Lc — Language Creator & Devkit

go get github.com/pt-main/lc

Lc is a production-oriented toolkit for building things like language tools, compiler, interpreters or bytecode-driven processors in Go.

It is intentionally straightforward to adopt, while preserving industrial runtime properties:

• explicit execution lifecycle,
• deterministic output assembly,
• context-aware cancellation,
• thread-safe core primitives,
• clear extension contracts for parsers and command handlers, plugins.

Lc does not enforce one grammar style or one VM model.
Instead, it gives you one runtime surface with two engine backends:

• String Engine for text-first processing.
• Byte Engine for binary instruction execution.

Engine model

String Engine

Input string (code) and process that - edit, execute, generate code, etc.

Default lifecycle:

1. store input in scope;
2. parse input to []ParsedNode;
3. dispatch handlers by ParsedNode.Switch;
4. emit output through UEP.Generator (if need).

Byte Engine

Input bytecode and process that.

Default lifecycle:

1. store input in scope;
2. parse input to []ParsedBytes;
3. decode opcode from ParsedBytes.Switch bytes using configured endianness;
4. dispatch opcode handler;
5. advance instruction pointer automatically or manually.

Quick start

StringEngine Example

package main

import (
	"fmt"
	"strings"

	"github.com/pt-main/lc"
	enginepkg "github.com/pt-main/lc/engine"
	"github.com/pt-main/lc/parsing/stringParsing"
	"github.com/pt-main/lc/public"
)

func main() {
	parser := &stringParsing.Parser2{}

	engine, err := lc.NewEngineBuilder(public.StringEngineType, public.StringResType).
		WithPipeline([]string{"main"}).
		WithStringParser(parser).
		WithDefaultEvents(true).
		Build()
	if err != nil {
		panic(err)
	}

	err = engine.NewCommandString("print", func(se *enginepkg.StringEngine, node stringParsing.ParsedNode) error {
		args, _ := node.Metadata["args"].(string)
		return se.UEP.Generator.AddString(args, "main")
	}, "append text to output")
	if err != nil {
		panic(err)
	}

	err = engine.ProcessString(strings.Join([]string{
		"print service_start",
		"print service_ready",
	}, "\n"))
	if err != nil {
		panic(err)
	}

	out, err := engine.GetUEP().Generator.GetStringRes("\n")
	if err != nil {
		panic(err)
	}
	fmt.Println(out)
}

ByteEngine Example

package main

import (
	"fmt"

	"github.com/pt-main/lc"
	"github.com/pt-main/lc/parsing/byteParsing"
	enginepkg "github.com/pt-main/lc/engine"
	"github.com/pt-main/lc/tooling/bytecode"
	"github.com/pt-main/lc/public"
)

func main() {
	parser := &byteParsing.Parser1{
		Config: byteParsing.Parser1Config{
			GConfig: bytecode.GenerationConfig{
				CommandBytelen:   1,
				ArgscountBytelen: 1,
				ArglenBytelen:    1,
				Endianess:        public.LittleEndian,
			},
			Shifter: bytecode.Shift{},
		},
	}

	engine, err := lc.NewEngineBuilder(public.ByteEngineType, public.ByteResType).
		WithPipeline([]string{"main"}).
		WithByteParser(parser).
		WithDefaultEvents(true).
		Build()
	if err != nil {
		panic(err)
	}

	err = engine.NewCommandByte(1, func(be *enginepkg.ByteEngine, node byteParsing.ParsedBytes) error {
		return be.UEP.Generator.AddBytes(node.Raw, "main")
	}, "mirror instruction bytes", true)
	if err != nil {
		panic(err)
	}

	code := []byte{
		0x01, 0x01, 0x03, 0x61, 0x62, 0x63, // opcode=1, args=1, argLen=3, arg="abc"
	}

	err = engine.ProcessBytes(code)
	if err != nil {
		panic(err)
	}

	out, err := engine.GetUEP().Generator.GetBytesRes()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x\n", out)
}

Tools and features

Powerful core and UEP (Universal Engine Params)

Engines core contains all necessary tools for runtime work. UEP contains then.

You can use it like:

engine, _ := lc.NewStringEngine(...)
engine.UEP.Generator.AddString(...)
engine.UEP...

Or:

engine, _ := lc.NewEngineBuilder(...).
	[...].
	Build()
engine.GetUEP().Generator.AddString(...)
engine.GetUEP()...

Events

Engine arch is event-driven. Events can communicate with Events.Scope, work with context (Events.Context), call by pipeline.

Event handlers input *Events, *EventInput.

You can override Events by implementing core.EventsInterface.

Example

events := core.NewEvents(context.Background()) // new manager
events.NewEvent("event1", handler1) // create main handler in "event1" event
events.NewEvent("event1", handler2) // append handler to end of "event1"
events.NewEventBefore("event1", handler3) // append handler to start of "event1"
// "event1" - [handler3, handler1, handler2]

Generator

Powerful tool for codegen.

Work with points pipeline for storing code in independent points. Can generate bytes or string.

Example

pipeline := []string{"pre", "main"}
generator := core.NewGenerator([result-type], pipeline)
generator.AddStrings([]string{ // add strings to main
	"string1 ",
	"string2.",
}, "main")
generator.AddStrings([]string{ // add strings to pre
	"string3 ",
	"string4. ",
}, "pre")
res := core.GetStringRes(generator, "") // get code
// res = string3 string4. string1 string2.

Scope

The Scope is a thread-safe map[string]interface{} shared across all event handlers, parsers, and commands. It serves as a runtime context for passing data between pipeline stages.

Important: Do not overwrite keys from public/ package in your custom handlers unless you know exactly what you're doing — they are used by default events.

Custom scope usage

engine, _ := lc.NewEngineBuilder(...).
	WithScope(core.ScopeType{
		"tenant_id": "prod-001",
		"env":       "production",
	}).
	Build()

// later, in your command handler:
func myHandler(se *engine.StringEngine, node stringParsing.ParsedNode) error {
	tenant, _ := core.ScopeGet[string](se.UEP.Scope, "tenant_id")
	fmt.Println("Running for tenant:", tenant)
	return nil
}

Logger

Structured logger built into UEP. Supports status-based formatting and log level filtering.

Example

logger := core.NewLogger("") // uses default format: "[?BE]%s[?RT] [?CN][%v][?RT] [?GN][%s][?RT]\n"
logger.Logging["debug"] = true  // enable debug output
// other logging will be disabled

// in your engine builder:
engine, _ := lc.NewEngineBuilder(...).
	WithLogger(logger).
	Build()

// in your handlers:
func myHandler(se *engine.StringEngine, node stringParsing.ParsedNode) error {
	se.UEP.Logger.PrintLog("debug", "Processing node: "+node.Switch)
	se.UEP.Logger.PrintLog("error", "Error: "+...) // disabled
	...
}

Custom status format

logger := core.NewLogger("")
logger.Statuses["warn"] = "[?YW]WARN[?RT] [%v] [?RD]%s[?RT]\n" // pt-main/tap color format
logger.PrintLog("warn", "This is a warning")

Plugin System

Lc has a built‑in plugin manager that allows dynamic registration and execution of external logic. Plugins are isolated via their own events and scope.

Creating a plugin

import "github.com/pt-main/lc/tooling/plugin"

myPlugin := plugin.NewPlugin(
	"my_plugin",          // name
	"init_event",         // event called on init
	"main_event",         // event called on Run()
	"close_event",        // event called on Close()
)

// Add handlers to plugin events
myPlugin.Events.NewEvent("init_event", func(ev *core.Events, _ *EventInput) error {
	ev.Scope["plugin_ready"] = true
	return nil
})

myPlugin.Events.NewEvent("main_event", func(ev *core.Events, _ *EventInput) error {
	// input is whatever was passed to plugin.Run()
	return nil
})

Registering and using a plugin

engne, _ := lc.NewEngineBuilder(...).
	WithPlugins(myPlugin).
	Build()

// Later, call plugin methods:
result, err := engine.Plugins.CallPlugin("my_plugin", "some input")

Parsers — ready‑to‑use implementations

Lc ships with several parsers for different use cases:

StringParsing parsers

Parser	Description	Best for
Lexer	Token-based lexer with regexp2 rules, supports bracket balancing and prev/next links	Tokenization
Parser1	Regex-based grammar with line continuation and bracket balancing	DSLs with line-oriented syntax
Parser2	Simple command args line parser	Quick prototyping, shell-like languages
Parser3	PEG-inspired parser with combinators (Sequence, Choice, Repeat, Optional, Named)	Complex grammars, AST generation
Adapter	Parser3 adapter for string engine.

Example: Parser2 (simplest)

parser := &stringParsing.Parser2{}
// Input: "print hello world"
// Output: ParsedNode{Switch: "print", Metadata: {args: "hello world"}}

ByteParsing parsers

Parser	Description
Parser1	Binary instruction decoder with configurable field lengths and endianness

parser := &byteParsing.Parser1{
	Config: byteParsing.Parser1Config{
		GConfig: bytecode.GenerationConfig{
			CommandBytelen:   1,
			ArgscountBytelen: 1,
			ArglenBytelen:    1,
			Endianess:        public.LittleEndian,
		},
		Shifter: bytecode.Shift{},
	},
}

Context support

All Process* methods have WithCtx variants that accept context.Context. This allows:

• Timeout-based cancellation
• Graceful shutdown
• Request-scoped values

ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

err := engine.ProcessStringWithCtx(input, ctx)
if errors.Is(err, context.DeadlineExceeded) {
	fmt.Println("Execution timed out")
}

Execution semantics

• Event handlers run in registration order.
• Generator result follows declared pipeline order.
• Process[*]WithCtx respects cancellation/deadline.
• Default String dispatch skips unknown commands.
• Default Byte dispatch expects valid opcode/autoshift registration for processed commands.

Observability

Lc provides core mechanisms for operational visibility:

• thread-safe core.Logger,
• event lifecycle hooks (call start/call end),
• centralized runtime scope for contextual metadata,
• structured error wrapping in default event flows.

License

Apache 2.0 - see LICENSE.

By Pt.