pub struct Variable {
    pub name: String,
    pub value: String,
    pub type: String,
    pub members: Vec<Variable>,
    pub var_table_index: Option<i32>,
    pub status: Option<StatusMessage>,
}
Expand description

Represents a variable or an argument possibly of a compound object type. Note how the following variables are represented:

  1. A simple variable:

    int x = 5

    { name: “x”, value: “5”, type: “int” } // Captured variable

  2. A compound object:

    struct T { int m1; int m2; }; T x = { 3, 7 };

    { // Captured variable name: “x”, type: “T”, members { name: “m1”, value: “3”, type: “int” }, members { name: “m2”, value: “7”, type: “int” } }

  3. A pointer where the pointee was captured:

    T x = { 3, 7 }; T* p = &x;

    { // Captured variable name: “p”, type: “T*”, value: “0x00500500”, members { name: “m1”, value: “3”, type: “int” }, members { name: “m2”, value: “7”, type: “int” } }

  4. A pointer where the pointee was not captured:

    T* p = new T;

    { // Captured variable name: “p”, type: “T*”, value: “0x00400400” status { is_error: true, description { format: “unavailable” } } }

The status should describe the reason for the missing value, such as <optimized out>, <inaccessible>, <pointers limit reached>.

Note that a null pointer should not have members.

  1. An unnamed value:

    int* p = new int(7);

    { // Captured variable name: “p”, value: “0x00500500”, type: “int*”, members { value: “7”, type: “int” } }

  2. An unnamed pointer where the pointee was not captured:

    int* p = new int(7); int** pp = &p;

    { // Captured variable name: “pp”, value: “0x00500500”, type: “int**”, members { value: “0x00400400”, type: “int*” status { is_error: true, description: { format: “unavailable” } } } } }

To optimize computation, memory and network traffic, variables that repeat in the output multiple times can be stored once in a shared variable table and be referenced using the var_table_index field. The variables stored in the shared table are nameless and are essentially a partition of the complete variable. To reconstruct the complete variable, merge the referencing variable with the referenced variable.

When using the shared variable table, the following variables:

 T x = { 3, 7 };
 T* p = &x;
 T& r = x;

 { name: "x", var_table_index: 3, type: "T" }  // Captured variables
 { name: "p", value "0x00500500", type="T*", var_table_index: 3 }
 { name: "r", type="T&", var_table_index: 3 }

 {  // Shared variable table entry #3:
     members { name: "m1", value: "3", type: "int" },
     members { name: "m2", value: "7", type: "int" }
 }

Note that the pointer address is stored with the referencing variable and not with the referenced variable. This allows the referenced variable to be shared between pointers and references.

The type field is optional. The debugger agent may or may not support it.

Fields§

§name: String

Name of the variable, if any.

§value: String

Simple value of the variable.

§type: String

Variable type (e.g. MyClass). If the variable is split with var_table_index, type goes next to value. The interpretation of a type is agent specific. It is recommended to include the dynamic type rather than a static type of an object.

§members: Vec<Variable>

Members contained or pointed to by the variable.

§var_table_index: Option<i32>

Reference to a variable in the shared variable table. More than one variable can reference the same variable in the table. The var_table_index field is an index into variable_table in Breakpoint.

§status: Option<StatusMessage>

Status associated with the variable. This field will usually stay unset. A status of a single variable only applies to that variable or expression. The rest of breakpoint data still remains valid. Variables might be reported in error state even when breakpoint is not in final state.

The message may refer to variable name with refers_to set to VARIABLE_NAME. Alternatively refers_to will be set to VARIABLE_VALUE. In either case variable value and members will be unset.

Example of error message applied to name: Invalid expression syntax.

Example of information message applied to value: Not captured.

Examples of error message applied to value:

  • Malformed string,
  • Field f not found in class C
  • Null pointer dereference

Trait Implementations§

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impl Clone for Variable

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fn clone(&self) -> Variable

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Variable

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl Default for Variable

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fn default() -> Self

Returns the “default value” for a type. Read more
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impl Message for Variable

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fn encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.
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fn clear(&mut self)

Clears the message, resetting all fields to their default.
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fn encode<B>(&self, buf: &mut B) -> Result<(), EncodeError>
where B: BufMut, Self: Sized,

Encodes the message to a buffer. Read more
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fn encode_to_vec(&self) -> Vec<u8>
where Self: Sized,

Encodes the message to a newly allocated buffer.
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fn encode_length_delimited<B>(&self, buf: &mut B) -> Result<(), EncodeError>
where B: BufMut, Self: Sized,

Encodes the message with a length-delimiter to a buffer. Read more
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fn encode_length_delimited_to_vec(&self) -> Vec<u8>
where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.
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fn decode<B>(buf: B) -> Result<Self, DecodeError>
where B: Buf, Self: Default,

Decodes an instance of the message from a buffer. Read more
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fn decode_length_delimited<B>(buf: B) -> Result<Self, DecodeError>
where B: Buf, Self: Default,

Decodes a length-delimited instance of the message from the buffer.
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fn merge<B>(&mut self, buf: B) -> Result<(), DecodeError>
where B: Buf, Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self. Read more
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fn merge_length_delimited<B>(&mut self, buf: B) -> Result<(), DecodeError>
where B: Buf, Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.
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impl PartialEq for Variable

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fn eq(&self, other: &Variable) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl StructuralPartialEq for Variable

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FromRef<T> for T
where T: Clone,

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fn from_ref(input: &T) -> T

Converts to this type from a reference to the input type.
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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [Span], returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoRequest<T> for T

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fn into_request(self) -> Request<T>

Wrap the input message T in a tonic::Request
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a [WithDispatch] wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a [WithDispatch] wrapper. Read more