Struct ContextStack

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pub struct ContextStack { /* private fields */ }

Expand description

Context stack for nested evaluations

Implementations§

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impl ContextStack

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pub fn new(root: Arc<Value>) -> Self

Create a new context stack with Arc root data

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pub fn push(&mut self, data: Value)

Pushes a new context frame for nested evaluation.

Used by operators that need to create a nested data context without metadata.

§Arguments

data - The data value for the new context frame

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pub fn push_with_metadata( &mut self, data: Value, metadata: HashMap<String, Value>, )

Pushes a frame with metadata for iteration operations.

Used by array operators like map, filter, and reduce to provide iteration context including index and key information.

§Arguments

data - The current item being processed
metadata - Iteration metadata (typically includes “index” and optionally “key”)

§Example

During array iteration:

let mut metadata = HashMap::new();
metadata.insert("index".to_string(), json!(0));
context.push_with_metadata(item_value, metadata);

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pub fn pop(&mut self) -> Option<ContextFrame>

Pops the current context frame from the stack.

Restores the previous context after nested evaluation completes. Returns None if there are no frames to pop (root is never popped).

§Returns

The popped context frame, or None if the stack is empty.

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pub fn get_at_level(&self, level: isize) -> Option<ContextFrameRef<'_>>

Accesses data at a context level relative to current.

This method enables access to parent contexts during nested operations, which is essential for complex JSONLogic expressions.

§Arguments

level - The number of levels to traverse up the context stack
- 0: returns the current context
- N (positive or negative): goes up N levels from current

§Returns

A reference to the context frame at the specified level, or None if the level exceeds the stack depth.

§Note

The sign of the level is ignored; both positive and negative values traverse up the stack the same way. This maintains backward compatibility with existing usage patterns.