Implement graph and query with cursor

tshemsedinov · tshemsedinov · commit 875028c0f5fd · 2018-04-26T01:53:46.000+03:00
diff --git a/JavaScript/1-graph.js b/JavaScript/1-graph.js
@@ -0,0 +1,106 @@
+'use strict';
+
+class Vertex {
+  constructor(graph, data) {
+    this.graph = graph;
+    this.data = data;
+    this.links = new Map();
+  }
+  link(...args) {
+    const distinct = new Set(args);
+    const links = this.links;
+    const keyField = this.graph.keyField;
+    let item, key;
+    for (item of distinct) {
+      key = item.data[keyField];
+      links.set(key, null);
+    }
+    return this;
+  }
+}
+
+class Cursor {
+  constructor(vertices) {
+    this.vertices = vertices;
+  }
+  linked(...names) {
+    const vertices = this.vertices;
+    const result = new Set();
+    let vertex, condition, name;
+    for (vertex of vertices) {
+      condition = true;
+      for (name of names) {
+        condition = condition && vertex.links.has(name);
+      }
+      if (condition) result.add(vertex);
+    }
+    return new Cursor(result);
+  }
+}
+
+class Graph {
+  constructor(keyField) {
+    this.keyField = keyField;
+    this.vertices = new Map();
+  }
+  add(data) {
+    const vertex = new Vertex(this, data);
+    const key = data[this.keyField];
+    if (this.vertices.get(key) === undefined) {
+      this.vertices.set(key, vertex);
+    }
+    return vertex;
+  }
+  select(query) {
+    const vertices = new Set();
+    let vertex, condition, data, field;
+    for (vertex of this.vertices.values()) {
+      condition = true;
+      data = vertex.data;
+      if (data) {
+        for (field in query) {
+          condition = condition && data[field] === query[field];
+        }
+        if (condition) vertices.add(vertex);
+      }
+    }
+    return new Cursor(vertices);
+  }
+}
+
+// Usage
+
+const graph = new Graph('name');
+
+const marcus = graph.add(
+  { name: 'Marcus Aurelius', city: 'Rome', born: 121, dynasty: 'Antonine' }
+);
+const lucius = graph.add(
+  { name: 'Lucius Verus', city: 'Rome', born: 130, dynasty: 'Antonine' }
+);
+const pius = graph.add(
+  { name: 'Antoninus Pius', city: 'Lanuvium', born: 86, dynasty: 'Antonine' }
+);
+const hadrian = graph.add(
+  { name: 'Hadrian', city: 'Santiponce', born: 76, dynasty: 'Nerva–Trajan' }
+);
+const trajan = graph.add(
+  { name: 'Trajan', city: 'Sevilla', born: 98, dynasty: 'Nerva–Trajan' }
+);
+
+marcus.link(lucius);
+lucius.link(trajan, marcus, marcus, marcus);
+pius.link(marcus, lucius);
+hadrian.link(trajan);
+trajan.link(lucius, marcus);
+
+console.dir({ graph }, { depth: null });
+
+const res = graph
+  .select({ city: 'Rome', dynasty: 'Antonine' })
+  .linked('Trajan');
+
+console.log('\nQuery result:\n');
+for (const item of res.vertices) {
+  console.dir(item.data);
+}
