Tutorial: build a Turbo editor for your own language

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# Tutorial: build a Turbo editor for your own language

By the end of this tutorial you will have a working full-screen terminal IDE — menu bar, movable windows, mouse, themes, a file tree, terminal windows and syntax colouring — for a language of your choosing. We will build one for **Zig**, and it will be about eighty lines of Go.

No knowledge of turbo-core is required. You need Go 1.26 or later and a terminal.

## Prerequisites

- Go 1.26 or later on your PATH.
- A checkout of turbo-core beside where you are about to work. If you do not have one:

```bash
git clone ssh://git@rickub.com/turbo-editors/turbo-core.git
```

## Step 1 — Make the module

Beside your turbo-core checkout, type:

```bash
mkdir turbo-zig && cd turbo-zig
go mod init example.com/turbo-zig
```

You should see:

```
go: creating new go.mod: module example.com/turbo-zig
```

We now have an empty module. Next we point it at the library.

## Step 2 — Depend on turbo-core

Type:

```bash
go mod edit -require=rickub.com/turbo-editors/turbo-core@v0.1.0
go mod edit -replace=rickub.com/turbo-editors/turbo-core=../turbo-core
```

Nothing is printed. Look at `go.mod`:

```bash
cat go.mod
```

You should see a `require` line and a `replace` line naming turbo-core. The `replace` is what makes the checkout beside you the one that gets used.

## Step 3 — Say which editor this is

Create `profile.go`:

```go
package main

import "rickub.com/turbo-editors/turbo-core/profile"

// zig is the editor we are building.
func zig() profile.Profile {
	return profile.Profile{
		Name:        "Turbo Zig",
		Slug:        "turbo-zig",
		Language:    "Zig",
		ToolsMenu:   "~Z~ig",
		RootMarkers: []string{"build.zig"},
		Server: profile.Server{
			Command:     "zls",
			InstallHint: "see https://github.com/zigtools/zls",
		},
		Templates: profile.Templates{
			Settings: settingsTemplate,
			Snippets: snippetsTemplate,
			Tools:    toolsTemplate,
		},
	}
}
```

That is the whole of what makes this editor different from Turbo Go. We have not written the templates yet — that is the next step.

## Step 4 — Write the three starter files

Create `templates.go`:

```go
package main

const settingsTemplate = `# turbo-zig project settings.

[editor]

theme = %q
autosave = false
autosave_delay = %q
`

const snippetsTemplate = `# turbo-zig snippets.
#
# A snippet with no group goes into %s.
# Your own live in:
#   %s

[[snippet]]
name = "TODO"
body = "TODO: "
`

const toolsTemplate = `# turbo-zig tools.

[[tool]]
name = "~B~uild"
command = "zig build"
output = "popup"

[[tool]]
name = "~T~est"
command = "zig build test"
output = "popup"

[[tool]]
name = "~R~un"
command = "zig build run"
output = "terminal"
`
```

The blanks matter: `settingsTemplate` takes the theme name and the autosave delay, `snippetsTemplate` takes the ungrouped group's name and the user's snippets path. The [Profile reference](../reference/profile.md) lists them exactly.

## Step 5 — Write the command

Create `main.go`:

```go
package main

import (
	"context"
	"fmt"
	"os"

	"github.com/gdamore/tcell/v2"

	"rickub.com/turbo-editors/turbo-core/app"
)

func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, "turbo-zig:", err)
		os.Exit(1)
	}
}

func run() error {
	screen, err := tcell.NewScreen()
	if err != nil {
		return err
	}
	if err := screen.Init(); err != nil {
		return err
	}
	defer screen.Fini()
	screen.EnableMouse()
	screen.EnablePaste()

	p := zig()
	editor := app.New(screen, "turbo-classic", p)

	files := os.Args[1:]
	if len(files) == 0 {
		editor.NewFile()
	}
	for _, file := range files {
		editor.Open(file)
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	editor.StartLanguageServer(ctx, app.ProjectRoot(p, files))
	defer editor.Language().Stop(context.Background())

	return editor.Run()
}
```

## Step 6 — Run it

Type:

```bash
go mod tidy
go run . main.go
```

Your terminal fills with a blue desktop. Along the top you should see:

```
 File  Edit  Search  Run  Options  Window  Snippets  Zig  Help
```

and a window in the middle showing `main.go`. Press **F10** to open the menu bar, the arrow keys to move along it, and **Alt-X** to leave.

We have a working editor. Everything on that bar works: **F3** opens a file, **F8** opens a terminal window with a real shell in it, **F9** opens the project tree, **Options ▸ Theme** offers eleven colour themes.

## Step 7 — Colour the language

Zig files are not coloured yet, because nothing has told the library what Zig is. Create `syntax.go`:

```go
package main

import "rickub.com/turbo-editors/turbo-core/syntax"

// registerZig teaches the library a very small amount of Zig: its keywords,
// its comments and its strings.
func registerZig() {
	syntax.Register(syntax.Definition{
		Language:   "zig",
		Extensions: []string{".zig"},
		Highlight:  highlightZig,
	})
}

var zigKeywords = map[string]bool{
	"const": true, "var": true, "fn": true, "pub": true, "return": true,
	"if": true, "else": true, "while": true, "for": true, "struct": true,
	"try": true, "defer": true, "test": true, "comptime": true,
}

func highlightZig(src string) [][]syntax.Span {
	return syntax.ScanLines(src, func(line []rune, carry struct{}) ([]syntax.Span, struct{}) {
		s := syntax.NewLineScanner(line)
		for !s.AtEnd() {
			switch r := s.Peek(0); {
			case r == ' ' || r == '\t':
				s.SkipSpaces()
			case s.HasPrefix(0, "//"):
				s.TakeRest(syntax.ClassComment)
			case r == '"':
				syntax.TakeQuoted(s, '"', syntax.ClassString)
			case syntax.IsDigit(r):
				s.TakeWhile(syntax.ClassNumber, syntax.IsWordRune)
			case syntax.IsLetter(r) || r == '_':
				start := s.Pos()
				for !s.AtEnd() && syntax.IsWordRune(s.Peek(0)) {
					s.Advance(1)
				}
				class := syntax.ClassIdentifier
				if zigKeywords[string(line[start:s.Pos()])] {
					class = syntax.ClassKeyword
				}
				s.Emit(start, s.Pos(), class)
			default:
				s.Advance(1)
			}
		}
		return s.Spans(), carry
	})
}
```

Add one line to `run`, just above `p := zig()`:

```go
	registerZig()
```

## Step 8 — See it coloured

Write a Zig file and open it:

```bash
cat > hello.zig <<'EOF'
// A greeting.
const std = @import("std");

pub fn main() void {
    std.debug.print("hello {d}\n", .{42});
}
EOF
go run . hello.zig
```

`const`, `pub`, `fn` are drawn in the keyword colour, `// A greeting.` in the comment colour, `"hello {d}\n"` in the string colour and `42` in the number colour. Press **Alt-X** to leave.

## What now?

You have an editor. What it does not yet have is a real scanner — the one above knows fourteen keywords and nothing about `\\` multiline strings or `\\'` character literals.

- To write a proper one → [Add a language](../how-to/add-a-language.md)
- To make completion work → [Talk to a language server](../how-to/talk-to-a-language-server.md)
- To see every field you skipped → [Profile reference](../reference/profile.md)
- To understand why the library is shaped this way → [Architecture](../explanation/architecture.md)