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//! Cypher scalar functions — graph category. Split out of the monolithic
//! `evaluate_scalar_function` dispatcher; arms are verbatim. Routed from
//! `super::evaluate_scalar_function`; returns `Ok(None)` when `name` is not
//! one of this category's functions so the dispatcher tries the next.
use super::super::helpers::*;
use super::super::*;
use crate::datatypes::values::Value;
use crate::graph::storage::GraphRead;
impl<'a> CypherExecutor<'a> {
pub(super) fn eval_graph_fn(
&self,
name: &str,
args: &[Expression],
row: &ResultRow,
) -> Result<Option<Value>, String> {
let result: Result<Value, String> = match name {
"nodes" => {
// nodes(p) returns the list of nodes in a path
// (source + intermediates + target).
//
// Phase A.1 / C2 — native `Value::List(Vec<Value::Node>)`.
// Each element is a full NodeValue (id, labels, properties)
// mirroring what `RETURN n` would emit. Replaces the
// pre-A.1 JSON-string list of dicts.
if let Some(Expression::Variable(var)) = args.first() {
if let Some(path) = row.path_bindings.get(var) {
let mut items: Vec<Value> = Vec::with_capacity(path.path.len() + 1);
if let Some(src) = materialize_node_value(path.source, self.graph) {
items.push(Value::Node(Box::new(src)));
}
for (node_idx, _conn_type) in &path.path {
if let Some(node) = materialize_node_value(*node_idx, self.graph) {
items.push(Value::Node(Box::new(node)));
}
}
return Ok(Some(Value::List(items)));
}
}
Ok(Value::Null)
}
"relationships" | "rels" => {
// relationships(p) — list of relationships in a path.
//
// Phase A.1 / C2 — native `Value::List(Vec<Value::Relationship>)`.
// Each element is a full RelValue (id, start, end, type,
// properties), recovered by walking the path's
// (node_idx, _) pairs and looking up the connecting
// edge between consecutive nodes (mirrors
// materialize_path_value's hop-recovery).
if let Some(Expression::Variable(var)) = args.first() {
if let Some(path) = row.path_bindings.get(var) {
let mut items: Vec<Value> = Vec::with_capacity(path.path.len());
let mut prev_idx = path.source;
for (node_idx, _conn_type) in &path.path {
if let Some(edge_idx) = self.graph.graph.find_edge(prev_idx, *node_idx)
{
if let Some(rel) = materialize_rel_value(edge_idx, self.graph) {
items.push(Value::Relationship(Box::new(rel)));
}
}
prev_idx = *node_idx;
}
return Ok(Some(Value::List(items)));
}
}
Ok(Value::Null)
}
"type" => {
// type(r) returns the relationship type
if let Some(Expression::Variable(var)) = args.first() {
if let Some(edge) = row.edge_bindings.get(var) {
if let Some(edge_data) = {
let g = &self.graph.graph;
g.edge_weight(edge.edge_index)
} {
return Ok(Some(Value::String(
edge_data
.connection_type_str(&self.graph.interner)
.to_string(),
)));
}
}
}
Ok(Value::Null)
}
"id" => {
// id(n) returns the node id. Accepts a bound variable, a
// NodeRef, or a materialised node value (collect()[0] etc.).
if let Some(arg) = args.first() {
if let Some(idx) = self.node_arg_index(arg, row) {
if let Some(node) = self.graph.graph.node_weight(idx) {
return Ok(Some(resolve_node_property(node, "id", self.graph)));
}
}
if let Ok(Value::Node(nv)) = self.evaluate_expression(arg, row) {
return Ok(Some(
nv.properties.get("id").cloned().unwrap_or(Value::Null),
));
}
}
Ok(Value::Null)
}
// shortest_path_length(a, b) → undirected BFS hop count
// between two bound node variables. Real query: "how many
// hops from A to B" without materializing the full path.
// Wraps `graph_algorithms::shortest_path_cost` (already
// public for the wheel's `.shortest_path_length()` method)
// so every binding reaches it through Cypher.
//
// Returns Null if either argument isn't a bound node
// variable, or if the nodes are not connected. Returns 0
// for self-loops (a == b).
//
// 2026-05-25 broad-scan lift, Batch 4.
"shortest_path_length" => {
if args.len() != 2 {
return Err("shortest_path_length() requires 2 node-variable args: \
shortest_path_length(a, b)"
.into());
}
let (a_var, b_var) = match (&args[0], &args[1]) {
(Expression::Variable(a), Expression::Variable(b)) => (a, b),
_ => {
return Err("shortest_path_length() args must be bound node variables \
(e.g. MATCH (a),(b) RETURN shortest_path_length(a, b))"
.into());
}
};
let a_idx = row.node_bindings.get(a_var);
let b_idx = row.node_bindings.get(b_var);
let (Some(&src), Some(&tgt)) = (a_idx, b_idx) else {
return Ok(Some(Value::Null));
};
let cost = crate::graph::algorithms::graph_algorithms::shortest_path_cost(
self.graph, src, tgt,
);
match cost {
Some(n) => Ok(Value::Int64(n as i64)),
None => Ok(Value::Null),
}
}
// degree(n) / inDegree(n) / outDegree(n) → the node's edge
// count. `degree` is both directions (a self-loop counts
// twice — the standard graph-theory convention, matching
// `degree_centrality`); `inDegree` counts incoming edges,
// `outDegree` outgoing. Accepts a bound node variable, a
// `NodeRef`, or a materialised node value (carried through
// `WITH n AS x` / `collect(n)[0]` / `UNWIND`); returns Null
// when the argument isn't a resolvable node.
//
// Real query: "find hubs" — `MATCH (n) WHERE degree(n) > 100
// RETURN n`. Previously impossible: there was no degree
// function and the `size((n)--())` pattern-count shorthand
// isn't supported by the parser.
"degree" | "indegree" | "outdegree" => {
use petgraph::Direction;
let Some(arg) = args.first() else {
return Ok(Some(Value::Null));
};
// Resolve to a live NodeIndex. Fast path: a bound variable
// or NodeRef. Fallback: a materialised node value (passed
// through `WITH n AS x`, `collect(n)[0]`, `UNWIND`) — resolve
// it by its (primary label, id) via the same lookup
// `MATCH (n {id:…})` uses, so degree() stays consistent with
// id()/labels() on carried-through nodes.
let idx = match self.node_arg_index(arg, row) {
Some(idx) => idx,
None => match self.evaluate_expression(arg, row) {
Ok(Value::Node(nv)) => match (nv.labels.first(), nv.properties.get("id")) {
(Some(label), Some(id_val)) => {
match self.graph.lookup_by_id_readonly(label, id_val) {
Some(idx) => idx,
None => return Ok(Some(Value::Null)),
}
}
_ => return Ok(Some(Value::Null)),
},
_ => return Ok(Some(Value::Null)),
},
};
let g = &self.graph.graph;
let count = match name {
"indegree" => g.edges_directed(idx, Direction::Incoming).count(),
"outdegree" => g.edges_directed(idx, Direction::Outgoing).count(),
// "degree": both directions.
_ => {
g.edges_directed(idx, Direction::Outgoing).count()
+ g.edges_directed(idx, Direction::Incoming).count()
}
};
Ok(Value::Int64(count as i64))
}
"labels" => {
// labels(n) returns the list of node labels: primary
// first, then secondaries in insertion order.
//
// Routes through `DirGraph::node_labels`, which reads
// secondaries from `secondary_label_index` (the
// canonical source maintained by the choke-point label
// API). This works uniformly across all three
// backends, including disk — where the backend
// `node_labels_of` would only see the primary because
// disk-materialised NodeData carries empty
// extra_labels.
if let Some(arg) = args.first() {
// Bound variable or NodeRef → live labels (includes
// secondaries via the canonical index).
if let Some(idx) = self.node_arg_index(arg, row) {
let keys = self.graph.node_labels(idx);
if !keys.is_empty() {
let labels: Vec<Value> = keys
.iter()
.map(|k| Value::String(self.graph.interner.resolve(*k).to_string()))
.collect();
return Ok(Some(Value::List(labels)));
}
}
// Materialised node value (e.g. `collect(a)[0]`,
// `head(collect(a))`) → read its labels directly. The
// value carries the full set (see materialize_node_value).
if let Ok(Value::Node(nv)) = self.evaluate_expression(arg, row) {
return Ok(Some(Value::List(
nv.labels.into_iter().map(Value::String).collect(),
)));
}
}
Ok(Value::Null)
}
"keys" => {
// keys(n) or keys(r) — return property names as a list.
//
// Phase A.1 / C2 — native `Value::List(Vec<Value::String>)`.
// For nodes, derive the key set from `materialize_node_value`
// so it exactly matches `keys(properties(n))` and the property
// dict carried by `RETURN n`: virtual id/title/type, every
// user-set property, the alias-recovered columns (non-literal
// `unique_id_field`/`node_title_field`), and — on the columnar
// (disk/mapped) backends — the per-type metadata columns that a
// bare `property_keys()` walk would miss. The materialiser
// omits null-valued aliases, so the key set is consistent with
// what `n.<name>` resolves at query time.
if let Some(arg) = args.first() {
if let Some(idx) = self.node_arg_index(arg, row) {
if let Some(node_value) = materialize_node_value(idx, self.graph) {
// BTreeMap keys are already sorted + unique.
let keys: Vec<Value> = node_value
.properties
.into_keys()
.map(Value::String)
.collect();
return Ok(Some(Value::List(keys)));
}
}
// Materialised node value (collect()[0] etc.) → its keys.
if let Ok(Value::Node(nv)) = self.evaluate_expression(arg, row) {
let mut keys: Vec<String> = nv.properties.keys().cloned().collect();
keys.sort();
keys.dedup();
return Ok(Some(Value::List(
keys.into_iter().map(Value::String).collect(),
)));
}
if let Expression::Variable(var) = arg {
if let Some(edge) = row.edge_bindings.get(var) {
if let Some(edge_data) = {
let g = &self.graph.graph;
g.edge_weight(edge.edge_index)
} {
let mut keys: Vec<String> = vec!["type".to_string()];
keys.extend(
edge_data
.property_keys(&self.graph.interner)
.map(String::from),
);
keys.sort();
return Ok(Some(Value::List(
keys.into_iter().map(Value::String).collect(),
)));
}
}
}
}
Ok(Value::Null)
}
"properties" => {
// properties(n) / properties(r) → native Value::Map.
//
// Phase A.1 / C2 — emits `Value::Map(BTreeMap)` directly.
// For nodes, delegate to `materialize_node_value` so the map
// is byte-for-byte the property dict `RETURN n` produces:
// virtual id/title/type, every user-set property, AND the
// alias-recovered columns (a non-literal `unique_id_field` /
// `node_title_field` hoisted into `node.id()`/`node.title()`).
// Reusing the materializer keeps the two in lockstep across
// backends — including the columnar (disk/mapped) metadata
// walk that a bare `property_keys()` loop here would miss.
// For relationships, includes `type` + every user-set
// edge property.
if args.len() != 1 {
return Err("properties() requires 1 argument: a node or relationship".into());
}
let arg = &args[0];
if let Some(idx) = self.node_arg_index(arg, row) {
if let Some(node_value) = materialize_node_value(idx, self.graph) {
return Ok(Some(Value::Map(node_value.properties)));
}
}
// Materialised node value (collect()[0] etc.) → its property map.
if let Ok(Value::Node(nv)) = self.evaluate_expression(arg, row) {
return Ok(Some(Value::Map(nv.properties)));
}
if let Expression::Variable(var) = arg {
if let Some(edge) = row.edge_bindings.get(var.as_str()) {
if let Some(edge_data) = {
let g = &self.graph.graph;
g.edge_weight(edge.edge_index)
} {
let mut props: std::collections::BTreeMap<String, Value> =
std::collections::BTreeMap::new();
props.insert(
"type".to_string(),
Value::String(
edge_data
.connection_type_str(&self.graph.interner)
.to_string(),
),
);
for key in edge_data.property_keys(&self.graph.interner) {
if let Some(val) = edge_data.get_property(key) {
props.insert(key.to_string(), val.clone());
}
}
return Ok(Some(Value::Map(props)));
}
}
}
Ok(Value::Null)
}
"start_node" | "startnode" => {
// start_node(r) / startNode(r) → source node of the
// bound relationship in the graph. Look up via
// `edge_index` rather than `EdgeBinding.source` —
// the binding stores the pattern's left endpoint,
// which is *not* the same as the edge's graph source
// when the matcher anchored on the right endpoint and
// walked incoming.
if let Some(Expression::Variable(var)) = args.first() {
if let Some(edge) = row.edge_bindings.get(var.as_str()) {
if let Some((src, _)) = self.graph.graph.edge_endpoints(edge.edge_index) {
return Ok(Some(Value::NodeRef(src.index() as u32)));
}
}
}
Ok(Value::Null)
}
"end_node" | "endnode" => {
// end_node(r) / endNode(r) → target node of the
// bound relationship in the graph. See `start_node`
// above for the reason we go through `edge_index`.
if let Some(Expression::Variable(var)) = args.first() {
if let Some(edge) = row.edge_bindings.get(var.as_str()) {
if let Some((_, tgt)) = self.graph.graph.edge_endpoints(edge.edge_index) {
return Ok(Some(Value::NodeRef(tgt.index() as u32)));
}
}
}
Ok(Value::Null)
}
// ── Text predicates (0.8.20) ──────────────────────────────
_ => return Ok(None),
};
result.map(Some)
}
}