graphology-utils/getters.js

Miscellaneous utils for graphology.

/**
 * Graphology Weight Getter
 * =========================
 *
 * Function creating weight getters.
 */
function coerceWeight(value) {
  // Ensuring target value is a correct number
  if (typeof value !== 'number' || isNaN(value)) return 1;

  return value;
}

function createNodeValueGetter(nameOrFunction, defaultValue) {
  var getter = {};

  var coerceToDefault = function (v) {
    if (typeof v === 'undefined') return defaultValue;

    return v;
  };

  if (typeof defaultValue === 'function') coerceToDefault = defaultValue;

  var get = function (attributes) {
    return coerceToDefault(attributes[nameOrFunction]);
  };

  var returnDefault = function () {
    return coerceToDefault(undefined);
  };

  if (typeof nameOrFunction === 'string') {
    getter.fromAttributes = get;
    getter.fromGraph = function (graph, node) {
      return get(graph.getNodeAttributes(node));
    };
    getter.fromEntry = function (node, attributes) {
      return get(attributes);
    };
  } else if (typeof nameOrFunction === 'function') {
    getter.fromAttributes = function () {
      throw new Error(
        'graphology-utils/getters/createNodeValueGetter: irrelevant usage.'
      );
    };
    getter.fromGraph = function (graph, node) {
      return coerceToDefault(
        nameOrFunction(node, graph.getNodeAttributes(node))
      );
    };
    getter.fromEntry = function (node, attributes) {
      return coerceToDefault(nameOrFunction(node, attributes));
    };
  } else {
    getter.fromAttributes = returnDefault;
    getter.fromGraph = returnDefault;
    getter.fromEntry = returnDefault;
  }

  return getter;
}

function createEdgeValueGetter(nameOrFunction, defaultValue) {
  var getter = {};

  var coerceToDefault = function (v) {
    if (typeof v === 'undefined') return defaultValue;

    return v;
  };

  if (typeof defaultValue === 'function') coerceToDefault = defaultValue;

  var get = function (attributes) {
    return coerceToDefault(attributes[nameOrFunction]);
  };

  var returnDefault = function () {
    return coerceToDefault(undefined);
  };

  if (typeof nameOrFunction === 'string') {
    getter.fromAttributes = get;
    getter.fromGraph = function (graph, edge) {
      return get(graph.getEdgeAttributes(edge));
    };
    getter.fromEntry = function (edge, attributes) {
      return get(attributes);
    };
    getter.fromPartialEntry = getter.fromEntry;
    getter.fromMinimalEntry = getter.fromEntry;
  } else if (typeof nameOrFunction === 'function') {
    getter.fromAttributes = function () {
      throw new Error(
        'graphology-utils/getters/createEdgeValueGetter: irrelevant usage.'
      );
    };
    getter.fromGraph = function (graph, edge) {
      // TODO: we can do better, check #310
      var extremities = graph.extremities(edge);
      return coerceToDefault(
        nameOrFunction(
          edge,
          graph.getEdgeAttributes(edge),
          extremities[0],
          extremities[1],
          graph.getNodeAttributes(extremities[0]),
          graph.getNodeAttributes(extremities[1]),
          graph.isUndirected(edge)
        )
      );
    };
    getter.fromEntry = function (e, a, s, t, sa, ta, u) {
      return coerceToDefault(nameOrFunction(e, a, s, t, sa, ta, u));
    };
    getter.fromPartialEntry = function (e, a, s, t) {
      return coerceToDefault(nameOrFunction(e, a, s, t));
    };
    getter.fromMinimalEntry = function (e, a) {
      return coerceToDefault(nameOrFunction(e, a));
    };
  } else {
    getter.fromAttributes = returnDefault;
    getter.fromGraph = returnDefault;
    getter.fromEntry = returnDefault;
    getter.fromMinimalEntry = returnDefault;
  }

  return getter;
}

exports.createNodeValueGetter = createNodeValueGetter;
exports.createEdgeValueGetter = createEdgeValueGetter;
exports.createEdgeWeightGetter = function (name) {
  return createEdgeValueGetter(name, coerceWeight);
};