LKscript - simple scripting everywhere.
About
LK is a simple but powerful scripting language that is designed to be small, fast, and easily embedded in other applications. It enables people to extend the built-in functionality of their programs, and provides a cross-platform standard library of function calls. The core LK engine, including lexical analyzer, parser, compiler, and virtual machine comprises roughly 6600 lines of ISO-standard C++ code, and is only dependent on the Standard C++ Library (STL), making it extremely lightweight and portable.
Features
- Dynamically typed, functions are first-class values
- Support for arrays and tables (hashes)
- Large standard library of built-in functions
- API for extensions loadable at runtime
- Stack-based virtual machine with debugging hooks
- Written in standard C++11 and works on 32/64 bit Windows, Linux, OSX
- Embeds readily into GUI applications written in wxWidgets
Example
The standard one:
Of course, more examples can be found in the manual.
Documentation
View the manual here.
Download
Check out the latest source code from: https://svn.lkscript.org/lk/trunk
Download a precompiled binary distribution: Windows 64 bit (19.6 MB) - November 13, 2019 or OSX 10.14 (13.4 MB) - May 17, 2019
C++ API
An example of calling the LK language engine from a C++ command-line program:
#include <stdlib.h>
#include <string.h>
#include <memory>
#include <lk/absyn.h>
#include <lk/env.h>
#include <lk/eval.h>
#include <lk/parse.h>
#include <lk/lex.h>
#include <lk/stdlib.h>
#include <lk/invoke.h>
#include <lk/codegen.h>
#include <lk/vm.h>
void fcall_out( lk::invoke_t &cxt )
{
LK_DOC("out", "Output data to the console.", "(...):none");
for (size_t i=0;i<cxt.arg_count();i++)
fputs( lk::to_utf8(cxt.arg(i).as_string()).c_str(), stdout );
}
void fcall_outln( lk::invoke_t &cxt )
{
LK_DOC("outln", "Output data to the console followed by a newline.", "(...):none");
for (size_t i=0;i<cxt.arg_count();i++)
fputs( lk::to_utf8(cxt.arg(i).as_string()).c_str(), stdout );
fputs( "\n", stdout );
fflush( stdout );
}
void fcall_in( lk::invoke_t &cxt )
{
#define NBUF 2048
LK_DOC("in", "Input text from the user.", "(none):string");
char buf[NBUF];
fgets( buf, NBUF-1, stdin );
cxt.result().assign( lk::from_utf8( buf ) );
}
int main(int argc, char *argv[])
{
bool parse_only = false;
bool use_vm = true;
if ( argc <= 1 )
{
printf("no input file specified\n");
return -1;
}
if ( argc > 2 )
{
if( strcmp( argv[2], "--parse" ) == 0 ) parse_only = true;
if( strcmp( argv[2], "--eval" ) == 0 ) use_vm = false;
}
lk::input_file p( argv[1] );
lk::parser parse( p );
std::auto_ptr<lk::node_t> tree( parse.script() );
int i=0;
while ( i < parse.error_count() )
printf( "%s\n", parse.error(i++).c_str() );
if ( tree.get() == NULL || parse.token() != lk::lexer::END)
printf("parsing did not reach end of input\n");
if ( tree.get() == NULL || parse.error_count() > 0 || parse.token() != lk::lexer::END )
return -1;
if ( parse_only ) return 0;
lk::env_t env;
env.register_func( fcall_in );
env.register_func( fcall_out );
env.register_func( fcall_outln );
env.register_funcs( lk::stdlib_basic() );
env.register_funcs( lk::stdlib_string() );
env.register_funcs( lk::stdlib_math() );
if ( use_vm )
{
lk::code_gen C;
if ( C.emitasm( tree.get() ) )
{
std::vector<unsigned int> code;
std::vector<lk::vardata_t> data;
std::vector<lk_string> id;
std::vector<lk::srcpos_t> dbg;
C.bytecode( code, data, id, dbg );
lk::vm V;
V.load( code, data, id, dbg );
V.initialize( &env );
if ( !V.run() )
{
printf("vm: %s\n", (const char*)V.error().c_str());
return -1;
}
}
else
{
printf("codegen: %s\n", (const char*)C.error().c_str() );
return -1;
}
}
else
{
lk::eval ev( tree.get(), &env );
if ( !ev.run() )
{
for( size_t i=0;i<ev.error_count();i++ )
printf("eval: %s\n", (const char*) ev.get_error(i).c_str() );
return -1;
}
}
return 0;
}
Author
Aron P. Dobos
License
Copyright (c) 2017, Alliance for Sustainable Energy, LLC.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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