agson/lib/agson/traversals.js

Querying and manipulating JSON graphs

(function() {
  var Just, Nothing, Traversal, fromNullable, isArray, isObject, list, maybeMap, maybeMapValues, nothing, object, recurse, traversal, _ref, _ref1;

  _ref = require('data.maybe'), Just = _ref.Just, Nothing = _ref.Nothing, fromNullable = _ref.fromNullable;

  _ref1 = require('./util'), maybeMap = _ref1.maybeMap, maybeMapValues = _ref1.maybeMapValues, isArray = _ref1.isArray, isObject = _ref1.isObject;

  Traversal = require('./Traversal');

  traversal = Traversal.of;

  nothing = {
    modify: Nothing,
    get: Nothing
  };

  list = traversal("list", function(mta) {
    return {
      modify: function(f) {
        return mta.chain(function(ta) {
          if (!isArray(ta)) {
            return Nothing();
          } else {
            return Just(maybeMap(ta, function(a) {
              return f(fromNullable(a));
            }));
          }
        });
      },
      get: function() {
        return mta.chain(function(ta) {
          if (!isArray(ta)) {
            return Nothing();
          } else {
            return Just(ta);
          }
        });
      }
    };
  });

  object = traversal("object", function(mo) {
    return {
      modify: function(f) {
        return mo.map(function(object) {
          if (!isObject(object)) {
            return Nothing();
          } else {
            return maybeMapValues(object, function(value) {
              return f(fromNullable(value));
            });
          }
        });
      },
      get: function() {
        return mo.chain(function(object) {
          if (!isObject(object)) {
            return Nothing();
          } else {
            return Just(object);
          }
        });
      }
    };
  });

  recurse = function(lensf) {
    return traversal("recurse(...)", function(ma) {
      var abl;
      abl = lensf();
      return {
        modify: function(f) {
          return ma.chain(function(a) {
            var mb, storeb;
            storeb = abl.runM(ma);
            mb = storeb.get();
            if (mb.isNothing) {
              return f(ma);
            } else {
              return f(storeb.modify(f));
            }
          });
        },
        get: function() {
          return ma.chain(function(a) {
            return abl.runM(ma).get().map(function(bs) {
              return bs.concat([a]);
            }).orElse(function() {
              return Just([a]);
            });
          });
        }
      };
    });
  };

  module.exports = {
    list: list,
    object: object,
    recurse: recurse
  };

}).call(this);