/
Graph.js
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Graph.js
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// @flow strict-local
import {fromNodeId} from './types';
import AdjacencyList, {type SerializedAdjacencyList} from './AdjacencyList';
import type {Edge, NodeId} from './types';
import type {TraversalActions, GraphVisitor} from '@parcel/types';
import assert from 'assert';
import nullthrows from 'nullthrows';
export type NullEdgeType = 1;
export type GraphOpts<TNode, TEdgeType: number = 1> = {|
nodes?: Map<NodeId, TNode>,
adjacencyList?: SerializedAdjacencyList<TEdgeType>,
rootNodeId?: ?NodeId,
|};
export type SerializedGraph<TNode, TEdgeType: number = 1> = {|
nodes: Map<NodeId, TNode>,
adjacencyList: SerializedAdjacencyList<TEdgeType>,
rootNodeId: ?NodeId,
|};
export type AllEdgeTypes = -1;
export const ALL_EDGE_TYPES: AllEdgeTypes = -1;
export default class Graph<TNode, TEdgeType: number = 1> {
nodes: Map<NodeId, TNode>;
adjacencyList: AdjacencyList<TEdgeType>;
rootNodeId: ?NodeId;
constructor(opts: ?GraphOpts<TNode, TEdgeType>) {
this.nodes = opts?.nodes || new Map();
this.setRootNodeId(opts?.rootNodeId);
let adjacencyList = opts?.adjacencyList;
this.adjacencyList = adjacencyList
? AdjacencyList.deserialize(adjacencyList)
: new AdjacencyList<TEdgeType>();
}
setRootNodeId(id: ?NodeId) {
this.rootNodeId = id;
}
static deserialize(
opts: GraphOpts<TNode, TEdgeType>,
): Graph<TNode, TEdgeType> {
return new this({
nodes: opts.nodes,
adjacencyList: opts.adjacencyList,
rootNodeId: opts.rootNodeId,
});
}
serialize(): SerializedGraph<TNode, TEdgeType> {
return {
nodes: this.nodes,
adjacencyList: this.adjacencyList.serialize(),
rootNodeId: this.rootNodeId,
};
}
// Returns an iterator of all edges in the graph. This can be large, so iterating
// the complete list can be costly in large graphs. Used when merging graphs.
getAllEdges(): Iterator<Edge<TEdgeType | NullEdgeType>> {
return this.adjacencyList.getAllEdges();
}
addNode(node: TNode): NodeId {
let id = this.adjacencyList.addNode();
this.nodes.set(id, node);
return id;
}
hasNode(id: NodeId): boolean {
return this.nodes.has(id);
}
getNode(id: NodeId): ?TNode {
return this.nodes.get(id);
}
addEdge(
from: NodeId,
to: NodeId,
type: TEdgeType | NullEdgeType = 1,
): boolean {
if (Number(type) === 0) {
throw new Error(`Edge type "${type}" not allowed`);
}
if (!this.getNode(from)) {
throw new Error(`"from" node '${fromNodeId(from)}' not found`);
}
if (!this.getNode(to)) {
throw new Error(`"to" node '${fromNodeId(to)}' not found`);
}
return this.adjacencyList.addEdge(from, to, type);
}
hasEdge(
from: NodeId,
to: NodeId,
type?: TEdgeType | NullEdgeType | Array<TEdgeType | NullEdgeType> = 1,
): boolean {
return this.adjacencyList.hasEdge(from, to, type);
}
getNodeIdsConnectedTo(
nodeId: NodeId,
type:
| TEdgeType
| NullEdgeType
| Array<TEdgeType | NullEdgeType>
| AllEdgeTypes = 1,
): Array<NodeId> {
this._assertHasNodeId(nodeId);
return this.adjacencyList.getNodeIdsConnectedTo(nodeId, type);
}
getNodeIdsConnectedFrom(
nodeId: NodeId,
type:
| TEdgeType
| NullEdgeType
| Array<TEdgeType | NullEdgeType>
| AllEdgeTypes = 1,
): Array<NodeId> {
this._assertHasNodeId(nodeId);
return this.adjacencyList.getNodeIdsConnectedFrom(nodeId, type);
}
// Removes node and any edges coming from or to that node
removeNode(nodeId: NodeId) {
if (!this.hasNode(nodeId)) {
return;
}
for (let {type, from} of this.adjacencyList.getInboundEdgesByType(nodeId)) {
this._removeEdge(
from,
nodeId,
type,
// Do not allow orphans to be removed as this node could be one
// and is already being removed.
false,
);
}
for (let {type, to} of this.adjacencyList.getOutboundEdgesByType(nodeId)) {
this._removeEdge(nodeId, to, type);
}
let wasRemoved = this.nodes.delete(nodeId);
assert(wasRemoved);
}
removeEdges(nodeId: NodeId, type: TEdgeType | NullEdgeType = 1) {
if (!this.hasNode(nodeId)) {
return;
}
for (let to of this.getNodeIdsConnectedFrom(nodeId, type)) {
this._removeEdge(nodeId, to, type);
}
}
removeEdge(
from: NodeId,
to: NodeId,
type: TEdgeType | NullEdgeType = 1,
removeOrphans: boolean = true,
) {
if (!this.adjacencyList.hasEdge(from, to, type)) {
throw new Error(
`Edge from ${fromNodeId(from)} to ${fromNodeId(to)} not found!`,
);
}
this._removeEdge(from, to, type, removeOrphans);
}
// Removes edge and node the edge is to if the node is orphaned
_removeEdge(
from: NodeId,
to: NodeId,
type: TEdgeType | NullEdgeType = 1,
removeOrphans: boolean = true,
) {
if (!this.adjacencyList.hasEdge(from, to, type)) {
return;
}
this.adjacencyList.removeEdge(from, to, type);
if (removeOrphans && this.isOrphanedNode(to)) {
this.removeNode(to);
}
}
isOrphanedNode(nodeId: NodeId): boolean {
if (!this.hasNode(nodeId)) {
return false;
}
if (this.rootNodeId == null) {
// If the graph does not have a root, and there are inbound edges,
// this node should not be considered orphaned.
return !this.adjacencyList.hasInboundEdges(nodeId);
}
// Otherwise, attempt to traverse backwards to the root. If there is a path,
// then this is not an orphaned node.
let hasPathToRoot = false;
// go back to traverseAncestors
this.traverseAncestors(
nodeId,
(ancestorId, _, actions) => {
if (ancestorId === this.rootNodeId) {
hasPathToRoot = true;
actions.stop();
}
},
ALL_EDGE_TYPES,
);
if (hasPathToRoot) {
return false;
}
return true;
}
updateNode(nodeId: NodeId, node: TNode): void {
this._assertHasNodeId(nodeId);
this.nodes.set(nodeId, node);
}
// Update a node's downstream nodes making sure to prune any orphaned branches
replaceNodeIdsConnectedTo(
fromNodeId: NodeId,
toNodeIds: $ReadOnlyArray<NodeId>,
replaceFilter?: null | (NodeId => boolean),
type?: TEdgeType | NullEdgeType = 1,
): void {
this._assertHasNodeId(fromNodeId);
let outboundEdges = this.getNodeIdsConnectedFrom(fromNodeId, type);
let childrenToRemove = new Set(
replaceFilter
? outboundEdges.filter(toNodeId => replaceFilter(toNodeId))
: outboundEdges,
);
for (let toNodeId of toNodeIds) {
childrenToRemove.delete(toNodeId);
if (!this.hasEdge(fromNodeId, toNodeId, type)) {
this.addEdge(fromNodeId, toNodeId, type);
}
}
for (let child of childrenToRemove) {
this._removeEdge(fromNodeId, child, type);
}
}
traverse<TContext>(
visit: GraphVisitor<NodeId, TContext>,
startNodeId: ?NodeId,
type:
| TEdgeType
| NullEdgeType
| Array<TEdgeType | NullEdgeType>
| AllEdgeTypes = 1,
): ?TContext {
return this.dfs({
visit,
startNodeId,
getChildren: nodeId => this.getNodeIdsConnectedFrom(nodeId, type),
});
}
filteredTraverse<TValue, TContext>(
filter: (NodeId, TraversalActions) => ?TValue,
visit: GraphVisitor<TValue, TContext>,
startNodeId: ?NodeId,
type?: TEdgeType | Array<TEdgeType | NullEdgeType> | AllEdgeTypes,
): ?TContext {
return this.traverse(mapVisitor(filter, visit), startNodeId, type);
}
traverseAncestors<TContext>(
startNodeId: ?NodeId,
visit: GraphVisitor<NodeId, TContext>,
type:
| TEdgeType
| NullEdgeType
| Array<TEdgeType | NullEdgeType>
| AllEdgeTypes = 1,
): ?TContext {
return this.dfs({
visit,
startNodeId,
getChildren: nodeId => this.getNodeIdsConnectedTo(nodeId, type),
});
}
dfs<TContext>({
visit,
startNodeId,
getChildren,
}: {|
visit: GraphVisitor<NodeId, TContext>,
getChildren(nodeId: NodeId): Array<NodeId>,
startNodeId?: ?NodeId,
|}): ?TContext {
let traversalStartNode = nullthrows(
startNodeId ?? this.rootNodeId,
'A start node is required to traverse',
);
this._assertHasNodeId(traversalStartNode);
let visited = new Set<NodeId>();
let stopped = false;
let skipped = false;
let actions: TraversalActions = {
skipChildren() {
skipped = true;
},
stop() {
stopped = true;
},
};
let walk = (nodeId, context: ?TContext) => {
if (!this.hasNode(nodeId)) return;
visited.add(nodeId);
skipped = false;
let enter = typeof visit === 'function' ? visit : visit.enter;
if (enter) {
let newContext = enter(nodeId, context, actions);
if (typeof newContext !== 'undefined') {
// $FlowFixMe[reassign-const]
context = newContext;
}
}
if (skipped) {
return;
}
if (stopped) {
return context;
}
for (let child of getChildren(nodeId)) {
if (visited.has(child)) {
continue;
}
visited.add(child);
let result = walk(child, context);
if (stopped) {
return result;
}
}
if (
typeof visit !== 'function' &&
visit.exit &&
// Make sure the graph still has the node: it may have been removed between enter and exit
this.hasNode(nodeId)
) {
let newContext = visit.exit(nodeId, context, actions);
if (typeof newContext !== 'undefined') {
// $FlowFixMe[reassign-const]
context = newContext;
}
}
if (skipped) {
return;
}
if (stopped) {
return context;
}
};
return walk(traversalStartNode);
}
bfs(visit: (nodeId: NodeId) => ?boolean): ?NodeId {
let rootNodeId = nullthrows(
this.rootNodeId,
'A root node is required to traverse',
);
let queue: Array<NodeId> = [rootNodeId];
let visited = new Set<NodeId>([rootNodeId]);
while (queue.length > 0) {
let node = queue.shift();
let stop = visit(rootNodeId);
if (stop === true) {
return node;
}
for (let child of this.getNodeIdsConnectedFrom(node)) {
if (!visited.has(child)) {
visited.add(child);
queue.push(child);
}
}
}
return null;
}
topoSort(type?: TEdgeType): Array<NodeId> {
let sorted: Array<NodeId> = [];
this.traverse(
{
exit: nodeId => {
sorted.push(nodeId);
},
},
null,
type,
);
return sorted.reverse();
}
findAncestor(nodeId: NodeId, fn: (nodeId: NodeId) => boolean): ?NodeId {
let res = null;
this.traverseAncestors(nodeId, (nodeId, ctx, traversal) => {
if (fn(nodeId)) {
res = nodeId;
traversal.stop();
}
});
return res;
}
findAncestors(
nodeId: NodeId,
fn: (nodeId: NodeId) => boolean,
): Array<NodeId> {
let res = [];
this.traverseAncestors(nodeId, (nodeId, ctx, traversal) => {
if (fn(nodeId)) {
res.push(nodeId);
traversal.skipChildren();
}
});
return res;
}
findDescendant(nodeId: NodeId, fn: (nodeId: NodeId) => boolean): ?NodeId {
let res = null;
this.traverse((nodeId, ctx, traversal) => {
if (fn(nodeId)) {
res = nodeId;
traversal.stop();
}
}, nodeId);
return res;
}
findDescendants(
nodeId: NodeId,
fn: (nodeId: NodeId) => boolean,
): Array<NodeId> {
let res = [];
this.traverse((nodeId, ctx, traversal) => {
if (fn(nodeId)) {
res.push(nodeId);
traversal.skipChildren();
}
}, nodeId);
return res;
}
_assertHasNodeId(nodeId: NodeId) {
if (!this.hasNode(nodeId)) {
throw new Error('Does not have node ' + fromNodeId(nodeId));
}
}
}
export function mapVisitor<NodeId, TValue, TContext>(
filter: (NodeId, TraversalActions) => ?TValue,
visit: GraphVisitor<TValue, TContext>,
): GraphVisitor<NodeId, TContext> {
function makeEnter(visit) {
return function mappedEnter(nodeId, context, actions) {
let value = filter(nodeId, actions);
if (value != null) {
return visit(value, context, actions);
}
};
}
if (typeof visit === 'function') {
return makeEnter(visit);
}
let mapped = {};
if (visit.enter != null) {
mapped.enter = makeEnter(visit.enter);
}
if (visit.exit != null) {
mapped.exit = function mappedExit(nodeId, context, actions) {
let exit = visit.exit;
if (!exit) {
return;
}
let value = filter(nodeId, actions);
if (value != null) {
return exit(value, context, actions);
}
};
}
return mapped;
}