sct_ecl/

eval.rs

//! The evaluator: an expression constraint to the set of concept ordinals it
//! selects, as set algebra over the materialized closure, the attribute
//! graph, and the reference set tables of one edition.
//!
//! The semantics are the ECL specification's
//! (<https://docs.snomed.org/snomed-ct-specifications/snomed-ct-expression-constraint-language>,
//! the quick reference in Appendix D): `<` is the closure's descendants,
//! `^` the active members, a refinement the sources whose attribute rows
//! satisfy the attributes with their cardinalities per role group, and the
//! filters and history supplements restrict or extend the set. The edition
//! is reached through [`Model`]; nothing here walks a graph edge by edge.

use std::fmt;

use concept_graph::attributes::{Row, ValueRef};
use concept_graph::ordinal::Ordinal;
use concept_graph::refsets::{Table, ValueRef as FieldRef};
use roaring::RoaringBitmap;

use crate::ast::{
    Acceptability, Attribute, AttributeSet, AttributeValue, Cardinality, Comparison, ConceptFilter,
    ConceptSet, ConstraintOperator, DefinitionStatus, DescriptionFilter, DialectIdValue, Equality,
    ExpressionConstraint, FieldValue, FilterConstraint, FocusConcept, HistorySupplement,
    MemberFilter, Refinement, RefsetFields, Sctid, SubAttributeSet, SubExpressionConstraint,
    SubRefinement, TimeValue, TypeToken, TypedSearchTerm,
};

/// The historical association reference set root
/// (`900000000000522004 |Historical association reference set|`).
pub const HISTORICAL_ASSOCIATION: u64 = 900_000_000_000_522_004;
/// `900000000000527005 |SAME AS association reference set|`.
pub const SAME_AS: u64 = 900_000_000_000_527_005;
/// `900000000000526001 |REPLACED BY association reference set|`.
pub const REPLACED_BY: u64 = 900_000_000_000_526_001;
/// `900000000000528000 |WAS A association reference set|`.
pub const WAS_A: u64 = 900_000_000_000_528_000;
/// `1186924009 |PARTIALLY EQUIVALENT TO association reference set|`.
pub const PARTIALLY_EQUIVALENT_TO: u64 = 1_186_924_009;
/// The reference set field every member carries.
const REFERENCED_COMPONENT: &str = "referencedComponentId";
/// The association reference set field a history supplement follows.
const TARGET_COMPONENT: &str = "targetComponentId";

/// A failure to evaluate.
#[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
pub enum EvalError {
    /// The expression names a concept the edition does not have.
    #[error("the edition has no concept {0}")]
    UnknownConcept(Sctid),
    /// A `^` focus is not a reference set with members in the edition.
    #[error("{0} is not a reference set with members in the edition")]
    NotAReferenceSet(Sctid),
    /// An alternate identifier scheme alias resolves to no identifier scheme.
    #[error("`{0}` is not an identifier scheme alias of the edition")]
    UnknownScheme(String),
    /// An alternate identifier names no concept.
    #[error("no concept has the alternate identifier {scheme}#{code}")]
    UnknownIdentifier {
        /// The scheme alias.
        scheme: String,
        /// The code.
        code: String,
    },
    /// A reference set has no field of the name.
    #[error("reference set {refset} has no field `{field}`")]
    UnknownField {
        /// The reference set.
        refset: Sctid,
        /// The field.
        field: String,
    },
    /// A construct the edition's data cannot answer.
    #[error("{0} is not supported")]
    Unsupported(&'static str),
    /// A dialect alias the specification does not list.
    #[error("`{0}` is not a dialect alias")]
    UnknownDialect(String),
    /// The edition's storage failed.
    #[error("the edition could not be read: {0}")]
    Storage(String),
}

/// One concept filter with its concept sets resolved, for the model.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ConceptPredicate {
    /// The concept is active (or, `false`, inactive).
    Active(bool),
    /// The definition status is one of the allowed ones.
    DefinitionStatus {
        /// Sufficiently defined concepts pass.
        defined: bool,
        /// Primitive concepts pass.
        primitive: bool,
    },
    /// The module is one of `modules` (SCTIDs), or is not when negated.
    Module {
        /// The module SCTIDs.
        modules: Vec<u64>,
        /// `!=`.
        negated: bool,
    },
    /// The effective time compares to one of `values` (`YYYYMMDD`; `!=` means
    /// to none of them).
    EffectiveTime {
        /// The operator.
        operator: Comparison,
        /// The times.
        values: Vec<u32>,
    },
}

/// One description filter with its concept sets and aliases resolved, for
/// the model; every predicate of one `{{ D ... }}` must hold for the same
/// description.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum DescriptionPredicate {
    /// The term matches one of the search terms (or, `!=`, none).
    Term {
        /// The operator.
        operator: Equality,
        /// The search terms.
        terms: Vec<TypedSearchTerm>,
    },
    /// The language code (the primary subtag) is one of `codes`.
    Language {
        /// The operator.
        operator: Equality,
        /// Two-letter codes.
        codes: Vec<String>,
    },
    /// The description type is one of `types` (SCTIDs).
    Type {
        /// The operator.
        operator: Equality,
        /// The description type SCTIDs.
        types: Vec<u64>,
    },
    /// The description is acceptable in one of the language reference sets,
    /// with one of the listed acceptabilities when any are listed.
    Dialect {
        /// The operator.
        operator: Equality,
        /// `(language reference set SCTID, allowed acceptabilities)`.
        dialects: Vec<(u64, Vec<Acceptability>)>,
    },
    /// The description is active (or, `false`, inactive).
    Active(bool),
    /// The description identifier is one of `ids`.
    Id {
        /// The operator.
        operator: Equality,
        /// The description identifiers.
        ids: Vec<u64>,
    },
}

/// `900000000000548007 |Preferred|`.
const PREFERRED: u64 = 900_000_000_000_548_007;
/// `900000000000549004 |Acceptable|`.
const ACCEPTABLE: u64 = 900_000_000_000_549_004;
/// `900000000000073002 |Defined|`.
const DEFINED: u64 = 900_000_000_000_073_002;
/// `900000000000074008 |Primitive|`.
const PRIMITIVE: u64 = 900_000_000_000_074_008;
/// `900000000000003001 |Fully specified name|`.
const FULLY_SPECIFIED_NAME: u64 = 900_000_000_000_003_001;
/// `900000000000013009 |Synonym|`.
const SYNONYM: u64 = 900_000_000_000_013_009;
/// `900000000000550004 |Definition|`.
const DEFINITION: u64 = 900_000_000_000_550_004;

/// The edition an expression is evaluated against.
pub trait Model {
    /// The ordinal of a concept, `None` when the edition lacks it.
    ///
    /// # Errors
    ///
    /// Returns [`EvalError::Storage`] when the edition cannot be read.
    fn concept(&self, id: Sctid) -> Result<Option<Ordinal>, EvalError>;
    /// The SCTID of a concept.
    ///
    /// # Errors
    ///
    /// Returns [`EvalError::Storage`] when the edition cannot be read.
    fn sctid(&self, concept: Ordinal) -> Result<Option<Sctid>, EvalError>;
    /// Every concept, active and inactive.
    fn all(&self) -> RoaringBitmap;
    /// The concepts with no parent.
    fn roots(&self) -> RoaringBitmap;
    /// The concepts with no child.
    fn leaves(&self) -> RoaringBitmap;
    /// The transitive descendants, self excluded.
    fn descendants(&self, concept: Ordinal) -> &RoaringBitmap;
    /// The transitive ancestors, self excluded.
    fn ancestors(&self, concept: Ordinal) -> &RoaringBitmap;
    /// The direct children.
    fn children(&self, concept: Ordinal) -> RoaringBitmap;
    /// The direct parents.
    fn parents(&self, concept: Ordinal) -> RoaringBitmap;
    /// The attribute relationships.
    fn attributes(&self) -> &concept_graph::attributes::Attributes;
    /// The reference set member tables.
    fn members(&self) -> &concept_graph::refsets::RefsetMembers;
    /// The alternate identifiers.
    fn identifiers(&self) -> &concept_graph::identifiers::Identifiers;
    /// The identifier scheme an alias names (case-insensitively).
    ///
    /// # Errors
    ///
    /// Returns [`EvalError::Storage`] when the edition cannot be read.
    fn scheme(&self, alias: &str) -> Result<Option<u64>, EvalError>;
    /// The concepts of `within` whose concept rows satisfy every predicate.
    ///
    /// # Errors
    ///
    /// Returns [`EvalError`] for a predicate the edition cannot answer.
    fn filter_concepts(
        &self,
        within: &RoaringBitmap,
        predicates: &[ConceptPredicate],
    ) -> Result<RoaringBitmap, EvalError>;
    /// The concepts of `within` that have one description satisfying every
    /// predicate.
    ///
    /// # Errors
    ///
    /// Returns [`EvalError`] for a predicate the edition cannot answer.
    fn filter_descriptions(
        &self,
        within: &RoaringBitmap,
        predicates: &[DescriptionPredicate],
    ) -> Result<RoaringBitmap, EvalError>;
}

/// Evaluates `constraint` against `model`.
///
/// # Errors
///
/// Returns [`EvalError`] when the expression names something the edition
/// does not have, or asks for a construct its data cannot answer.
pub fn evaluate<M: Model>(
    model: &M,
    constraint: &ExpressionConstraint,
) -> Result<RoaringBitmap, EvalError> {
    Evaluator { model }.expression(constraint)
}

struct Evaluator<'m, M: Model> {
    model: &'m M,
}

impl<M: Model> fmt::Debug for Evaluator<'_, M> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("Evaluator")
    }
}

/// The kinds of the attribute types a set of type concepts names, or every
/// kind for `*`.
#[derive(Debug, Clone, PartialEq, Eq)]
enum Kinds {
    Any,
    These(Vec<u32>),
}

impl Kinds {
    fn contains(&self, kind: u32) -> bool {
        match self {
            Self::Any => true,
            Self::These(kinds) => kinds.contains(&kind),
        }
    }

    fn iter(&self, total: usize) -> Box<dyn Iterator<Item = u32> + '_> {
        match self {
            Self::Any => Box::new(0..u32::try_from(total).unwrap_or(u32::MAX)),
            Self::These(kinds) => Box::new(kinds.iter().copied()),
        }
    }
}

/// What an attribute's value must satisfy.
#[derive(Debug)]
enum ValueTest {
    /// The value is a concept in (or, negated, not in) the set; `None` is `*`.
    Concept {
        set: Option<RoaringBitmap>,
        negated: bool,
    },
    Number(Comparison, f64),
    Text(Equality, Vec<TypedSearchTerm>),
    Boolean(Equality, bool),
}

impl ValueTest {
    fn matches(&self, value: ValueRef<'_>) -> bool {
        match (self, value) {
            // NOTE: `= *` matches any value, a concrete one too; the specification
            // spells the wildcard as any value and the reference servers agree.
            (Self::Concept { set: None, negated }, _) => !*negated,
            (
                Self::Concept {
                    set: Some(set),
                    negated,
                },
                ValueRef::Concept(target),
            ) => set.contains(target.index()) != *negated,
            (Self::Number(operator, expected), ValueRef::Number(text)) => text
                .parse::<f64>()
                .is_ok_and(|actual| compare_numbers(*operator, actual, *expected)),
            (Self::Text(operator, terms), ValueRef::String(text)) => {
                let hit = terms.iter().any(|term| term_matches(term, text));
                hit == (*operator == Equality::Equal)
            }
            (Self::Boolean(operator, expected), ValueRef::String(text)) => {
                let actual = text.eq_ignore_ascii_case("true");
                let boolean = actual || text.eq_ignore_ascii_case("false");
                boolean && ((actual == *expected) == (*operator == Equality::Equal))
            }
            _ => false,
        }
    }
}

fn compare_numbers(operator: Comparison, actual: f64, expected: f64) -> bool {
    match operator {
        Comparison::Equal => (actual - expected).abs() < f64::EPSILON,
        Comparison::NotEqual => (actual - expected).abs() >= f64::EPSILON,
        Comparison::Less => actual < expected,
        Comparison::LessOrEqual => actual <= expected,
        Comparison::Greater => actual > expected,
        Comparison::GreaterOrEqual => actual >= expected,
    }
}

fn compare_times(operator: Comparison, actual: u32, expected: u32) -> bool {
    match operator {
        Comparison::Equal => actual == expected,
        Comparison::NotEqual => actual != expected,
        Comparison::Less => actual < expected,
        Comparison::LessOrEqual => actual <= expected,
        Comparison::Greater => actual > expected,
        Comparison::GreaterOrEqual => actual >= expected,
    }
}

/// Whether `pattern`, with `*` for any run of characters and `\*`, `\"`,
/// `\\` for the literal characters, matches the whole of `text`
/// (case-insensitively, as description matching is).
#[must_use]
pub fn wild_matches(pattern: &str, text: &str) -> bool {
    let pattern: Vec<char> = pattern.to_lowercase().chars().collect();
    let text: Vec<char> = text.to_lowercase().chars().collect();
    wild_at(&pattern, &text)
}

fn wild_at(pattern: &[char], text: &[char]) -> bool {
    match pattern.split_first() {
        None => text.is_empty(),
        Some(('*', rest)) => (0..=text.len()).any(|skip| {
            text.get(skip..)
                .is_some_and(|remaining| wild_at(rest, remaining))
        }),
        Some(('\\', rest)) => {
            let Some((escaped, after)) = rest.split_first() else {
                return false;
            };
            text.split_first()
                .is_some_and(|(first, remaining)| first == escaped && wild_at(after, remaining))
        }
        Some((expected, rest)) => text
            .split_first()
            .is_some_and(|(first, remaining)| first == expected && wild_at(rest, remaining)),
    }
}

/// Whether every word of a match term is a prefix of some word of `text`,
/// case-insensitively, or a wild pattern matches the whole text.
#[must_use]
pub fn term_matches(term: &TypedSearchTerm, text: &str) -> bool {
    match term {
        TypedSearchTerm::Match(words) => {
            let lower = text.to_lowercase();
            let text_words: Vec<&str> = lower
                .split(|c: char| !c.is_alphanumeric())
                .filter(|w| !w.is_empty())
                .collect();
            words.iter().all(|word| {
                let word = unescape(word).to_lowercase();
                text_words.iter().any(|t| t.starts_with(word.as_str()))
            })
        }
        TypedSearchTerm::Wild(pattern) => wild_matches(pattern, text),
    }
}

/// `\"` and `\\` to the character they escape.
fn unescape(word: &str) -> String {
    let mut out = String::with_capacity(word.len());
    let mut chars = word.chars();
    while let Some(c) = chars.next() {
        if c == '\\' {
            if let Some(next) = chars.next() {
                out.push(next);
            }
        } else {
            out.push(c);
        }
    }
    out
}

/// Whether `count` satisfies a cardinality; `None` is the default `[1..*]`.
fn within(cardinality: Option<Cardinality>, count: u32) -> bool {
    let Cardinality { min, max } = cardinality.unwrap_or(Cardinality { min: 1, max: None });
    count >= min && max.is_none_or(|max| count <= max)
}

impl<M: Model> Evaluator<'_, M> {
    fn expression(&self, constraint: &ExpressionConstraint) -> Result<RoaringBitmap, EvalError> {
        match constraint {
            ExpressionConstraint::Sub(sub) => self.sub(sub),
            ExpressionConstraint::Refined { focus, refinement } => {
                let focus = self.sub(focus)?;
                self.refinement(&focus, refinement)
            }
            ExpressionConstraint::Conjunction(operands) => {
                let mut result: Option<RoaringBitmap> = None;
                for operand in operands {
                    let set = self.sub(operand)?;
                    result = Some(match result {
                        None => set,
                        Some(current) => current & set,
                    });
                }
                Ok(result.unwrap_or_default())
            }
            ExpressionConstraint::Disjunction(operands) => {
                let mut result = RoaringBitmap::new();
                for operand in operands {
                    result |= self.sub(operand)?;
                }
                Ok(result)
            }
            ExpressionConstraint::Exclusion { left, right } => {
                Ok(self.sub(left)? - self.sub(right)?)
            }
            ExpressionConstraint::Dotted { focus, attributes } => {
                let mut set = self.sub(focus)?;
                for attribute in attributes {
                    let kinds = self.kinds(attribute)?;
                    set = self.values_of(&set, &kinds);
                }
                Ok(set)
            }
        }
    }

    /// `subexpressionconstraint`: the focus, the member-of, the operator, then
    /// the filters and the history supplement.
    fn sub(&self, sub: &SubExpressionConstraint) -> Result<RoaringBitmap, EvalError> {
        let mut set = self.focus(&sub.focus)?;
        if let Some(member_of) = &sub.member_of {
            set = self.member_of(&set, member_of.fields.as_ref(), &sub.member_filters)?;
        }
        if let Some(operator) = sub.operator {
            set = self.operate(operator, &set, matches!(sub.focus, FocusConcept::Wildcard));
        }
        for filter in &sub.filters {
            set = match filter {
                FilterConstraint::Concept(filters) => {
                    let predicates = self.concept_predicates(filters)?;
                    self.model.filter_concepts(&set, &predicates)?
                }
                FilterConstraint::Description(filters) => {
                    let predicates = self.description_predicates(filters)?;
                    self.model.filter_descriptions(&set, &predicates)?
                }
            };
        }
        if let Some(history) = &sub.history {
            set = self.history(set, history)?;
        }
        Ok(set)
    }

    fn focus(&self, focus: &FocusConcept) -> Result<RoaringBitmap, EvalError> {
        match focus {
            FocusConcept::Wildcard => Ok(self.model.all()),
            FocusConcept::Reference(reference) => {
                let ordinal = self
                    .model
                    .concept(reference.id)?
                    .ok_or(EvalError::UnknownConcept(reference.id))?;
                Ok(RoaringBitmap::from_iter([ordinal.index()]))
            }
            FocusConcept::AltIdentifier(alt) => {
                let scheme = self
                    .model
                    .scheme(&alt.scheme)?
                    .ok_or_else(|| EvalError::UnknownScheme(alt.scheme.clone()))?;
                let ordinal = self
                    .model
                    .identifiers()
                    .lookup(scheme, &alt.code)
                    .ok_or_else(|| EvalError::UnknownIdentifier {
                        scheme: alt.scheme.clone(),
                        code: alt.code.clone(),
                    })?;
                Ok(RoaringBitmap::from_iter([ordinal.index()]))
            }
            FocusConcept::Nested(inner) => self.expression(inner),
        }
    }

    /// The constraint operator over a set; the whole edition has the roots
    /// and the leaves as its answers.
    fn operate(
        &self,
        operator: ConstraintOperator,
        set: &RoaringBitmap,
        whole: bool,
    ) -> RoaringBitmap {
        if whole {
            let all = self.model.all();
            return match operator {
                ConstraintOperator::DescendantOrSelfOf
                | ConstraintOperator::AncestorOrSelfOf
                | ConstraintOperator::ChildOrSelfOf
                | ConstraintOperator::ParentOrSelfOf => all,
                ConstraintOperator::DescendantOf | ConstraintOperator::ChildOf => {
                    all - self.model.roots()
                }
                ConstraintOperator::AncestorOf | ConstraintOperator::ParentOf => {
                    all - self.model.leaves()
                }
                ConstraintOperator::Top => self.model.roots(),
                ConstraintOperator::Bottom => self.model.leaves(),
            };
        }
        let mut out = RoaringBitmap::new();
        match operator {
            ConstraintOperator::Top => {
                for concept in set {
                    if self.model.ancestors(Ordinal::new(concept)).is_disjoint(set) {
                        out.insert(concept);
                    }
                }
                return out;
            }
            ConstraintOperator::Bottom => {
                for concept in set {
                    if self
                        .model
                        .descendants(Ordinal::new(concept))
                        .is_disjoint(set)
                    {
                        out.insert(concept);
                    }
                }
                return out;
            }
            _ => {}
        }
        for concept in set {
            let ordinal = Ordinal::new(concept);
            match operator {
                ConstraintOperator::DescendantOf | ConstraintOperator::DescendantOrSelfOf => {
                    out |= self.model.descendants(ordinal);
                }
                ConstraintOperator::AncestorOf | ConstraintOperator::AncestorOrSelfOf => {
                    out |= self.model.ancestors(ordinal);
                }
                ConstraintOperator::ChildOf | ConstraintOperator::ChildOrSelfOf => {
                    out |= self.model.children(ordinal);
                }
                ConstraintOperator::ParentOf | ConstraintOperator::ParentOrSelfOf => {
                    out |= self.model.parents(ordinal);
                }
                ConstraintOperator::Top | ConstraintOperator::Bottom => {}
            }
        }
        if matches!(
            operator,
            ConstraintOperator::DescendantOrSelfOf
                | ConstraintOperator::AncestorOrSelfOf
                | ConstraintOperator::ChildOrSelfOf
                | ConstraintOperator::ParentOrSelfOf
        ) {
            out |= set;
        }
        out
    }

    /// `^`: the referenced components (or the selected fields) of the active
    /// members of the reference sets in `set`, those rows passing the member
    /// filters.
    fn member_of(
        &self,
        set: &RoaringBitmap,
        fields: Option<&RefsetFields>,
        filter_groups: &[Vec<MemberFilter>],
    ) -> Result<RoaringBitmap, EvalError> {
        let mut out = RoaringBitmap::new();
        for concept in set {
            let Some(id) = self.model.sctid(Ordinal::new(concept))? else {
                continue;
            };
            let Some(table) = self.model.members().table(id.0) else {
                return Err(EvalError::NotAReferenceSet(id));
            };
            let columns = Self::selected_columns(id, table, fields)?;
            for row in 0..table.len() {
                if !self.row_passes(table, row, filter_groups)? {
                    continue;
                }
                for column in &columns {
                    match column {
                        None => {
                            if let Some(member) = table.concept(row) {
                                out.insert(member.index());
                            }
                        }
                        Some(field) => {
                            if let Some(FieldRef::Concept(value)) = table.value(row, *field) {
                                out.insert(value.index());
                            }
                        }
                    }
                }
            }
        }
        Ok(out)
    }

    /// The columns a field selection names: `None` is the referenced
    /// component, `Some(i)` a field; `[*]` is every concept-valued column.
    fn selected_columns(
        refset: Sctid,
        table: &Table,
        fields: Option<&RefsetFields>,
    ) -> Result<Vec<Option<usize>>, EvalError> {
        Ok(match fields {
            None => vec![None],
            Some(RefsetFields::Any) => {
                let mut columns = vec![None];
                columns.extend(
                    table
                        .kinds()
                        .iter()
                        .enumerate()
                        .filter(|(_, kind)| **kind == concept_graph::refsets::FieldKind::Component)
                        .map(|(i, _)| Some(i)),
                );
                columns
            }
            Some(RefsetFields::Names(names)) => {
                let mut columns = Vec::new();
                for name in names {
                    if name.eq_ignore_ascii_case(REFERENCED_COMPONENT) {
                        columns.push(None);
                    } else {
                        columns.push(Some(table.field(name).ok_or_else(|| {
                            EvalError::UnknownField {
                                refset,
                                field: name.clone(),
                            }
                        })?));
                    }
                }
                columns
            }
        })
    }

    /// Whether row `row` of `table` satisfies every member filter.
    fn row_passes(
        &self,
        table: &Table,
        row: usize,
        filter_groups: &[Vec<MemberFilter>],
    ) -> Result<bool, EvalError> {
        for filter in filter_groups.iter().flatten() {
            let passes = match filter {
                MemberFilter::Active { operator, value } => {
                    if *value != (*operator == Equality::Equal) {
                        return Err(EvalError::Unsupported(
                            "a member filter on inactive members: the tables hold active members",
                        ));
                    }
                    true
                }
                MemberFilter::EffectiveTime { operator, values } => {
                    let actual = table.effective_time(row).unwrap_or_default();
                    times_match(*operator, values, actual)
                }
                MemberFilter::Module { operator, value } => {
                    let modules = self.sctids_of(value)?;
                    let inside = table.module(row).is_some_and(|m| modules.contains(&m));
                    inside == (*operator == Equality::Equal)
                }
                MemberFilter::Field { name, value } => {
                    let Some(column) = table.field(name) else {
                        return Ok(false);
                    };
                    self.field_passes(table.value(row, column), value)?
                }
            };
            if !passes {
                return Ok(false);
            }
        }
        Ok(true)
    }

    fn field_passes(
        &self,
        actual: Option<FieldRef<'_>>,
        expected: &FieldValue,
    ) -> Result<bool, EvalError> {
        Ok(match (expected, actual) {
            (FieldValue::Expression { operator, value }, Some(FieldRef::Concept(concept))) => {
                let set = self.sub(value)?;
                set.contains(concept.index()) == (*operator == Equality::Equal)
            }
            (FieldValue::Expression { operator, .. }, _) => *operator == Equality::NotEqual,
            (FieldValue::Numeric { operator, value }, Some(FieldRef::Integer(actual))) => {
                let expected: f64 = value.0.parse().unwrap_or(f64::NAN);
                #[expect(
                    clippy::as_conversions,
                    clippy::cast_precision_loss,
                    reason = "reference set integers are small"
                )]
                let actual = actual as f64;
                compare_numbers(*operator, actual, expected)
            }
            (FieldValue::String { operator, terms }, Some(FieldRef::String(text))) => {
                terms.iter().any(|t| term_matches(t, text)) == (*operator == Equality::Equal)
            }
            (FieldValue::Boolean { operator, value }, Some(FieldRef::String(text))) => {
                let actual = text.eq_ignore_ascii_case("true");
                (actual == *value) == (*operator == Equality::Equal)
            }
            (FieldValue::Time { operator, values }, Some(FieldRef::String(text))) => {
                let actual: u32 = text.parse().unwrap_or_default();
                times_match(*operator, values, actual)
            }
            (FieldValue::Time { operator, values }, Some(FieldRef::Integer(actual))) => {
                let actual = u32::try_from(actual).unwrap_or_default();
                times_match(*operator, values, actual)
            }
            _ => false,
        })
    }

    /// The SCTIDs a concept set names: a plain reference or a reference set
    /// as written (the metadata concepts need not be in the edition), any
    /// other constraint by evaluation.
    fn sctids_of(&self, set: &ConceptSet) -> Result<Vec<u64>, EvalError> {
        match set {
            ConceptSet::Set(references) => Ok(references.iter().map(|r| r.id.0).collect()),
            ConceptSet::Expression(sub)
                if sub.operator.is_none()
                    && sub.member_of.is_none()
                    && sub.filters.is_empty()
                    && sub.member_filters.is_empty()
                    && sub.history.is_none() =>
            {
                match &sub.focus {
                    FocusConcept::Reference(reference) => Ok(vec![reference.id.0]),
                    _ => self.sctids_of_set(&self.sub(sub)?),
                }
            }
            ConceptSet::Expression(sub) => self.sctids_of_set(&self.sub(sub)?),
        }
    }

    fn sctids_of_set(&self, set: &RoaringBitmap) -> Result<Vec<u64>, EvalError> {
        let mut ids = Vec::new();
        for concept in set {
            if let Some(id) = self.model.sctid(Ordinal::new(concept))? {
                ids.push(id.0);
            }
        }
        Ok(ids)
    }

    fn acceptabilities(
        set: Option<&crate::ast::AcceptabilitySet>,
    ) -> Result<Vec<Acceptability>, EvalError> {
        match set {
            None => Ok(Vec::new()),
            Some(crate::ast::AcceptabilitySet::Tokens(tokens)) => Ok(tokens.clone()),
            Some(crate::ast::AcceptabilitySet::Concepts(references)) => references
                .iter()
                .map(|reference| match reference.id.0 {
                    PREFERRED => Ok(Acceptability::Preferred),
                    ACCEPTABLE => Ok(Acceptability::Acceptable),
                    _ => Err(EvalError::Unsupported(
                        "an acceptability concept other than preferred or acceptable",
                    )),
                })
                .collect(),
        }
    }

    /// The `{{ C ... }}` filters with their concept sets resolved.
    fn concept_predicates(
        &self,
        filters: &[ConceptFilter],
    ) -> Result<Vec<ConceptPredicate>, EvalError> {
        let mut predicates = Vec::new();
        for filter in filters {
            predicates.push(match filter {
                ConceptFilter::Active { operator, value } => {
                    ConceptPredicate::Active(*value == (*operator == Equality::Equal))
                }
                ConceptFilter::DefinitionStatus { operator, tokens } => {
                    let defined = tokens.contains(&DefinitionStatus::Defined);
                    let primitive = tokens.contains(&DefinitionStatus::Primitive);
                    let equal = *operator == Equality::Equal;
                    ConceptPredicate::DefinitionStatus {
                        defined: defined == equal,
                        primitive: primitive == equal,
                    }
                }
                ConceptFilter::DefinitionStatusId { operator, value } => {
                    let ids = self.sctids_of(value)?;
                    let equal = *operator == Equality::Equal;
                    ConceptPredicate::DefinitionStatus {
                        defined: ids.contains(&DEFINED) == equal,
                        primitive: ids.contains(&PRIMITIVE) == equal,
                    }
                }
                ConceptFilter::Module { operator, value } => ConceptPredicate::Module {
                    modules: self.sctids_of(value)?,
                    negated: *operator == Equality::NotEqual,
                },
                ConceptFilter::EffectiveTime { operator, values } => {
                    ConceptPredicate::EffectiveTime {
                        operator: *operator,
                        values: values
                            .iter()
                            .map(|v| v.0.parse().unwrap_or_default())
                            .collect(),
                    }
                }
            });
        }
        Ok(predicates)
    }

    /// The `{{ D ... }}` filters with their concept sets and aliases resolved.
    fn description_predicates(
        &self,
        filters: &[DescriptionFilter],
    ) -> Result<Vec<DescriptionPredicate>, EvalError> {
        let mut predicates = Vec::new();
        for filter in filters {
            predicates.push(match filter {
                DescriptionFilter::Term { operator, terms } => DescriptionPredicate::Term {
                    operator: *operator,
                    terms: terms.clone(),
                },
                DescriptionFilter::Language { operator, codes } => DescriptionPredicate::Language {
                    operator: *operator,
                    codes: codes.clone(),
                },
                DescriptionFilter::TypeId { operator, value } => DescriptionPredicate::Type {
                    operator: *operator,
                    types: self.sctids_of(value)?,
                },
                DescriptionFilter::Type { operator, tokens } => DescriptionPredicate::Type {
                    operator: *operator,
                    types: tokens
                        .iter()
                        .map(|t| match t {
                            TypeToken::Synonym => SYNONYM,
                            TypeToken::FullySpecifiedName => FULLY_SPECIFIED_NAME,
                            TypeToken::Definition => DEFINITION,
                        })
                        .collect(),
                },
                DescriptionFilter::DialectId {
                    operator,
                    value,
                    acceptability,
                } => {
                    let shared = Self::acceptabilities(acceptability.as_ref())?;
                    let dialects = match value {
                        DialectIdValue::Expression(sub) => self
                            .sctids_of(&ConceptSet::Expression(sub.clone()))?
                            .into_iter()
                            .map(|id| (id, shared.clone()))
                            .collect(),
                        DialectIdValue::Set(items) => {
                            let mut out = Vec::new();
                            for (reference, own) in items {
                                let allowed = if own.is_some() {
                                    Self::acceptabilities(own.as_ref())?
                                } else {
                                    shared.clone()
                                };
                                out.push((reference.id.0, allowed));
                            }
                            out
                        }
                    };
                    DescriptionPredicate::Dialect {
                        operator: *operator,
                        dialects,
                    }
                }
                DescriptionFilter::Dialect {
                    operator,
                    aliases,
                    acceptability,
                } => {
                    let shared = Self::acceptabilities(acceptability.as_ref())?;
                    let mut dialects = Vec::new();
                    for alias in aliases {
                        let refset = crate::dialects::refset(&alias.alias)
                            .ok_or_else(|| EvalError::UnknownDialect(alias.alias.clone()))?;
                        let allowed = if alias.acceptability.is_some() {
                            Self::acceptabilities(alias.acceptability.as_ref())?
                        } else {
                            shared.clone()
                        };
                        dialects.push((refset, allowed));
                    }
                    DescriptionPredicate::Dialect {
                        operator: *operator,
                        dialects,
                    }
                }
                DescriptionFilter::Module { .. } => {
                    return Err(EvalError::Unsupported(
                        "a description module filter: the store keeps no description module",
                    ));
                }
                DescriptionFilter::EffectiveTime { .. } => {
                    return Err(EvalError::Unsupported(
                        "a description effective time filter: the store keeps no description time",
                    ));
                }
                DescriptionFilter::Active { operator, value } => {
                    DescriptionPredicate::Active(*value == (*operator == Equality::Equal))
                }
                DescriptionFilter::Id { operator, ids } => DescriptionPredicate::Id {
                    operator: *operator,
                    ids: ids.iter().map(|id| id.0).collect(),
                },
            });
        }
        Ok(predicates)
    }

    /// The history supplement: the inactive concepts whose association in the
    /// chosen reference sets targets a member of `set`.
    fn history(
        &self,
        mut set: RoaringBitmap,
        history: &HistorySupplement,
    ) -> Result<RoaringBitmap, EvalError> {
        let refsets: Vec<u64> = match history {
            HistorySupplement::Minimum => vec![SAME_AS],
            HistorySupplement::Moderate => {
                vec![SAME_AS, REPLACED_BY, WAS_A, PARTIALLY_EQUIVALENT_TO]
            }
            HistorySupplement::Default | HistorySupplement::Maximum => {
                match self.model.concept(Sctid(HISTORICAL_ASSOCIATION))? {
                    Some(root) => {
                        let mut ids = Vec::new();
                        for concept in self.model.descendants(root) {
                            if let Some(id) = self.model.sctid(Ordinal::new(concept))? {
                                ids.push(id.0);
                            }
                        }
                        ids
                    }
                    None => Vec::new(),
                }
            }
            HistorySupplement::Subset(constraint) => {
                let mut ids = Vec::new();
                for concept in self.expression(constraint)? {
                    if let Some(id) = self.model.sctid(Ordinal::new(concept))? {
                        ids.push(id.0);
                    }
                }
                ids
            }
        };
        let mut added = RoaringBitmap::new();
        for refset in refsets {
            let Some(table) = self.model.members().table(refset) else {
                continue;
            };
            let Some(target) = table.field(TARGET_COMPONENT) else {
                continue;
            };
            for row in 0..table.len() {
                if let (Some(FieldRef::Concept(value)), Some(member)) =
                    (table.value(row, target), table.concept(row))
                    && set.contains(value.index())
                {
                    added.insert(member.index());
                }
            }
        }
        set |= added;
        Ok(set)
    }

    /// The attribute type kinds an attribute name names.
    fn kinds(&self, name: &SubExpressionConstraint) -> Result<Kinds, EvalError> {
        if matches!(name.focus, FocusConcept::Wildcard)
            && name.operator.is_none()
            && name.filters.is_empty()
        {
            return Ok(Kinds::Any);
        }
        let types = self.sub(name)?;
        let attributes = self.model.attributes();
        let mut kinds = Vec::new();
        for concept in types {
            if let Some(id) = self.model.sctid(Ordinal::new(concept))?
                && let Some(kind) = attributes.kind(id.0)
            {
                kinds.push(kind);
            }
        }
        Ok(Kinds::These(kinds))
    }

    /// The concept values of the attributes of `kinds` on the sources in `set`.
    fn values_of(&self, set: &RoaringBitmap, kinds: &Kinds) -> RoaringBitmap {
        let attributes = self.model.attributes();
        let mut out = RoaringBitmap::new();
        for source in set {
            for row in attributes.rows(Ordinal::new(source)) {
                if let ValueRef::Concept(target) = row.value
                    && kinds.contains(row.kind)
                {
                    out.insert(target.index());
                }
            }
        }
        out
    }

    /// `eclrefinement` over the focus set.
    fn refinement(
        &self,
        focus: &RoaringBitmap,
        refinement: &Refinement,
    ) -> Result<RoaringBitmap, EvalError> {
        match refinement {
            Refinement::Single(one) => self.sub_refinement(focus, one),
            Refinement::Conjunction(items) => {
                let mut result = focus.clone();
                for item in items {
                    result &= self.sub_refinement(&result, item)?;
                }
                Ok(result)
            }
            Refinement::Disjunction(items) => {
                let mut result = RoaringBitmap::new();
                for item in items {
                    result |= self.sub_refinement(focus, item)?;
                }
                Ok(result)
            }
        }
    }

    fn sub_refinement(
        &self,
        focus: &RoaringBitmap,
        item: &SubRefinement,
    ) -> Result<RoaringBitmap, EvalError> {
        match item {
            SubRefinement::AttributeSet(set) => self.attribute_set(focus, set),
            SubRefinement::Nested(inner) => self.refinement(focus, inner),
            SubRefinement::Group {
                cardinality,
                attributes,
            } => {
                let tests = self.compile_set(attributes)?;
                let graph = self.model.attributes();
                // A concept whose rows satisfy the set within one group satisfies
                // it over all its rows, so the ungrouped answer (the inverted
                // index) narrows the concepts whose groups are counted, unless
                // zero groups may match.
                let candidates = if cardinality.is_none_or(|c| c.min >= 1) {
                    self.attribute_set(focus, attributes)?
                } else {
                    focus.clone()
                };
                let mut out = RoaringBitmap::new();
                for concept in &candidates {
                    let rows: Vec<Row<'_>> = graph.rows(Ordinal::new(concept)).collect();
                    let mut groups: Vec<Vec<&Row<'_>>> = Vec::new();
                    let mut current: Option<u32> = None;
                    for row in &rows {
                        // NOTE: ECL treats each ungrouped relationship (group 0) as
                        // its own group; the rows arrive sorted by group.
                        if row.group == 0 || current != Some(row.group) {
                            groups.push(Vec::new());
                            current = Some(row.group);
                        }
                        if let Some(last) = groups.last_mut() {
                            last.push(row);
                        }
                    }
                    let matching = groups
                        .iter()
                        .filter(|group| set_holds(&tests, group))
                        .count();
                    if within(*cardinality, u32::try_from(matching).unwrap_or(u32::MAX)) {
                        out.insert(concept);
                    }
                }
                Ok(out)
            }
        }
    }

    /// An ungrouped attribute set over the focus: each attribute is a set of
    /// sources (a fast path when the default cardinality and a concept value
    /// allow the inverted index, else a row scan), joined by the junction.
    fn attribute_set(
        &self,
        focus: &RoaringBitmap,
        set: &AttributeSet,
    ) -> Result<RoaringBitmap, EvalError> {
        match set {
            AttributeSet::Single(one) => self.sub_attribute_set(focus, one),
            AttributeSet::Conjunction(items) => {
                let mut result = focus.clone();
                for item in items {
                    result &= self.sub_attribute_set(&result, item)?;
                }
                Ok(result)
            }
            AttributeSet::Disjunction(items) => {
                let mut result = RoaringBitmap::new();
                for item in items {
                    result |= self.sub_attribute_set(focus, item)?;
                }
                Ok(result)
            }
        }
    }

    fn sub_attribute_set(
        &self,
        focus: &RoaringBitmap,
        item: &SubAttributeSet,
    ) -> Result<RoaringBitmap, EvalError> {
        match item {
            SubAttributeSet::Attribute(attribute) => self.attribute(focus, attribute),
            SubAttributeSet::Nested(inner) => self.attribute_set(focus, inner),
        }
    }

    /// One attribute over the focus, ungrouped.
    fn attribute(
        &self,
        focus: &RoaringBitmap,
        attribute: &Attribute,
    ) -> Result<RoaringBitmap, EvalError> {
        let test = self.compile(attribute)?;
        let graph = self.model.attributes();
        if attribute.reverse {
            return Ok(self.reverse(focus, &test));
        }
        let default = attribute.cardinality.is_none();
        if default
            && let ValueTest::Concept {
                set,
                negated: false,
            } = &test.value
        {
            let mut out = RoaringBitmap::new();
            for kind in test.kinds.iter(graph.types().len()) {
                match set {
                    None => {
                        if let Some(sources) = graph.sources_of_kind(kind) {
                            out |= sources;
                        }
                    }
                    Some(values) => {
                        for target in graph.targets_of_kind(kind) {
                            if values.contains(*target) {
                                out.extend(
                                    graph.sources(kind, Ordinal::new(*target)).iter().copied(),
                                );
                            }
                        }
                    }
                }
            }
            return Ok(out & focus);
        }
        let mut out = RoaringBitmap::new();
        for concept in focus {
            let count = graph
                .rows(Ordinal::new(concept))
                .filter(|row| test.matches(row))
                .count();
            if within(
                attribute.cardinality,
                u32::try_from(count).unwrap_or(u32::MAX),
            ) {
                out.insert(concept);
            }
        }
        Ok(out)
    }

    /// `R attribute = X`: the values of the attribute whose sources are in the
    /// value set, counted per value for the cardinality, within the focus.
    fn reverse(&self, focus: &RoaringBitmap, test: &AttributeTest) -> RoaringBitmap {
        let graph = self.model.attributes();
        let sources = match &test.value {
            ValueTest::Concept {
                set: Some(set),
                negated: false,
            } => Some(set),
            _ => None,
        };
        let mut out = RoaringBitmap::new();
        for target in focus {
            let mut count = 0_u32;
            for kind in test.kinds.iter(graph.types().len()) {
                for source in graph.sources(kind, Ordinal::new(target)) {
                    if sources.is_none_or(|set| set.contains(*source)) {
                        count = count.saturating_add(1);
                    }
                }
            }
            if within(test.cardinality, count) {
                out.insert(target);
            }
        }
        out
    }

    /// The compiled tests of an attribute set, for per-group evaluation.
    fn compile_set(&self, set: &AttributeSet) -> Result<CompiledSet, EvalError> {
        Ok(match set {
            AttributeSet::Single(one) => CompiledSet::Single(Box::new(self.compile_item(one)?)),
            AttributeSet::Conjunction(items) => CompiledSet::Conjunction(
                items
                    .iter()
                    .map(|i| self.compile_item(i))
                    .collect::<Result<_, _>>()?,
            ),
            AttributeSet::Disjunction(items) => CompiledSet::Disjunction(
                items
                    .iter()
                    .map(|i| self.compile_item(i))
                    .collect::<Result<_, _>>()?,
            ),
        })
    }

    fn compile_item(&self, item: &SubAttributeSet) -> Result<CompiledItem, EvalError> {
        Ok(match item {
            SubAttributeSet::Attribute(attribute) => {
                CompiledItem::Attribute(self.compile(attribute)?)
            }
            SubAttributeSet::Nested(inner) => CompiledItem::Nested(self.compile_set(inner)?),
        })
    }

    fn compile(&self, attribute: &Attribute) -> Result<AttributeTest, EvalError> {
        let kinds = self.kinds(&attribute.name)?;
        let value = match &attribute.value {
            AttributeValue::Expression { operator, value } => {
                let set = if matches!(value.focus, FocusConcept::Wildcard)
                    && value.operator.is_none()
                    && value.filters.is_empty()
                    && value.member_of.is_none()
                {
                    None
                } else {
                    Some(self.sub(value)?)
                };
                ValueTest::Concept {
                    set,
                    negated: *operator == Equality::NotEqual,
                }
            }
            AttributeValue::Numeric { operator, value } => {
                ValueTest::Number(*operator, value.0.parse().unwrap_or(f64::NAN))
            }
            AttributeValue::String { operator, terms } => ValueTest::Text(*operator, terms.clone()),
            AttributeValue::Boolean { operator, value } => ValueTest::Boolean(*operator, *value),
        };
        Ok(AttributeTest {
            kinds,
            value,
            cardinality: attribute.cardinality,
        })
    }
}

/// Whether `values` (one time or a set) match `actual` under `operator`.
fn times_match(operator: Comparison, values: &[TimeValue], actual: u32) -> bool {
    let expected = values
        .iter()
        .map(|v| v.0.parse::<u32>().unwrap_or_default());
    match operator {
        Comparison::NotEqual => expected.clone().all(|e| actual != e),
        _ => expected
            .into_iter()
            .any(|e| compare_times(operator, actual, e)),
    }
}

/// A compiled attribute: the type kinds, the value test, the cardinality.
#[derive(Debug)]
struct AttributeTest {
    kinds: Kinds,
    value: ValueTest,
    cardinality: Option<Cardinality>,
}

impl AttributeTest {
    fn matches(&self, row: &Row<'_>) -> bool {
        self.kinds.contains(row.kind) && self.value.matches(row.value)
    }
}

#[derive(Debug)]
enum CompiledSet {
    Single(Box<CompiledItem>),
    Conjunction(Vec<CompiledItem>),
    Disjunction(Vec<CompiledItem>),
}

#[derive(Debug)]
enum CompiledItem {
    Attribute(AttributeTest),
    Nested(CompiledSet),
}

/// Whether the rows of one group satisfy the set.
fn set_holds(set: &CompiledSet, rows: &[&Row<'_>]) -> bool {
    match set {
        CompiledSet::Single(item) => item_holds(item, rows),
        CompiledSet::Conjunction(items) => items.iter().all(|i| item_holds(i, rows)),
        CompiledSet::Disjunction(items) => items.iter().any(|i| item_holds(i, rows)),
    }
}

fn item_holds(item: &CompiledItem, rows: &[&Row<'_>]) -> bool {
    match item {
        CompiledItem::Nested(set) => set_holds(set, rows),
        CompiledItem::Attribute(test) => {
            let count = rows.iter().filter(|row| test.matches(row)).count();
            within(test.cardinality, u32::try_from(count).unwrap_or(u32::MAX))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::{Cardinality, compare_numbers, term_matches, wild_matches, within};
    use crate::ast::{Comparison, TypedSearchTerm};

    #[test]
    fn cardinalities_patterns_and_words_match_as_the_specification_says() {
        assert!(within(None, 1) && within(None, 5) && !within(None, 0));
        assert!(within(
            Some(Cardinality {
                min: 0,
                max: Some(0)
            }),
            0
        ));
        assert!(!within(
            Some(Cardinality {
                min: 0,
                max: Some(0)
            }),
            1
        ));
        assert!(within(Some(Cardinality { min: 2, max: None }), 2));
        assert!(wild_matches("cardi*opathy", "Cardiomyopathy"));
        assert!(!wild_matches("cardi*opathy", "Cardiomyopathy X"));
        assert!(wild_matches("*itis", "Bronchitis"));
        assert!(wild_matches("a\\*b", "A*B"));
        assert!(!wild_matches("a\\*b", "AXB"));
        let term = TypedSearchTerm::Match(vec![String::from("hea"), String::from("att")]);
        assert!(term_matches(&term, "Heart attack"));
        assert!(!term_matches(&term, "Heart"));
        assert!(compare_numbers(Comparison::GreaterOrEqual, 500.0, 500.0));
        assert!(!compare_numbers(Comparison::Less, 500.0, 500.0));
    }
}