Disable UpdateExpression from Chapter 3 (#76)

* Disable UpdateExpression from Chapter 3

This is not a specified operator in the documentation

* move disalloed syntax to new file

* fix tsc errors

* Bump version

Author: remo5000

package.json

@@ -1,6 +1,6 @@
 {
   "name": "js-slang",
-  "version": "0.1.8",
+  "version": "0.1.9",
   "description": "Javascript-based interpreter for slang, written in Typescript",
   "author": {
     "name": "Source Academy",

src/__tests__/__snapshots__/block_scoping.ts.snap

@@ -1,13 +1,5 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`Cannot leave blank expressions in for loops 1`] = `"Line 2: For statement cannot have empty init expression."`;
-
-exports[`Cannot leave blank expressions in for loops 2`] = `"Line 2: For statement cannot have empty test expression."`;
-
-exports[`Cannot leave blank expressions in for loops 3`] = `"Line 2: For statement cannot have empty update expression."`;
-
-exports[`Cannot leave blank expressions in for loops 4`] = `"Line 2: For statement cannot have empty init,test,update expressions."`;
-
 exports[`Cannot overwrite loop variables within a block 1`] = `"Line 5: Cannot assign new value to constant x"`;
 
 exports[`const uses block scoping instead of function scoping 1`] = `

src/__tests__/__snapshots__/disallowed_syntax.ts.snap

@@ -0,0 +1,11 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Cannot leave blank expressions in for loops 1`] = `"Line 2: For statement cannot have empty init expression."`;
+
+exports[`Cannot leave blank expressions in for loops 2`] = `"Line 2: For statement cannot have empty test expression."`;
+
+exports[`Cannot leave blank expressions in for loops 3`] = `"Line 2: For statement cannot have empty update expression."`;
+
+exports[`Cannot leave blank expressions in for loops 4`] = `"Line 2: For statement cannot have empty init,test,update expressions."`;
+
+exports[`Cannot use update expressions 1`] = `"Line 3: Update expressions are not allowed"`;

src/__tests__/block_scoping.ts

@@ -154,43 +154,3 @@ test("Cannot overwrite loop variables within a block", () => {
   });
 });
 
-test("Cannot leave blank expressions in for loops", () => {
-  const code = [
-    `
-    for(; i < 3; i++) {
-      break;
-    }
-  `,
-    `
-    for(let i = 0; ; i++) {
-      break;
-    }
-  `,
-    `
-    for(let i = 0; i < 3;) {
-      break;
-    }
-  `,
-    `
-    for(;;) {
-      break;
-    }
-  `
-  ];
-  const scheduler = "preemptive";
-  const promises = code.map(c => {
-    const context = mockContext(3);
-    return runInContext(c, context, { scheduler }).then(obj => ({
-      context,
-      obj
-    }));
-  });
-  return Promise.all(promises).then(results => {
-    results.map(res => {
-      const { context, obj } = res;
-      expect(obj.status).toBe("error");
-      const errors = parseError(context.errors);
-      expect(errors).toMatchSnapshot();
-    });
-  });
-});

src/__tests__/disallowed_syntax.ts

@@ -0,0 +1,59 @@
+import { mockContext } from '../mocks/context'
+import { parseError, runInContext } from '../index'
+
+test("Cannot leave blank expressions in for loops", () => {
+  const code = [
+    `
+    for(; i < 3; i = i + 1) {
+      break;
+    }
+  `,
+    `
+    for(let i = 0; ; i = i + 1) {
+      break;
+    }
+  `,
+    `
+    for(let i = 0; i < 3;) {
+      break;
+    }
+  `,
+    `
+    for(;;) {
+      break;
+    }
+  `
+  ];
+  const scheduler = "preemptive";
+  const promises = code.map(c => {
+    const context = mockContext(3);
+    return runInContext(c, context, { scheduler }).then(obj => ({
+      context,
+      obj
+    }));
+  });
+  return Promise.all(promises).then(results => {
+    results.map(res => {
+      const { context, obj } = res;
+      expect(obj.status).toBe("error");
+      const errors = parseError(context.errors);
+      expect(errors).toMatchSnapshot();
+    });
+  });
+});
+
+test("Cannot use update expressions", () => {
+  const code = `
+  let x = 3;
+  x++;
+  x;
+  `;
+  const context = mockContext(3);
+  const promise = runInContext(code, context, { scheduler: "preemptive" });
+  return promise.then(obj => {
+    expect(obj.status).toBe("error");
+    const errors = parseError(context.errors);
+    expect(errors).toMatchSnapshot();
+  });
+});
+

src/syntaxTypes.ts

@@ -29,9 +29,9 @@ const syntaxTypes: { [nodeName: string]: number } = {
   ObjectExpression: 3,
   MemberExpression: 3,
   Property: 3,
-  UpdateExpression: 3,
 
   // Week 5
+  UpdateExpression: 5,
   EmptyStatement: 5,
   // previously Week 10
   NewExpression: 10,