mirror of
https://github.com/amitwh/markdown-converter.git
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feat(flowchart): pure graph store with undo/redo + injectable IO
Amit Haridas
This commit is contained in:
@@ -0,0 +1,261 @@
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/**
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* Pure graph store for the flow chart editor.
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*
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* Graph = { nodes: Node[], edges: Edge[] }
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* Node: { id, kind, x, y, label }
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* Edge: { id, fromNodeId, toNodeId, kind: 'solid'|'dotted'|'thick', label? }
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*
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* IO is injected for unit tests + persistence:
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* { persistencePath, readFile, writeFile, now }
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*
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* @module flowchart-store
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*/
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const NODE_KINDS = ['process', 'decision', 'terminator', 'subroutine', 'document'];
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const EDGE_KINDS = ['solid', 'dotted', 'thick'];
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const UNDO_LIMIT = 50;
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function clone(obj) {
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return JSON.parse(JSON.stringify(obj));
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}
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function newId(prefix) {
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// 12 hex chars; monotonic enough for in-memory use.
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return `${prefix}_${Math.random().toString(16).slice(2, 10)}${Date.now().toString(16).slice(-4)}`;
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}
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function isValidNode(node) {
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return (
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node &&
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typeof node.id === 'string' &&
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NODE_KINDS.includes(node.kind) &&
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Number.isFinite(node.x) &&
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Number.isFinite(node.y) &&
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typeof node.label === 'string'
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);
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}
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function isValidEdge(edge) {
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return (
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edge &&
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typeof edge.id === 'string' &&
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typeof edge.fromNodeId === 'string' &&
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typeof edge.toNodeId === 'string' &&
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EDGE_KINDS.includes(edge.kind)
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);
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}
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/**
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* @param {object} io
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* @param {string} io.persistencePath Absolute path for auto-save JSON.
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* @param {(path:string) => Promise<string|null>} io.readFile
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* @param {(path:string, content:string) => Promise<void>} io.writeFile
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* @param {() => number} io.now
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*/
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function create(io) {
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if (!io || typeof io !== 'object') {
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throw new Error('flowchart-store: io bundle is required');
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}
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let graph = { nodes: [], edges: [] };
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const undoStack = [];
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const redoStack = [];
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const listeners = new Set();
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function emit() {
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for (const fn of listeners) {
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try {
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fn(getGraph());
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} catch {
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// Don't let a subscriber crash the store.
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}
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}
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}
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function snapshot() {
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undoStack.push(clone(graph));
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if (undoStack.length > UNDO_LIMIT) undoStack.shift();
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redoStack.length = 0;
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}
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function getGraph() {
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return clone(graph);
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}
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function addNode({ kind, x, y, label = '' }) {
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if (!NODE_KINDS.includes(kind)) {
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throw new Error(`flowchart-store: unknown node kind "${kind}"`);
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}
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snapshot();
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const node = { id: newId('n'), kind, x, y, label };
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graph.nodes.push(node);
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emit();
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return node;
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}
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function findNodeIndex(id) {
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return graph.nodes.findIndex((n) => n.id === id);
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}
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function findEdgeIndex(id) {
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return graph.edges.findIndex((e) => e.id === id);
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}
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function moveNode(id, x, y) {
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const idx = findNodeIndex(id);
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if (idx === -1) throw new Error(`flowchart-store: unknown node id "${id}"`);
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snapshot();
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graph.nodes[idx] = { ...graph.nodes[idx], x, y };
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emit();
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}
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function setNodeLabel(id, label) {
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const idx = findNodeIndex(id);
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if (idx === -1) throw new Error(`flowchart-store: unknown node id "${id}"`);
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snapshot();
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graph.nodes[idx] = { ...graph.nodes[idx], label };
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emit();
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}
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function setNodeKind(id, kind) {
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if (!NODE_KINDS.includes(kind)) {
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throw new Error(`flowchart-store: unknown node kind "${kind}"`);
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}
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const idx = findNodeIndex(id);
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if (idx === -1) throw new Error(`flowchart-store: unknown node id "${id}"`);
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snapshot();
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graph.nodes[idx] = { ...graph.nodes[idx], kind };
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emit();
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}
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function removeNode(id) {
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const idx = findNodeIndex(id);
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if (idx === -1) return;
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snapshot();
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graph.nodes.splice(idx, 1);
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graph.edges = graph.edges.filter((e) => e.fromNodeId !== id && e.toNodeId !== id);
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emit();
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}
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function connect(fromNodeId, toNodeId, kind = 'solid') {
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if (fromNodeId === toNodeId) {
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throw new TypeError('flowchart-store: cannot connect a node to itself');
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}
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if (!EDGE_KINDS.includes(kind)) {
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throw new Error(`flowchart-store: unknown edge kind "${kind}"`);
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}
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snapshot();
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const edge = { id: newId('e'), fromNodeId, toNodeId, kind };
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graph.edges.push(edge);
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emit();
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return edge;
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}
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function disconnect(edgeId) {
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const idx = findEdgeIndex(edgeId);
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if (idx === -1) return;
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snapshot();
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graph.edges.splice(idx, 1);
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emit();
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}
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function setEdgeKind(edgeId, kind) {
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if (!EDGE_KINDS.includes(kind)) {
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throw new Error(`flowchart-store: unknown edge kind "${kind}"`);
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}
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const idx = findEdgeIndex(edgeId);
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if (idx === -1) throw new Error(`flowchart-store: unknown edge id "${edgeId}"`);
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snapshot();
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graph.edges[idx] = { ...graph.edges[idx], kind };
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emit();
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}
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function setEdgeLabel(edgeId, label) {
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const idx = findEdgeIndex(edgeId);
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if (idx === -1) throw new Error(`flowchart-store: unknown edge id "${edgeId}"`);
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snapshot();
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graph.edges[idx] = { ...graph.edges[idx], label };
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emit();
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}
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function undo() {
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const prior = undoStack.pop();
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if (!prior) return;
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redoStack.push(clone(graph));
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graph = prior;
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emit();
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}
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function redo() {
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const next = redoStack.pop();
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if (!next) return;
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undoStack.push(clone(graph));
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graph = next;
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emit();
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}
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function canUndo() {
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return undoStack.length > 0;
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}
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function canRedo() {
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return redoStack.length > 0;
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}
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function subscribe(fn) {
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listeners.add(fn);
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return () => listeners.delete(fn);
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}
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function serialize() {
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return JSON.stringify(graph);
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}
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function deserialize(json) {
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let parsed;
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try {
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parsed = typeof json === 'object' ? json : JSON.parse(json);
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} catch {
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graph = { nodes: [], edges: [] };
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return;
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}
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const nodes = Array.isArray(parsed.nodes) ? parsed.nodes.filter(isValidNode) : [];
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const nodeIds = new Set(nodes.map((n) => n.id));
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const edges = Array.isArray(parsed.edges)
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? parsed.edges.filter(
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(e) => isValidEdge(e) && nodeIds.has(e.fromNodeId) && nodeIds.has(e.toNodeId)
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)
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: [];
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graph = { nodes, edges };
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undoStack.length = 0;
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redoStack.length = 0;
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emit();
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}
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function toJSON() {
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return clone(graph);
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}
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return {
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getGraph,
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addNode,
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moveNode,
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setNodeLabel,
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setNodeKind,
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removeNode,
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connect,
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disconnect,
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setEdgeKind,
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setEdgeLabel,
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undo,
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redo,
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canUndo,
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canRedo,
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subscribe,
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serialize,
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deserialize,
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toJSON,
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};
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}
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module.exports = { create, NODE_KINDS, EDGE_KINDS };
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