Add predefined suiweb

src/js/SuiWeb.js

@@ -1,81 +1,376 @@
+// @ts-nocheck
+/* eslint-disable eslint-comments/no-unlimited-disable */
+/* eslint-disable */
 /**
- * Provides component for rendering elements written in SJDON notation.
+ *  SuiWeb 
+ *  Simple User Interface Tool for Web Exercises
+ * 
+ *  @author   bkrt
+ *  @version  0.3.4
+ *  @date     11.12.2021
+ *
+ *  0.3.4 - only null or undefined qualify as uninitialized state
+ *  0.3.3 - parseSJDON rewritten to use createElement
+ *        - flatten children array for props.children in JSX
+ *  0.3.2 - save and restore of active element improved 
+ *  0.3.1 - parseSJDON rewritten 
+ *  0.3.0 - style property 
+ *  0.2.3 - ES6 modules
+ *  0.2.2 - component state and hooks
+ *  0.2.1 - parse SJDON rewritten, function components 
+ *  0.2.0 - render single SJDON structures to DOM
+ * 
+ *  Based on ideas and code from 
+ *  Rodrigo Pombo: Build your own React
+ *  https://pomb.us/build-your-own-react/
+ * 
+ *  Thanks to Rodrigo Pombo for a great tutorial and for sharing the 
+ *  code of the Didact library. Didact is a much more sophisticated
+ *  re-implementtation of React's basics than the simple SuiWeb.
  */
-export class SuiWeb
+
+/* =====================================================================
+ *  SJDON - Conversion
+ * =====================================================================
+*/
+
+//  parseSJDON: convert SJDON to createElement calls
+//
+//  note: this function can also help to use React with SJDON syntax
+//
+//  to simplify calls add something like this to your components:
+//  let s = (data) => reactFromSJDON(data, React.createElement)
+// 
+function parseSJDON([type, ...rest], create = createElement)
 {
-    /**
+    const isObj = (obj) => typeof (obj) === 'object' && !Array.isArray(obj)
-     * Renders the specified {@link data `data`} and appends it to the specified {@link element `element`}.
+    const children = rest.filter(item => !isObj(item))
-     *
+    const repr = create(type,
-     * @param {NodeDescriptor} data
+        Object.assign({}, ...rest.filter(isObj)),
-     * The node to render written in SJDON notation.
+        ...children.map(ch => Array.isArray(ch) ? parseSJDON(ch, create) : ch)
-     *
+    )
-     * @param {HTMLElement} element
+    repr.sjdon = children
-     * The element to add the rendered node to.
+    return repr
-     *
+}
-     * @returns {Node}
-     * The resulting element.
-     */
-    static render(data, element)
-    {
-        if (Array.isArray(data))
-        {
-            let descriptor = data[0];
-            let args = data.slice(1);
 
-            if (typeof descriptor === "function" || typeof descriptor === "string")
-            {
-                /**
-                 * @type {HTMLElement}
-                 */
-                let result;
 
-                if (typeof descriptor === "function")
+//  create an element representation
-                {
+// 
-                    /**
+function createElement(type, props, ...children)
-                     * @type {any[]}
+{
-                     */
+    return {
-                    let arg = [];
+        type,
+        props: {
+            ...props,
+            children: children.flat().map(child =>
+                typeof child === "object"
+                    ? child
+                    : createTextElement(child)
+            ),
+        },
+    }
+}
 
-                    if (typeof args[0] === "object" && !Array.isArray(args[0]))
+
+//  create a text element representation
+//
+function createTextElement(text)
+{
+    return {
+        type: "TEXT_ELEMENT",
+        props: {
+            nodeValue: text,
+            children: [],
+        },
+    }
+}
+
+/* =====================================================================
+ *  Render node tree to DOM
+ * =====================================================================
+*/
+
+//  global context
+let contextStore = createStore();
+
+
+//  remove children and render new subtree
+//
+function render(element, container)
+{
+    while (container.firstChild)
     {
-                        arg = [args[0]];
+        container.removeChild(container.lastChild);
-                        args = args.slice(1);
+    }
+    renderInit(element, container, 0);
+}
+
+
+//  render subtree
+//  and call effects after rendering
+//
+function renderInit(element, container, n, childIndex)
+{
+    contextStore("effects", []);
+
+    // save focus and cursor position of active element
+    let [focusSelector, position] = getFocusInput();
+
+    // ** render the element **
+    renderElem(element, container, n, childIndex);
+
+    // restore focus and cursor position of active element
+    setFocusInput(focusSelector, position);
+
+    // run effects
+    contextStore("effects").forEach(fun => fun());
+    contextStore("effects", []);
+}
+
+
+//  render an element
+//  - if it is in SJDON form: parse first
+//  - render function or host component
+//
+function renderElem(element, container, n, childIndex)
+{
+    if (Array.isArray(element))
+    {
+        element = parseSJDON(element);
     }
 
-                    result = /** @type {HTMLElement} */ (SuiWeb.render(descriptor(...arg), element));
+    if (element.type instanceof Function)
-                }
-                else
     {
-                    result = element.ownerDocument.createElement(descriptor);
+        updateFunctionComponent(element, container, n, childIndex);
-                    element.appendChild(result);
+    } else
+    {
+        updateHostComponent(element, container, childIndex);
+    }
+}
+
+
+//  function component
+//  - run function to get child node
+//  - render child node
+//
+function updateFunctionComponent(element, container, n, childIndex)
+{
+    // save re-render function to context
+    contextStore("re-render", () => renderInit(element, container, n, n));
+    let children = element.sjdon ?? element.props.children;
+    let node = element.type({ ...element.props, children });
+    renderElem(node, container, n, childIndex);
+}
+
+
+//  host component
+//  - create dom node
+//  - assign properties
+//  - render child nodes
+//  - add host to dom
+//
+function updateHostComponent(element, container, childIndex)
+{
+
+    // create DOM node
+    const dom =
+        element.type == "TEXT_ELEMENT"
+            ? document.createTextNode("")
+            : document.createElement(element.type)
+
+    // assign the element props
+    const isProperty = key => key !== "children"
+    Object.keys(element.props)
+        .filter(isProperty)
+        .forEach(name =>
+        {
+            if (name == "style")
+            {
+                updateStyleAttribute(dom, element.props.style);
+            } else
+            {
+                dom[name] = element.props[name];
+            }
+        })
+
+    // render children
+    element.props.children.forEach((child, index) =>
+    {
+        renderElem(child, dom, index);
+    });
+
+    if (typeof (childIndex) == 'number')
+    {
+        // re-render: replace node
+        container.replaceChild(dom, container.childNodes[childIndex]);
+    } else
+    {
+        // add node to container
+        container.appendChild(dom);
+    }
+}
+
+
+//  update style attribute, value can be:
+//  - a CSS string: set to style attribute
+//  - an object: merged to style attribute
+//  - an array of objects: merged to style attribute
+//
+function updateStyleAttribute(dom, styles)
+{
+    if (typeof (styles) == "string")
+    {
+        dom.style = styles;
+    } else if (Array.isArray(styles))
+    {
+        Object.assign(dom.style, ...styles);
+    } else if (typeof (styles) == "object")
+    {
+        Object.assign(dom.style, styles);
+    }
+}
+
+
+/* =====================================================================
+ *  Handling state
+ * =====================================================================
+*/
+
+//  element state
+let stateHooks = createStore();
+
+
+//  state hook
+//  - access state via id and key
+//  - return state and update function
+//
+function useState(id, key, init)
+{
+    let idKey = "id:" + id + "-key:" + key;
+
+    //  prepare render function 
+    let renderFunc = contextStore("re-render");
+
+    //  define function to update state
+    function updateValue(updateFun, rerender = true)
+    {
+        stateHooks(idKey, updateFun(stateHooks(idKey)));
+        if (rerender) renderFunc();
     }
 
-                for (let arg of args)
+    //  new state: set initial value
+    if ([undefined, null].includes(stateHooks(idKey)))
     {
-                    if (typeof arg === "object" && !Array.isArray(arg))
+        stateHooks(idKey, init);
-                    {
-                        Object.assign(result, arg);
-                    }
-                    else
-                    {
-                        SuiWeb.render(arg, result);
-                    }
     }
 
-                return result;
+    return [stateHooks(idKey), updateValue];
-            }
+}
-            else
+
+
+//  effect hook
+//  add function to effects array
+//
+function useEffect(fun)
+{
+    contextStore("effects", [...contextStore("effects"), fun]);
+}
+
+
+//  create a key-value-store
+//  return accessor function
+//
+function createStore()
+{
+    let data = {};
+    function access(key, ...value)
     {
-                throw new SyntaxError();
+        if (value.length === 0)
-            }
-        }
-        else if (typeof data === "string")
         {
-            return element.appendChild(element.ownerDocument.createTextNode(data));
+            return data[key];
-        }
+        } else
-        else
         {
-            throw new SyntaxError();
+            data[key] = value[0];
+            return value[0];
+        }
+    }
+    return access;
+}
+
+
+/* =====================================================================
+ *  Get and set focus and position in certain elements
+ *  Note: this is a quick&dirty solution that probably fails when 
+ *  elements are added or removed
+ * =====================================================================
+*/
+
+//  create a CSS selector for a given node
+//
+function getSelectorOf(node)
+{
+    let selector = ""
+    while (node != document.body)
+    {
+        if (selector != "") selector = ">" + selector
+
+        if (node.id)
+        {
+            selector = "#" + node.id + selector
+            break
+        }
+
+        let index = Array.from(node.parentNode.children)
+            .filter(item => item.tagName == node.tagName)
+            .findIndex(item => item == node)
+
+        selector = node.tagName + ":nth-of-type(" + (index + 1) + ")" + selector
+        node = node.parentNode
+    }
+    return selector
+}
+
+//  find a selector for the element that has focus and the cursor 
+//  position in the element
+//
+function getFocusInput()
+{
+    const active = document.activeElement;
+    let sel = active ? getSelectorOf(active) : undefined
+    let position = active ? active.selectionStart : undefined;
+    return [sel, position];
+}
+
+//  set focus to an element in a list of elements matching a 
+//  selector and position cursor in the element
+//
+function setFocusInput(selector, position)
+{
+    if (selector && typeof (selector) == 'string')
+    {
+        console.log("Sel:" + selector)
+        let el = document.querySelector(selector);
+        if (el) el.focus();
+        if (el && "selectionStart" in el
+            && "selectionEnd" in el
+            && position !== undefined)
+        {
+            el.selectionStart = position;
+            el.selectionEnd = position;
         }
     }
 }
+
+
+/* =====================================================================
+ *  Module export
+ * =====================================================================
+*/
+
+export { render, createElement, useState, useEffect };
+
+
+/* =====================================================================
+ *  EOF
+ * =====================================================================
+*/