gscript

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Introduction

This is a statically and strongly typed language written in Go, the syntax of Java and Go is referenced.

Target

Provides the ability to write Go language in script form, retains the advantages of Go language (goroutine, etc.), and adds more syntactic sugar for ease of use.

The current Alpha version is for study and experimentation only.

hello_world.gs:

println("hello world");

❯ gscript hello_world.gs
hello world

Playground

Online address: https://gscript.crossoverjie.top/

Source code:https://github.com/crossoverJie/gscript-homepage

Features

• Class declaration
• Function declaration and call
• Primitive type: int/string/float/bool/byte
• Array type
• nil type
• any type
• Function type
• Closure：Functions as First-Class Objects
• Native function
• Standard library
  • Map
• Variable arguments
• Operator overloading
• Native support json
• Native support http
• Example
  • LeetCode
    • LeetCode: Linked list cycle
    • LeetCode: Two sum
  • Print fibonacci
  • Print YangHui triangle
  • HTTP Service
• PKG manager
• Unit Test command line

Demo

Hello world

println("hello world");

Print fibonacci

func int() fib(){
    int a = 0;
    int b = 1;
    int fibonacci(){
        int c = a;
        a = b;
        b = a+c;
        return c;
    }
    return fibonacci;
}

func int() f = fib();

for (int i = 0; i < 10; i++){
    println(f());
}

Webapp

This is a dynamic web application written in GScript.

https://gscript.crossoverjie.top/api/index

Source code： https://github.com/crossoverjie/gscript-homepage

YangHui triangle

int num(int x,int y){
	if (y==1 || y ==x) {
		return 1;
	}
    int v1 = num(x - 1, y - 1);
    int v2 = num(x - 1, y);
	int c = v1+v2;
    // int c = num(x - 1, y - 1)+num(x - 1, y);
	return c;
}

printTriangle(int row){
	for (int i = 1; i <= row; i++) {
        for (int j = 1; j <= row - i; j++) {
           print(" ");
        }
        for (int j = 1; j <= i; j++) {
            print(num(i, j) + " ");
        }
        println("");
    }
}

printTriangle(7);

// output:
      1 
     1 1 
    1 2 1 
   1 3 3 1 
  1 4 6 4 1 
 1 5 10 10 5 1 
1 6 15 20 15 6 1

More examples:https://github.com/crossoverJie/gscript/tree/main/example

Install

Binary

Download the latest binaries here

🐳Docker

docker pull crossoverjie/gscript

REPL

docker run --rm -it  crossoverjie/gscript:latest gscript

Run script

docker run --rm -v $PWD:/usr/src/gscript -w /usr/src/gscript crossoverjie/gscript gscript {yourpath}/temp.gs

Build from Source Code

git clone https://github.com/crossoverJie/gscript.git
cd gscript
make build-code
./gscript

REPL

> ./gscript 

Syntax

Primitive

The current version supports four primitive type: int/string/float/bool and nil type.

Variable declaration syntax: type identifier (= expr)?.

int a=10;
string b,c;
float e = 10.1;
bool f = false;
byte by = 1;
string x = ^
{
    "name": "bob",
    "age": 20,
    "skill": {
        "lang": [
            {
                "go": {
                    "feature": [
                        "goroutine",
                        true
                    ]
                }
            }
        ]
    }
}^

Array

Array declaration syntax: ('[' DECIMAL_LITERAL ']')? '{' (variableInitializer (',' variableInitializer)* (',')? )? '}'

// Declare and initialize
int[] a={1,2,3};
println(a);

// Declare an empty array and specify the length
int[] table = [4]{};

println("");
// Append data to array.
append(a,4);
println(a);
for(int i=0;i<len(a);i++){
	println(a[i]);
}

// Access to data by index.
int b=a[2];
println(b);

// byte array
string s = "10";
byte[] a= toByteArray(s);
printf("a=%v ",a);
string s1 = toString(a);
printf("s1=%s",s1);
assertEqual(s1,s);

// slice an array into a new array.
int[] a = {1,2,3};
int s=1;
int[] b = a[s:len(a)];
println(b);
// output: [2 3]

any type

An any type may hold values of all type.

any a =10;
println(a);

int fun1(any a,int b){
	return a+b;
}
int v =fun1(1,2);
println(v);
assertEqual(v,3);

any v2 = fun1(1,2);
println(v2);
assertEqual(v2,3);

int fun2(int a, any b){
	return a+b;
}
int v3 =fun2(1,2);
println(v3);
assertEqual(v3,3);

int fun3(any a, any b){
	return a+b;
}
int v4 =fun3(1,2);
println(v4);
assertEqual(v4,3);

int fun4(any a, any b){
	return a+b;
}
string v5 =fun4("10", "20");
println(v5);
assertEqual(v5,"1020");

Example: Standard library

Class

class ListNode{
    int value;
    ListNode next;
    ListNode(int v, ListNode n){
        value =v;
        next = n;
    }
}

// The new keyword is not required to call the constructor.
ListNode l1 = ListNode(1, nil);

// Using . to access object property or method.
println(l1.value);

The default comes with a parameterless constructor

class Person{
	int age=10;
	string name="abc";
	int getAge(){
		return 100+age;
	}
}

// parameterless constructor
Person xx= Person();
println(xx.age);
assertEqual(xx.age, 10);
println(xx.getAge());
assertEqual(xx.getAge(), 110);

function

// cycle linked list
bool hasCycle(ListNode head){
    if (head == nil){
        return false;
    }
    if (head.next == nil){
        return false;
    }

    ListNode fast = head.next;
    ListNode slow = head;
    bool ret = false;
    for (fast.next != nil){
        if (fast.next == nil){
            return false;
        }
        if (fast.next.next == nil){
            return false;
        }
        if (slow.next == nil){
            return false;
        }
        if (fast == slow){
            ret = true;
            return true;
        }

        fast = fast.next.next;
        slow = slow.next;
    }
    return ret;
}

ListNode l1 = ListNode(1, nil);
bool b1 =hasCycle(l1);
println(b1);
assertEqual(b1, false);

ListNode l4 = ListNode(4, nil);
ListNode l3 = ListNode(3, l4);
ListNode l2 = ListNode(2, l3);
bool b2 = hasCycle(l2);
println(b2);
assertEqual(b2, false);

l4.next = l2;
bool b3 = hasCycle(l2);
println(b3);
assertEqual(b3, true);

Function declaration syntax: typeTypeOrVoid? IDENTIFIER formalParameters ('[' ']')*

add(int a){}

When there is no return value, the return type can also be ignored.

Closure

Function type syntax: func typeTypeOrVoid '(' typeList? ')'

// External variable, global shared.
int varExternal =10;
func int(int) f1(){
	// Closure variable.
	int varInner = 20;
	int innerFun(int a){
		println(a);
		int c=100;
		varExternal++;
		varInner++;
		return varInner;
	}
	return innerFun;
}

// f2 is a function type, the return type and parameter are both int.
func int(int) f2 = f1();
for(int i=0;i<2;i++){
	println("varInner=" + f2(i) + ", varExternal=" + varExternal);
}
println("=======");
func int(int) f3 = f1();
for(int i=0;i<2;i++){
	println("varInner=" + f3(i) + ", varExternal=" + varExternal);
}

Output:

0
varInner=21, varExternal=11
1
varInner=22, varExternal=12
=======
0
varInner=21, varExternal=13
1
varInner=22, varExternal=14

Variable arguments

GScript also support variable arguments：

int add(string s, int ...num){
	println(s);
	int sum = 0;
	for(int i=0;i<len(num);i++){
		int v = num[i];
		sum = sum+v;
	}
	return sum;
}
int x = add("abc", 1,2,3,4);
println(x);
assertEqual(x, 10);

Operator overloading

Operator that Gscript support:

• +-*/
• == != < <= > >=

Overloading function must be operator, and append operator.

class Person{
	int age;
	Person(int a){
		age = a;
	}
}
Person operator + (Person p1, Person p2){
	Person pp = Person(p1.age+p2.age);
	return pp;
}
Person operator - (Person p1, Person p2){
	Person pp = Person(p1.age-p2.age);
	return pp;
}
Person operator * (Person p1, Person p2){
	Person pp = Person(p1.age * p2.age);
	return pp;
}
Person operator / (Person p1, Person p2){
	Person pp = Person(p1.age / p2.age);
	return pp;
}
bool operator == (Person p1, Person p2){
	return p1.age==p2.age;
}
bool operator != (Person p1, Person p2){
	return p1.age!=p2.age;
}
bool operator > (Person p1, Person p2){
	return p1.age>p2.age;
}
bool operator >= (Person p1, Person p2){
	return p1.age>=p2.age;
}
bool operator < (Person p1, Person p2){
	return p1.age<p2.age;
}
bool operator <= (Person p1, Person p2){
	return p1.age<=p2.age;
}
Person p1 = Person(10);
Person p2 = Person(20);
//Person p3 =  operator(p1,p2);
Person p3 = p1+p2;
println("p3.age="+p3.age);
assertEqual(p3.age, 30);

Person p4 = p1-p2;
println("p4.age="+p4.age);
println(100-10);

Person p5 = p1*p2;
println("p5.age="+p5.age);
assertEqual(p5.age, 200);

Person p6 = p2/p1;
println("p6.age="+p6.age);
assertEqual(p6.age, 2);

bool b1 = p1 == p2;
println("b1=="+b1);
assertEqual(b1,false);

bool b2 = p1 != p2;
println("b2=="+b2);
assertEqual(b2,true);

bool b3 = p1 > p2;
println("b3=="+b3);
assertEqual(b3,false);

bool b4 = p1 >= p2;
println("b4=="+b4);
assertEqual(b4,false);

bool b5 = p1 < p2;
println("b5=="+b5);
assertEqual(b5,true);

bool b6 = p1 <= p2;
println("b6=="+b6);
assertEqual(b6,true);

More examples: https://github.com/crossoverJie/gscript/tree/main/example

Standard library

Standard library source code: https://github.com/crossoverJie/gscript/tree/main/internal

Native function

printf("hello %s ","123");
printf("hello-%s-%s ","123","abc");
printf("hello-%s-%d ","123",123);

string s = sprintf("nice to meet %s", "you");
println(s);
assertEqual(s,"nice to meet you");

int[] a={1,2,3};
// len return array length.
println(len(a));

// Append data to array.
append(a,4);
println(a);
// output: [1,2,3,4]

// Assert function
assertEqual(len(a),4);

// Return hashcode
int hashcode = hash(key);


// Serialize to JSON string.
class P{
	string name;
	P(string n){
		name = n;
	}
}
class Object{
	P p;
	int x;
	Object(P pp, int xx){
		p = pp;
		x = xx;
	}
}
P p1 = P("abc");
Object o1 = Object(p1, 100);
string json = JSON(o1);
println(json); //{"p":{"name":"abc"},"x":100}

// Query json with path
int x = JSONGet(json,"x");
println(x);
assertEqual(x,100);

string name = JSONGet(json,"p.name");
println(name);
assertEqual(name,"abc");

// Get command-line arguments.
System s = System();
string[] args = s.getOSArgs();

Reference JSON query syntax: xjson

Map

Function Definition

class Map{
	put(any key, any value){}
	any get(any key){}
}

Usage

int count =100;
Map m1 = Map();
for (int i=0;i<count;i++){
	string key = i+"";
	string value = key;
	m1.put(key,value);
}
println(m1.getSize());
assertEqual(m1.getSize(),count);

for (int i=0;i<count;i++){
	string key = i+"";
	string value = m1.get(key);
	println("key="+key+ ":"+ value);
	assertEqual(key,value);
}

StringBuilder

Function Definition

class StringBuilder{
	byte[] buf = [0]{};

	// append contents to buf, it returns the length of s
	int writeString(string s){}

	// append b to buf, it returns the length of b.
	int WriteBytes(byte[] b){}

	// copies the buffer to a new.
	grow(int n){}

	string String(){}
}

Usage

StringBuilder b = StringBuilder();
b.writeString("10");
b.writeString("20");
int l = b.writeString("30");
string s = b.String();
printf("s:%s, len=%d ",s,l);
assertEqual(s,"102030");
byte[] b2 = toByteArray("40");
b.WriteBytes(b2);
s = b.String();
assertEqual(s,"10203040");
println(s);

Strings

Function Definition

class Strings{
	// concatenates the elements of its first argument to create a single string. The separator
	// string sep is placed between elements in the resulting string.
	string join(string[] elems, string sep){}

	// tests whether the string s begins with prefix.
	bool hasPrefix(string s, string prefix){}
}

Usage

Strings s = Strings();
string[] elems = {"name=xxx","age=xx"};
string ret = s.join(elems, "&");
println(ret);
assertEqual(ret, "name=xxx&age=xx");

bool b = s.hasPrefix("http://www.xx.com", "http");
println(b);
assertEqual(b,true);
b = s.hasPrefix("http://www.xx.com", "https");
println(b);
assertEqual(b,false);

http

Standard library:

// http lib
// Response json
FprintfJSON(int code, string path, string json){}
// Resonse html
FprintfHTML(int code, string path, string html){}

// path (relative paths may omit leading slash)
string QueryPath(string path){}

string FormValue(string path, string key){}
class HttpContext{
    string path;
    JSON(int code, any v){
        string json = JSON(v);
        FprintfJSON(code, path, json);
    }
    HTML(int code, any v) {
        string html = v;
        FprintfHTML(code, path, html);
    }
    string queryPath() {
        string p = QueryPath(path);
        return p;
    }

    string formValue(string key){
        string v = FormValue(path, key);
        return v;
    }
}
// Bind route
httpHandle(string method, string path, func (HttpContext) handle){
    // println("path="+path);
    HttpContext ctx = HttpContext();
    handle(ctx);
}
// Run http server.
httpRun(string addr){}

Start http service:

class Person{
    string name;
}
func (HttpContext) handle (HttpContext ctx){
    Person p = Person();
    p.name = "abc";
    println("p.name=" + p.name);
    println("ctx=" + ctx);
    ctx.JSON(200, p);
}

func (HttpContext) handle1 (HttpContext ctx){
    Person p = Person();
    p.name = "def";
    println("p.name=" + p.name);
    println("ctx=" + ctx);
    ctx.JSON(200, p);
}
func (HttpContext) handle2 (HttpContext ctx){
    DateTime d = DateTime();
    string local = d.getCurrentTime("Asia/Shanghai","2006-01-02 15:04:05");
    println(local);
    string html =^
    <html>
    <title>hello</title>
    <h1>current ^+ local +^</h1>
    <p>hahaha</p>
    </html>
    ^;
    string queryPath = ctx.queryPath();
    println("queryPath = " + queryPath);

    // http://127.0.0.1:8000/p/2?id=100
    string id = ctx.formValue("id");
    println("id="+id);
    ctx.HTML(200, html);
}
httpHandle("get", "/p", handle);
httpHandle("get", "/p/1", handle1);
httpHandle("get", "/p/2", handle2);
httpRun(":8000");

Contact author

crossoverJie#gmail.com