Added basic classes and fields

.vscodeignore

@@ -0,0 +1,5 @@
+.vscode/**
+.vscode-test/**
+docs/**
+.gitignore
+vsc-extension-quickstart.md

browser.js

@@ -33,7 +33,7 @@ exampleProgram.onchange = e => {
 }
 let defaultProgram = 0
 if (window.location.hash) {
-  defaultProgram = +(window.location.hash.replace(/[^\w\s]/gi, '').trim())
+  defaultProgram = +window.location.hash.replace(/[^\w\s]/gi, '').trim()
 }
 code.value = examplePrograms[defaultProgram].program
 

cli.js

@@ -10,6 +10,11 @@ let options = {
   prompt: '>'
 }
 
+const printReturnValue = lastLine =>
+  JSON.stringify(
+    lastLine && typeof lastLine.toString === 'function' ? lastLine.toString() : lastLine
+  )
+
 const runPrompt = () => {
   const prompt = options.prompt + ' '
   process.stdout.write(prompt)
@@ -27,16 +32,16 @@ const runPrompt = () => {
     let code = line
     if (!line.endsWith(';') && !line.endsWith('}')) code += ';'
     // TODO: Support multi-line block statements
-    const lastLine = run(code, env, options.debug)
-    console.log(JSON.stringify(lastLine))
+    const lastLine = run(code, env, console.log, options.debug)
+    console.log(printReturnValue(lastLine))
     process.stdout.write(prompt)
   })
 }
 
 const runFile = filename => {
   try {
     const file = fs.readFileSync(filename, 'utf8')
-    run(file, undefined, options.debug)
+    run(file, undefined, undefined, options.debug)
   } catch (e) {
     console.error(`YALI could not read the file ${filename}`)
     console.error(e)

examples/classExample.lox

@@ -0,0 +1,24 @@
+class Lox {
+  breakfast() {
+    print "Toast";
+  }
+}
+
+fun hello () {
+  print "Would you like some breakfast?";
+}
+
+print Lox;
+
+print hello;
+var loxInstance = Lox();
+
+loxInstance.category = "Breakfast";
+print loxInstance.category;
+
+print Lox();
+
+// class Bagel {}
+// var bagel = Bagel();
+// print bagel; // Prints "Bagel instance".
+// print bagel.lox;

interpreter.js

@@ -5,6 +5,9 @@ const {
   Call,
   Literal,
   Logical,
+  Class,
+  Get,
+  Set,
   Var,
   Grouping,
   Return,
@@ -53,6 +56,51 @@ class LoxCallable {
     }
     return null
   }
+
+  toString() {
+    return `<${this.declaration.name.lexeme}()>`
+  }
+}
+
+class LoxClass extends LoxCallable {
+  constructor(name) {
+    super()
+    this.name = name
+  }
+
+  call() {
+    return new LoxInstance(this)
+  }
+
+  toString() {
+    return `<${this.name}>`
+  }
+}
+
+class LoxInstance {
+  constructor(klass) {
+    this.klass = klass
+    this.fields = new Map()
+  }
+
+  get (token) {
+    const name = token.lexeme
+    if (this.fields.has(name)) {
+      return this.fields.get(name)
+    }
+
+    throw runtimeError(`Undefined property ${name}`, token)
+    // return null
+  }
+
+  set (token, value) {
+    const name = token.lexeme
+    this.fields.set(name, value)
+  }
+
+  toString () {
+    return `<+${this.klass.name}>`
+  }
 }
 
 class Interpreter {
@@ -75,6 +123,9 @@ class Interpreter {
     if (expr instanceof Block) return this.visitBlock(expr)
     else if (expr instanceof LoxFunction) return this.visitFunction(expr)
     else if (expr instanceof Assignment) return this.visitAssignment(expr)
+    else if (expr instanceof Class) return this.visitClass(expr)
+    else if (expr instanceof Get) return this.visitGet(expr)
+    else if (expr instanceof Set) return this.visitSet(expr)
     else if (expr instanceof Logical) return this.visitLogical(expr)
     else if (expr instanceof Call) return this.visitCall(expr)
     else if (expr instanceof While) return this.visitWhile(expr)
@@ -146,6 +197,35 @@ class Interpreter {
     return null
   }
 
+  visitClass(stmt) {
+    // We set the name before initializing it so classes can self-reference
+    this.environment.set(stmt.name, null)
+    const klass = new LoxClass(stmt.name.lexeme)
+    // console.log(klass)
+    this.environment.assign(stmt.name, klass)
+    return null
+  }
+
+  visitGet(expr) {
+    const object = this.evaluate(expr.object)
+    if (object instanceof LoxInstance) {
+      return object.get(expr.name)
+    }
+
+    throw runtimeError('Only instances have properties', expr.name)
+  }
+
+  visitSet(expr) {
+    const object = this.evaluate(expr.object)
+    if (!(object instanceof LoxInstance)) {
+      throw runtimeError('Only instances have fields', expr.name)
+    }
+
+    var val = this.evaluate(expr.value)
+
+    return object.set(expr.name, val)
+  }
+
   visitBlock(expr) {
     this.interpretBlock(expr.statements, new Environment(this.environment))
     return null

parser.js

@@ -6,6 +6,9 @@ const {
   Call,
   Literal,
   While,
+  Class,
+  Get,
+  Set,
   Grouping,
   Return,
   LoxFunction,
@@ -21,6 +24,7 @@ const { parseError: ParseError } = require('./errors')
 const token = tokenizer.tokenEnum
 
 const FUNCTION_TYPE = 'function'
+const METHOD_TYPE = 'method'
 
 class Parser {
   constructor(tokens) {
@@ -43,15 +47,29 @@ class Parser {
 
   declaration() {
     if (this.match(token.FUN)) return this.fun(FUNCTION_TYPE)
+    if (this.match(token.CLASS)) return this.classDeclaration()
     if (this.match(token.VAR)) return this.varDeclaration()
 
     return this.statement()
   }
 
+  classDeclaration() {
+    const name = this.consume(token.IDENTIFIER, `Expected class name`)
+    this.consume(token.LEFT_BRACE, 'expected "{" before class body')
+
+    let methods = []
+    while (!this.check(token.RIGHT_BRACE)) {
+      methods.push(this.fun(METHOD_TYPE))
+    }
+
+    this.consume(token.RIGHT_BRACE, 'expected "}" after class body')
+    return new Class(name, methods)
+  }
+
   fun(type) {
     const name = this.consume(token.IDENTIFIER, `Expected ${type} name`)
 
-    const params = []
+    let params = []
     this.consume(token.LEFT_PAREN, `Expected paren after ${type} name`)
     if (!this.check(token.RIGHT_PAREN)) {
       do {
@@ -104,6 +122,8 @@ class Parser {
       if (expr instanceof Var) {
         const nameToken = expr.name
         return new Assignment(nameToken, value)
+      } else if (expr instanceof Get) {
+        return new Set(expr.object, expr.name, value)
       }
       throw ParseError('Expected Expression', equalToken)
     }
@@ -243,6 +263,9 @@ class Parser {
     while (true) {
       if (this.match(token.LEFT_PAREN)) {
         expr = this.finishCall(expr)
+      } else if (this.match(token.DOT)) {
+        const name = this.consume(token.IDENTIFIER, 'Expected property name after "."')
+        expr = new Get(expr, name)
       } else {
         break
       }
@@ -275,6 +298,8 @@ class Parser {
       return new Grouping(expr)
     }
 
+    console.log('primary')
+
     throw ParseError('Expected Expression', this.peek())
   }
 

types.js

@@ -27,6 +27,21 @@ class Var {
   }
 }
 
+class Get {
+  constructor(object, name) {
+    this.object = object
+    this.name = name
+  }
+}
+
+class Set {
+  constructor(object, name, value) {
+    this.object = object
+    this.name = name
+    this.value = value
+  }
+}
+
 class Grouping {
   constructor(expression) {
     this.expression = expression
@@ -73,11 +88,13 @@ class While {
 
 class Call {
   constructor(callee, paren, args) {
-    ;(this.callee = callee), (this.paren = paren)
+    this.callee = callee
+    this.paren = paren
     this.arguments = args
   }
 }
 
+// Runtime Classes
 class Callable {
   constructor(name, func) {
     this.lexeme = name
@@ -96,6 +113,13 @@ class Return {
   }
 }
 
+class Class {
+  constructor(name, methods) {
+    this.name = name
+    this.methods = methods
+  }
+}
+
 class LoxFunction {
   constructor(name, params, bodyStatements) {
     this.name = name
@@ -112,6 +136,9 @@ module.exports = {
   Call,
   Callable,
   While,
+  Class,
+  Get,
+  Set,
   Literal,
   Return,
   Logical,