LevelDB Directed Graph Map

Directed graph data structure implemented using LevelDB. Similiar to multi-key maps or bidirectional maps.

See directed-graph-map for a synchronous, in-memory version.

const run = async () => {
  const db = level('./optional-db-path');
  const dg = new LevelDirectedGraphMap(db, [], { namespace: 'example' });
  await dg.ready;
                              //  A
  await dg.addEdge('A', 'X'); //  ├── X
  await dg.addEdge('A', 'Y'); //  ├── Y
  await dg.addEdge('A', 'Z'); //  └── Z

  await dg.getTargets('A');   //  X, Y, Z

  await dg.size(); // 3
  await dg.edges(); // [['A', 'X'], ['A', 'Y'], ['A', 'Z']]
  await dg.sources(); // ['A']
  await dg.targets(); // ['X', 'Y', 'Z']
}

run();

Install

yarn add level-level-directed-graph-map

Usage

const level = require('level');
const LevelDirectedGraphMap = require('level-directed-graph-map');

const run = async () => {
  const db = level('./optional-db-path');
  const dgm = new LevelDirectedGraphMap(db, [['A', 'B']], { namespace: 'example' });
  await dgm.ready;

  //  A
  //  └── B
  
  await dgm.hasEdge('A', 'B'); // true
  
  await dgm.addEdge('B', 'C');
  
  //  A
  //  └── B
  //      └── C
  
  await  dgm.hasEdge('B', 'C'); // true
  await  dgm.getTargets('A'); // new Set(['B']);
  await  dgm.getTargets('B'); // new Set(['C']);
  await  dgm.getTargets('C'); // new Set();
  await  dgm.getSources('A'); // new Set();
  await  dgm.getSources('B'); // new Set(['A']);
  await  dgm.getSources('C'); // new Set(['B']);
  
  await  dgm.removeSource('A');
  
  //  B
  //  └── C
  
  await dgm.hasEdge('A', 'B'); // false
  await dgm.getTargets('A'); // new Set();
  
  await dgm.removeTarget('C');
  
  //  Empty
  
  await dgm.getTargets('B'); // new Set();
  await dgm.hasEdge('B', 'C'); // false
  
  await dgm.addEdge('A', 'B');
  
  //  A
  //  └── B
  
  await dgm.hasEdge('A', 'B'); // true
  
  await dgm.removeEdge('A', 'B');
  
  //  Empty
  
  await dgm.hasEdge('A', 'B'); // false
}

run();

API

Table of Contents

• LevelDirectedGraphMap
  • addEdge
  • removeEdge
  • hasEdge
  • removeSource
  • removeTarget
  • hasSource
  • hasTarget
  • getSources
  • getTargets
  • edges
  • size
  • sources
  • targets
• LevelDirectedGraphMap#ready

LevelDirectedGraphMap

Class representing a Level Directed Graph Map

Parameters

• db Object? Object implementing the LevelUp interface
• edges Iterable<[string, string]> Iterable containing source -> target pairs (optional, default [])
• options Object Options object (optional, default {})

addEdge

Add an edge to the graph map.

Parameters

• source string Source of the edge
• target string Target of the edge

Returns Promise<void>

removeEdge

Remove an edge from the graph map.

Parameters

• source string Source of the edge
• target string Target of the edge

Returns Promise<void>

hasEdge

Test if a edge exists in the graph map.

Parameters

• source string Source of the edge
• target string Target of the edge

Returns Promise<boolean> Whether the edge exists in the graph map.

removeSource

Remove all edges from a source.

Parameters

• source string Source of the edge

Returns Promise<void>

removeTarget

Remove all edges to a target.

Parameters

• target string Target of the edge

Returns Promise<void>

hasSource

Test if a source exists in the graph map.

Parameters

• source string Source of the edge

Returns Promise<boolean> Whether the source exists in the graph map.

hasTarget

Test if a target exists in the graph map.

Parameters

• target string Target of the edge

Returns Promise<boolean> Whether the target exists in the graph map.

getSources

Get all sources with edges to a target.

Parameters

• target string Target of the edge

Returns Promise<Set<string>> Set of sources

getTargets

Get all targets with edges from a source.

Parameters

• source string Source of the edge

Returns Promise<Set<string>> Set of targets

edges

Array of edges

Returns Promise<Array<[string, string]>>

size

Edge count. Costly operation, use sparingly.

Returns Promise<number>

sources

Set of sources

Returns Promise<Set<string>>

targets

Set of targets

Returns Promise<Set<string>>

LevelDirectedGraphMap#ready

Resolves when the map is initialized and ready for use