Objects of this class represent expressions that can be evaluated to produce a boolean value. More...

#include <booleanExpression.h>

Public Types
enum class	BinaryOperator { EqualTo , NotEqualTo , LessThan , LessThanOrEqualTo , GreaterThan , GreaterThanOrEqualTo , And , Or }
	Operators for combining two subexpressions. More...

enum class	UnaryOperator { Not }
	Operators applied to a single subexpression. More...

using	BinaryVisitor = TfFunctionRef< void(SdfBooleanExpression const &, BinaryOperator, SdfBooleanExpression const &)>
	The Visit() method will invoke this callback if the receiver represents a binary operator applied to two subexpressions.

using	UnaryVisitor = TfFunctionRef< void(SdfBooleanExpression const &, UnaryOperator)>
	The Visit() method will invoke this callback if the receiver represents an operator applied to a single subexpression.

using	VariableVisitor = TfFunctionRef< void(TfToken const &)>
	The Visit() method will invoke this callback if the receiver represents a variable.

using	ConstantVisitor = TfFunctionRef< void(VtValue const &)>
	The Visit() method will invoke this callback if the receiver represents a constant.

using	VariableCallback = TfFunctionRef< VtValue(TfToken const &)>
	Provides the current value for a given variable.

using	NameTransform = TfFunctionRef< TfToken(TfToken const &)>
	Encapsulates a transformation that may be applied to a variable name.

Public Member Functions
	SdfBooleanExpression ()=default
	Constructs an empty expression.

SDF_API	SdfBooleanExpression (std::string const &text)
	Constructs an expression by parsing a string representation.

SDF_API bool	IsEmpty () const
	An expression is empty if it was default constructed or if there was a problem parsing its string representation.

SDF_API std::string	GetText () const
	Provides a string representation that can be parsed by SdfBooleanExpression(std::string const&).

SDF_API std::string const &	GetParseError () const
	Return parsing errors as a string if this expression was constructed from a string and parse errors were encountered.

SDF_API std::set< TfToken >	GetVariableNames () const
	Provides the collection of variable names referenced by the expression.

SDF_API void	Visit (VariableVisitor variable, ConstantVisitor constant, BinaryVisitor binary, UnaryVisitor unary) const
	Invokes one of the given callbacks based on the type of the expression.

SDF_API bool	Evaluate (VariableCallback const &variableCallback) const
	Evaluates the expression.

SDF_API SdfBooleanExpression	RenameVariables (NameTransform const &transform) const
	Applies the provided transform to each variable name and returns the resulting expression.

	TF_DECLARE_REF_PTRS (_Node)

Static Public Member Functions
static SDF_API SdfBooleanExpression	MakeVariable (TfToken const &variableName)
	Constructs an expression representing a variable.

static SDF_API SdfBooleanExpression	MakeConstant (VtValue const &value)
	Constructs an expression wrapping a constant value.

static SDF_API SdfBooleanExpression	MakeBinaryOp (SdfBooleanExpression lhs, BinaryOperator op, SdfBooleanExpression rhs)
	Constructs an expression that applies the provided operator to the result of the two provided subexpressions.

static SDF_API SdfBooleanExpression	MakeUnaryOp (SdfBooleanExpression expression, UnaryOperator op)
	Constructs an expression that applies the provided operator to the result of the provided subexpression.

static SDF_API bool	Validate (std::string const &expression, std::string *errorMessage=nullptr)
	Determines if the provided string can be parsed as an expression.

Friends
SDF_API friend std::ostream &	operator<< (std::ostream &, SdfBooleanExpression const &)

Detailed Description

Objects of this class represent expressions that can be evaluated to produce a boolean value.

See Sdf_Page_BooleanExpressions for more details.

Definition at line 29 of file booleanExpression.h.

Member Typedef Documentation

◆ BinaryVisitor

using BinaryVisitor = TfFunctionRef<void(SdfBooleanExpression const&, BinaryOperator, SdfBooleanExpression const&)>

The Visit() method will invoke this callback if the receiver represents a binary operator applied to two subexpressions.

Given the expression width > 10.0, the callback would be invoked with the arguments:

argument	value
lhs	SdfBooleanExpression representing `width`
op	BinaryOperator::GreaterThan
rhs	SdfBooleanExpression representing `10.0`

See also: MakeBinaryOp()

Definition at line 142 of file booleanExpression.h.

◆ ConstantVisitor

using ConstantVisitor = TfFunctionRef<void(VtValue const&)>

The Visit() method will invoke this callback if the receiver represents a constant.

See also: MakeConstant()

Definition at line 169 of file booleanExpression.h.

◆ NameTransform

using NameTransform = TfFunctionRef<TfToken(TfToken const&)>

Encapsulates a transformation that may be applied to a variable name.

Used by RenameVariables().

Definition at line 187 of file booleanExpression.h.

◆ UnaryVisitor

using UnaryVisitor = TfFunctionRef<void(SdfBooleanExpression const&, UnaryOperator)>

The Visit() method will invoke this callback if the receiver represents an operator applied to a single subexpression.

Given the expression !(width > 10.0), the callback would be invoked with the arguments:

argument	value
expression	SdfBooleanExpression representing `width > 10.0`
op	UnaryOp::Not

See also: MakeUnaryOp()

Definition at line 156 of file booleanExpression.h.

◆ VariableCallback

using VariableCallback = TfFunctionRef<VtValue (TfToken const&)>

Provides the current value for a given variable.

Used by Evaluate() when evaluating the expression.

Definition at line 179 of file booleanExpression.h.

◆ VariableVisitor

using VariableVisitor = TfFunctionRef<void(TfToken const&)>

The Visit() method will invoke this callback if the receiver represents a variable.

See also: MakeVariable()

Definition at line 163 of file booleanExpression.h.

Member Enumeration Documentation

◆ BinaryOperator

enum class BinaryOperator

strong

Operators for combining two subexpressions.

See also: MakeBinaryOp

Enumerator
EqualTo	The `==` operator.
NotEqualTo	The `!=` operator.
LessThan	The `<` operator.
LessThanOrEqualTo	The `<=` operator.
GreaterThan	The `>` operator.
GreaterThanOrEqualTo	The `>=` operator.
And	The `&&` operator.
Or	The `\|\|` operator.

Definition at line 70 of file booleanExpression.h.

◆ UnaryOperator

enum class UnaryOperator

strong

Operators applied to a single subexpression.

See also: MakeUnaryOp

Enumerator
Not	The `!` operator.

Definition at line 113 of file booleanExpression.h.

Constructor & Destructor Documentation

◆ SdfBooleanExpression() [1/2]

SdfBooleanExpression ( )

default

Constructs an empty expression.

◆ SdfBooleanExpression() [2/2]

SDF_API SdfBooleanExpression ( std::string const & text )

explicit

Constructs an expression by parsing a string representation.

If an error occurs while parsing the string, the result will be an empty expression. See also GetParseError().

Member Function Documentation

◆ Evaluate()

SDF_API bool Evaluate ( VariableCallback const & variableCallback ) const

Evaluates the expression.

If the expression contains any variables, variableCallback will be invoked to determine their current values.

◆ GetParseError()

SDF_API std::string const & GetParseError ( ) const

Return parsing errors as a string if this expression was constructed from a string and parse errors were encountered.

◆ GetText()

SDF_API std::string GetText ( ) const

Provides a string representation that can be parsed by SdfBooleanExpression(std::string const&).

If the expression was constructed from a string, the existing formatting will be preserved.

◆ GetVariableNames()

SDF_API std::set< TfToken > GetVariableNames ( ) const

Provides the collection of variable names referenced by the expression.

◆ IsEmpty()

SDF_API bool IsEmpty ( ) const

An expression is empty if it was default constructed or if there was a problem parsing its string representation.

◆ MakeBinaryOp()

static SDF_API SdfBooleanExpression MakeBinaryOp	(	SdfBooleanExpression	lhs,
		BinaryOperator	op,
		SdfBooleanExpression	rhs
	)

static

Constructs an expression that applies the provided operator to the result of the two provided subexpressions.

The expression width > 10.0 would be constructed with the arguments:

argument	value
lhs	`SdfBooleanExpression::MakeVariable(TfToken("width"));`
op	BinaryOperator::GreaterThan
rhs	`SdfBooleanExpression::MakeConstant(VtValue(10.0));`

See also: BinaryVisitor

◆ MakeConstant()

static SDF_API SdfBooleanExpression MakeConstant ( VtValue const & value )

static

Constructs an expression wrapping a constant value.

See also: ConstantVisitor

◆ MakeUnaryOp()

static SDF_API SdfBooleanExpression MakeUnaryOp	(	SdfBooleanExpression	expression,
		UnaryOperator	op
	)

static

Constructs an expression that applies the provided operator to the result of the provided subexpression.

The expression !(width > 10.0) would be constructed with the arguments:

argument	value
expression	SdfBooleanExpression representing `width > 10.0`
op	UnaryOp::Not

See also: UnaryVisitor

◆ MakeVariable()

static SDF_API SdfBooleanExpression MakeVariable ( TfToken const & variableName )

static

Constructs an expression representing a variable.

See also: VariableVisitor

◆ RenameVariables()

SDF_API SdfBooleanExpression RenameVariables ( NameTransform const & transform ) const

Applies the provided transform to each variable name and returns the resulting expression.

◆ Validate()

static SDF_API bool Validate	(	std::string const &	expression,
		std::string *	errorMessage = `nullptr`
	)

static

Determines if the provided string can be parsed as an expression.

Returns true if the expression is valid, otherwise returns false. If the string is not a valid expression, errorMessage (if non-null) will be filled with an explanatory error message.

◆ Visit()

SDF_API void Visit	(	VariableVisitor	variable,
		ConstantVisitor	constant,
		BinaryVisitor	binary,
		UnaryVisitor	unary
	)		const

Invokes one of the given callbacks based on the type of the expression.

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

pxr/usd/sdf/booleanExpression.h

Public Types

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

Member Typedef Documentation

◆ BinaryVisitor

◆ ConstantVisitor

◆ NameTransform

◆ UnaryVisitor

◆ VariableCallback

◆ VariableVisitor

Member Enumeration Documentation

◆ BinaryOperator

◆ UnaryOperator

Constructor & Destructor Documentation

◆ SdfBooleanExpression() [1/2]

◆ SdfBooleanExpression() [2/2]

Member Function Documentation

◆ Evaluate()

◆ GetParseError()

◆ GetText()

◆ GetVariableNames()

◆ IsEmpty()

◆ MakeBinaryOp()

◆ MakeConstant()

◆ MakeUnaryOp()

◆ MakeVariable()

◆ RenameVariables()

◆ Validate()

◆ Visit()