(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
  typeof define === 'function' && define.amd ? define(['exports'], factory) :
  (global = global || self, factory(global.riotDOMBindings = {}));
}(this, (function (exports) { 'use strict';

  /**
   * Convert a string from camel case to dash-case
   * @param   {string} string - probably a component tag name
   * @returns {string} component name normalized
   */

  /**
   * Convert a string containing dashes to camel case
   * @param   {string} string - input string
   * @returns {string} my-string -> myString
   */
  function dashToCamelCase(string) {
    return string.replace(/-(\w)/g, (_, c) => c.toUpperCase())
  }

  /**
   * Move all the child nodes from a source tag to another
   * @param   {HTMLElement} source - source node
   * @param   {HTMLElement} target - target node
   * @returns {undefined} it's a void method ¯\_(ツ)_/¯
   */

  // Ignore this helper because it's needed only for svg tags
  function moveChildren(source, target) {
    if (source.firstChild) {
      target.appendChild(source.firstChild);
      moveChildren(source, target);
    }
  }

  /**
   * Remove the child nodes from any DOM node
   * @param   {HTMLElement} node - target node
   * @returns {undefined}
   */
  function cleanNode(node) {
    clearChildren(node.childNodes);
  }

  /**
   * Clear multiple children in a node
   * @param   {HTMLElement[]} children - direct children nodes
   * @returns {undefined}
   */
  function clearChildren(children) {
    Array.from(children).forEach(removeNode);
  }

  /**
   * Remove a node from the DOM
   * @param   {HTMLElement} node - target node
   * @returns {undefined}
   */
  function removeNode(node) {
    const {parentNode} = node;
    if (node.remove)
      node.remove();
    /* istanbul ignore else */
    else if (parentNode)
      parentNode.removeChild(node);
  }

  const EACH = 0;
  const IF = 1;
  const SIMPLE = 2;
  const TAG = 3;
  const SLOT = 4;

  var bindingTypes = {
    EACH,
    IF,
    SIMPLE,
    TAG,
    SLOT
  };

  const ATTRIBUTE = 0;
  const EVENT = 1;
  const TEXT = 2;
  const VALUE = 3;

  var expressionTypes = {
    ATTRIBUTE,
    EVENT,
    TEXT,
    VALUE
  };

  /**
   * Create the template meta object in case of <template> fragments
   * @param   {TemplateChunk} componentTemplate - template chunk object
   * @returns {Object} the meta property that will be passed to the mount function of the TemplateChunk
   */
  function createTemplateMeta(componentTemplate) {
    const fragment = componentTemplate.dom.cloneNode(true);

    return {
      avoidDOMInjection: true,
      fragment,
      children: Array.from(fragment.childNodes)
    }
  }

  const {indexOf, slice} = [];

  const append = (get, parent, children, start, end, before) => {
    const isSelect = 'selectedIndex' in parent;
    let noSelection = isSelect;
    while (start < end) {
      const child = get(children[start], 1);
      parent.insertBefore(child, before);
      if (isSelect && noSelection && child.selected) {
        noSelection = !noSelection;
        let {selectedIndex} = parent;
        parent.selectedIndex = selectedIndex < 0 ?
          start :
          indexOf.call(parent.querySelectorAll('option'), child);
      }
      start++;
    }
  };

  const eqeq = (a, b) => a == b;

  const identity = O => O;

  const indexOf$1 = (
    moreNodes,
    moreStart,
    moreEnd,
    lessNodes,
    lessStart,
    lessEnd,
    compare
  ) => {
    const length = lessEnd - lessStart;
    /* istanbul ignore if */
    if (length < 1)
      return -1;
    while ((moreEnd - moreStart) >= length) {
      let m = moreStart;
      let l = lessStart;
      while (
        m < moreEnd &&
        l < lessEnd &&
        compare(moreNodes[m], lessNodes[l])
      ) {
        m++;
        l++;
      }
      if (l === lessEnd)
        return moreStart;
      moreStart = m + 1;
    }
    return -1;
  };

  const isReversed = (
    futureNodes,
    futureEnd,
    currentNodes,
    currentStart,
    currentEnd,
    compare
  ) => {
    while (
      currentStart < currentEnd &&
      compare(
        currentNodes[currentStart],
        futureNodes[futureEnd - 1]
      )) {
        currentStart++;
        futureEnd--;
      }  return futureEnd === 0;
  };

  const next = (get, list, i, length, before) => i < length ?
                get(list[i], 0) :
                (0 < i ?
                  get(list[i - 1], -0).nextSibling :
                  before);

  const remove = (get, children, start, end) => {
    while (start < end)
      drop(get(children[start++], -1));
  };

  // - - - - - - - - - - - - - - - - - - -
  // diff related constants and utilities
  // - - - - - - - - - - - - - - - - - - -

  const DELETION = -1;
  const INSERTION = 1;
  const SKIP = 0;
  const SKIP_OND = 50;

  const HS = (
    futureNodes,
    futureStart,
    futureEnd,
    futureChanges,
    currentNodes,
    currentStart,
    currentEnd,
    currentChanges
  ) => {

    let k = 0;
    /* istanbul ignore next */
    let minLen = futureChanges < currentChanges ? futureChanges : currentChanges;
    const link = Array(minLen++);
    const tresh = Array(minLen);
    tresh[0] = -1;

    for (let i = 1; i < minLen; i++)
      tresh[i] = currentEnd;

    const nodes = currentNodes.slice(currentStart, currentEnd);

    for (let i = futureStart; i < futureEnd; i++) {
      const index = nodes.indexOf(futureNodes[i]);
      if (-1 < index) {
        const idxInOld = index + currentStart;
        k = findK(tresh, minLen, idxInOld);
        /* istanbul ignore else */
        if (-1 < k) {
          tresh[k] = idxInOld;
          link[k] = {
            newi: i,
            oldi: idxInOld,
            prev: link[k - 1]
          };
        }
      }
    }

    k = --minLen;
    --currentEnd;
    while (tresh[k] > currentEnd) --k;

    minLen = currentChanges + futureChanges - k;
    const diff = Array(minLen);
    let ptr = link[k];
    --futureEnd;
    while (ptr) {
      const {newi, oldi} = ptr;
      while (futureEnd > newi) {
        diff[--minLen] = INSERTION;
        --futureEnd;
      }
      while (currentEnd > oldi) {
        diff[--minLen] = DELETION;
        --currentEnd;
      }
      diff[--minLen] = SKIP;
      --futureEnd;
      --currentEnd;
      ptr = ptr.prev;
    }
    while (futureEnd >= futureStart) {
      diff[--minLen] = INSERTION;
      --futureEnd;
    }
    while (currentEnd >= currentStart) {
      diff[--minLen] = DELETION;
      --currentEnd;
    }
    return diff;
  };

  // this is pretty much the same petit-dom code without the delete map part
  // https://github.com/yelouafi/petit-dom/blob/bd6f5c919b5ae5297be01612c524c40be45f14a7/src/vdom.js#L556-L561
  const OND = (
    futureNodes,
    futureStart,
    rows,
    currentNodes,
    currentStart,
    cols,
    compare
  ) => {
    const length = rows + cols;
    const v = [];
    let d, k, r, c, pv, cv, pd;
    outer: for (d = 0; d <= length; d++) {
      /* istanbul ignore if */
      if (d > SKIP_OND)
        return null;
      pd = d - 1;
      /* istanbul ignore next */
      pv = d ? v[d - 1] : [0, 0];
      cv = v[d] = [];
      for (k = -d; k <= d; k += 2) {
        if (k === -d || (k !== d && pv[pd + k - 1] < pv[pd + k + 1])) {
          c = pv[pd + k + 1];
        } else {
          c = pv[pd + k - 1] + 1;
        }
        r = c - k;
        while (
          c < cols &&
          r < rows &&
          compare(
            currentNodes[currentStart + c],
            futureNodes[futureStart + r]
          )
        ) {
          c++;
          r++;
        }
        if (c === cols && r === rows) {
          break outer;
        }
        cv[d + k] = c;
      }
    }

    const diff = Array(d / 2 + length / 2);
    let diffIdx = diff.length - 1;
    for (d = v.length - 1; d >= 0; d--) {
      while (
        c > 0 &&
        r > 0 &&
        compare(
          currentNodes[currentStart + c - 1],
          futureNodes[futureStart + r - 1]
        )
      ) {
        // diagonal edge = equality
        diff[diffIdx--] = SKIP;
        c--;
        r--;
      }
      if (!d)
        break;
      pd = d - 1;
      /* istanbul ignore next */
      pv = d ? v[d - 1] : [0, 0];
      k = c - r;
      if (k === -d || (k !== d && pv[pd + k - 1] < pv[pd + k + 1])) {
        // vertical edge = insertion
        r--;
        diff[diffIdx--] = INSERTION;
      } else {
        // horizontal edge = deletion
        c--;
        diff[diffIdx--] = DELETION;
      }
    }
    return diff;
  };

  const applyDiff = (
    diff,
    get,
    parentNode,
    futureNodes,
    futureStart,
    currentNodes,
    currentStart,
    currentLength,
    before
  ) => {
    const live = [];
    const length = diff.length;
    let currentIndex = currentStart;
    let i = 0;
    while (i < length) {
      switch (diff[i++]) {
        case SKIP:
          futureStart++;
          currentIndex++;
          break;
        case INSERTION:
          // TODO: bulk appends for sequential nodes
          live.push(futureNodes[futureStart]);
          append(
            get,
            parentNode,
            futureNodes,
            futureStart++,
            futureStart,
            currentIndex < currentLength ?
              get(currentNodes[currentIndex], 0) :
              before
          );
          break;
        case DELETION:
          currentIndex++;
          break;
      }
    }
    i = 0;
    while (i < length) {
      switch (diff[i++]) {
        case SKIP:
          currentStart++;
          break;
        case DELETION:
          // TODO: bulk removes for sequential nodes
          if (-1 < live.indexOf(currentNodes[currentStart]))
            currentStart++;
          else
            remove(
              get,
              currentNodes,
              currentStart++,
              currentStart
            );
          break;
      }
    }
  };

  const findK = (ktr, length, j) => {
    let lo = 1;
    let hi = length;
    while (lo < hi) {
      const mid = ((lo + hi) / 2) >>> 0;
      if (j < ktr[mid])
        hi = mid;
      else
        lo = mid + 1;
    }
    return lo;
  };

  const smartDiff = (
    get,
    parentNode,
    futureNodes,
    futureStart,
    futureEnd,
    futureChanges,
    currentNodes,
    currentStart,
    currentEnd,
    currentChanges,
    currentLength,
    compare,
    before
  ) => {
    applyDiff(
      OND(
        futureNodes,
        futureStart,
        futureChanges,
        currentNodes,
        currentStart,
        currentChanges,
        compare
      ) ||
      HS(
        futureNodes,
        futureStart,
        futureEnd,
        futureChanges,
        currentNodes,
        currentStart,
        currentEnd,
        currentChanges
      ),
      get,
      parentNode,
      futureNodes,
      futureStart,
      currentNodes,
      currentStart,
      currentLength,
      before
    );
  };

  const drop = node => (node.remove || dropChild).call(node);

  function dropChild() {
    const {parentNode} = this;
    /* istanbul ignore else */
    if (parentNode)
      parentNode.removeChild(this);
  }

  /*! (c) 2018 Andrea Giammarchi (ISC) */

  const domdiff = (
    parentNode,     // where changes happen
    currentNodes,   // Array of current items/nodes
    futureNodes,    // Array of future items/nodes
    options         // optional object with one of the following properties
                    //  before: domNode
                    //  compare(generic, generic) => true if same generic
                    //  node(generic) => Node
  ) => {
    if (!options)
      options = {};

    const compare = options.compare || eqeq;
    const get = options.node || identity;
    const before = options.before == null ? null : get(options.before, 0);

    const currentLength = currentNodes.length;
    let currentEnd = currentLength;
    let currentStart = 0;

    let futureEnd = futureNodes.length;
    let futureStart = 0;

    // common prefix
    while (
      currentStart < currentEnd &&
      futureStart < futureEnd &&
      compare(currentNodes[currentStart], futureNodes[futureStart])
    ) {
      currentStart++;
      futureStart++;
    }

    // common suffix
    while (
      currentStart < currentEnd &&
      futureStart < futureEnd &&
      compare(currentNodes[currentEnd - 1], futureNodes[futureEnd - 1])
    ) {
      currentEnd--;
      futureEnd--;
    }

    const currentSame = currentStart === currentEnd;
    const futureSame = futureStart === futureEnd;

    // same list
    if (currentSame && futureSame)
      return futureNodes;

    // only stuff to add
    if (currentSame && futureStart < futureEnd) {
      append(
        get,
        parentNode,
        futureNodes,
        futureStart,
        futureEnd,
        next(get, currentNodes, currentStart, currentLength, before)
      );
      return futureNodes;
    }

    // only stuff to remove
    if (futureSame && currentStart < currentEnd) {
      remove(
        get,
        currentNodes,
        currentStart,
        currentEnd
      );
      return futureNodes;
    }

    const currentChanges = currentEnd - currentStart;
    const futureChanges = futureEnd - futureStart;
    let i = -1;

    // 2 simple indels: the shortest sequence is a subsequence of the longest
    if (currentChanges < futureChanges) {
      i = indexOf$1(
        futureNodes,
        futureStart,
        futureEnd,
        currentNodes,
        currentStart,
        currentEnd,
        compare
      );
      // inner diff
      if (-1 < i) {
        append(
          get,
          parentNode,
          futureNodes,
          futureStart,
          i,
          get(currentNodes[currentStart], 0)
        );
        append(
          get,
          parentNode,
          futureNodes,
          i + currentChanges,
          futureEnd,
          next(get, currentNodes, currentEnd, currentLength, before)
        );
        return futureNodes;
      }
    }
    /* istanbul ignore else */
    else if (futureChanges < currentChanges) {
      i = indexOf$1(
        currentNodes,
        currentStart,
        currentEnd,
        futureNodes,
        futureStart,
        futureEnd,
        compare
      );
      // outer diff
      if (-1 < i) {
        remove(
          get,
          currentNodes,
          currentStart,
          i
        );
        remove(
          get,
          currentNodes,
          i + futureChanges,
          currentEnd
        );
        return futureNodes;
      }
    }

    // common case with one replacement for many nodes
    // or many nodes replaced for a single one
    /* istanbul ignore else */
    if ((currentChanges < 2 || futureChanges < 2)) {
      append(
        get,
        parentNode,
        futureNodes,
        futureStart,
        futureEnd,
        get(currentNodes[currentStart], 0)
      );
      remove(
        get,
        currentNodes,
        currentStart,
        currentEnd
      );
      return futureNodes;
    }

    // the half match diff part has been skipped in petit-dom
    // https://github.com/yelouafi/petit-dom/blob/bd6f5c919b5ae5297be01612c524c40be45f14a7/src/vdom.js#L391-L397
    // accordingly, I think it's safe to skip in here too
    // if one day it'll come out like the speediest thing ever to do
    // then I might add it in here too

    // Extra: before going too fancy, what about reversed lists ?
    //        This should bail out pretty quickly if that's not the case.
    if (
      currentChanges === futureChanges &&
      isReversed(
        futureNodes,
        futureEnd,
        currentNodes,
        currentStart,
        currentEnd,
        compare
      )
    ) {
      append(
        get,
        parentNode,
        futureNodes,
        futureStart,
        futureEnd,
        next(get, currentNodes, currentEnd, currentLength, before)
      );
      return futureNodes;
    }

    // last resort through a smart diff
    smartDiff(
      get,
      parentNode,
      futureNodes,
      futureStart,
      futureEnd,
      futureChanges,
      currentNodes,
      currentStart,
      currentEnd,
      currentChanges,
      currentLength,
      compare,
      before
    );

    return futureNodes;
  };

  /**
   * Quick type checking
   * @param   {*} element - anything
   * @param   {string} type - type definition
   * @returns {boolean} true if the type corresponds
   */
  function checkType(element, type) {
    return typeof element === type
  }

  /**
   * Check if an element is part of an svg
   * @param   {HTMLElement}  el - element to check
   * @returns {boolean} true if we are in an svg context
   */
  function isSvg(el) {
    const owner = el.ownerSVGElement;

    return !!owner || owner === null
  }

  /**
   * Check if an element is a template tag
   * @param   {HTMLElement}  el - element to check
   * @returns {boolean} true if it's a <template>
   */
  function isTemplate(el) {
    return !isNil(el.content)
  }

  /**
   * Check that will be passed if its argument is a function
   * @param   {*} value - value to check
   * @returns {boolean} - true if the value is a function
   */
  function isFunction(value) {
    return checkType(value, 'function')
  }

  /**
   * Check if a value is a Boolean
   * @param   {*}  value - anything
   * @returns {boolean} true only for the value is a boolean
   */
  function isBoolean(value) {
    return checkType(value, 'boolean')
  }

  /**
   * Check if a value is an Object
   * @param   {*}  value - anything
   * @returns {boolean} true only for the value is an object
   */
  function isObject(value) {
    return !isNil(value) && checkType(value, 'object')
  }

  /**
   * Check if a value is null or undefined
   * @param   {*}  value - anything
   * @returns {boolean} true only for the 'undefined' and 'null' types
   */
  function isNil(value) {
    return value === null || value === undefined
  }

  const UNMOUNT_SCOPE = Symbol('unmount');

  const EachBinding = Object.seal({
    // dynamic binding properties
    // childrenMap: null,
    // node: null,
    // root: null,
    // condition: null,
    // evaluate: null,
    // template: null,
    // isTemplateTag: false,
    nodes: [],
    // getKey: null,
    // indexName: null,
    // itemName: null,
    // afterPlaceholder: null,
    // placeholder: null,

    // API methods
    mount(scope, parentScope) {
      return this.update(scope, parentScope)
    },
    update(scope, parentScope) {
      const { placeholder, nodes, childrenMap } = this;
      const collection = scope === UNMOUNT_SCOPE ? null : this.evaluate(scope);
      const items = collection ? Array.from(collection) : [];
      const parent = placeholder.parentNode;

      // prepare the diffing
      const {
        newChildrenMap,
        batches,
        futureNodes
      } = createPatch(items, scope, parentScope, this);

      // patch the DOM only if there are new nodes
      domdiff(parent, nodes, futureNodes, {
        before: placeholder,
        node: patch(
          Array.from(childrenMap.values()),
          parentScope
        )
      });

      // trigger the mounts and the updates
      batches.forEach(fn => fn());

      // update the children map
      this.childrenMap = newChildrenMap;
      this.nodes = futureNodes;

      return this
    },
    unmount(scope, parentScope) {
      this.update(UNMOUNT_SCOPE, parentScope);

      return this
    }
  });

  /**
   * Patch the DOM while diffing
   * @param   {TemplateChunk[]} redundant - redundant tepmplate chunks
   * @param   {*} parentScope - scope of the parent template
   * @returns {Function} patch function used by domdiff
   */
  function patch(redundant, parentScope) {
    return (item, info) => {
      if (info < 0) {
        const element = redundant.pop();
        if (element) {
          const {template, context} = element;
          // notice that we pass null as last argument because
          // the root node and its children will be removed by domdiff
          template.unmount(context, parentScope, null);
        }
      }

      return item
    }
  }

  /**
   * Check whether a template must be filtered from a loop
   * @param   {Function} condition - filter function
   * @param   {Object} context - argument passed to the filter function
   * @returns {boolean} true if this item should be skipped
   */
  function mustFilterItem(condition, context) {
    return condition ? Boolean(condition(context)) === false : false
  }

  /**
   * Extend the scope of the looped template
   * @param   {Object} scope - current template scope
   * @param   {string} options.itemName - key to identify the looped item in the new context
   * @param   {string} options.indexName - key to identify the index of the looped item
   * @param   {number} options.index - current index
   * @param   {*} options.item - collection item looped
   * @returns {Object} enhanced scope object
   */
  function extendScope(scope, {itemName, indexName, index, item}) {
    scope[itemName] = item;
    if (indexName) scope[indexName] = index;
    return scope
  }

  /**
   * Loop the current template items
   * @param   {Array} items - expression collection value
   * @param   {*} scope - template scope
   * @param   {*} parentScope - scope of the parent template
   * @param   {EeachBinding} binding - each binding object instance
   * @returns {Object} data
   * @returns {Map} data.newChildrenMap - a Map containing the new children template structure
   * @returns {Array} data.batches - array containing the template lifecycle functions to trigger
   * @returns {Array} data.futureNodes - array containing the nodes we need to diff
   */
  function createPatch(items, scope, parentScope, binding) {
    const { condition, template, childrenMap, itemName, getKey, indexName, root, isTemplateTag } = binding;
    const newChildrenMap = new Map();
    const batches = [];
    const futureNodes = [];

    items.forEach((item, index) => {
      const context = extendScope(Object.create(scope), {itemName, indexName, index, item});
      const key = getKey ? getKey(context) : index;
      const oldItem = childrenMap.get(key);

      if (mustFilterItem(condition, context)) {
        return
      }

      const componentTemplate = oldItem ? oldItem.template : template.clone();
      const el = oldItem ? componentTemplate.el : root.cloneNode();
      const mustMount = !oldItem;
      const meta = isTemplateTag && mustMount ? createTemplateMeta(componentTemplate) : {};

      if (mustMount) {
        batches.push(() => componentTemplate.mount(el, context, parentScope, meta));
      } else {
        batches.push(() => componentTemplate.update(context, parentScope));
      }

      // create the collection of nodes to update or to add
      // in case of template tags we need to add all its children nodes
      if (isTemplateTag) {
        const children = meta.children || componentTemplate.children;
        futureNodes.push(...children);
      } else {
        futureNodes.push(el);
      }

      // delete the old item from the children map
      childrenMap.delete(key);

      // update the children map
      newChildrenMap.set(key, {
        template: componentTemplate,
        context,
        index
      });
    });

    return {
      newChildrenMap,
      batches,
      futureNodes
    }
  }

  function create(node, { evaluate, condition, itemName, indexName, getKey, template }) {
    const placeholder = document.createTextNode('');
    const parent = node.parentNode;
    const root = node.cloneNode();

    parent.insertBefore(placeholder, node);
    removeNode(node);

    return {
      ...EachBinding,
      childrenMap: new Map(),
      node,
      root,
      condition,
      evaluate,
      isTemplateTag: isTemplate(root),
      template: template.createDOM(node),
      getKey,
      indexName,
      itemName,
      placeholder
    }
  }

  /**
   * Binding responsible for the `if` directive
   */
  const IfBinding = Object.seal({
    // dynamic binding properties
    // node: null,
    // evaluate: null,
    // isTemplateTag: false,
    // placeholder: null,
    // template: null,

    // API methods
    mount(scope, parentScope) {
      return this.update(scope, parentScope)
    },
    update(scope, parentScope) {
      const value = !!this.evaluate(scope);
      const mustMount = !this.value && value;
      const mustUnmount = this.value && !value;
      const mount = () => {
        const pristine = this.node.cloneNode();

        this.placeholder.parentNode.insertBefore(pristine, this.placeholder);
        this.template = this.template.clone();
        this.template.mount(pristine, scope, parentScope);
      };

      switch (true) {
      case mustMount:
        mount();
        break
      case mustUnmount:
        this.unmount(scope);
        break
      default:
        if (value) this.template.update(scope, parentScope);
      }

      this.value = value;

      return this
    },
    unmount(scope, parentScope) {
      this.template.unmount(scope, parentScope, true);

      return this
    }
  });

  function create$1(node, { evaluate, template }) {
    const parent = node.parentNode;
    const placeholder = document.createTextNode('');

    parent.insertBefore(placeholder, node);
    removeNode(node);

    return {
      ...IfBinding,
      node,
      evaluate,
      placeholder,
      template: template.createDOM(node)
    }
  }

  /**
   * Returns the memoized (cached) function.
   * // borrowed from https://www.30secondsofcode.org/js/s/memoize
   * @param {Function} fn - function to memoize
   * @returns {Function} memoize function
   */
  function memoize(fn) {
    const cache = new Map();
    const cached = val => {
      return cache.has(val) ? cache.get(val) : cache.set(val, fn.call(this, val)) && cache.get(val)
    };
    cached.cache = cache;
    return cached
  }

  /**
   * Evaluate a list of attribute expressions
   * @param   {Array} attributes - attribute expressions generated by the riot compiler
   * @returns {Object} key value pairs with the result of the computation
   */
  function evaluateAttributeExpressions(attributes) {
    return attributes.reduce((acc, attribute) => {
      const {value, type} = attribute;

      switch (true) {
      // spread attribute
      case !attribute.name && type === ATTRIBUTE:
        return {
          ...acc,
          ...value
        }
      // value attribute
      case type === VALUE:
        acc.value = attribute.value;
        break
      // normal attributes
      default:
        acc[dashToCamelCase(attribute.name)] = attribute.value;
      }

      return acc
    }, {})
  }

  const REMOVE_ATTRIBUTE = 'removeAttribute';
  const SET_ATTIBUTE = 'setAttribute';
  const ElementProto = typeof Element === 'undefined' ? {} : Element.prototype;
  const isNativeHtmlProperty = memoize(name => ElementProto.hasOwnProperty(name) ); // eslint-disable-line

  /**
   * Add all the attributes provided
   * @param   {HTMLElement} node - target node
   * @param   {Object} attributes - object containing the attributes names and values
   * @returns {undefined} sorry it's a void function :(
   */
  function setAllAttributes(node, attributes) {
    Object
      .entries(attributes)
      .forEach(([name, value]) => attributeExpression(node, { name }, value));
  }

  /**
   * Remove all the attributes provided
   * @param   {HTMLElement} node - target node
   * @param   {Object} newAttributes - object containing all the new attribute names
   * @param   {Object} oldAttributes - object containing all the old attribute names
   * @returns {undefined} sorry it's a void function :(
   */
  function removeAllAttributes(node, newAttributes, oldAttributes) {
    const newKeys = newAttributes ? Object.keys(newAttributes) : [];

    Object
      .keys(oldAttributes)
      .filter(name => !newKeys.includes(name))
      .forEach(attribute => node.removeAttribute(attribute));
  }

  /**
   * This methods handles the DOM attributes updates
   * @param   {HTMLElement} node - target node
   * @param   {Object} expression - expression object
   * @param   {string} expression.name - attribute name
   * @param   {*} value - new expression value
   * @param   {*} oldValue - the old expression cached value
   * @returns {undefined}
   */
  function attributeExpression(node, { name }, value, oldValue) {
    // is it a spread operator? {...attributes}
    if (!name) {
      if (oldValue) {
        // remove all the old attributes
        removeAllAttributes(node, value, oldValue);
      }

      // is the value still truthy?
      if (value) {
        setAllAttributes(node, value);
      }

      return
    }

    // handle boolean attributes
    if (
      !isNativeHtmlProperty(name) && (
        isBoolean(value) ||
        isObject(value) ||
        isFunction(value)
      )
    ) {
      node[name] = value;
    }

    node[getMethod(value)](name, normalizeValue(name, value));
  }

  /**
   * Get the attribute modifier method
   * @param   {*} value - if truthy we return `setAttribute` othewise `removeAttribute`
   * @returns {string} the node attribute modifier method name
   */
  function getMethod(value) {
    return isNil(value) ||
      value === false ||
      value === '' ||
      isObject(value) ||
      isFunction(value) ?
      REMOVE_ATTRIBUTE :
      SET_ATTIBUTE
  }

  /**
   * Get the value as string
   * @param   {string} name - attribute name
   * @param   {*} value - user input value
   * @returns {string} input value as string
   */
  function normalizeValue(name, value) {
    // be sure that expressions like selected={ true } will be always rendered as selected='selected'
    if (value === true) return name

    return value
  }

  const RE_EVENTS_PREFIX = /^on/;

  const getCallbackAndOptions = value => Array.isArray(value) ? value : [value, false];

  // see also https://medium.com/@WebReflection/dom-handleevent-a-cross-platform-standard-since-year-2000-5bf17287fd38
  const EventListener = {
    handleEvent(event) {
      this[event.type](event);
    }
  };
  const ListenersWeakMap = new WeakMap();

  const createListener = node => {
    const listener = Object.create(EventListener);
    ListenersWeakMap.set(node, listener);
    return listener
  };

  /**
   * Set a new event listener
   * @param   {HTMLElement} node - target node
   * @param   {Object} expression - expression object
   * @param   {string} expression.name - event name
   * @param   {*} value - new expression value
   * @returns {value} the callback just received
   */
  function eventExpression(node, { name }, value) {
    const normalizedEventName = name.replace(RE_EVENTS_PREFIX, '');
    const eventListener = ListenersWeakMap.get(node) || createListener(node);
    const [callback, options] = getCallbackAndOptions(value);
    const handler = eventListener[normalizedEventName];
    const mustRemoveEvent = handler && !callback;
    const mustAddEvent = callback && !handler;

    if (mustRemoveEvent) {
      node.removeEventListener(normalizedEventName, eventListener);
    }

    if (mustAddEvent) {
      node.addEventListener(normalizedEventName, eventListener, options);
    }

    eventListener[normalizedEventName] = callback;
  }

  /**
   * Normalize the user value in order to render a empty string in case of falsy values
   * @param   {*} value - user input value
   * @returns {string} hopefully a string
   */
  function normalizeStringValue(value) {
    return isNil(value) ? '' : value
  }

  /**
   * Get the the target text node to update or create one from of a comment node
   * @param   {HTMLElement} node - any html element containing childNodes
   * @param   {number} childNodeIndex - index of the text node in the childNodes list
   * @returns {HTMLTextNode} the text node to update
   */
  const getTextNode = (node, childNodeIndex) => {
    const target = node.childNodes[childNodeIndex];

    if (target.nodeType === Node.COMMENT_NODE) {
      const textNode = document.createTextNode('');
      node.replaceChild(textNode, target);

      return textNode
    }

    return target
  };

  /**
   * This methods handles a simple text expression update
   * @param   {HTMLElement} node - target node
   * @param   {Object} data - expression object
   * @param   {*} value - new expression value
   * @returns {undefined}
   */
  function textExpression(node, data, value) {
    node.data = normalizeStringValue(value);
  }

  /**
   * This methods handles the input fileds value updates
   * @param   {HTMLElement} node - target node
   * @param   {Object} expression - expression object
   * @param   {*} value - new expression value
   * @returns {undefined}
   */
  function valueExpression(node, expression, value) {
    node.value = normalizeStringValue(value);
  }

  var expressions = {
    [ATTRIBUTE]: attributeExpression,
    [EVENT]: eventExpression,
    [TEXT]: textExpression,
    [VALUE]: valueExpression
  };

  const Expression = Object.seal({
    // Static props
    // node: null,
    // value: null,

    // API methods
    /**
     * Mount the expression evaluating its initial value
     * @param   {*} scope - argument passed to the expression to evaluate its current values
     * @returns {Expression} self
     */
    mount(scope) {
      // hopefully a pure function
      this.value = this.evaluate(scope);

      // IO() DOM updates
      apply(this, this.value);

      return this
    },
    /**
     * Update the expression if its value changed
     * @param   {*} scope - argument passed to the expression to evaluate its current values
     * @returns {Expression} self
     */
    update(scope) {
      // pure function
      const value = this.evaluate(scope);

      if (this.value !== value) {
        // IO() DOM updates
        apply(this, value);
        this.value = value;
      }

      return this
    },
    /**
     * Expression teardown method
     * @returns {Expression} self
     */
    unmount() {
      // unmount only the event handling expressions
      if (this.type === EVENT) apply(this, null);

      return this
    }
  });

  /**
   * IO() function to handle the DOM updates
   * @param {Expression} expression - expression object
   * @param {*} value - current expression value
   * @returns {undefined}
   */
  function apply(expression, value) {
    return expressions[expression.type](expression.node, expression, value, expression.value)
  }

  function create$2(node, data) {
    return {
      ...Expression,
      ...data,
      node: data.type === TEXT ?
        getTextNode(node, data.childNodeIndex) :
        node
    }
  }

  /**
   * Create a flat object having as keys a list of methods that if dispatched will propagate
   * on the whole collection
   * @param   {Array} collection - collection to iterate
   * @param   {Array<string>} methods - methods to execute on each item of the collection
   * @param   {*} context - context returned by the new methods created
   * @returns {Object} a new object to simplify the the nested methods dispatching
   */
  function flattenCollectionMethods(collection, methods, context) {
    return methods.reduce((acc, method) => {
      return {
        ...acc,
        [method]: (scope) => {
          return collection.map(item => item[method](scope)) && context
        }
      }
    }, {})
  }

  function create$3(node, { expressions }) {
    return {
      ...flattenCollectionMethods(
        expressions.map(expression => create$2(node, expression)),
        ['mount', 'update', 'unmount']
      )
    }
  }

  // Riot.js constants that can be used accross more modules

  const 
    PARENT_KEY_SYMBOL = Symbol('parent');

  function extendParentScope(attributes, scope, parentScope) {
    if (!attributes || !attributes.length) return parentScope

    const expressions = attributes.map(attr => ({
      ...attr,
      value: attr.evaluate(scope)
    }));

    return Object.assign(
      Object.create(parentScope || null),
      evaluateAttributeExpressions(expressions)
    )
  }

  // this function is only meant to fix an edge case
  // https://github.com/riot/riot/issues/2842
  const getRealParent = (scope, parentScope) => parentScope ?
    parentScope === scope ? scope[PARENT_KEY_SYMBOL] : parentScope
    : undefined;

  const SlotBinding = Object.seal({
    // dynamic binding properties
    // node: null,
    // name: null,
    attributes: [],
    // template: null,

    getTemplateScope(scope, parentScope) {
      return extendParentScope(this.attributes, scope, parentScope)
    },

    // API methods
    mount(scope, parentScope) {
      const templateData = scope.slots ? scope.slots.find(({id}) => id === this.name) : false;
      const {parentNode} = this.node;
      const realParent = getRealParent(scope, parentScope);

      this.template = templateData && create$6(
        templateData.html,
        templateData.bindings
      ).createDOM(parentNode);

      if (this.template) {
        this.template.mount(this.node, this.getTemplateScope(scope, realParent), realParent);
        this.template.children = moveSlotInnerContent(this.node);
      }

      removeNode(this.node);

      return this
    },
    update(scope, parentScope) {
      if (this.template) {
        const realParent = getRealParent(scope, parentScope);
        this.template.update(this.getTemplateScope(scope, realParent), realParent);
      }

      return this
    },
    unmount(scope, parentScope, mustRemoveRoot) {
      if (this.template) {
        this.template.unmount(this.getTemplateScope(scope, parentScope), null, mustRemoveRoot);
      }

      return this
    }
  });

  /**
   * Move the inner content of the slots outside of them
   * @param   {HTMLNode} slot - slot node
   * @param   {HTMLElement} children - array to fill with the child nodes detected
   * @returns {HTMLElement[]} list of the node moved
   */
  function moveSlotInnerContent(slot, children = []) {
    const child = slot.firstChild;
    if (child) {
      slot.parentNode.insertBefore(child, slot);
      return [child, ...moveSlotInnerContent(slot)]
    }

    return children
  }

  /**
   * Create a single slot binding
   * @param   {HTMLElement} node - slot node
   * @param   {string} options.name - slot id
   * @returns {Object} Slot binding object
   */
  function createSlot(node, { name, attributes }) {
    return {
      ...SlotBinding,
      attributes,
      node,
      name
    }
  }

  /**
   * Create a new tag object if it was registered before, otherwise fallback to the simple
   * template chunk
   * @param   {Function} component - component factory function
   * @param   {Array<Object>} slots - array containing the slots markup
   * @param   {Array} attributes - dynamic attributes that will be received by the tag element
   * @returns {TagImplementation|TemplateChunk} a tag implementation or a template chunk as fallback
   */
  function getTag(component, slots = [], attributes = []) {
    // if this tag was registered before we will return its implementation
    if (component) {
      return component({ slots, attributes })
    }

    // otherwise we return a template chunk
    return create$6(slotsToMarkup(slots), [
      ...slotBindings(slots), {
      // the attributes should be registered as binding
      // if we fallback to a normal template chunk
        expressions: attributes.map(attr => {
          return {
            type: ATTRIBUTE,
            ...attr
          }
        })
      }
    ])
  }


  /**
   * Merge all the slots bindings into a single array
   * @param   {Array<Object>} slots - slots collection
   * @returns {Array<Bindings>} flatten bindings array
   */
  function slotBindings(slots) {
    return slots.reduce((acc, { bindings }) => acc.concat(bindings), [])
  }

  /**
   * Merge all the slots together in a single markup string
   * @param   {Array<Object>} slots - slots collection
   * @returns {string} markup of all the slots in a single string
   */
  function slotsToMarkup(slots) {
    return slots.reduce((acc, slot) => {
      return acc + slot.html
    }, '')
  }


  const TagBinding = Object.seal({
    // dynamic binding properties
    // node: null,
    // evaluate: null,
    // name: null,
    // slots: null,
    // tag: null,
    // attributes: null,
    // getComponent: null,

    mount(scope) {
      return this.update(scope)
    },
    update(scope, parentScope) {
      const name = this.evaluate(scope);

      // simple update
      if (name === this.name) {
        this.tag.update(scope);
      } else {
        // unmount the old tag if it exists
        this.unmount(scope, parentScope, true);

        // mount the new tag
        this.name = name;
        this.tag = getTag(this.getComponent(name), this.slots, this.attributes);
        this.tag.mount(this.node, scope);
      }

      return this
    },
    unmount(scope, parentScope, keepRootTag) {
      if (this.tag) {
        // keep the root tag
        this.tag.unmount(keepRootTag);
      }

      return this
    }
  });

  function create$4(node, { evaluate, getComponent, slots, attributes }) {
    return {
      ...TagBinding,
      node,
      evaluate,
      slots,
      attributes,
      getComponent
    }
  }

  var bindings = {
    [IF]: create$1,
    [SIMPLE]: create$3,
    [EACH]: create,
    [TAG]: create$4,
    [SLOT]: createSlot
  };

  /**
   * Text expressions in a template tag will get childNodeIndex value normalized
   * depending on the position of the <template> tag offset
   * @param   {Expression[]} expressions - riot expressions array
   * @param   {number} textExpressionsOffset - offset of the <template> tag
   * @returns {Expression[]} expressions containing the text expressions normalized
   */
  function fixTextExpressionsOffset(expressions, textExpressionsOffset) {
    return expressions.map(e => e.type === TEXT ? {
      ...e,
      childNodeIndex: e.childNodeIndex + textExpressionsOffset
    } : e)
  }

  /**
   * Bind a new expression object to a DOM node
   * @param   {HTMLElement} root - DOM node where to bind the expression
   * @param   {Object} binding - binding data
   * @param   {number|null} templateTagOffset - if it's defined we need to fix the text expressions childNodeIndex offset
   * @returns {Binding} Binding object
   */
  function create$5(root, binding, templateTagOffset) {
    const { selector, type, redundantAttribute, expressions } = binding;
    // find the node to apply the bindings
    const node = selector ? root.querySelector(selector) : root;
    // remove eventually additional attributes created only to select this node
    if (redundantAttribute) node.removeAttribute(redundantAttribute);
    const bindingExpressions = expressions || [];
    // init the binding
    return (bindings[type] || bindings[SIMPLE])(
      node,
      {
        ...binding,
        expressions: templateTagOffset && !selector ?
          fixTextExpressionsOffset(bindingExpressions, templateTagOffset) :
          bindingExpressions
      }
    )
  }

  // in this case a simple innerHTML is enough
  function createHTMLTree(html, root) {
    const template = isTemplate(root) ? root : document.createElement('template');
    template.innerHTML = html;
    return template.content
  }

  // for svg nodes we need a bit more work
  function createSVGTree(html, container) {
    // create the SVGNode
    const svgNode = container.ownerDocument.importNode(
      new window.DOMParser()
        .parseFromString(
          `<svg xmlns="http://www.w3.org/2000/svg">${html}</svg>`,
          'application/xml'
        )
        .documentElement,
      true
    );

    return svgNode
  }

  /**
   * Create the DOM that will be injected
   * @param {Object} root - DOM node to find out the context where the fragment will be created
   * @param   {string} html - DOM to create as string
   * @returns {HTMLDocumentFragment|HTMLElement} a new html fragment
   */
  function createDOMTree(root, html) {
    if (isSvg(root)) return createSVGTree(html, root)

    return createHTMLTree(html, root)
  }

  /**
   * Inject the DOM tree into a target node
   * @param   {HTMLElement} el - target element
   * @param   {HTMLFragment|SVGElement} dom - dom tree to inject
   * @returns {undefined}
   */
  function injectDOM(el, dom) {
    switch (true) {
    case isSvg(el):
      moveChildren(dom, el);
      break
    case isTemplate(el):
      el.parentNode.replaceChild(dom, el);
      break
    default:
      el.appendChild(dom);
    }
  }

  /**
   * Create the Template DOM skeleton
   * @param   {HTMLElement} el - root node where the DOM will be injected
   * @param   {string} html - markup that will be injected into the root node
   * @returns {HTMLFragment} fragment that will be injected into the root node
   */
  function createTemplateDOM(el, html) {
    return html && (typeof html === 'string' ?
      createDOMTree(el, html) :
      html)
  }

  /**
   * Template Chunk model
   * @type {Object}
   */
  const TemplateChunk = Object.freeze({
    // Static props
    // bindings: null,
    // bindingsData: null,
    // html: null,
    // isTemplateTag: false,
    // fragment: null,
    // children: null,
    // dom: null,
    // el: null,

    /**
     * Create the template DOM structure that will be cloned on each mount
     * @param   {HTMLElement} el - the root node
     * @returns {TemplateChunk} self
     */
    createDOM(el) {
      // make sure that the DOM gets created before cloning the template
      this.dom = this.dom || createTemplateDOM(el, this.html);

      return this
    },

    // API methods
    /**
     * Attach the template to a DOM node
     * @param   {HTMLElement} el - target DOM node
     * @param   {*} scope - template data
     * @param   {*} parentScope - scope of the parent template tag
     * @param   {Object} meta - meta properties needed to handle the <template> tags in loops
     * @returns {TemplateChunk} self
     */
    mount(el, scope, parentScope, meta = {}) {
      if (!el) throw new Error('Please provide DOM node to mount properly your template')

      if (this.el) this.unmount(scope);

      // <template> tags require a bit more work
      // the template fragment might be already created via meta outside of this call
      const {fragment, children, avoidDOMInjection} = meta;
      // <template> bindings of course can not have a root element
      // so we check the parent node to set the query selector bindings
      const {parentNode} = children ? children[0] : el;
      const isTemplateTag = isTemplate(el);
      const templateTagOffset = isTemplateTag ? Math.max(
        Array.from(parentNode.childNodes).indexOf(el),
        0
      ) : null;
      this.isTemplateTag = isTemplateTag;

      // create the DOM if it wasn't created before
      this.createDOM(el);

      if (this.dom) {
        // create the new template dom fragment if it want already passed in via meta
        this.fragment = fragment || this.dom.cloneNode(true);
      }

      // store root node
      // notice that for template tags the root note will be the parent tag
      this.el = this.isTemplateTag ? parentNode : el;
      // create the children array only for the <template> fragments
      this.children = this.isTemplateTag ? children || Array.from(this.fragment.childNodes) : null;

      // inject the DOM into the el only if a fragment is available
      if (!avoidDOMInjection && this.fragment) injectDOM(el, this.fragment);

      // create the bindings
      this.bindings = this.bindingsData.map(binding => create$5(
        this.el,
        binding,
        templateTagOffset
      ));
      this.bindings.forEach(b => b.mount(scope, parentScope));

      return this
    },
    /**
     * Update the template with fresh data
     * @param   {*} scope - template data
     * @param   {*} parentScope - scope of the parent template tag
     * @returns {TemplateChunk} self
     */
    update(scope, parentScope) {
      this.bindings.forEach(b => b.update(scope, parentScope));

      return this
    },
    /**
     * Remove the template from the node where it was initially mounted
     * @param   {*} scope - template data
     * @param   {*} parentScope - scope of the parent template tag
     * @param   {boolean|null} mustRemoveRoot - if true remove the root element,
     * if false or undefined clean the root tag content, if null don't touch the DOM
     * @returns {TemplateChunk} self
     */
    unmount(scope, parentScope, mustRemoveRoot) {
      if (this.el) {
        this.bindings.forEach(b => b.unmount(scope, parentScope, mustRemoveRoot));

        switch (true) {
        // <template> tags should be treated a bit differently
        // we need to clear their children only if it's explicitly required by the caller
        // via mustRemoveRoot !== null
        case this.children && mustRemoveRoot !== null:
          clearChildren(this.children);
          break

        // remove the root node only if the mustRemoveRoot === true
        case mustRemoveRoot === true:
          removeNode(this.el);
          break

        // otherwise we clean the node children
        case mustRemoveRoot !== null:
          cleanNode(this.el);
          break
        }

        this.el = null;
      }

      return this
    },
    /**
     * Clone the template chunk
     * @returns {TemplateChunk} a clone of this object resetting the this.el property
     */
    clone() {
      return {
        ...this,
        el: null
      }
    }
  });

  /**
   * Create a template chunk wiring also the bindings
   * @param   {string|HTMLElement} html - template string
   * @param   {Array} bindings - bindings collection
   * @returns {TemplateChunk} a new TemplateChunk copy
   */
  function create$6(html, bindings = []) {
    return {
      ...TemplateChunk,
      html,
      bindingsData: bindings
    }
  }

  exports.bindingTypes = bindingTypes;
  exports.createBinding = create$5;
  exports.createExpression = create$2;
  exports.expressionTypes = expressionTypes;
  exports.template = create$6;

  Object.defineProperty(exports, '__esModule', { value: true });

})));