flow: flat context, object spread/destructure, return, general gardening

packages/sandbox/src/sandbox.js

@@ -6,11 +6,22 @@ export default class Sandbox {
 
   constructor(ast, context) {
     this.ast = ast;
-    this.reset().setContext(context);
+    this.reset();
+    this.context = context;
   }
 
-  context() {
+  get context() {
-    return this.rootScope()?.getAll() || {};
+    return this.rootScope?.context || {};
+  }
+
+  set context(context) {
+    const {rootScope} = this;
+    if (rootScope) {
+      rootScope.context = context;
+    }
+    else {
+      this.setNodeScope(this.ast, new Scope(context));
+    }
   }
 
   evaluate(node) {
@@ -48,43 +59,34 @@ export default class Sandbox {
           value: value.then((value) => scope.set(left.name, value)),
         };
       }
-      scope.set(left.name, value);
+      return {value: scope.set(left.name, value)};
-      return {value};
     }
-    /* eslint-disable no-param-reassign */
-    const assign = (O, P, value, optional) => {
-      // eslint-disable-next-line object-curly-newline
-      if (optional) {
-        // eslint-disable-next-line babel/no-unused-expressions
-        O && (O[P] = value);
-      }
-      else {
-        O[P] = value;
-      }
-      return value;
-    };
-    /* eslint-enable no-param-reassign */
-    const makeAsync = (O, P, value, optional) => (
-      Promise
-        .all([O, P, value])
-        .then(([O, P, value]) => assign(O, P, value, optional))
-    );
     const {
       computed,
       object,
       optional,
       property,
     } = left;
+    const assign = (O, P, value) => {
+      if (optional && !O) {
+        return undefined;
+      }
+      // eslint-disable-next-line no-param-reassign, no-return-assign
+      return O[P] = value;
+    };
+    const makeAsync = (O, P, value) => (
+      Promise.all([O, P, value]).then(([O, P, value]) => assign(O, P, value))
+    );
     const O = this.evaluate(object);
     const P = computed ? this.evaluate(property) : {value: property.name};
     // eslint-disable-next-line no-bitwise
     if (Vasync | O.async | P.async) {
       return {
         async: true,
-        value: makeAsync(O.value, P.value, value, optional),
+        value: makeAsync(O.value, P.value, value),
       };
     }
-    return {value: assign(O.value, P.value, value, optional)};
+    return {value: assign(O.value, P.value, value)};
   }
 
   evaluateAwaitExpression({argument}) {
@@ -237,22 +239,63 @@ export default class Sandbox {
     let isAsync = false;
     const entries = [];
     for (let i = 0; i < properties.length; i++) {
-      const {computed, key, value} = properties[i];
+      if (types.isObjectProperty(properties[i])) {
-      const k = computed ? this.evaluate(key) : {value: key.name};
+        const {computed, key, value} = properties[i];
-      const v = this.evaluate(value);
+        const k = computed ? this.evaluate(key) : {value: key.name};
-      // eslint-disable-next-line no-bitwise
+        const v = this.evaluate(value);
-      isAsync |= k.async | v.async;
+        // eslint-disable-next-line no-bitwise
-      if (k.async || v.async) {
+        isAsync |= k.async | v.async;
-        entries.push(Promise.all([k.value, v.value]));
+        if (k.async || v.async) {
+          entries.push(Promise.all([k.value, v.value]));
+        }
+        else {
+          entries.push([k.value, v.value]);
+        }
       }
-      else {
+      if (types.isSpreadElement(properties[i])) {
-        entries.push([k.value, v.value]);
+        const {argument} = properties[i];
+        const spreading = this.evaluate(argument);
+        // eslint-disable-next-line no-bitwise
+        isAsync |= spreading.async;
+        if (spreading.async) {
+          entries.push(Promise.resolve(spreading.value).then((spreading) => {
+            const entries = [];
+            const keys = Object.keys(spreading);
+            for (let i = 0; i < keys.length; ++i) {
+              const key = keys[i];
+              entries.push([key, spreading[key]]);
+            }
+            return entries;
+          }));
+        }
+        else {
+          const keys = Object.keys(spreading.value);
+          for (let i = 0; i < keys.length; ++i) {
+            const key = keys[i];
+            entries.push([key, spreading.value[key]]);
+          }
+        }
       }
     }
     return {
       async: !!isAsync,
       value: isAsync
-        ? Promise.all(entries).then(Object.fromEntries)
+        ? Promise.all(entries)
+          .then((entries) => {
+            const reduced = [];
+            for (let i = 0; i < entries.length; ++i) {
+              const entry = entries[i];
+              if (Array.isArray(entry[0])) {
+                for (let j = 0; j < entry.length; j++) {
+                  reduced.push(entry[j]);
+                }
+              }
+              else {
+                reduced.push(entry);
+              }
+            }
+            return Object.fromEntries(reduced);
+          })
         : Object.fromEntries(entries),
     };
   }
@@ -335,13 +378,12 @@ export default class Sandbox {
     this.parents = new WeakMap();
     this.scopes = new WeakMap();
     this.runner = (function* traverse() {
-      yield* self.traverse(self.ast);
+      return yield* self.traverse(self.ast);
-      return undefined;
     }());
     return this;
   }
 
-  rootScope() {
+  get rootScope() {
     return this.nodeScope(this.ast);
   }
 
@@ -385,11 +427,6 @@ export default class Sandbox {
     return undefined;
   }
 
-  setContext(context) {
-    this.setNodeScope(this.ast, new Scope(context || this.context()));
-    return this;
-  }
-
   setNextScope(node, scope = this.nodeScope(node)) {
     const nodes = this.nextNodes(node, types.VISITOR_KEYS[node.type]);
     for (let i = 0; i < nodes.length; i++) {
@@ -405,6 +442,44 @@ export default class Sandbox {
     this.scopes.set(node, scope);
   }
 
+  destructure(id, init, scope) {
+    this.setNextScope(id, scope);
+    const {properties} = id;
+    const promises = [];
+    for (let i = 0; i < properties.length; ++i) {
+      const property = properties[i];
+      this.setNextScope(property, scope);
+      const k = property.computed
+        ? this.evaluate(property.key)
+        : {value: property.key.name};
+      if (k.async) {
+        promises.push(Promise.resolve(k.value).then((k) => {
+          if (types.isIdentifier(property.value)) {
+            const {name} = property.value;
+            scope.allocate(name, init[k]);
+            return undefined;
+          }
+          return this.destructure(property.value, init[k], scope);
+        }));
+        // eslint-disable-next-line no-continue
+        continue;
+      }
+      if (types.isIdentifier(property.value)) {
+        const {name} = property.value;
+        scope.allocate(name, init[k.value]);
+      }
+      else {
+        const promiseOrVoid = this.destructure(property.value, init[k.value], scope);
+        if (promiseOrVoid) {
+          promises.push(promiseOrVoid);
+        }
+      }
+    }
+    return promises.length > 0
+      ? Promise.all(promises)
+      : undefined;
+  }
+
   * traverse(node) {
     let keys = types.VISITOR_KEYS[node.type];
     if (!keys) {
@@ -420,33 +495,47 @@ export default class Sandbox {
     }
     this.setNextScope(node, scope);
     if (types.isVariableDeclarator(node)) {
-      const {id, init} = node;
+      const {id} = node;
-      const {async, value} = this.evaluate(init);
+      const init = this.evaluate(node.init);
-      if (async) {
+      if (types.isIdentifier(id)) {
-        yield {
+        if (init.async) {
-          async: true,
+          yield {
-          value: Promise.resolve(value).then((value) => {
+            async: true,
-            scope.allocate(id.name, value);
+            value: Promise.resolve(init.value).then((value) => {
-          }),
+              scope.allocate(id.name, value);
-        };
+            }),
+          };
+        }
+        else {
+          scope.allocate(id.name, init.value);
+        }
       }
-      else {
+      else if (types.isObjectPattern(id)) {
-        scope.allocate(id.name, value);
+        const promiseOrVoid = init.async
+          ? Promise.resolve(init.value).then((init) => this.destructure(id, init, scope))
+          : this.destructure(id, init.value, scope);
+        if (promiseOrVoid) {
+          yield {
+            async: true,
+            value: promiseOrVoid,
+          };
+        }
       }
     }
     // Blocks...
     if (types.isIfStatement(node)) {
       const {async, value} = this.evaluate(node.test);
+      const branch = (value) => {
+        keys = [value ? 'consequent' : 'alternate'];
+      };
       if (async) {
         yield {
           async: true,
-          value: Promise.resolve(value).then((value) => {
+          value: Promise.resolve(value).then(branch),
-            keys = [value ? 'consequent' : 'alternate'];
-          }),
         };
       }
       else {
-        keys = [value ? 'consequent' : 'alternate'];
+        branch(value);
       }
     }
     // Loops...
@@ -480,7 +569,11 @@ export default class Sandbox {
       // Recur...
       const nodes = this.nextNodes(node, keys);
       for (let i = 0; i < nodes.length; i++) {
-        yield* this.traverse(nodes[i]);
+        const r = yield* this.traverse(nodes[i]);
+        if (r) {
+          // eslint-disable-next-line consistent-return
+          return r;
+        }
       }
       // Loops...
       if (types.isForStatement(node)) {
@@ -520,6 +613,10 @@ export default class Sandbox {
       scope = scope.pop();
     }
     // Evaluate...
+    if (types.isReturnStatement(node)) {
+      // eslint-disable-next-line consistent-return
+      return this.evaluate(node.argument);
+    }
     if (types.isDirective(node)) {
       yield this.evaluate(node.value);
     }

packages/sandbox/src/scope.js

@@ -5,27 +5,18 @@ export default class Scope {
   context = {};
 
   constructor(context = {}) {
-    this.context = Object
+    this.context = context;
-      .fromEntries(
-        Object.entries(context)
-          .map(([key, value]) => [key, {value}]),
-      );
   }
 
   allocate(key, value) {
-    if (this.context[key]) {
+    this.context[key] = value;
-      this.context[key].value = value;
-    }
-    else {
-      this.context[key] = {value};
-    }
   }
 
   get(key) {
     let walk = this;
     while (walk) {
-      if (walk.context[key]) {
+      if (key in walk.context) {
-        return walk.context[key].value;
+        return walk.context[key];
       }
       walk = walk.parent;
     }
@@ -39,7 +30,7 @@ export default class Scope {
     while (walk) {
       const entries = Object.entries(walk.context);
       for (let i = 0; i < entries.length; i++) {
-        const [key, {value}] = entries[i];
+        const [key, value] = entries[i];
         if (!keys.has(key)) {
           keys.add(key);
           all[key] = value;
@@ -65,8 +56,8 @@ export default class Scope {
   set(key, value) {
     let walk = this;
     while (walk) {
-      if (walk.context[key]) {
+      if (key in walk.context) {
-        walk.context[key].value = value;
+        walk.context[key] = value;
         return value;
       }
       walk = walk.parent;

packages/sandbox/test/assignment-expression.js

@@ -3,7 +3,52 @@ import {expect} from 'chai';
 
 import Sandbox from '../src/sandbox';
 
-it('evaluates AssignmentExpression', () => {
+it('evaluates async AssignmentExpression', async () => {
-  expect(new Sandbox(parse('let foo = 69; foo = 420')).next().value)
+  const o = {allowAwaitOutsideFunction: true};
+  const sandbox = new Sandbox(parse('let foo = await 69; foo + 351', o));
+  const {async, value} = sandbox.next().value;
+  expect(async)
+    .to.be.true;
+  await value;
+  expect(sandbox.next().value)
     .to.deep.include({value: 420});
 });
+
+it('evaluates AssignmentExpression', () => {
+  expect(new Sandbox(parse('let foo = 69; foo + 351')).next().value)
+    .to.deep.include({value: 420});
+});
+
+it('destructures', () => {
+  const sandbox = new Sandbox(parse('const {a, b} = {a: 1, b: 2}; [a, b];'));
+  expect(sandbox.next().value)
+    .to.deep.include({value: [1, 2]});
+});
+
+it('destructures async key', async () => {
+  const o = {allowAwaitOutsideFunction: true};
+  const sandbox = new Sandbox(parse('const k = "a"; const {[await k]: a, b} = {a: 1, b: 2}; [a, b];', o));
+  const {async, value} = sandbox.next().value;
+  expect(async)
+    .to.be.true;
+  await value;
+  expect(sandbox.next().value)
+    .to.deep.include({value: [1, 2]});
+});
+
+it('destructures async value', async () => {
+  const o = {allowAwaitOutsideFunction: true};
+  const sandbox = new Sandbox(parse('const {a, b} = await {a: 1, b: 2}; [a, b];', o));
+  const {async, value} = sandbox.next().value;
+  expect(async)
+    .to.be.true;
+  await value;
+  expect(sandbox.next().value)
+    .to.deep.include({value: [1, 2]});
+});
+
+it('nested destructures', () => {
+  const sandbox = new Sandbox(parse('const {a, b: {c}} = {a: 1, b: {c: 2}}; [a, c];'));
+  expect(sandbox.next().value)
+    .to.deep.include({value: [1, 2]});
+});

packages/sandbox/test/context.js

@@ -5,9 +5,9 @@ import Sandbox from '../src/sandbox';
 
 it('can update context', () => {
   const sandbox = new Sandbox(parse('foo = 420'), {foo: 69});
-  expect(sandbox.context())
+  expect(sandbox.context)
     .to.deep.equal({foo: 69});
   sandbox.run();
-  expect(sandbox.context())
+  expect(sandbox.context)
     .to.deep.equal({foo: 420});
 });

packages/sandbox/test/object-expression.js

@@ -3,7 +3,38 @@ import {expect} from 'chai';
 
 import Sandbox from '../src/sandbox';
 
+it('evaluates async ObjectExpression', async () => {
+  const context = {
+    b: () => Promise.resolve(2),
+  };
+  const o = {allowAwaitOutsideFunction: true};
+  const sandbox = new Sandbox(parse('({a: 1, b: await b()})', o), context);
+  const {async, value} = sandbox.next().value;
+  expect(async).to.be.true;
+  expect(await value)
+    .to.deep.include({a: 1, b: 2});
+});
+
 it('evaluates ObjectExpression', () => {
   expect(new Sandbox(parse('({a: 1, b: 2})')).next().value)
     .to.deep.include({value: {a: 1, b: 2}});
 });
+
+it('evaluates async SpreadElement', async () => {
+  const context = {
+    b: () => Promise.resolve({a: 2}),
+  };
+  const o = {allowAwaitOutsideFunction: true};
+  const sandbox = new Sandbox(parse('({a: 1, ...(await b())})', o), context);
+  const {async, value} = sandbox.next().value;
+  expect(async).to.be.true;
+  expect(await value)
+    .to.deep.include({a: 2});
+});
+
+it('evaluates SpreadElement', () => {
+  expect(new Sandbox(parse('({...({a: 1}), a: 2})')).next().value)
+    .to.deep.include({value: {a: 2}});
+  expect(new Sandbox(parse('({a: 0, ...({a: 1})})')).next().value)
+    .to.deep.include({value: {a: 1}});
+});

packages/sandbox/test/return.js

@@ -0,0 +1,14 @@
+import {parse} from '@babel/parser';
+import {expect} from 'chai';
+
+import Sandbox from '../src/sandbox';
+
+it('evaluates ReturnStatement', async () => {
+  const o = {allowReturnOutsideFunction: true};
+  const sandbox = new Sandbox(parse('return 69', o));
+  const {done, value} = sandbox.next();
+  expect(done)
+    .to.be.true;
+  expect(value.value)
+    .to.deep.equal(69);
+});