Cpp.Null Class

Namespace: Cpp
Superclasses: AstNodeProperties

Represents the null nodes in the syntax tree of your code

Since R2026a

Description

The PQL class Cpp.Null represents the node null in the syntax tree of your code.

void foo() {
    int *p = nullptr;
    void *q = NULL;
}

The two null tokens nullptr and NULL in the example correspond to null nodes in the tree and are what Cpp.Null matches.

Predicates

expand all

Type

Type	Raisable	Printable
`Null`	Yes	No

Syntaxes

This class defines these predicates that act on the objects of this class. In addition, objects of this class can access the predicates defined by the base class AstNodeProperties. An object of this class is an object of AstNodeProperties class.

Predicates Description Example

Predicates	Description	Example
`is(required Cpp.Null &null)`	Matches a `null` syntax node and binds it to the output variable `null`. Use this to directly select `null` tokens like `nullptr` or `NULL`.	This PQL defect checks for `null` nodes in the code. defect FindNullIs = when Cpp.Null.is(&n) and n.nodeText(&txt) raise "Found null token via is: \"{txt}\"" on n In this C++ code the defect finds the direct `null` tokens such as `nullptr` and `NULL`. #include <iostream> void f() { int p = nullptr; // matched by Cpp.Null.is void q = NULL; // matched by Cpp.Null.is } int main(){ f(); return 0; }
`cast(Cpp.Node.Node node, required Cpp.Null &cast)`	Checks whether a generic `Node` is a `null` node and if so binds it to `cast`. Use this when you have a `Node` value and need to treat it as a `null`.	This PQL defect checks for a `null` node that is inside a declaration. defect FindNullCast = when Cpp.Declaration.is(&decl) and decl.getADescendant(&nodes) and Cpp.Null.cast(nodes, &cast) and cast.nodeText(&txt) raise "Found null via cast: \"{txt}\"" on cast In this C++ code the defect finds the `nullptr` in the `p` declaration. void g() { int p = nullptr; } int main(){ g(); return 0; }
`isa(Cpp.Node.Node node)`	Tests whether a given `Node` is a `null` node. Use this in boolean conditions or negations to accept or reject `null` nodes.	This PQL defect checks for a `null` node that is inside a declaration. defect FindNull = when Cpp.Declaration.is(&decl) and decl.getADescendant(&nodes) and Cpp.Null.isa(nodes) and nodes.nodeText(&txt) raise "Found null via cast: \"{txt}\"" on nodes In this C++ code the defect finds the `nullptr` in the `p` declaration. void g() { int p = nullptr; } int main(){ g(); return 0; }

is(required Cpp.Null &null)

Matches a null syntax node and binds it to the output variable null. Use this to directly select null tokens like nullptr or NULL.

This PQL defect checks for null nodes in the code.

defect FindNullIs =
when
    Cpp.Null.is(&n)
and n.nodeText(&txt)
raise "Found null token via is: \"{txt}\""
on n

In this C++ code the defect finds the direct null tokens such as nullptr and NULL.

#include <iostream>
void f() {
    int *p = nullptr; // matched by Cpp.Null.is
    void *q = NULL;   // matched by Cpp.Null.is
}
int main(){ f(); return 0; }

cast(Cpp.Node.Node node, required Cpp.Null &cast)

Checks whether a generic Node is a null node and if so binds it to cast. Use this when you have a Node value and need to treat it as a null.

This PQL defect checks for a null node that is inside a declaration.

defect FindNullCast =
when
    Cpp.Declaration.is(&decl)
    and decl.getADescendant(&nodes)
    and Cpp.Null.cast(nodes, &cast)
    and cast.nodeText(&txt)
raise "Found null via cast: \"{txt}\""
on cast

In this C++ code the defect finds the nullptr in the *p declaration.

void g() {
    int *p = nullptr; 
}
int main(){ g(); return 0; }

isa(Cpp.Node.Node node)

Tests whether a given Node is a null node. Use this in boolean conditions or negations to accept or reject null nodes.

This PQL defect checks for a null node that is inside a declaration.

defect FindNull =
when
    Cpp.Declaration.is(&decl)
    and decl.getADescendant(&nodes)
    and Cpp.Null.isa(nodes)
    and nodes.nodeText(&txt)
raise "Found null via cast: \"{txt}\""
on nodes

In this C++ code the defect finds the nullptr in the *p declaration.

void g() {
    int *p = nullptr; 
}
int main(){ g(); return 0; }

Version History

Introduced in R2026a