange.Stage(stage, Usd.PrimIsLoaded & ~Usd.PrimIsAbstract))
 *  for prim in it:
 *      if Usd.ModelAPI(prim).GetKind() == Kind.Tokens.component:
 *          it.PruneChildren()
 *      else:
 *          nonComponents.append(prim)
 *  

Finally, since iterators in python are not directly dereferencable, we provide the python only methods GetCurrentPrim() and IsValid(), documented in the python help system.

Definition at line 118 of file primRange.h.

Constructor & Destructor Documentation

UsdPrimRange ( const UsdPrim & start )

inlineexplicit

Construct a PrimRange that traverses the subtree rooted at start in depth-first order, visiting prims that pass the default predicate (as defined by UsdPrimDefaultPredicate).

Definition at line 231 of file primRange.h.

UsdPrimRange	(	const UsdPrim &	start,
		const Usd_PrimFlagsPredicate &	predicate
	)

inline

Construct a PrimRange that traverses the subtree rooted at start in depth-first order, visiting prims that pass predicate.

Definition at line 238 of file primRange.h.

Member Function Documentation

static UsdPrimRange AllPrims ( const UsdPrim & start )

inlinestatic

Construct a PrimRange that traverses the subtree rooted at start in depth-first order, visiting all prims (including deactivated, undefined, and abstract prims).

Definition at line 283 of file primRange.h.

static UsdPrimRange AllPrimsPreAndPostVisit ( const UsdPrim & start )

inlinestatic

Construct a PrimRange that traverses the subtree rooted at start in depth-first order, visiting all prims (including deactivated, undefined, and abstract prims) with pre- and post-order visitation.

Pre- and post-order visitation means that each prim appears twice in the range; not only prior to all its descendants as with an ordinary traversal but also immediately following its descendants. This lets client code maintain state for subtrees. See UsdPrimRange::iterator::IsPostVisit().

Definition at line 297 of file primRange.h.

iterator begin ( ) const

inline

Return an iterator to the start of this range.

Definition at line 310 of file primRange.h.

const_iterator cbegin ( ) const

inline

Return a const_iterator to the start of this range.

Definition at line 314 of file primRange.h.

const_iterator cend ( ) const

inline

Return the past-the-end const_iterator for this range.

Definition at line 328 of file primRange.h.

bool empty ( ) const

inline

Return true if this range contains no prims, false otherwise.

Definition at line 347 of file primRange.h.

iterator end ( ) const

inline

Return the past-the-end iterator for this range.

Definition at line 326 of file primRange.h.

UsdPrim front ( ) const

inline

Return the first element of this range. The range must not be empty().

Definition at line 319 of file primRange.h.

void increment_begin ( )

inline

Modify this range by advancing the beginning by one.

The range must not be empty, and the range must not be a pre- and post-order range.

Definition at line 332 of file primRange.h.

operator bool ( ) const

inlineexplicit

Return true if this range contains one or more prims, false otherwise.

Definition at line 350 of file primRange.h.

bool operator!= ( UsdPrimRange const & other ) const

inline

Return true if this range is not equivalent to other.

Definition at line 364 of file primRange.h.

bool operator== ( UsdPrimRange const & other ) const

inline

Return true if this range is equivalent to other.

Definition at line 353 of file primRange.h.

static UsdPrimRange PreAndPostVisit ( const UsdPrim & start )

inlinestatic

Create a PrimRange that traverses the subtree rooted at start in depth-first order, visiting prims that pass the default predicate (as defined by UsdPrimDefaultPredicate) with pre- and post-order visitation.

Pre- and post-order visitation means that each prim appears twice in the range; not only prior to all its descendants as with an ordinary traversal but also immediately following its descendants. This lets client code maintain state for subtrees. See UsdPrimRange::iterator::IsPostVisit().

Definition at line 256 of file primRange.h.

static UsdPrimRange PreAndPostVisit	(	const UsdPrim &	start,
		const Usd_PrimFlagsPredicate &	predicate
	)

inlinestatic

Create a PrimRange that traverses the subtree rooted at start in depth-first order, visiting prims that pass predicate with pre- and post-order visitation.

Pre- and post-order visitation means that each prim appears twice in the range; not only prior to all its descendants as with an ordinary traversal but also immediately following its descendants. This lets client code maintain state for subtrees. See UsdPrimRange::iterator::IsPostVisit().

Definition at line 272 of file primRange.h.

void set_begin ( iterator const & newBegin )

inline

Set the start of this range to newBegin.

The newBegin iterator must be within this range's begin() and end(), and must not have UsdPrimRange::iterator::IsPostVisit() be true.

Definition at line 339 of file primRange.h.

static USD_API UsdPrimRange Stage	(	const UsdStagePtr &	stage,
		const Usd_PrimFlagsPredicate &	predicate = `UsdPrimDefaultPredicate`
	)

static

Create a PrimRange that traverses all the prims on stage, and visits those that pass the default predicate (as defined by UsdPrimDefaultPredicate).

The documentation for this class was generated from the following file:

pxr/usd/usd/primRange.h

Classes

Public Types

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation