Implement basic execution system and UI

This is a rather large commit that includes all of the following:
- React UI with code editor, runtime renderer and input-output panes
- Language providers for a sample language and Brainfuck
- Implementation of code execution in a web worker
- All-at-once unabortable execution of program fully functional

engines/brainfuck/constants.ts

@@ -0,0 +1,81 @@
+import { MonacoTokensProvider } from "../types";
+
+export type BFRS = {
+  tape: { [k: number]: number };
+  pointer: number;
+};
+
+export enum BF_OP {
+  LEFT = "<",
+  RIGHT = ">",
+  INCR = "+",
+  DECR = "-",
+  OUT = ".",
+  IN = ",",
+  LOOPIN = "[",
+  LOOPOUT = "]",
+}
+
+/** A single instruction of the program */
+export type BFInstruction = {
+  /** Type of instruction */
+  type: BF_OP;
+  /** Used for location of opposite end of loops */
+  param?: number;
+};
+
+/** A single element of the program's AST */
+export type BFAstStep = {
+  instr: BFInstruction;
+  location: { line: number; char: number };
+};
+
+/** Sample program printing "Hello World!" */
+export const sampleProgram = [
+  "+++++ +++               Set Cell #0 to 8",
+  "[",
+  "    >++++               Add 4 to Cell #1; this will always set Cell #1 to 4",
+  "    [                   as the cell will be cleared by the loop",
+  "        >++             Add 4*2 to Cell #2",
+  "        >+++            Add 4*3 to Cell #3",
+  "        >+++            Add 4*3 to Cell #4",
+  "        >+              Add 4 to Cell #5",
+  "        <<<<-           Decrement the loop counter in Cell #1",
+  "    ]                   Loop till Cell #1 is zero",
+  "    >+                  Add 1 to Cell #2",
+  "    >+                  Add 1 to Cell #3",
+  "    >-                  Subtract 1 from Cell #4",
+  "    >>+                 Add 1 to Cell #6",
+  "    [<]                 Move back to the first zero cell you find; this will",
+  "                        be Cell #1 which was cleared by the previous loop",
+  "    <-                  Decrement the loop Counter in Cell #0",
+  "]                       Loop till Cell #0 is zero",
+  "",
+  "The result of this is:",
+  "Cell No :   0   1   2   3   4   5   6",
+  "Contents:   0   0  72 104  88  32   8",
+  "Pointer :   ^",
+  "",
+  ">>.                     Cell #2 has value 72 which is 'H'",
+  ">---.                   Subtract 3 from Cell #3 to get 101 which is 'e'",
+  "+++++ ++..+++.          Likewise for 'llo' from Cell #3",
+  ">>.                     Cell #5 is 32 for the space",
+  "<-.                     Subtract 1 from Cell #4 for 87 to give a 'W'",
+  "<.                      Cell #3 was set to 'o' from the end of 'Hello'",
+  "+++.----- -.----- ---.  Cell #3 for 'rl' and 'd'",
+  ">>+.                    Add 1 to Cell #5 gives us an exclamation point",
+  ">++.                    And finally a newline from Cell #6",
+].join("\n");
+
+/** Tokens provider */
+export const editorTokensProvider: MonacoTokensProvider = {
+  tokenizer: {
+    root: [
+      [/[-\+]/, "operator"],
+      [/[<>]/, "annotation"],
+      [/[\[\]]/, "keyword"],
+      [/[\,\.]/, "type.identifier"],
+    ],
+  },
+  defaultToken: "comment",
+};