PointerScript

Scripting language with pointers and native library access. PointerScript feels like C but has awesome features like operator overloading, dynamic typing and even though you have direct low level access your code is more safe thanks to boundary checks. Additionally finding errors is less painful as you get a full backtrace when a runtime error occurs or you receive e.g. a segmentation fault.

Language

Documentation

Most of PointerScript is similar to Javascript and/or C. For a full Documentation see LanguageDoc.md

Standard Library

PointerScript has no standard-library. You can use all C libraries using the built-in ffi (Import statement). There are a couple of easy-to-use libraries (sockets, regexp, http, json, lists, maps etc.) in this repository

Testing

You can run tests for the interpreter by executing the runTests.sh script in the repository.

Introduction

The following is a small code sample, annotated with comments to explain what is happening.

//using the import statement you can import any function from the C standard library
import puts, qsort;

//this defines an array of 4 signed 32-bit integers.
//Using var nums: var[4]; we could create an array of dynamically typed variables instead.
var nums: i32[4] = [1337, 666, 3112, 42];

//here we use the standard C function qsort to sort the array
//the last argument to qsort is a function pointer, here we use a lambda expression
qsort(nums, sizeof nums, sizeof i32, (a: i32*, b: i32*) -> *a - *b);

//using the foreach loop on arrays is similar to a for loop from 0 to sizeof nums
foreach(i, val in nums)
{
	// the language as built-in string formatting
	puts("nums[$i] = $val");
}

JIT Compilation

There are three main steps involved when running PointerScript code:

• parsing the source code (handeled by the built-in recusive descent parser)
• predicting types of expressions
• converting the code to GNU libjit IR
• converting the IR to machine code (handled by my fork of libjit)

The following shows the process of these steps inspecting the lambda function from the above code example.

Predicting types

Using the --dump-predictions flag to view predictions made by PointerScript:

(a: i32*, b: i32*) -> *a - *b
                      ││ │ │└─> meta: i32[1] ast: identifier
                      ││ │ └──> meta: int ast: prefix_dereference
                      ││ └────> type: int ast: op_sub
                      │└──────> meta: i32[1] ast: identifier
                      └───────> meta: int ast: prefix_dereference

libjit IR

Using the --dump-jit flag to dump libjit IR of the lambda expresssion:

function (lambda expression)([l1 : parent_frame], l2 : ptr, l3 : long, l4 : ulong, l5 : long, l6 : ulong) : struct<16>
[...]
	i18 = load_relative_int(l3, 0)
	l19 = expand_int(i18)
	i22 = load_relative_int(l5, 0)
	l23 = expand_int(i22)
	l26 = l19 - l23
	return_struct_from_regs(l26, 1)
[...]
end

x64 machine code

Using the --dump-asm flag to dump assembly of the lambda expresssion:

function (lambda expression)(ptr, long, ulong, long, ulong) : struct<16>
    7fb7e050a260:	8b 12                	mov    (%rdx),%edx
    7fb7e050a262:	48 63 c2             	movslq %edx,%rax
    7fb7e050a265:	45 8b 00             	mov    (%r8),%r8d
    7fb7e050a268:	4d 63 c0             	movslq %r8d,%r8
    7fb7e050a26b:	49 2b c0             	sub    %r8,%rax
    7fb7e050a26e:	ba 01 00 00 00       	mov    $0x1,%edx
    7fb7e050a273:	c3                   	retq

More example code

There are examples including the usage of Types, Structs, Arrays, Threading and many more in the examples directory of this repository. The most interresting ones are listed here:

• pi and circle Basic mathematic expressions and loops
• fork Using posix functions for creating child processes
• array and bubblesort Basic array usage
• struct Basic struct usage
• threads Using libpthread
• gtk Using GTK for creating a window with a clickable button.
• window Using libSDL for creating X windows. (Example orginally by @Webfreak001)

Installing

Pointerscript uses libjit which is included in the repository as a submodule.

#Install dependencies (this might differ if you are not using debian)
# everything below apart from git and build-essential is required by libjit
sudo apt install git build-essential bison flex autoconf automake libtool texinfo

#Recursively clone the repository
git clone --recursive https://github.com/M4GNV5/PointerScript

#Compile...
cd PointerScript
make -j4 #-j specifies the number of tasks to run in parallel

#Done! PointerScript is at ./bin/ptrs
bin/ptrs --help

License

EUPL v1.2

Copyright (C) 2020 Jakob Löw (jakob@löw.com)

Licensed under the EUPL, Version 1.2 or - as soon they will be approved by the European Commission - subsequent versions of the EUPL (the "Licence"); You may not use this work except in compliance with the Licence.

You may obtain a copy of the Licence at: http://ec.europa.eu/idabc/eupl.html

Unless required by applicable law or agreed to in writing, software distributed under the Licence is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the Licence for the specific language governing permissions and limitations under the Licence.