Struct MergedMapping 

pub struct MergedMapping<'a> { /* private fields */ }

A view over a Mapping that transparently expands alias references (*name) and merge keys (<<:).

MergedMapping borrows an AnchorRegistry and collects its entries when it is created: the merge sources are followed and alias values are resolved then, so an undefined alias or invalid merge key is reported by new. The underlying syntax tree is not modified and the returned nodes are live CST nodes, but entries added, removed or replaced after the view was created are not seen.

Direct keys in the base mapping always shadow keys contributed by merge sources, matching the YAML 1.1 merge-key semantics. When a merge value is a sequence of aliases (<<: [*a, *b]), earlier aliases take precedence over later ones, again per the YAML 1.1 spec.

Returned values are YamlNodes backed by real CST nodes, so they preserve the original formatting and quoting style.

This view is read-only. Mapping::set replaces the value node you pass; it does not turn a resolved map back into <<: *name.

Examples

use yaml_edit::{Document, anchor_resolution::{DocumentResolvedExt, MappingMergedExt}};
use std::str::FromStr;

let yaml = r#"
defaults: &defaults
  timeout: 30
  retries: 3

production:
  <<: *defaults
  host: prod.example.com
  timeout: 60
"#;

let doc = Document::from_str(yaml).unwrap();
let root = doc.as_mapping().unwrap();
let registry = doc.build_anchor_registry();

let prod = root.get_mapping("production").unwrap();
let merged = prod.merged(&registry).unwrap();

// Direct key wins over merged value.
assert_eq!(merged.get("timeout").unwrap().to_i64(), Some(60));
// Merged key from defaults is visible.
assert_eq!(merged.get("retries").unwrap().to_i64(), Some(3));
// Direct-only key is visible.
assert!(merged.get("host").is_some());
// `<<` itself is hidden.
assert!(merged.get("<<").is_none());

Implementations

impl<'a> MergedMapping<'a>

pub fn new( base: Mapping, registry: &'a AnchorRegistry, ) -> Result<Self, ResolveError>

Create a new merged view over base, resolving aliases against registry.

Fails if a << operand in base, or in a mapping merged into it, is an undefined alias or not a mapping, if a value visible through the view is an undefined alias, or if a key is or holds an undefined or recursive alias.

pub fn base(&self) -> &Mapping

Return the underlying (un-merged) Mapping.

Useful when you want to mutate the original mapping or read its raw (non-resolved) contents.

pub fn registry(&self) -> &AnchorRegistry

Return the AnchorRegistry this view resolves against.

pub fn get(&self, key: impl AsYaml) -> Option<YamlNode>

Get the value associated with key, resolving aliases and merge keys.

Direct entries in the base mapping take precedence over keys contributed by <<: merge sources. The merge key itself is hidden: looking up "<<" only finds a quoted '<<' key, which is an ordinary string.

If the matched value is an alias (*name), the resolved target node is returned.

pub fn contains_key(&self, key: impl AsYaml) -> bool

Returns true if a value would be returned by get for key.

pub fn iter(&self) -> impl Iterator<Item = (YamlNode, YamlNode)> + '_

Iterate over (key, value) pairs in the merged view.

Direct entries appear first, in their original document order. Merged-in entries follow, with duplicates (and any direct-key matches already yielded) filtered out. Keys are compared as YAML values, so the integer 1 and the string '1' are distinct. The << merge key itself is never yielded.

pub fn keys(&self) -> impl Iterator<Item = YamlNode> + '_

Iterate over the keys of the merged view.

pub fn values(&self) -> impl Iterator<Item = YamlNode> + '_

Iterate over the values of the merged view.

pub fn len(&self) -> usize

Number of distinct keys visible through the merged view.

pub fn is_empty(&self) -> bool

Returns true if the merged view has no entries.

pub fn get_merged( &self, key: impl AsYaml, ) -> Result<Option<MergedMapping<'a>>, ResolveError>

Get a nested mapping by key and return it as another MergedMapping that shares the same registry.

Returns Ok(None) if the key does not exist or the value is not a mapping, and fails as new does on the nested mapping.

Trait Implementations

impl<'a> Clone for MergedMapping<'a>

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 MergedMapping<'_>

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

Formats the value using the given formatter.

impl MappingView for MergedMapping<'_>

fn get(&self, key: &dyn AsYaml) -> Option<YamlNode>

Look up the value associated with key.

fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = (YamlNode, YamlNode)> + 'a>

Iterate over (key, value) pairs.

fn contains_key(&self, key: &dyn AsYaml) -> bool

Returns true if get would return Some for key.

fn len(&self) -> usize

Number of entries visible through this view.

fn is_empty(&self) -> bool

Returns true if the view has no entries.

fn keys<'a>(&'a self) -> Box<dyn Iterator<Item = YamlNode> + 'a>

Iterate over the keys.

fn values<'a>(&'a self) -> Box<dyn Iterator<Item = YamlNode> + 'a>

Iterate over the values.