1 files changed, 194 insertions, 0 deletions
diff --git a/dev/vm.js b/dev/vm.js
new file mode 100644
index 00000000..79e92772
--- /dev/null
+++ b/dev/vm.js
@@ -0,0 +1,194 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * 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/>.
+ */
+
+const fs = require('fs');
+const vm = require('vm');
+const path = require('path');
+const assert = require('assert');
+
+
+function getContextEnvironmentRecords(context, names) {
+    // Enables export of values from the declarative environment record
+    if (!Array.isArray(names) || names.length === 0) {
+        return [];
+    }
+
+    let scriptSource = '(() => {\n    "use strict";\n    const results = [];';
+    for (const name of names) {
+        scriptSource += `\n    try { results.push(${name}); } catch (e) { results.push(void 0); }`;
+    }
+    scriptSource += '\n    return results;\n})();';
+
+    const script = new vm.Script(scriptSource, {filename: 'getContextEnvironmentRecords'});
+
+    const contextHasNames = Object.prototype.hasOwnProperty.call(context, 'names');
+    const contextNames = context.names;
+    context.names = names;
+
+    const results = script.runInContext(context, {});
+
+    if (contextHasNames) {
+        context.names = contextNames;
+    } else {
+        delete context.names;
+    }
+
+    return Array.from(results);
+}
+
+function isDeepStrictEqual(val1, val2) {
+    if (val1 === val2) { return true; }
+
+    if (Array.isArray(val1)) {
+        if (Array.isArray(val2)) {
+            return isArrayDeepStrictEqual(val1, val2);
+        }
+    } else if (typeof val1 === 'object' && val1 !== null) {
+        if (typeof val2 === 'object' && val2 !== null) {
+            return isObjectDeepStrictEqual(val1, val2);
+        }
+    }
+
+    return false;
+}
+
+function isArrayDeepStrictEqual(val1, val2) {
+    const ii = val1.length;
+    if (ii !== val2.length) { return false; }
+
+    for (let i = 0; i < ii; ++i) {
+        if (!isDeepStrictEqual(val1[i], val2[i])) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+function isObjectDeepStrictEqual(val1, val2) {
+    const keys1 = Object.keys(val1);
+    const keys2 = Object.keys(val2);
+
+    if (keys1.length !== keys2.length) { return false; }
+
+    const keySet = new Set(keys1);
+    for (const key of keys2) {
+        if (!keySet.delete(key)) { return false; }
+    }
+
+    for (const key of keys1) {
+        if (!isDeepStrictEqual(val1[key], val2[key])) {
+            return false;
+        }
+    }
+
+    const tag1 = Object.prototype.toString.call(val1);
+    const tag2 = Object.prototype.toString.call(val2);
+    if (tag1 !== tag2) { return false; }
+
+    return true;
+}
+
+function deepStrictEqual(actual, expected) {
+    try {
+        // This will fail on prototype === comparison on cross context objects
+        assert.deepStrictEqual(actual, expected);
+    } catch (e) {
+        if (!isDeepStrictEqual(actual, expected)) {
+            throw e;
+        }
+    }
+}
+
+
+function createURLClass() {
+    const BaseURL = URL;
+    return function URL(url) {
+        const u = new BaseURL(url);
+        this.hash = u.hash;
+        this.host = u.host;
+        this.hostname = u.hostname;
+        this.href = u.href;
+        this.origin = u.origin;
+        this.password = u.password;
+        this.pathname = u.pathname;
+        this.port = u.port;
+        this.protocol = u.protocol;
+        this.search = u.search;
+        this.searchParams = u.searchParams;
+        this.username = u.username;
+    };
+}
+
+
+class VM {
+    constructor(context={}) {
+        context.URL = createURLClass();
+        this._context = vm.createContext(context);
+        this._assert = {
+            deepStrictEqual
+        };
+    }
+
+    get context() {
+        return this._context;
+    }
+
+    get assert() {
+        return this._assert;
+    }
+
+    get(names) {
+        if (typeof names === 'string') {
+            return getContextEnvironmentRecords(this._context, [names])[0];
+        } else if (Array.isArray(names)) {
+            return getContextEnvironmentRecords(this._context, names);
+        } else {
+            throw new Error('Invalid argument');
+        }
+    }
+
+    set(values) {
+        if (typeof values === 'object' && values !== null) {
+            Object.assign(this._context, values);
+        } else {
+            throw new Error('Invalid argument');
+        }
+    }
+
+    execute(fileNames) {
+        const single = !Array.isArray(fileNames);
+        if (single) {
+            fileNames = [fileNames];
+        }
+
+        const results = [];
+        for (const fileName of fileNames) {
+            const absoluteFileName = path.resolve(__dirname, '..', 'ext', fileName);
+            const source = fs.readFileSync(absoluteFileName, {encoding: 'utf8'});
+            const script = new vm.Script(source, {filename: absoluteFileName});
+            results.push(script.runInContext(this._context, {}));
+        }
+
+        return single ? results[0] : results;
+    }
+}
+
+
+module.exports = {
+    VM
+};