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fix(rvlite): finish multi-row MATCH for RETURN columns, SET, DELETE and comma patterns #1237

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fix(rvlite): finish multi-row MATCH for RETURN columns, SET, DELETE and comma patterns #1237

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196 changes: 125 additions & 71 deletions crates/rvlite/src/cypher/executor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
use super::ast::*;
use super::graph_store::*;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::collections::{HashMap, HashSet};
use thiserror::Error;

#[derive(Debug, Error)]
Expand Down Expand Up @@ -101,17 +101,24 @@ impl ExecutionResult {
/// Cypher query executor
pub struct Executor<'a> {
graph: &'a mut PropertyGraph,
/// Set once a MATCH has run in the current query, so an empty `matched_rows`
/// means "no rows" rather than "no MATCH".
matched: bool,
}

impl<'a> Executor<'a> {
pub fn new(graph: &'a mut PropertyGraph) -> Self {
Self { graph }
Self {
graph,
matched: false,
}
}

/// Execute a parsed Cypher query
pub fn execute(&mut self, query: &Query) -> Result<ExecutionResult, ExecutionError> {
let mut context = ExecutionContext::new();
let mut result = None;
self.matched = false;

for statement in &query.statements {
result = Some(self.execute_statement(statement, &mut context)?);
Expand Down Expand Up @@ -256,11 +263,21 @@ impl<'a> Executor<'a> {
clause: &MatchClause,
context: &mut ExecutionContext,
) -> Result<ExecutionResult, ExecutionError> {
let mut matches = Vec::new();
// Comma-separated patterns combine as a cross product; a variable that
// appears in more than one pattern must bind to the same element.
let mut matches = vec![ExecutionContext::new()];

for pattern in &clause.patterns {
let pattern_matches = self.match_pattern(pattern)?;
matches.extend(pattern_matches);
let mut combined = Vec::new();
for left in &matches {
for right in &pattern_matches {
if let Some(ctx) = merge_bindings(left, right) {
combined.push(ctx);
}
}
}
matches = combined;
}

// Apply WHERE filter if present
Expand All @@ -273,10 +290,31 @@ impl<'a> Executor<'a> {

// Store each matched binding set as a separate row so RETURN can iterate all of them
context.matched_rows = matches.into_iter().map(|ctx| ctx.variables).collect();
self.matched = true;

Ok(ExecutionResult::new(vec![]))
}

/// One context per matched row, each holding the outer bindings plus that
/// row's bindings. Without a preceding MATCH this is the outer context alone.
fn row_contexts(&self, context: &ExecutionContext) -> Vec<ExecutionContext> {
if !self.matched {
return vec![context.clone()];
}
context
.matched_rows
.iter()
.map(|bindings| {
let mut row_ctx = ExecutionContext::new();
row_ctx.variables = context.variables.clone();
for (k, v) in bindings {
row_ctx.bind(k.clone(), v.clone());
}
row_ctx
})
.collect()
}

fn match_pattern(&self, pattern: &Pattern) -> Result<Vec<ExecutionContext>, ExecutionError> {
match pattern {
Pattern::Node(node_pattern) => self.match_node_pattern(node_pattern),
Expand Down Expand Up @@ -421,54 +459,22 @@ impl<'a> Executor<'a> {
) -> Result<ExecutionResult, ExecutionError> {
let mut columns = Vec::new();
for item in &clause.items {
let col_name = item
.alias
.clone()
.unwrap_or_else(|| match &item.expression {
Expression::Variable(var) => var.clone(),
_ => "?column?".to_string(),
});
let col_name = column_name(item);
if !columns.contains(&col_name) {
columns.push(col_name);
}
}

let mut result = ExecutionResult::new(columns.clone());

// If MATCH produced multiple rows, iterate each row; otherwise use the current context
let row_bindings: Vec<&HashMap<String, ContextValue>> = if !context.matched_rows.is_empty()
{
context.matched_rows.iter().collect()
} else {
vec![&context.variables]
};

for bindings in row_bindings {
// Build a temporary context for this row by merging matched bindings with outer context
let mut row_ctx = ExecutionContext::new();
for (k, v) in &context.variables {
row_ctx.bind(k.clone(), v.clone());
}
for (k, v) in bindings {
row_ctx.bind(k.clone(), v.clone());
}

for row_ctx in self.row_contexts(context) {
let mut row = HashMap::new();
for col_name in &columns {
// Find the expression for this column
let expr = clause
.items
.iter()
.find(|item| {
let name = item
.alias
.clone()
.unwrap_or_else(|| match &item.expression {
Expression::Variable(var) => var.clone(),
_ => "?column?".to_string(),
});
&name == col_name
})
.find(|item| &column_name(item) == col_name)
.map(|item| &item.expression);

if let Some(expr) = expr {
Expand All @@ -487,24 +493,26 @@ impl<'a> Executor<'a> {
clause: &SetClause,
context: &ExecutionContext,
) -> Result<ExecutionResult, ExecutionError> {
for item in &clause.items {
match item {
SetItem::Property {
variable,
property,
value,
} => {
let val = self.evaluate_expression(value, context)?;
if let Some(ContextValue::Node(node)) = context.get(variable) {
if let Some(node_mut) = self.graph.get_node_mut(&node.id) {
node_mut.set_property(property.clone(), val);
for row_ctx in self.row_contexts(context) {
for item in &clause.items {
match item {
SetItem::Property {
variable,
property,
value,
} => {
let val = self.evaluate_expression(value, &row_ctx)?;
if let Some(ContextValue::Node(node)) = row_ctx.get(variable) {
if let Some(node_mut) = self.graph.get_node_mut(&node.id) {
node_mut.set_property(property.clone(), val);
}
}
}
}
_ => {
return Err(ExecutionError::UnsupportedOperation(
"Only property SET supported".to_string(),
))
_ => {
return Err(ExecutionError::UnsupportedOperation(
"Only property SET supported".to_string(),
))
}
}
}
}
Expand All @@ -517,24 +525,34 @@ impl<'a> Executor<'a> {
clause: &DeleteClause,
context: &ExecutionContext,
) -> Result<ExecutionResult, ExecutionError> {
for expr in &clause.expressions {
if let Expression::Variable(var) = expr {
if let Some(ctx_val) = context.get(var) {
match ctx_val {
ContextValue::Node(node) => {
if clause.detach {
self.graph.delete_node(&node.id)?;
} else {
return Err(ExecutionError::ExecutionError(
"Cannot delete node with relationships without DETACH"
.to_string(),
));
// Cross products can bind the same element in several rows; delete it once.
let mut deleted_nodes = HashSet::new();
let mut deleted_edges = HashSet::new();

for row_ctx in self.row_contexts(context) {
for expr in &clause.expressions {
if let Expression::Variable(var) = expr {
if let Some(ctx_val) = row_ctx.get(var) {
match ctx_val {
ContextValue::Node(node) => {
if clause.detach {
if deleted_nodes.insert(node.id.clone()) {
self.graph.delete_node(&node.id)?;
}
} else {
return Err(ExecutionError::ExecutionError(
"Cannot delete node with relationships without DETACH"
.to_string(),
));
}
}
ContextValue::Edge(edge) => {
if deleted_edges.insert(edge.id.clone()) {
self.graph.delete_edge(&edge.id)?;
}
}
_ => {}
}
ContextValue::Edge(edge) => {
self.graph.delete_edge(&edge.id)?;
}
_ => {}
}
}
}
Expand Down Expand Up @@ -653,3 +671,39 @@ impl<'a> Executor<'a> {
}
}
}

/// Column name for a RETURN item: its alias, else `n` or `n.prop`.
fn column_name(item: &ReturnItem) -> String {
if let Some(alias) = &item.alias {
return alias.clone();
}
match &item.expression {
Expression::Variable(var) => var.clone(),
Expression::Property { object, property } => match &**object {
Expression::Variable(var) => format!("{}.{}", var, property),
_ => "?column?".to_string(),
},
_ => "?column?".to_string(),
}
}

/// Combine two binding sets, or `None` if they bind one variable to different elements.
fn merge_bindings(left: &ExecutionContext, right: &ExecutionContext) -> Option<ExecutionContext> {
let mut merged = left.clone();
for (var, value) in &right.variables {
if let Some(existing) = merged.get(var) {
let same = match (existing, value) {
(ContextValue::Node(a), ContextValue::Node(b)) => a.id == b.id,
(ContextValue::Edge(a), ContextValue::Edge(b)) => a.id == b.id,
(ContextValue::Value(a), ContextValue::Value(b)) => a == b,
_ => false,
};
if !same {
return None;
}
} else {
merged.bind(var.clone(), value.clone());
}
}
Some(merged)
}
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