sinter_extract/

extract.rs

use sinter_core::{
    Edge, Evidence, FieldBinding, Node, NodeId, Reference, Relation, Span, SymbolKind,
};
use streaming_iterator::StreamingIterator;
use tree_sitter::{Node as TsNode, Parser, Query, QueryCursor};

/// Upper bound on a stored doc body; markdown sections and long
/// docstrings are truncated here, keeping the beginning.
const DOC_CAP_BYTES: usize = 4096;

use sinter_core::FileFacts;

use crate::language::LanguageSpec;

#[derive(Debug, thiserror::Error)]
pub enum ExtractError {
    #[error("bad grammar or query for {language}: {message}")]
    Query {
        language: &'static str,
        message: String,
    },
    #[error("parser returned no tree for {0}")]
    Parse(String),
}

/// One reusable extractor per (language, thread): parser and compiled query
/// are pooled here, never rebuilt per file.
pub struct Extractor {
    spec: &'static LanguageSpec,
    parser: Parser,
    query: Query,
    /// Secondary inline grammar (spec.inline): parses designated
    /// container-node ranges of the primary tree; captures merge into
    /// the same facts through the same contract.
    inline: Option<(Parser, Query)>,
}

/// A definition or scope-only entry, pre-qualification.
struct RawEntry {
    start: usize,
    end: usize,
    name: String,
    /// None for scope-only entries (e.g. impl blocks).
    kind: Option<SymbolKind>,
    /// Extra scope prefix from the same match (e.g. Go receiver type).
    qualifier: Option<String>,
    signature: String,
    doc: Option<String>,
}

/// A reference site, pre-enclosure.
struct RawRef {
    start: usize,
    end: usize,
    name: String,
    path: Option<String>,
    alias: Option<String>,
    relation: Relation,
}

/// A local binding site, pre-scoping.
struct RawLocal {
    start: usize,
    end: usize,
    name: String,
    type_name: Option<String>,
}

/// Everything collect() gathers besides definitions.
#[derive(Default)]
struct Collected {
    refs: Vec<RawRef>,
    locals: Vec<RawLocal>,
    /// (span, field name, written type) — owner resolved after entries exist.
    fields: Vec<(usize, usize, String, String)>,
    /// (span, embedded type name) — owner resolved after entries exist.
    embeds: Vec<(usize, usize, String)>,
    /// (impl block span, trait name) — trait-impl pairing facts.
    trait_impls: Vec<(usize, usize, String)>,
    /// Import-alias name spans: identical local captures are the import
    /// binding itself, not a shadow.
    alias_spans: Vec<(usize, usize)>,
    /// Definition name spans: a blanket type-reference capture also lands
    /// on `struct Foo`'s own name, which is a definition, not a use.
    def_name_spans: Vec<(usize, usize)>,
    /// Explicit doc captures (`@doc`, e.g. Python docstrings): (span, text).
    /// Attached to the smallest containing definition, overriding any
    /// sibling-comment doc.
    docs: Vec<(usize, usize, String)>,
}

impl Extractor {
    pub fn new(spec: &'static LanguageSpec) -> Result<Self, ExtractError> {
        let language = (spec.grammar)();
        let mut parser = Parser::new();
        parser
            .set_language(&language)
            .map_err(|e| ExtractError::Query {
                language: spec.name,
                message: e.to_string(),
            })?;
        let query = Query::new(&language, spec.query_source).map_err(|e| ExtractError::Query {
            language: spec.name,
            message: e.to_string(),
        })?;
        let inline = spec
            .inline
            .map(|i| {
                let language = (i.grammar)();
                let mut parser = Parser::new();
                parser
                    .set_language(&language)
                    .map_err(|e| (spec.name, e.to_string()))?;
                let query = Query::new(&language, i.query_source)
                    .map_err(|e| (spec.name, e.to_string()))?;
                Ok((parser, query))
            })
            .transpose()
            .map_err(
                |(language, message): (&'static str, String)| ExtractError::Query {
                    language,
                    message,
                },
            )?;
        Ok(Self {
            spec,
            parser,
            query,
            inline,
        })
    }

    /// Extract facts from one file. `file` is the repo-relative path.
    pub fn extract(&mut self, file: &str, source: &str) -> Result<FileFacts, ExtractError> {
        let tree = self
            .parser
            .parse(source, None)
            .ok_or_else(|| ExtractError::Parse(file.to_string()))?;
        let root = tree.root_node();

        let mut entries = Vec::new();
        let mut collected = Collected::default();
        collect(
            &self.query,
            self.spec,
            root,
            source,
            &mut entries,
            &mut collected,
        );
        // Secondary inline grammar (spec.inline): parse the container
        // nodes' ranges of the same source, so capture spans are already
        // file-absolute, and merge through the identical contract.
        if let (Some((parser, query)), Some(ispec)) = (&mut self.inline, self.spec.inline) {
            let ranges = container_ranges(root, ispec.container_kinds);
            if !ranges.is_empty() {
                // Both failure modes are broken invariants (container_ranges
                // yields sorted non-overlapping ranges; the primary parse
                // already succeeded) — swallowing them would silently drop
                // this file's inline refs and let the graph assert "no
                // links" without evidence. Fail loudly like the primary.
                parser.set_included_ranges(&ranges).map_err(|e| {
                    ExtractError::Parse(format!("{} (inline ranges: {e})", self.spec.name))
                })?;
                let inline_tree = parser
                    .parse(source, None)
                    .ok_or_else(|| ExtractError::Parse(format!("{} (inline)", self.spec.name)))?;
                collect(
                    query,
                    self.spec,
                    inline_tree.root_node(),
                    source,
                    &mut entries,
                    &mut collected,
                );
            }
        }
        entries.sort_by_key(|e| (e.start, usize::MAX - e.end));
        // Explicit @doc captures override sibling-comment docs on the
        // smallest definition containing them (Python docstrings). Several
        // captures on one definition (markdown section blocks) are joined
        // with blank lines in document order.
        let mut doc_set = vec![false; entries.len()];
        for (d_start, d_end, text) in &collected.docs {
            let owner = entries
                .iter_mut()
                .enumerate()
                .filter(|(_, e)| e.kind.is_some() && e.start <= *d_start && *d_end <= e.end)
                .min_by_key(|(_, e)| e.end - e.start);
            if let Some((i, entry)) = owner {
                let cleaned: Vec<&str> = text.lines().map(str::trim).collect();
                let trimmed = cleaned.join("\n");
                let trimmed = trimmed.trim_matches('\n');
                if trimmed.is_empty() {
                    continue;
                }
                entry.doc = match entry.doc.take().filter(|_| doc_set[i]) {
                    // Whole-section bodies can run long; keep the beginning
                    // (what ask/show surface) and stop appending past the cap.
                    Some(prev) if prev.len() >= DOC_CAP_BYTES => Some(prev),
                    Some(prev) => Some(format!("{prev}\n\n{trimmed}")),
                    None => Some(trimmed.to_string()),
                };
                doc_set[i] = true;
            }
        }
        // Two patterns may claim the same node (e.g. `const f = () => ...`
        // as variable and function): the more specific, non-variable kind
        // wins; sort puts identical spans adjacent.
        entries.dedup_by(|b, a| {
            let same = a.start == b.start && a.end == b.end && a.name == b.name;
            if same && a.kind == Some(SymbolKind::Variable) && b.kind.is_some() {
                a.kind = b.kind;
            }
            same
        });

        let file_id = NodeId::new(file);
        let mut nodes = vec![Node {
            id: file_id.clone(),
            kind: SymbolKind::File,
            name: file.to_string(),
            file: file.to_string(),
            span: Span {
                start: 0,
                end: source.len().max(1) as u64,
            },
            signature: String::new(),
            doc: None,
        }];
        let mut contains = Vec::new();

        // Containment stack: (end, scope name, node id if a real definition).
        let mut stack: Vec<(usize, String, Option<NodeId>)> = Vec::new();
        // (start, end, id, kind) of each definition, for enclosure and
        // declared-field owner lookup.
        let mut def_spans: Vec<(usize, usize, NodeId, SymbolKind)> = Vec::new();

        for entry in &entries {
            while stack.last().is_some_and(|(end, _, _)| *end <= entry.start) {
                stack.pop();
            }
            let mut path: Vec<&str> = stack.iter().map(|(_, name, _)| name.as_str()).collect();
            if let Some(q) = &entry.qualifier {
                path.push(q);
            }
            path.push(&entry.name);
            let qualified = path.join("::");
            // Children nest under the entry's qualified segment.
            let scope_segment = entry
                .qualifier
                .as_ref()
                .map_or(entry.name.clone(), |q| format!("{q}::{}", entry.name));

            let id = if let Some(kind) = entry.kind {
                let id = NodeId::new(format!("{file}#{qualified}@{}", entry.start));
                let parent = stack
                    .iter()
                    .rev()
                    .find_map(|(_, _, id)| id.clone())
                    .unwrap_or_else(|| file_id.clone());
                nodes.push(Node {
                    id: id.clone(),
                    kind,
                    name: entry.name.clone(),
                    file: file.to_string(),
                    span: Span {
                        start: entry.start as u64,
                        end: entry.end as u64,
                    },
                    signature: entry.signature.clone(),
                    doc: entry.doc.clone(),
                });
                contains.push(Edge {
                    src: parent,
                    dst: id.clone(),
                    relation: Relation::Contains,
                    evidence: Evidence::Structural,
                    confidence: Evidence::Structural.confidence(),
                    // Containment is structure, not a reference: no site.
                    site: None,
                });
                def_spans.push((entry.start, entry.end, id.clone(), kind));
                Some(id)
            } else {
                None
            };
            stack.push((entry.end, scope_segment, id));
        }

        // One span may be captured twice (a scoped type's name both with
        // its path and bare): keep the path-bearing one, never both.
        let mut refs = collected.refs;
        refs.retain(|r| !collected.def_name_spans.contains(&(r.start, r.end)));
        // Rust prelude/primitive names never name a corpus symbol unless
        // this file defines one of the same name (then it may shadow).
        if self.spec.name == "rust" {
            refs.retain(|r| {
                r.path.is_some()
                    || !RUST_PRELUDE.contains(&r.name.as_str())
                    || entries.iter().any(|e| e.name == r.name)
            });
        }
        refs.sort_by_key(|r| (r.start, r.end, r.path.is_none()));
        refs.dedup_by_key(|r| (r.start, r.end));
        let references = refs
            .into_iter()
            .map(|r| {
                let enclosing = def_spans
                    .iter()
                    .filter(|(s, e, _, _)| *s <= r.start && r.end <= *e)
                    .min_by_key(|(s, e, _, _)| e - s)
                    .map(|(_, _, id, _)| id.clone());
                Reference {
                    file: file.to_string(),
                    name: r.name,
                    path: r.path,
                    relation: r.relation,
                    span: Span {
                        start: r.start as u64,
                        end: r.end as u64,
                    },
                    enclosing,
                    alias: r.alias,
                }
            })
            .collect();

        // A local shadows from its introduction to the end of the innermost
        // definition containing it (file end at top level). A "local" whose
        // span is an import alias IS the import binding, not a shadow.
        let alias_spans = collected.alias_spans;
        let embeds = collected
            .embeds
            .iter()
            .filter_map(|(start, end, type_name)| {
                let owner = def_spans
                    .iter()
                    .filter(|(s, e, _, _)| s <= start && end <= e)
                    .min_by_key(|(s, e, _, _)| e - s)
                    .map(|(_, _, id, _)| id.clone())?;
                Some(sinter_core::Embed {
                    owner,
                    type_name: type_name.clone(),
                })
            })
            .collect();
        let mut raw_locals = collected
            .locals
            .into_iter()
            .filter(|l| !alias_spans.contains(&(l.start, l.end)))
            .collect::<Vec<_>>();
        // Typed and untyped query patterns can match the same binding.
        // Keep exactly one, preferring the typed capture.
        raw_locals.sort_by_key(|l| (l.start, l.end, l.name.clone(), l.type_name.is_none()));
        raw_locals.dedup_by(|b, a| a.start == b.start && a.end == b.end && a.name == b.name);
        let locals = raw_locals
            .into_iter()
            .map(|l| {
                let scope_end = def_spans
                    .iter()
                    .filter(|(s, e, _, _)| *s <= l.start && l.end <= *e)
                    .min_by_key(|(s, e, _, _)| e - s)
                    .map_or(source.len() as u64, |(_, e, _, _)| *e as u64);
                sinter_core::LocalBinding {
                    file: file.to_string(),
                    name: l.name,
                    span: Span {
                        start: l.start as u64,
                        end: l.end as u64,
                    },
                    scope_end,
                    type_name: l.type_name,
                }
            })
            .collect();

        let fields = collected
            .fields
            .iter()
            .filter_map(|(start, end, name, type_name)| {
                let owner = def_spans
                    .iter()
                    .filter(|(s, e, _, kind)| {
                        *s <= *start
                            && *end <= *e
                            && matches!(
                                kind,
                                SymbolKind::Struct
                                    | SymbolKind::Class
                                    | SymbolKind::Trait
                                    | SymbolKind::Interface
                            )
                    })
                    .min_by_key(|(s, e, _, _)| e - s)
                    .map(|(_, _, id, _)| id.clone())?;
                Some(FieldBinding {
                    owner,
                    name: name.clone(),
                    type_name: type_name.clone(),
                })
            })
            .collect();

        let trait_impls = collected
            .trait_impls
            .iter()
            .map(|(start, end, trait_name)| sinter_core::TraitImpl {
                file: file.to_string(),
                trait_name: trait_name.clone(),
                span: Span {
                    start: *start as u64,
                    end: *end as u64,
                },
            })
            .collect();
        let scopes = crate::scope::node_scopes(self.spec.name, source, &nodes);
        let body_terms = crate::body_terms::body_terms(source, &nodes, &scopes);
        Ok(FileFacts {
            file: file.to_string(),
            content_hash: blake3::hash(source.as_bytes()).to_hex().to_string(),
            has_syntax_errors: root.has_error(),
            nodes,
            contains,
            references,
            locals,
            fields,
            embeds,
            trait_impls,
            scopes,
            body_terms,
        })
    }
}

/// Bare Rust names that always come from the prelude or are primitive
/// types: a reference to one is noise unless the file shadows it.
const RUST_PRELUDE: &[&str] = &[
    "Ok", "Err", "Some", "None", "Vec", "String", "Box", "Option", "Result", "Self", "bool",
    "char", "str", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "i128",
    "isize", "f32", "f64",
];

/// Byte ranges of every node of the given kinds, in document order —
/// the included-range input for a secondary inline parse. Matched nodes
/// are not descended into, so ranges never overlap.
fn container_ranges(root: TsNode<'_>, kinds: &[&str]) -> Vec<tree_sitter::Range> {
    let mut out = Vec::new();
    let mut stack = vec![root];
    while let Some(node) = stack.pop() {
        if kinds.contains(&node.kind()) {
            out.push(node.range());
        } else {
            for i in (0..node.child_count()).rev() {
                stack.extend(node.child(i));
            }
        }
    }
    out.sort_by_key(|r| r.start_byte);
    out
}

/// Run one query over one tree; group captures per match by the universal
/// contract, appending to `entries`/`out` (called once per grammar).
fn collect(
    query: &Query,
    spec: &LanguageSpec,
    root: TsNode<'_>,
    source: &str,
    entries: &mut Vec<RawEntry>,
    out: &mut Collected,
) {
    {
        let mut cursor = QueryCursor::new();
        let mut matches = cursor.matches(query, root, source.as_bytes());
        while let Some(m) = matches.next() {
            let mut def: Option<(TsNode, SymbolKind)> = None;
            let mut scope: Option<TsNode> = None;
            let mut name: Option<TsNode> = None;
            let mut qualifier: Option<TsNode> = None;
            let mut reference: Option<(TsNode, Relation)> = None;
            let mut refpath: Option<TsNode> = None;
            let mut import_path: Option<TsNode> = None;
            let mut import_module: Option<TsNode> = None;
            let mut import_name: Option<TsNode> = None;
            let mut import_alias: Option<TsNode> = None;
            let mut import_star = false;
            let mut match_locals: Vec<TsNode> = Vec::new();
            let mut local_type: Option<TsNode> = None;
            let mut field_name: Option<TsNode> = None;
            let mut field_type: Option<TsNode> = None;
            let mut trait_name: Option<TsNode> = None;
            let mut trait_impl: Option<TsNode> = None;
            for cap in m.captures {
                let cap_name = &query.capture_names()[cap.index as usize];
                if let Some(kind_str) = cap_name.strip_prefix("def.") {
                    if let Some(kind) = SymbolKind::from_str_opt(kind_str) {
                        def = Some((cap.node, kind));
                    }
                } else if let Some(rel) = cap_name.strip_prefix("ref.") {
                    let relation = match rel {
                        "use" => Relation::Uses,
                        _ => Relation::Calls,
                    };
                    reference = Some((cap.node, relation));
                } else {
                    match *cap_name {
                        "scope" => scope = Some(cap.node),
                        "name" => name = Some(cap.node),
                        "qualifier" => qualifier = Some(cap.node),
                        "refpath" => refpath = Some(cap.node),
                        "import" => import_path = Some(cap.node),
                        "import.module" => import_module = Some(cap.node),
                        "import.name" => import_name = Some(cap.node),
                        "import.alias" => import_alias = Some(cap.node),
                        "import.star" => import_star = true,
                        "local" => match_locals.push(cap.node),
                        "local.type" => local_type = Some(cap.node),
                        "field.name" => field_name = Some(cap.node),
                        "field.type" => field_type = Some(cap.node),
                        "trait" => trait_name = Some(cap.node),
                        "trait.impl" => trait_impl = Some(cap.node),
                        "doc" => out.docs.push((
                            cap.node.start_byte(),
                            cap.node.end_byte(),
                            text(cap.node, source).to_string(),
                        )),
                        "embed" => out.embeds.push((
                            cap.node.start_byte(),
                            cap.node.end_byte(),
                            text(cap.node, source).to_string(),
                        )),
                        _ => {}
                    }
                }
            }
            let sep = spec.path_separators.first().copied().unwrap_or(".");
            if let (Some(t), Some(block)) = (trait_name, trait_impl) {
                out.trait_impls.push((
                    block.start_byte(),
                    block.end_byte(),
                    text(t, source).to_string(),
                ));
            }
            if let (Some(name), Some(ty)) = (field_name, field_type) {
                out.fields.push((
                    name.start_byte(),
                    ty.end_byte(),
                    text(name, source).to_string(),
                    text(ty, source).to_string(),
                ));
            }
            if let Some(a) = import_alias {
                out.alias_spans.push((a.start_byte(), a.end_byte()));
            }
            let alias = import_alias.map(|a| text(a, source).to_string());
            for l in &match_locals {
                out.locals.push(RawLocal {
                    start: l.start_byte(),
                    end: l.end_byte(),
                    name: text(*l, source).to_string(),
                    type_name: local_type.map(|t| text(t, source).to_string()),
                });
            }
            if let Some(path_node) = import_path {
                // Whole-path import (`use a::b`, `import "pkg"`), possibly
                // with an alias, Go's dot form, or glob semantics
                // (`@import.star` alongside: bash `source` binds every name).
                out.refs.push(RawRef {
                    start: path_node.start_byte(),
                    end: path_node.end_byte(),
                    name: text(path_node, source)
                        .trim_matches(['"', '\'', '`'])
                        .to_string(),
                    path: None,
                    alias: alias.or_else(|| import_star.then(|| "*".to_string())),
                    relation: Relation::Imports,
                });
            } else if let (Some(module), Some(item)) = (import_module, import_name) {
                // From-style import: module and item joined so the import
                // binds the item itself. Alias renames the local binding.
                let module_text = text(module, source).trim_matches(['"', '\'', '`']);
                out.refs.push(RawRef {
                    start: module.start_byte().min(item.start_byte()),
                    end: item.end_byte().max(module.end_byte()),
                    name: format!("{module_text}{sep}{}", text(item, source)),
                    path: None,
                    alias,
                    relation: Relation::Imports,
                });
            } else if let (Some(module), true) = (import_module, import_star) {
                // Glob import: every top-level name of the module is bound.
                let module_text = text(module, source).trim_matches(['"', '\'', '`']);
                out.refs.push(RawRef {
                    start: module.start_byte(),
                    end: module.end_byte(),
                    name: format!("{module_text}{sep}*"),
                    path: None,
                    alias: Some("*".to_string()),
                    relation: Relation::Imports,
                });
            }
            if let Some((node, relation)) = reference {
                out.refs.push(RawRef {
                    start: node.start_byte(),
                    end: node.end_byte(),
                    name: text(node, source).to_string(),
                    path: refpath.map(|p| qualified_path(p, node, source)),
                    alias: None,
                    relation,
                });
            }
            let container = def.map(|(n, _)| n).or(scope);
            if let (Some(container), Some(name_node)) = (container, name) {
                if def.is_some() {
                    out.def_name_spans
                        .push((name_node.start_byte(), name_node.end_byte()));
                }
                entries.push(RawEntry {
                    start: container.start_byte(),
                    end: container.end_byte(),
                    name: text(name_node, source).to_string(),
                    kind: def.map(|(_, k)| k),
                    qualifier: qualifier.map(|q| text(q, source).to_string()),
                    signature: signature(container, source),
                    doc: doc_comment(container, source, spec.comment_kinds, spec.doc_skip_kinds),
                });
            }
        }
    }
}

/// Path text for a qualified reference: the immediate receiver joined to
/// the referenced name by the separator written between them. Using the
/// receiver child rather than the whole `refpath` text keeps a method
/// chain (`a.b().c()`) from smearing the entire chain into the path of
/// its tail, and drops the whitespace/comments around the separator.
fn qualified_path(refpath: TsNode<'_>, name: TsNode<'_>, source: &str) -> String {
    let receiver = refpath
        .named_child(0)
        .filter(|c| refpath.id() != name.id() && c.end_byte() <= name.start_byte());
    let Some(receiver) = receiver else {
        return text(refpath, source).to_string();
    };
    let sep = source[receiver.end_byte()..name.start_byte()].trim();
    format!("{}{sep}{}", text(receiver, source), text(name, source))
}

fn text<'a>(node: TsNode<'_>, source: &'a str) -> &'a str {
    &source[node.start_byte()..node.end_byte()]
}

/// Declaration text up to the body. Brace languages cut at the first `{`;
/// a first line ending in `:` (Python-style) is the whole signature.
fn signature(node: TsNode<'_>, source: &str) -> String {
    let t = text(node, source);
    let first_line = t.lines().next().unwrap_or(t);
    let head = if first_line.trim_end().ends_with(':') || first_line.contains('{') {
        first_line.split('{').next().unwrap_or(first_line)
    } else {
        let up_to_brace = t.split('{').next().unwrap_or(t);
        if up_to_brace.len() == t.len() {
            first_line
        } else {
            up_to_brace
        }
    };
    head.split_whitespace().collect::<Vec<_>>().join(" ")
}

/// Contiguous comment siblings immediately above the definition (or its
/// parent declaration), stripped of comment markers. Generic across
/// languages: comment node kinds come from the spec.
fn doc_comment(
    node: TsNode<'_>,
    source: &str,
    comment_kinds: &[&str],
    skip_kinds: &[&str],
) -> Option<String> {
    let comments = preceding_comments(node, comment_kinds, skip_kinds).or_else(|| {
        node.parent()
            .and_then(|p| preceding_comments(p, comment_kinds, skip_kinds))
    })?;
    let mut lines = Vec::new();
    for c in comments {
        for line in text(c, source).lines() {
            let mut l = line.trim();
            for marker in ["///", "//!", "//", "/**", "/*", "*/", "--"] {
                if let Some(stripped) = l.strip_prefix(marker) {
                    l = stripped;
                    break;
                }
            }
            // Block-comment continuation: a leading `*` (Javadoc/C-style
            // interior line) is decoration — but `**bold**` is markdown.
            if let Some(rest) = l.strip_prefix('*')
                && !l.starts_with("**")
            {
                l = rest;
            }
            l = l.strip_suffix("*/").unwrap_or(l);
            lines.push(l.trim());
        }
    }
    while lines.first().is_some_and(|l| l.is_empty()) {
        lines.remove(0);
    }
    while lines.last().is_some_and(|l| l.is_empty()) {
        lines.pop();
    }
    if lines.is_empty() {
        None
    } else {
        Some(lines.join("\n"))
    }
}

fn preceding_comments<'t>(
    node: TsNode<'t>,
    comment_kinds: &[&str],
    skip_kinds: &[&str],
) -> Option<Vec<TsNode<'t>>> {
    let mut comments = Vec::new();
    let mut cur = node.prev_named_sibling();
    let mut skips = 0;
    while let Some(sib) = cur {
        if !comment_kinds.contains(&sib.kind()) {
            // Step over decorator-style macro lines (UCLASS, UPROPERTY)
            // that sit between a definition and its doc comment.
            if skips < 2 && comments.is_empty() && skip_kinds.contains(&sib.kind()) {
                skips += 1;
                cur = sib.prev_named_sibling();
                continue;
            }
            break;
        }
        comments.push(sib);
        cur = sib.prev_named_sibling();
    }
    comments.reverse();
    if comments.is_empty() {
        None
    } else {
        Some(comments)
    }
}