Struct Context 

pub struct Context { /* private fields */ }

The context: always data, metadata and temp_data, in that order. Each root starts as an object, and every write keeps it one: map, Ctx::set and Context::set refuse anything else at a root.

Read from JSON, it takes the three roots in any order and writes them in that order, reads a missing one as {}, takes any value at each (a trace’s redacted root is null), and refuses any other key, since expressions evaluate against the whole object and a fourth key would be readable by {"var": …}. An object anywhere in it holding a key twice is refused too: the engine reads the first, where a JSON parser keeps the last, so the two would disagree on what the context says.

Implementations

impl Context

pub fn data(&self) -> &OwnedDataValue

The data root.

pub fn metadata(&self) -> &OwnedDataValue

The metadata root.

pub fn temp_data(&self) -> &OwnedDataValue

The temp_data root.

pub fn as_value(&self) -> &OwnedDataValue

The object holding the three roots: what expressions evaluate against.

pub fn take_data(&mut self) -> OwnedDataValue

Takes the data root, leaving an empty object where it was so the context keeps its three roots and still serializes as one. metadata and temp_data are untouched.

The tree is moved, not cloned: its buffers, key order and numeric representation are the ones it had, so a completed child run’s result can cross into its parent without a deep copy. A second take returns the empty object the first left.

A root that is not an object (a trace’s redacted null) is returned as it is and replaced with {}, as every root starts as an object.

impl Context

pub fn get(&self, path: &Path) -> Option<&OwnedDataValue>

The value at path, if any.

pub fn set(&mut self, path: &Path, value: OwnedDataValue) -> Result<()>

Writes value at path by Path::set’s rules: a root takes only an object.

pub fn remove(&mut self, path: &Path) -> Result<Option<OwnedDataValue>>

Removes and returns the value at path. A root cannot be removed.

Trait Implementations

impl Clone for Context

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Context

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Context

fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl PartialEq for Context

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

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Context

fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Context