Initial commit.

.gitattributes

+# Disable line-ending conversions for this repository.
+* -text

.gitignore

+# dependencies
+/node_modules
+
+# testing
+/coverage
+
+# production
+/build
+
+# environments
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# misc
+*~
+.DS_Store

.gitmodules

+[submodule "stylelint-config"]
+	path = stylelint-config
+	url = git@git.unl.edu:soft-core/soft-260/stylelint-config.git
+[submodule "eslint-config"]
+	path = eslint-config
+	url = git@git.unl.edu:soft-core/soft-260/eslint-config.git

README.md

+# Quick Start
+
+Recursively clone this repository and `cd` into the root folder:
+
+```
+$ git clone --recursive git@git.unl.edu:soft-core/soft-260/generators-in-class.git
+$ cd generators-in-class
+```
+
+(If you forget `--recursive` when cloning, you can `cd` into your clone and run
+`git submodule update --init --recursive` instead.)
+
+Install dependencies:
+
+```
+$ npm install
+```
+
+(Near the end you may see some warnings because `create-react-app` transitively
+depends on some deprecated packages.)
+
+And then serve the application locally:
+
+```
+$ npm start
+```
+
+When you are done, press control-c to stop the server.

eslint-config @ 24df42fb

+Subproject commit 24df42fb655d234b83c93b0fb24d012e4d9ecb58

package.json

+{
+  "name": "@unlsoft/generators-in-class",
+  "version": "1.0.0",
+  "description": "Starter code for the in-class demonstration of generators.",
+  "private": true,
+  "license": "UNLICENSED",
+  "scripts": {
+    "postinstall:stylelint-config": "cd stylelint-config && npm install",
+    "postinstall:eslint-config": "cd eslint-config && npm install",
+    "postinstall:app": "cd simplifier && npm install",
+    "postinstall": "run-s postinstall:**",
+    "lint:app": "cd simplifier && npm run lint",
+    "lint": "run-s --continue-on-error lint:**",
+    "test-once:app": "cd simplifier && npm run test-once",
+    "test-once": "run-s --continue-on-error test-once:**",
+    "test": "run-s test-once",
+    "start": "cd simplifier && npm run start",
+    "build:app": "cd simplifier && npm run build",
+    "build": "run-s build:**"
+  },
+  "devDependencies": {
+    "ghooks": "^2.0.4",
+    "npm-run-all": "^4.1.5"
+  },
+  "config": {
+    "ghooks": {
+      "pre-commit": "npm run lint"
+    }
+  }
+}

simplifier.code-workspace

+{
+	"folders": [
+		{
+			"path": "."
+		}
+	],
+	"settings": {
+		"files.eol": "LF",
+		"files.exclude": {
+			"**/node_modules": true
+		},
+		"files.trimFinalNewlines": true,
+		"files.trimTrailingWhitespace": true
+	}
+}

simplifier/.gitignore

+# dependencies
+/node_modules
+
+# testing
+/coverage
+
+# production
+/build
+
+# environments
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# misc
+*~
+.DS_Store

simplifier/package.json

+{
+  "name": "@unlsoft/simplifier",
+  "version": "1.0.0",
+  "description": "Starter code for the in-class demonstration of generators.",
+  "private": true,
+  "license": "UNLICENSED",
+  "scripts": {
+    "lint:css": "stylelint \"**/*.css\" \"**/*.module.css\" \"!coverage/**\"",
+    "lint:js": "eslint --max-warnings 0 ./src",
+    "lint": "run-s --continue-on-error lint:**",
+    "test-once": "react-scripts test --watchAll=false --coverage",
+    "test": "react-scripts test --watchAll --coverage",
+    "start": "react-scripts start",
+    "build": "react-scripts build",
+    "eject": "react-scripts eject"
+  },
+  "homepage": ".",
+  "dependencies": {
+    "@reduxjs/toolkit": "^1.6.0",
+    "@testing-library/jest-dom": "^5.14.1",
+    "@testing-library/react": "^12.0.0",
+    "@testing-library/user-event": "^13.1.9",
+    "classnames": "^2.3.1",
+    "npm-run-all": "^4.1.5",
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2",
+    "react-redux": "^7.2.4",
+    "react-router-dom": "^5.2.0",
+    "react-scripts": "^4.0.3",
+    "workbox-background-sync": "^5.1.3",
+    "workbox-broadcast-update": "^5.1.3",
+    "workbox-cacheable-response": "^5.1.3",
+    "workbox-core": "^5.1.3",
+    "workbox-expiration": "^5.1.3",
+    "workbox-google-analytics": "^5.1.3",
+    "workbox-navigation-preload": "^5.1.3",
+    "workbox-precaching": "^5.1.3",
+    "workbox-range-requests": "^5.1.3",
+    "workbox-routing": "^5.1.3",
+    "workbox-strategies": "^5.1.3",
+    "workbox-streams": "^5.1.3"
+  },
+  "devDependencies": {
+    "@unlsoft/eslint-config": "file:../eslint-config",
+    "@unlsoft/stylelint-config": "file:../stylelint-config",
+    "eslint-plugin-jest-dom": "^3.9.0",
+    "stylelint": "^13.13.1"
+  },
+  "stylelint": {
+    "extends": "@unlsoft/stylelint-config"
+  },
+  "eslintConfig": {
+    "extends": [
+      "react-app",
+      "@unlsoft/eslint-config/react"
+    ]
+  },
+  "jest": {
+    "clearMocks": true,
+    "collectCoverageFrom": [
+      "src/features/**/*.js"
+    ],
+    "resetMocks": false,
+    "restoreMocks": false
+  },
+  "browserslist": {
+    "production": [
+      ">0.2%",
+      "not dead",
+      "not op_mini all"
+    ],
+    "development": [
+      "last 1 chrome version",
+      "last 1 firefox version",
+      "last 1 safari version"
+    ]
+  }
+}

simplifier/public/index.html

+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
+    <meta
+      name="description"
+      content="Starter code for the lab on graph search."
+    />
+    <meta name="theme-color" content="rgba(208 0 0 / 100%)" />
+    <link rel="icon" href="%PUBLIC_URL%/logo.svg" />
+    <link rel="apple-touch-icon" href="%PUBLIC_URL%/logo.svg" />
+    <title>Boolean Expression Simplifier</title>
+  </head>
+  <body>
+    <noscript>You need to enable JavaScript to run this app.</noscript>
+    <div id="root"></div>
+  </body>
+</html>

simplifier/public/logo.svg

+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 152 152">
+  <rect x="0" y="0" width="152" height="152" fill="rgba(0 0 0 / 100%)" />
+  <path d="M147,1H90V42h10V75.673L53.532,2.393,52.648,1H2V42H12v66H2v41H62V108H52V74.336l46.467,73.271L99.351,149H150V108H140V42h10V1Z" stroke-width="3" stroke="rgba(255 255 255 / 100%)" fill="rgba(208 0 0 / 100%)">
+  </path>
+</svg>

simplifier/public/manifest.json

+{
+  "short_name": "Simplifier",
+  "name": "Boolean Expression Simplifier",
+  "description": "Starter code for the in-class demonstration of generators.",
+  "icons": [
+    {
+      "src": "logo.svg",
+      "type": "image/svg+xml",
+      "sizes": "192x192 512x512",
+      "purpose": "any maskable"
+    }
+  ],
+  "start_url": ".",
+  "display": "standalone",
+  "orientation": "portrait",
+  "theme_color": "rgba(208 0 0 / 100%)",
+  "background_color": "rgba(255 255 255 / 100%)"
+}

simplifier/src/app.js

+import { Route } from 'react-router-dom';
+
+import { Simplifier } from './features/expressions/simplifier.js';
+
+export function App() {
+  return (
+    <>
+      <Route exact path={'/'}>
+        <h1>Boolean Expression Simplifier</h1>
+        <Simplifier />
+        <hr />
+        <div>
+          Examples:
+          <ul>
+            <li><code>(x && y) !== (x || y)</code></li>
+            <li><code>(!x && !y) || (x && !y) || (x && y)</code></li>
+          </ul>
+        </div>
+      </Route>
+    </>
+  );
+}

simplifier/src/features/expressions/exampleEnvironment.js

+/* eslint-disable no-magic-numbers */
+
+import { Operator, Variable, Environment } from './expressions.js';
+
+export const EXAMPLE_ENVIRONMENT = new Environment(
+  [
+    new Variable('x'),
+    new Variable('y'),
+  ],
+  [
+    new Operator('false', 0, () => false, 20),
+    new Operator('true', 0, () => true, 20),
+  ],
+  [
+    new Operator('!', 1, (value) => !value, 16),
+  ],
+  [
+    new Operator('&&', 2, (left, right) => left && right, 6),
+    new Operator('||', 2, (left, right) => left || right, 5),
+    new Operator('===', 2, (left, right) => left === right, 10),
+    new Operator('!==', 2, (left, right) => left !== right, 10),
+  ],
+);

simplifier/src/features/expressions/expressions.js

+export class Operator {
+  constructor(symbol, arity, semantics, precedence) {
+    this.symbol = symbol;
+    this.arity = arity;
+    this.apply = semantics;
+    this.precedence = precedence;
+  }
+
+  toString() {
+    return this.symbol;
+  }
+}
+
+export class Variable {
+  constructor(name) {
+    this.name = name;
+  }
+
+  get precedence() {
+    return Infinity;
+  }
+
+  evaluate(assignments) {
+    return assignments.get(this.name);
+  }
+
+  toString() {
+    return this.name;
+  }
+}
+
+export class Environment {
+  constructor(variables, nullaryOperators, unaryOperators, binaryOperators) {
+    console.assert(nullaryOperators.every((operator) => operator.arity === 0));
+    console.assert(unaryOperators.every((operator) => operator.arity === 1));
+    console.assert(binaryOperators.every((operator) => operator.arity === 2));
+    this.variables = variables;
+    this.nullaryOperators = nullaryOperators;
+    this.unaryOperators = unaryOperators;
+    this.binaryOperators = binaryOperators;
+  }
+}
+
+export class Expression {
+  constructor(operator, operands) {
+    console.assert(
+      operator.arity === operands.length,
+      `Tried to apply the operator ${operator} to ${operands.length} operands.`,
+    );
+    this.operator = operator;
+    this.operands = operands;
+  }
+
+  get precedence() {
+    return this.operator.precedence;
+  }
+
+  evaluate(assignments) {
+    return this.operator.apply(...this.operands.map((operand) => operand.evaluate(assignments)));
+  }
+
+  toString() {
+    const operands = this.operands.map(
+      (operand) => operand.precedence <= this.precedence ? `(${operand})` : `${operand}`,
+    );
+    switch (this.operator.arity) {
+    case 0:
+      return `${this.operator.symbol}`;
+    case 1:
+      return `${this.operator.symbol}${operands[0]}`;
+    case 2:
+      return `${operands[0]} ${this.operator.symbol} ${operands[1]}`;
+    default:
+      console.assert(
+        false,
+        `Tried to format the unsupported operator arity ${this.operator.arity} for ${this.operator}.`,
+      );
+      return `${this.operator}(${operands.join(', ')})`;
+    }
+  }
+}

simplifier/src/features/expressions/simplification.js

+import { Expression } from './expressions.js';
+
+function booleanAssignments(variables) {
+  const results = [];
+  for (let bits = 1 << variables.length; bits--;) {
+    const assignments = new Map();
+    for (let index = variables.length; index--;) {
+      assignments.set(variables[index].name, ((bits >> index) & 1) !== 0);
+    }
+    results.push(assignments);
+  }
+  return results;
+}
+
+function matches(expression, semantics, variables) {
+  for (const assignments of booleanAssignments(variables)) {
+    if (expression.evaluate(assignments) !== semantics(assignments)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+function expressionsOfSize(environment, operatorCount) {
+  const results = [];
+  if (operatorCount === 0) {
+    for (const variable of environment.variables) {
+      results.push(variable);
+    }
+  } else {
+    for (const operator of environment.unaryOperators) {
+      for (const subexpression of expressionsOfSize(environment, operatorCount - 1)) {
+        results.push(new Expression(operator, [subexpression]));
+      }
+    }
+    for (let leftOperatorCount = 0; leftOperatorCount < operatorCount; ++leftOperatorCount) {
+      const rightOperatorCount = operatorCount - leftOperatorCount - 1;
+      for (const operator of environment.binaryOperators) {
+        for (const leftSubexpression of expressionsOfSize(environment, leftOperatorCount)) {
+          for (const rightSubexpression of expressionsOfSize(environment, rightOperatorCount)) {
+            results.push(new Expression(operator, [leftSubexpression, rightSubexpression]));
+          }
+        }
+      }
+    }
+  }
+  return results;
+}
+
+function expressionsUpToSize(environment, maximumOperatorCount) {
+  const results = [];
+  for (const operator of environment.nullaryOperators) {
+    results.push(new Expression(operator, []));
+  }
+  for (let operatorCount = 0; operatorCount <= maximumOperatorCount; ++operatorCount) {
+    results.push(...expressionsOfSize(environment, operatorCount));
+  }
+  return results;
+}
+
+export function simplify(semantics, environment, maximumOperatorCount) {
+  for (const expression of expressionsUpToSize(environment, maximumOperatorCount)) {
+    if (matches(expression, semantics, environment.variables)) {
+      return expression;
+    }
+  }
+  return undefined;
+}

simplifier/src/features/expressions/simplifier.js

+import { useState } from 'react';
+
+import { EXAMPLE_ENVIRONMENT } from './exampleEnvironment.js';
+import { simplify } from './simplification.js';
+
+const MAXIMUM_NUMBER_OF_OPERATORS = 4;
+const SYNTAX_ERROR = '[no simplification available; check the expression syntax]';
+const NO_SIMPLIFICATION = '[no simplification available; try allowing more operators]';
+
+export function Simplifier() {
+  const [expression, setExpression] = useState('');
+  const [operatorCount, setOperatorCount] = useState(1);
+  const onExpressionChange = (event) => setExpression(event.target.value);
+  const onOperatorCountChange = (event) => setOperatorCount(Number(event.target.value));
+
+  let simplification = SYNTAX_ERROR;
+  try {
+    // eslint-disable-next-line no-eval
+    const rawSemantics = eval(`(${EXAMPLE_ENVIRONMENT.variables.join(', ')}) => ${expression}`);
+    const semantics = (assignments) =>
+      rawSemantics(...EXAMPLE_ENVIRONMENT.variables.map((variable) => assignments.get(variable.name)));
+    simplification = simplify(semantics, EXAMPLE_ENVIRONMENT, operatorCount);
+  } catch (_) {} // eslint-disable-line no-empty
+  if (simplification === undefined) {
+    simplification = NO_SIMPLIFICATION;
+  }
+
+  return (
+    <section>
+      <div>
+        Boolean variables:<br />
+        <code>x</code> and <code>y</code>
+      </div>
+      <hr />
+      <div>
+        <label>Expression to simplify:<br />
+          <input
+            type={'text'}
+            autoComplete={'off'}
+            value={expression}
+            onChange={onExpressionChange} />
+        </label>
+      </div>
+      <hr />
+      <div>
+        <label>Maximum number of operators:<br />
+          <input
+            type={'number'}
+            autoComplete={'off'}
+            min={0}
+            max={MAXIMUM_NUMBER_OF_OPERATORS}
+            value={operatorCount}
+            onChange={onOperatorCountChange} />
+        </label>
+      </div>
+      <hr />
+      <div>
+        <label>Simplified:<br />
+          <code><output>{`${simplification}`}</output></code>
+        </label>
+      </div>
+    </section>
+  );
+}

simplifier/src/index.css

+:root {
+  /* Colors */
+  --letterbox-color: rgba(0 0 0 / 100%);
+  --app-background-color: rgba(239 239 239 / 100%);
+  --font-color: rgba(0 0 0 / 100%);
+
+  /* Sizes */
+  --minimum-app-size: 300px;
+}
+
+body {
+  margin: 0;
+  font-family: sans-serif;
+  text-align: center;
+  color: var(--font-color);
+}
+
+#root {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  background: var(--letterbox-color);
+}
+
+#portrait {
+  position: relative;
+  box-sizing: border-box;
+  margin: auto;
+  padding: 1em;
+  min-width: var(--minimum-app-size);
+  min-height: var(--minimum-app-size);
+  width: 100%;
+  height: 100%;
+  max-width: 62.5vh;
+  background: var(--app-background-color);
+  overflow-x: hidden;
+  overflow-y: scroll;
+  transform: scale(1);
+}