Merge pull request #406 from toasted-nutbread/object-property-accessor

Object property accessor

1 files changed, 244 insertions, 0 deletions

diff --git a/ext/mixed/js/object-property-accessor.js b/ext/mixed/js/object-property-accessor.js
new file mode 100644
index 00000000..108afc0d
--- /dev/null
+++ b/ext/mixed/js/object-property-accessor.js
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2016-2020  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * Class used to get and set generic properties of an object by using path strings.
+ */
+class ObjectPropertyAccessor {
+    constructor(target, setter=null) {
+        this._target = target;
+        this._setter = (typeof setter === 'function' ? setter : null);
+    }
+
+    getProperty(pathArray, pathLength) {
+        let target = this._target;
+        const ii = typeof pathLength === 'number' ? Math.min(pathArray.length, pathLength) : pathArray.length;
+        for (let i = 0; i < ii; ++i) {
+            const key = pathArray[i];
+            if (!ObjectPropertyAccessor.hasProperty(target, key)) {
+                throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray.slice(0, i + 1))}`);
+            }
+            target = target[key];
+        }
+        return target;
+    }
+
+    setProperty(pathArray, value) {
+        if (pathArray.length === 0) {
+            throw new Error('Invalid path');
+        }
+
+        const target = this.getProperty(pathArray, pathArray.length - 1);
+        const key = pathArray[pathArray.length - 1];
+        if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) {
+            throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`);
+        }
+
+        if (this._setter !== null) {
+            this._setter(target, key, value, pathArray);
+        } else {
+            target[key] = value;
+        }
+    }
+
+    static getPathString(pathArray) {
+        const regexShort = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
+        let pathString = '';
+        let first = true;
+        for (let part of pathArray) {
+            switch (typeof part) {
+                case 'number':
+                    if (Math.floor(part) !== part || part < 0) {
+                        throw new Error('Invalid index');
+                    }
+                    part = `[${part}]`;
+                    break;
+                case 'string':
+                    if (!regexShort.test(part)) {
+                        const escapedPart = part.replace(/["\\]/g, '\\$&');
+                        part = `["${escapedPart}"]`;
+                    } else {
+                        if (!first) {
+                            part = `.${part}`;
+                        }
+                    }
+                    break;
+                default:
+                    throw new Error(`Invalid type: ${typeof part}`);
+            }
+            pathString += part;
+            first = false;
+        }
+        return pathString;
+    }
+
+    static getPathArray(pathString) {
+        const pathArray = [];
+        let state = 'empty';
+        let quote = 0;
+        let value = '';
+        let escaped = false;
+        for (const c of pathString) {
+            const v = c.codePointAt(0);
+            switch (state) {
+                case 'empty': // Empty
+                case 'id-start': // Expecting identifier start
+                    if (v === 0x5b) { // '['
+                        if (state === 'id-start') {
+                            throw new Error(`Unexpected character: ${c}`);
+                        }
+                        state = 'open-bracket';
+                    } else if (
+                        (v >= 0x41 && v <= 0x5a) || // ['A', 'Z']
+                        (v >= 0x61 && v <= 0x7a) || // ['a', 'z']
+                        v === 0x5f // '_'
+                    ) {
+                        state = 'id';
+                        value += c;
+                    } else {
+                        throw new Error(`Unexpected character: ${c}`);
+                    }
+                    break;
+                case 'id': // Identifier
+                    if (
+                        (v >= 0x41 && v <= 0x5a) || // ['A', 'Z']
+                        (v >= 0x61 && v <= 0x7a) || // ['a', 'z']
+                        (v >= 0x30 && v <= 0x39) || // ['0', '9']
+                        v === 0x5f // '_'
+                    ) {
+                        value += c;
+                    } else if (v === 0x5b) { // '['
+                        pathArray.push(value);
+                        value = '';
+                        state = 'open-bracket';
+                    } else if (v === 0x2e) { // '.'
+                        pathArray.push(value);
+                        value = '';
+                        state = 'id-start';
+                    } else {
+                        throw new Error(`Unexpected character: ${c}`);
+                    }
+                    break;
+                case 'open-bracket': // Open bracket
+                    if (v === 0x22 || v === 0x27) { // '"' or '\''
+                        quote = v;
+                        state = 'string';
+                    } else if (v >= 0x30 && v <= 0x39) { // ['0', '9']
+                        state = 'number';
+                        value += c;
+                    } else {
+                        throw new Error(`Unexpected character: ${c}`);
+                    }
+                    break;
+                case 'string': // Quoted string
+                    if (escaped) {
+                        value += c;
+                        escaped = false;
+                    } else if (v === 0x5c) { // '\\'
+                        escaped = true;
+                    } else if (v !== quote) {
+                        value += c;
+                    } else {
+                        state = 'close-bracket';
+                    }
+                    break;
+                case 'number': // Number
+                    if (v >= 0x30 && v <= 0x39) { // ['0', '9']
+                        value += c;
+                    } else if (v === 0x5d) { // ']'
+                        pathArray.push(Number.parseInt(value, 10));
+                        value = '';
+                        state = 'next';
+                    } else {
+                        throw new Error(`Unexpected character: ${c}`);
+                    }
+                    break;
+                case 'close-bracket': // Expecting closing bracket after quoted string
+                    if (v === 0x5d) { // ']'
+                        pathArray.push(value);
+                        value = '';
+                        state = 'next';
+                    } else {
+                        throw new Error(`Unexpected character: ${c}`);
+                    }
+                    break;
+                case 'next': // Expecting . or [
+                    if (v === 0x5b) { // '['
+                        state = 'open-bracket';
+                    } else if (v === 0x2e) { // '.'
+                        state = 'id-start';
+                    } else {
+                        throw new Error(`Unexpected character: ${c}`);
+                    }
+                    break;
+            }
+        }
+        switch (state) {
+            case 'empty':
+            case 'next':
+                break;
+            case 'id':
+                pathArray.push(value);
+                value = '';
+                break;
+            default:
+                throw new Error('Path not terminated correctly');
+        }
+        return pathArray;
+    }
+
+    static hasProperty(object, property) {
+        switch (typeof property) {
+            case 'string':
+                return (
+                    typeof object === 'object' &&
+                    object !== null &&
+                    !Array.isArray(object) &&
+                    Object.prototype.hasOwnProperty.call(object, property)
+                );
+            case 'number':
+                return (
+                    Array.isArray(object) &&
+                    property >= 0 &&
+                    property < object.length &&
+                    property === Math.floor(property)
+                );
+            default:
+                return false;
+        }
+    }
+
+    static isValidPropertyType(object, property) {
+        switch (typeof property) {
+            case 'string':
+                return (
+                    typeof object === 'object' &&
+                    object !== null &&
+                    !Array.isArray(object)
+                );
+            case 'number':
+                return (
+                    Array.isArray(object) &&
+                    property >= 0 &&
+                    property === Math.floor(property)
+                );
+            default:
+                return false;
+        }
+    }
+}