Bridge Script

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Bridge Script

Paradigm	Imperative (procedural), structured
Designed by	Mikhail Botcharov
Developer	Mikhail Botcharov
First appeared	2019 (2019)
Typing discipline	Static, strongly typed, manifest, nominal
OS	Cross-platform
Filename extensions	.bridge
Website	http://www.bridgescript.com/
Influenced by
C language, JavaScript

Search Bridge Script on Amazon.

Bridge script is statically typed, platform independent programming language. It's syntactically similar to C language . Bridge script does not have any built-in APIs in the interpreter. It provides mechanism to invoke external functions by defining a bridge (Library type) to invoke. Bridge script syntax derived from C syntax with simplicity in mind and built-in memory management.

Syntax

Types relationship

All basic Bridge script types have one to one mapping to C types.

Bridge script	C	size (bytes)
bool	char	1
i8	char	1
ui8	unsigned char	1
i16	short int	2
ui16	unsigned short int	2
i32	long int	4
ui32	unsigned long int	4
i64	long long int	8
ui64	unsigned long long int	8
float	float	4
double	double	8

For constant integer values HEX and Binary formats are provided.

HEX prefixes: 0X, 0x:

i32 v0 = 0xABCD1234 v1 = 0Xaaaa1111;

HEX postfixes: H, h:

ui8 v0 = A1H v1 = abh;

Binary postfixes: B, b:

ui8 v0 = 001101B v1 = 101b;

Float and double formats are the same as in C:

double d0 = -.25e-3, d1 = 0.002E-22;
float f0 = 1.5, f1 = 1.0E+3;

There is one built-in type that does not have corresponding C type – string type:

string str = "This is a string";

Structure type

struct – this keyword is used to declare structure definition.

struct MyStruct {
    ui32 v0;
    struct _SubStruct {
        bool _v0;
        i64 _v1;
    } v1;
    _SubStruct v2;
} var0;
MyStruct var1;

Arrays

Arrays declarations (where Type is any Bridge script type except array):

array<Type> – declares array without size.

array<Type, dim> – declares array of size dim.

array<Type, dim0, dim1> – declares 2-dimensional array.

Array can be declared with any number of dimensions. Dimension of array can be an expression evaluated at run time, in this case only one-dimensional array is allowed. Expression based dimension allows dynamically allocate array at run-time.

function array<ui8>@ AllocateArray(ui32 size) {
    array<ui8, size> arr;
    return arr;
}
array<ui8> arr0 @= AllocateArray(10);
array<ui8> arr1 @= AllocateArray(20);

array<ui32, 10> arr;
array<ui32, 2, 2> arr2;
arr2[0, 0] = 0;
arr2[0, 1] = 1;
arr2[1, 0] = 2;
arr2[1, 1] = 3;
arr[1] = arr2[0, 1];

Dynamic dimension as an expression:

array<i16, 2 * foo(n)> arr;

string variable can be assigned to array variable of type i8 or ui8 and vice versa, array must be static with at least one dimension.

array<ui8, 5> arr0;
string str = "Test";
arr0 = str;
array<ui8, 4> arr1;
arr1[0] = 0x41;
arr1[1] = 0x42;
arr1[2] = 0x43;
str = arr1;

Functions

Function definition syntax:

function Type FooName([arguments if any]) { return value; }

Where Type is function return type, function can have any number of arguments and return statement is optional.

function ui32 GetSum(ui32 a0, ui32 a1) {
    return a0 + a1;
}

Function variable declaration:

function<GetSum> fn;
array<function<GetSum>, 4> fnArr;
function<GetSum> fn0 = fn;

Uninitialized function variable is set to function instance by default.

Any function can be called implicitly:

• when returned by a function call:
  function ui32 F0(ui32 a) { return a + 1; }
  function ui32 F1(ui32 a) { return a + 2; }
  function function<F0> F(ui32 a) { if (a == 0) return F0; else return F1; }
  F(0)(10);
  F(1)(10);
• when function is in array:
  array<function<F0>, 2> fn;
  fn[0] = F0;
  fn[1] = F1;
  fn[0](10);
  fn[1](10);

References

All variables in the script are references (also see Special operators), however, to pass by reference you must use reference operator.

function ui32@ GetSum(ui32@ a0, ui32@ a1) {
    return a0 + a1;
}

Passing a variable by double reference allows to overwrite it's reference.

function bool GetRef(ui32@@ a0) {
    ui32 _var = 100;
    a @= _var; // reference assignment operator
    return true;
}
ui32 var = 10;
GetRef(var); // this function call will overwrite var reference by reference to _var

Another way to pass a reference by reference is to declare an array of reference type of size 1 and pass it by reference.

struct ST {
    array<ui32@, 4>@ arr;
    ui64 v64;
};
array<ST@, 1> refSt;
refSt[0].v64 = 0x0000000087654321;
function ui32 GetRef(array<ST@, 1> @ref) {
    ST st;
    st.v64 = 0x1234567800000000;
    ui32 i = 0;
    for (; i < sizeof(st.arr) / sizeof(i); ++i) {
        st.arr[i] = (i + 1) * 10;
    }
    ref[0] @= st;
    return 0;
}
GetRef(refSt);

Bridge script function and C function relationship

Brdge script	C
Function definition: function i32@ Foo(i32 arg) {}	Function definition: long int* Foo(long int arg){ return NULL;}
Function variable declaration: function<Foo> fn;	Function variable declaration: typedef long int* (*Foo_Type)(long int); Foo_Type fn = Foo;
Function invocation: i32 var @= fn(10);	Function invocation: i32 *p = fn(10);

Library type (Bridge)

Library type allows dynamic linking with external library. If external function return type is void then use ui32 as return type for library function description. To describe library function arguments only types of arguments are allowed.

Either library name or library path is allowed.

lib ("kernel32.dll") {
    ui32 GetModuleHandleA(array<ui8>@); // HMODULE GetModuleHandleA(LPCSTR lpModuleName);
} kernel;
array<ui8> moduleName @= str2arr("user32.dll");
ui32 handle = kernel.GetModuleHandleA(moduleName);

Built-in functions

array<ui8>@ str2arr(string@) – this function converts script's string to array of bytes.

array<ui16>@ str2warr(string@) – this function converts script's string to array of words (as Unicode).

string@ arr2str(array<ui8>@) – this function converts array of bytes to string.

string@ warr2str(array<ui16>@) – this function converts array of words (as unicode) to string.

Operators

These operators have the same functionality as in C.

Arithmetic operators:

+, ++, +=, -, --, -=, *, *=, /, /=, %, %=, =

Logical operators:

||, &&, !

Bitwise operators:

&, |, ~, ^, ^=,>>, <<

Comparison operators:

==, !=, <, <=, >, >=

Special operators

@= – this is reference assignment operator.

ui32 v0 = 10;
ui32 v1 @= v0; // now both variables point to the same memory

@ – this operator is used to pass/return a variable to/from a function and to declare structure member variables.

function ui32@ Get(ui32 a0, ui32@a1, ui32@@ a2) {
    a2 @= a1;
    return a0;
}
struct A {
    ui32@ v32;
    i8@ v0, v1, v2;
};

lock() – this operator locks memory which variable is referenced to. This operator should be used when you are passing local variable to asynchronous C function and caller goes out of scope. For example calling CreateThread() and passing local data as a parameter to the thread releases local variable when caller goes out of scope, hence you need to lock it and then unlock it in the thread.

unlock() – this operator unlocks memory locked by lock().

function ui32 Callback(array<ui8>@ a) {
    return a[0];
}
struct MyData {
    ui32 v0;
    function<Callback> fn;
    array<ui8, 4> v1;
};
function ui32 ThreadFoo(MyData@ arg) {
    unlock(arg);
    return arg.fn(arg.v1);
}
struct SECURITY_ATTRIBUTES {
    ui32 nLength;
    ui32 lpSecurityDescriptor;
    bool bInheritHandle;
};
lib("kernel32.dll") {
    ui32 CreateThread(SECURITY_ATTRIBUTES@, ui32, function<ThreadFoo>, MyData@, ui32, ui32@);
    ui32 WaitForMultipleObjects(ui32, array<ui32>@, ui32, ui32);
    ui32 CloseHandle(ui32);
} kernel;
SECURITY_ATTRIBUTES sa;
MyData data;
ui32 threadId;
data.v1[0] = 10;
array<ui32, 1> handle;
handle[0] = kernel.CreateThread(sa, 0, ThreadFoo, lock(data), 0, threadId);
kernel.WaitForMultipleObjects(1, handle, true, -1);

kernel.CloseHandle(handle[0]);

sizeof() – this operator returns size of memory allocated for that variable, it's useful to get size of a struct and an array, if array is dynamic and allocated externally this operator will return 0.

cast<Type>() – this is typecast operator. This is very powerful operator and it breaks memory constrains once you typecast a variable static type paradigm is broken.

struct A {
    ui32 v0;
    ui32 v1;
} a;
a.v0 = 10;
a.v1 = 20;
ui64 v @= cast<ui64>(a);
array<ui8, 4> arr1dim;
array<ui8, 2, 2> arr2dim;
ui32 i = 0;
for(; i < 4; ++i) {
    arr1dim[i] = 1;
}
struct Typecasted {
    ui8 v0, v1, v2, v3;
} tc;
tc @= cast<Typecasted>(arr1dim); // now both variables points to the same memory
arr2dim = arr1dim; // copy by value

array<ui8> arrNodim @= arr1dim; // now arrNodim points to the same memory

Statements

if, else, for, while, break, continue, switch, case, return – these statements have the same meaning as in C.

include statement:

include "script_to_include.bridge";

include statement path is relative to the current script.

Bridge script references and C pointers relationship

Reference operator has the same meaning as a pointer in C, it's used to declare member variable of a structure or to pass a variable by reference to a function.

Bridge script	C
struct A {     i8@ v0, v1; }; struct B {     A@ v0; }; struct C {     array<i8@>@ v0; };	struct A {     char *v0, *v1; }; struct B {     A *v0; }; struct C {     char **v0; };

Run-time error handling

If a run-time error occurs an error object is thrown, to catch it use error statement – error(e){}

Error object data members:

name – name of the error, type is string.

line – line number where error occurred, type is ui32.

position – first character position of the symbol, type is ui32.

file – file path, type is string.

trace – stack trace, type is string (new line separated strings).

symbol – symbol name, type is string.

function i8 f0() {

    ui32 v0 = 100, v1 = 0;
    v0 = v0 / v1;
}
function i8 f1() {
    f0();
}
f1();
error (e) {
    string err = e.name;
    string trace = e.trace;

}

Bridge script examples

GitHub repositories

• Hello World!
• Threads
• Window

Visual debugger

Bridge script interpreter provides debugging facilities through debugging API. I created Bridge debugger for Microsoft Windows(c) platform. It exposes all standard debugging features using GUI. Bridge debugger has built-in interpreter and provides such features as:

• compile/decompile script
• edit script (this feature is limited to simple editing, it does not replace editing tool, but rather nice to have if you need to fix your code)
• file view/browser
• debugger actions: run, step over, step in, step out, pause and stop
• set/delete breakpoints
• breakpoints view
• function view/browser (available when script is running)
• global variables view (available when script is running)
• threads view (available when script is running)
• thread stack and variables view for each running thread (available when script is running)
• build and debug output views

Compiled Bridge script can be debugged without decompiling it.

See also

• C programming language
• C variable types and declarations
• Operators in C and C++
• C standard library
• List of C-family programming languages (C-influenced languages)

References

This article "Bridge Script" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Bridge Script. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.

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