https://github.com/pawel-parma/lox-java

Lox implementation "following" the book: Crafting Interpreters
https://github.com/pawel-parma/lox-java

crafting-interpreters craftinginterpreters jlox lox lox-interpreter lox-language lox-programming-language

Last synced: 3 months ago
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Lox implementation "following" the book: Crafting Interpreters

• Host: GitHub
• URL: https://github.com/pawel-parma/lox-java
• Owner: Pawel-Parma
• License: mit
• Created: 2024-05-21T16:12:53.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2024-06-16T19:29:01.000Z (about 1 year ago)
• Last Synced: 2025-02-05T13:51:23.566Z (5 months ago)
• Topics: crafting-interpreters, craftinginterpreters, jlox, lox, lox-interpreter, lox-language, lox-programming-language
• Language: Java
• Homepage:
• Size: 123 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Jlox

Lox interpreter written in Java following the book [Crafting Interpreters](http://www.craftinginterpreters.com/).

## Branches:

- ### [*main*](https://github.com/Pawel-Parma/lox-java)

If you are in the main branch you are looking at the implementation derived from the book.  

It has some solved challenges and my own modifications.

 Changes:

  


   


    const - declaration for immutable data. Examples:

    


    // Values

    const x = 1;

    x = 2; // Error at 'x': Cannot reassign a constant.

    

    // Classes

    class A {

        init(b) { this.b = 1; }

    }

    const a = A(1);

    a.b = 2; // Error at 'b': Cannot modify a field of a constant object.

    

    // But this is allowed:

    var a_mut = a;

    a.b = 2; // No error

   

  


  


   


    break - statement for breaking out of loops. Example:

    

    for (var i = 0; i < 10; i = i + 1) {

        if (i == 5) break;

        print i;

    }


    Output:

    // 0

    // 1

    // 2

    // 3

    // 4

   

  


  


   


    continue - statement for skipping the rest of the loop body. Example: 

    

    for (var i = 0; i < 10; i = i + 1) {

        if (i % 2 == 0) continue;

        print i;

    }


    Output:

    // 1

    // 3

    // 5

    // 7

    // 9

   

  


  


   


    Escape sequences in strings - [ \n, \r, \t, \b, \', \", \\ ]. Note " ' " still works, no need for " \' ".

    Examples:    

    

    // New line

    print "Hello\nWorld"; // Hello

                          // World

                          // 

    

    // Tab

    print "Hello\tWorld"; // World  World


    // Backspace

    print "Hello\b World"; // Hell World

   

  


  


   


    String and number concatenation using the '+' operator.


    // string + number

    print "123" + 4; // 1234 (string)

    // number + string

    print 4 + "123"; // 4123 (string)

   

  


  


   


    def keyword before method declaration is now required.


    // Before

    class A {

        init() { print "A"; }

    }

    // Now

    class A {

        def init() { print "A"; }

    }

   

  


  


   


    lambda expressions - anonymous functions. Examples:


    // Single line

    const add = lambda(a, b) { return a + b; };

    print add(1, 2); // 3

    // Multi line

    const add = lambda(a, b) {

        var c = a + b;

        return c;

    };

    print add(3, 2); // 3

   

  


  


   


    imports - importing other files. Examples:


    // file1.lox

    import "file2";  // Hello from file2

    import "file3" as math;    

    fun foo() {

        print "Hello from foo of file1";

    }

    

    foo();  // Hello from foo of file1

    file2.foo();  // Hello from foo of file2

    print math.pow(2, -math.PI);  // 0.0625

    // file2.lox

    fun foo() {

        print "Hello from foo of file2";

    }

    print "Hello from file2";

    // file3.lox

    fun pow(val, exp) {

        if (exp < 0) {

            return 1 / pow(val, -exp);

        }

        var result = 1;

        for (var i = 0; i < exp; i = i + 1) {

            result = result * val;

        }

        return result;

    }

    const PI = 3.14;

   

  


  


   


    modulo operator. Examples:


    print 4 % 2; // 0

    print 5 % 2; // 1

   

  


- ### [*jlox*](https://github.com/Pawel-Parma/lox-java/tree/jlox)

If you are in the jlox branch you are looking at the implementation following the book.