gravlax - npm Package Compare versions

Comparing version 0.4.0 to 0.5.0

lib/ast-printer.js

@@ -1,16 +0,33 @@
-import { visitExpr } from "./ast.js";
+import {
+  visitExpr,
+  visitStmt
+} from "./ast.js";
 const astPrinter = {
+  assign: (stmt) => parenthesize("assign", stmt.name.lexeme, stmt.value),
   binary: (expr) => parenthesize(expr.operator.lexeme, expr.left, expr.right),
+  block: (block) => parenthesizeText(
+    "block",
+    ...block.statements.map((stmt) => visitStmt(stmt, astPrinter))
+  ),
+  expr: (stmt) => visitExpr(stmt.expression, astPrinter),
   grouping: (expr) => parenthesize("group", expr.expr),
   literal: (expr) => expr.value === null ? "nil" : String(expr.value),
-  unary: (expr) => parenthesize(expr.operator.lexeme, expr.right)
+  print: (stmt) => parenthesize("print", stmt.expression),
+  unary: (expr) => parenthesize(expr.operator.lexeme, expr.right),
+  "var-expr": (expr) => String(expr.name.literal),
+  "var-stmt": (stmt) => parenthesizeText(
+    "var",
+    String(stmt.name.literal),
+    ...stmt.initializer ? [visitExpr(stmt.initializer, astPrinter)] : []
+  )
 };
+function parenthesizeText(...parts) {
+  return "(" + parts.join(" ") + ")";
+}
 function parenthesize(name, ...exprs) {
-  const parts = ["(", name];
+  const parts = [name];
   for (const expr of exprs) {
-    parts.push(" ");
-    parts.push(visitExpr(expr, astPrinter));
+    parts.push(typeof expr == "string" ? expr : visitExpr(expr, astPrinter));
   }
-  parts.push(")");
-  return parts.join("");
+  return parenthesizeText(...parts);
 }
@@ -17,0 +34,0 @@ export {

lib/ast.js

 function visitExpr(expr, visitor) {
   return visitor[expr.kind](expr);
 }
+function visitStmt(stmt, visitor) {
+  return visitor[stmt.kind](stmt);
+}
 export {
-  visitExpr
+  visitExpr,
+  visitStmt
 };
 //# sourceMappingURL=ast.js.map

lib/interpreter.js

 import {
-  visitExpr
+  visitExpr,
+  visitStmt
 } from "./ast.js";
+import { Environment } from "./environment.js";
 import { runtimeError } from "./main.js";
 class Interpreter {
+  #environment = new Environment();
+  "var-expr"(expr) {
+    return this.#environment.get(expr.name);
+  }
+  "var-stmt"(stmt) {
+    let value = null;
+    if (stmt.initializer) {
+      value = this.evaluate(stmt.initializer);
+    }
+    this.#environment.define(stmt.name.lexeme, value);
+    return null;
+  }
+  assign(expr) {
+    const value = this.evaluate(expr.value);
+    this.#environment.assign(expr.name, value);
+    return value;
+  }
   binary(expr) {
@@ -56,12 +75,33 @@ const left = this.evaluate(expr.left);
   }
+  block(block) {
+    this.executeBlock(block.statements, new Environment(this.#environment));
+  }
   evaluate(expr) {
     return visitExpr(expr, this);
   }
+  execute(stmt) {
+    visitStmt(stmt, this);
+  }
+  executeBlock(stmts, environment) {
+    const prev = this.#environment;
+    try {
+      this.#environment = environment;
+      for (const stmt of stmts) {
+        this.execute(stmt);
+      }
+    } finally {
+      this.#environment = prev;
+    }
+  }
+  expr(stmt) {
+    this.evaluate(stmt.expression);
+  }
   grouping(expr) {
     return this.evaluate(expr.expr);
   }
-  interpret(expr) {
+  interpret(statements) {
     try {
-      const value = this.evaluate(expr);
-      console.log(stringify(value));
+      for (const statement of statements) {
+        this.execute(statement);
+      }
     } catch (e) {
@@ -76,2 +116,6 @@ if (e instanceof RuntimeError) {
   }
+  print(stmt) {
+    const value = this.evaluate(stmt.expression);
+    console.log(stringify(value));
+  }
   unary(expr) {
@@ -78,0 +122,0 @@ const right = this.evaluate(expr.right);

lib/main.js

@@ -6,5 +6,2 @@ import * as fs from "node:fs/promises";
 import { Scanner } from "./scanner.js";
-function add(a, b) {
-  return a + b;
-}
 async function runFile(interpreter, path) {
@@ -20,2 +17,6 @@ const contents = await fs.readFile(path, "utf-8");
 }
+function resetErrors() {
+  hadError = false;
+  hadRuntimeError = false;
+}
 async function runPrompt(interpreter) {
@@ -25,3 +26,3 @@ process.stdout.write("> ");
     run(interpreter, line);
-    hadError = false;
+    resetErrors();
     process.stdout.write("> ");
@@ -49,2 +50,3 @@ }
   console.error(`[line ${line}] Error${where}: ${message}`);
+  hadError = true;
 }
@@ -54,7 +56,7 @@ function run(interpreter, contents) {
   const tokens = scanner.scanTokens();
-  const expr = parse(tokens);
-  if (hadError || !expr) {
+  const statements = parse(tokens);
+  if (hadError || !statements) {
     return;
   }
-  interpreter.interpret(expr);
+  interpreter.interpret(statements);
 }
@@ -64,3 +66,3 @@ async function main() {
   if (args.length > 1) {
-    console.error("Usage:", args[1], "[script]");
+    console.error("Usage:", process.argv[1], "[script]");
     process.exit(64);
@@ -76,6 +78,6 @@ }
 export {
-  add,
   error,
   errorOnToken,
   main,
+  resetErrors,
   runFile,
@@ -82,0 +84,0 @@ runPrompt,

lib/parser.js

@@ -57,3 +57,68 @@ import { errorOnToken } from "./main.js";
   };
-  const expression = () => equality();
+  const declaration = () => {
+    try {
+      if (match("var")) {
+        return varDeclaration();
+      }
+      return statement();
+    } catch (e) {
+      if (e instanceof ParseError) {
+        synchronize();
+      } else {
+        throw e;
+      }
+    }
+  };
+  const varDeclaration = () => {
+    const name = consume("identifier", "Expect variable name.");
+    let initializer = null;
+    if (match("=")) {
+      initializer = expression();
+    }
+    consume(";", "Expect ';' after variable declaration.");
+    return { initializer, kind: "var-stmt", name };
+  };
+  const statement = () => {
+    if (match("print")) {
+      return printStatement();
+    } else if (match("{")) {
+      return { kind: "block", statements: block() };
+    }
+    return expressionStatement();
+  };
+  const expressionStatement = () => {
+    const expr = expression();
+    consume(";", "Expect ';' after expression.");
+    return { expression: expr, kind: "expr" };
+  };
+  const printStatement = () => {
+    const expr = expression();
+    consume(";", "Expect ';' after expression.");
+    return { expression: expr, kind: "print" };
+  };
+  const block = () => {
+    const statements = [];
+    while (!check("}") && !isAtEnd()) {
+      const d = declaration();
+      if (d) {
+        statements.push(d);
+      }
+    }
+    consume("}", "Expect '}' after block.");
+    return statements;
+  };
+  const expression = () => assignment();
+  const assignment = () => {
+    const expr = equality();
+    if (match("=")) {
+      const equals = previous();
+      const value = assignment();
+      if (expr.kind == "var-expr") {
+        const name = expr.name;
+        return { kind: "assign", name, value };
+      }
+      error(equals, "Invalid assignment target.");
+    }
+    return expr;
+  };
   const unary = () => {
@@ -80,2 +145,4 @@ if (match("!", "-")) {
       return { expr, kind: "grouping" };
+    } else if (match("identifier")) {
+      return { kind: "var-expr", name: previous() };
     }
@@ -100,3 +167,10 @@ throw error(peek(), "Expect expression.");
   try {
-    return expression();
+    const statements = [];
+    while (!isAtEnd()) {
+      const decl = declaration();
+      if (decl) {
+        statements.push(decl);
+      }
+    }
+    return statements;
   } catch (e) {
@@ -103,0 +177,0 @@ if (e instanceof ParseError) {

package.json

 {
 	"name": "gravlax",
-	"version": "0.4.0",
+	"version": "0.5.0",
 	"description": "A Lox interpreter with tasty TypeScript seasoning",
@@ -31,2 +31,3 @@ "repository": {
 		"lint:spelling": "cspell \"**\" \".github/**/*\"",
+		"pre-push": "pnpm run '/^lint(?!:packages).*$/'",
 		"prepare": "husky install",
@@ -33,0 +34,0 @@ "repl": "pnpm run:ts src/index.ts",

README.md

@@ -18,12 +18,17 @@ <h1 align="center">Gravlax</h1>
 
+This is my implementation of an interpreter for the Lox language from Robert Nystrom's _[Crafting Interpreters]_.
+I'm building this as part of my Winter 2024 batch at the [Recurse Center].
+
 ## Usage
 
 ```shell
-npm i gravlax
+npx gravlax [file.lox]
 ```
 
-```ts
-import { greet } from "gravlax";
+## Development
 
-greet("Hello, world! 💖");
+```shell
+pnpm install
+pnpm test
+pnpm repl
 ```
@@ -55,1 +60,4 @@
 > 💙 This package was templated with [`create-typescript-app`](https://github.com/JoshuaKGoldberg/create-typescript-app).
+
+[Crafting Interpreters]: https://craftinginterpreters.com/contents.html
+[Recurse Center]: https://www.recurse.com/

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Improved metrics

Total package byte prevSize

65367

increased by26.06%

Lines of code

719

increased by13.59%

Number of lines in readme file

62

increased by14.81%

Worsened metrics

Number of package files

25

decreased by-16.67%

No dependency changes