Struct ExternalContext 

pub struct ExternalContext { /* private fields */ }

A binding whose semantic layer is not reachable from here — held by a service that answers the questions itself, or simply not pulled onto this machine.

It is well-formed, so ContextLoader::is_parseable holds and the compiler’s coarse floor passes: the binding resolved, there is just no local MDL behind it. Beyond that it answers nothing. Every precondition against it comes back unanswerable rather than false, which is the point — a profile bound this way cannot quietly gate on schema facts nobody checked, and an author who wants such a gate is told to bind a context that can answer it instead.

This is what makes an offline delegating profile honest. Reporting empty collections without declining the probes would be worse than useless: has_metric would evaluate to a confident false about a layer this process has never seen.

Implementations

impl ExternalContext

pub fn new() -> Self

Trait Implementations

impl ContextLoader for ExternalContext

fn is_parseable(&self) -> bool

Whether the bound semantic layer assembled and parsed. Backs mdl_parseable / wren_project_exists.

fn metrics(&self) -> &[MetricInfo]

All queryable metrics (declared cube measures + implicit numeric columns).

fn dimensions(&self) -> &[DimensionInfo]

All groupable / queryable dimensions (cube dimensions + selectable columns).

fn time_dimensions(&self) -> &[DimensionInfo]

Time dimensions — the temporal subset that satisfies has_time_dimension.

fn models(&self) -> &[ModelInfo]

All models in the layer.

fn lineage(&self) -> &LineageGraph

The semantic lineage DAG (for lineage_resolvable, and as the graph an impact refers to).

fn can_answer(&self, _predicate: &str) -> bool

Capability probe: can this Context answer predicate at all? A false here is a different loud-fail from evaluating the predicate false — it means the semantic format cannot carry the answer, so the compiler must refuse rather than guess.

fn parse_error(&self) -> Option<&str>

The underlying parse/assembly failure text, when Self::is_parseable is false and the adapter has one to offer (e.g. a serde error from the bound project’s manifest). Message-only enrichment for the mdl_parseable precondition failure — never used for control flow. Defaults to None (no detail beyond the generic floor message); an adapter that keeps the real error around overrides it.

fn model(&self, name: &str) -> Option<&ModelInfo>

A single model by name.

fn host_analysis(&self) -> Option<HostAnalysis>

This layer’s own impact analysis, when it has one.

fn source_introspectable(&self) -> Option<bool>

Raw-shape probe (constitutive family): whether the bound raw source can have its schema introspected (the precondition source_introspectable). This inverts the consumer probes above: a constitutive component’s input is a raw source that has no MDL yet — the component’s output is the MDL. Some(true) = introspectable, Some(false) = a raw source is bound but not introspectable, None = this Context cannot answer raw-shape at all (an MDL-only adapter), which the compiler turns into an unanswerable loud-fail rather than guessing (the same distinction metric_additive draws). Defaults to None so a semantic-layer loader, which cannot answer raw-shape at all, is unaffected; a raw-source adapter overrides it (schema introspection is borrowed — dlt/wren — never built).

fn raw_docs_readable(&self) -> Option<bool>

Raw-shape probe (constitutive family): whether readable raw business docs back a knowledge enrichment (the precondition raw_docs_readable). Same Some/None semantics as Self::source_introspectable; defaults to None (MDL-only adapters cannot answer it).

fn lineage_diagnostics(&self) -> &[String]

Human-readable notes about where lineage construction had to degrade (e.g. a consumer’s SQL failed to parse and a cruder text scan was used, or a malformed consumer file was skipped). Surfaced into the IR’s resolved binding so a thinner-than-authored graph is never silent (no silent caps). Defaults to empty: an adapter with nothing to confess reports nothing.

fn metric_additivity(&self, metric: &str) -> Option<Additivity>

Additivity of a declared metric, or None when the metric is not declared or its additivity is not expressible (⇒ can_answer("metric_additive") is false for it).

impl Debug for ExternalContext

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

Formats the value using the given formatter.

impl Default for ExternalContext

fn default() -> Self

Returns the “default value” for a type.