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diago

A diagram toolkit for MoonBit with Dagre, ELK, and Railway layout engines, rendering SVG, ASCII, and Unicode outputs.

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moon add Milky2018/diago@0.3.2
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Version
0.3.2
License
Apache-2.0
Repository
Last updated
4 days ago
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README

#Diago

Diago is a diagram toolkit for MoonBit. It supports a D2-compatible text format and renders diagrams through multiple layout engines.

#Overview

This repository contains:

  • A backend-independent library facade (Milky2018/diago) for parsing, layout, and rendering
  • A native filesystem adapter (Milky2018/diago/fs) for file loading and relative imports
  • A CLI (cmd/diago) with explicit subcommands (render, fmt, validate, layout, themes, version)
  • A WASM-based playground (web/) deployed via GitHub Pages
  • A Node.js Markdown package (markdown/) for markdown-it, remark, and VitePress
  • Multiple layout engines: dagre, elk, and railway

#Installation

moon update
moon build

#Quick Start

moon run cmd/diago -- render diagram.txt

#Library API

The root package is supported on all MoonBit targets. It accepts source text and never reads the local filesystem implicitly:

///|
test {
  let ascii = @diago.compile(
    "a -> b",
    options=@diago.CompileOptions::new().with_output_mode(Ascii),
  )
  inspect(
    ascii,
    content=(
      #|+----+
      #|| a  |
      #||    |
      #|+----+
      #|   |  
      #|+----+
      #|| b  |
      #||    |
      #|+----+
      #|
    ),
  )
}

Imports are explicit and backend-independent through ParseOptions::with_import_resolver. Editors can call get_syntax_tokens on every target to obtain error-tolerant Unicode code-point ranges for comments, strings, literals, keywords, identifiers, operators, and punctuation.

#Unsupported D2 features

Diago does not currently support LaTeX labels (|tex or |latex) or sketch rendering (style.sketch, vars.d2-config.sketch, or the sketch render option). These inputs return UnsupportedFeature instead of silently falling back to plain text or ordinary SVG rendering. They can be reconsidered when backend-independent community implementations are available for all MoonBit targets.

Native applications can opt into local file access through the filesystem adapter:

///|
async fn main {
  let svg = @diago_fs.compile_file("diagram.d2")
}

compile_file and parse_file use moonbitlang/async/fs, resolve imports relative to the input file, and preserve a custom resolver supplied by the caller.

#Markdown package

The diago npm package renders exact lowercase diago fences to inline SVG at build time. It is Node.js 20+ and ESM-only and bundles the matching Diago Wasm:

import MarkdownIt from 'markdown-it'
import diago from 'diago/markdown-it'

const md = new MarkdownIt().use(diago)
const html = md.render('```diago\na -> b\n```', {
  path: 'docs/example.md',
})

The package also exports diago/remark and diago/vitepress. Failed diagrams remain code fences and produce structured diagnostics. File imports, sketch, and LaTeX are not supported in Markdown fences. Only use the adapters with trusted project-authored Markdown: generated inline SVG is active HTML and is not sanitized by the package. See markdown/README.md for the complete interface and CSP notes.

#CLI

Show help:

moon run cmd/diago -- --help

Common usage:

# Render SVG (default output: input.svg)
moon run cmd/diago -- render diagram.txt
moon run cmd/diago -- render diagram.txt diagram.svg
moon run cmd/diago -- render diagram.txt --output diagram.svg

# Choose layout engine
moon run cmd/diago -- render --layout elk diagram.txt diagram.svg
moon run cmd/diago -- render -l dagre diagram.txt diagram.svg

# ASCII / Unicode text
moon run cmd/diago -- render --format ascii diagram.txt --output diagram.ascii.txt
moon run cmd/diago -- render --format unicode diagram.txt --output diagram.unicode.txt

# Format / validate
moon run cmd/diago -- fmt diagram.txt
moon run cmd/diago -- fmt --check diagram.txt
moon run cmd/diago -- validate diagram.txt

# Watch mode (rebuilds output on file changes)
moon run cmd/diago -- render --watch diagram.txt

# Introspection
moon run cmd/diago -- layout
moon run cmd/diago -- layout elk
moon run cmd/diago -- themes
moon run cmd/diago -- version

#Example

Create a file example.txt:

server: Web Server
database: Database {
  shape: cylinder
}
cache: Cache {
  shape: oval
}

server -> database: queries
server -> cache: reads
cache -> database: fallback

Compile it:

moon run cmd/diago -- render example.txt example.svg

#Pipeline

At a high level:

Source → Lexer → Parser → AST → IR → Graph → Layout (dagre/elk/railway) → Render (SVG/ASCII/Unicode)

#Tests

moon check --target all --deny-warn
moon test --target all
moon build cmd/diago --target native --release
moon build cmd/wasm --target wasm --release
node scripts/wasm_smoke.mjs _build/wasm/release/build/cmd/wasm/wasm.wasm
npm ci --prefix web
npm test --prefix web
npm ci --prefix markdown
npm test --prefix markdown
npm run test:corpus --prefix markdown
npm run test:package --prefix markdown

#License

Apache-2.0 (see LICENSE).

#
DiagoError

source
pub(all) suberror DiagoError {
  ParseError(String)
  IOError(String)
  IrError(String)
  GraphError(String)
  LayoutError(String)
  RenderError(String)
  ConfigError(String)
  TargetError(String)
  UnsupportedFeature(String)
} derive(Eq, 
Debug)

#
CompileOptions

source
pub struct CompileOptions {
  output_mode : OutputMode
  layout_engine : LayoutEngine
  direction : 
Direction
  target_spec : String?
  layout_plugin : LayoutPlugin?
  route_plugin : RoutePlugin?
  parse_options : ParseOptions
  theme_name : String?
  dark_theme_id : Int?
  sketch : Bool?
  pad : Double?
  center : Bool?
  theme_overrides : 
ThemeOverrides?
  dark_theme_overrides : 
ThemeOverrides?
  scale : Double?
  no_xml_tag : Bool?
  salt : String?
  omit_version : Bool?
}

#
CompileOptions::new

source

#
CompileOptions::with_center

source
fn CompileOptions::with_center(self : CompileOptions, center : Bool?) -> CompileOptions

#
CompileOptions::with_dark_theme_id

source
fn CompileOptions::with_dark_theme_id(self : CompileOptions, dark_theme_id : Int?) -> CompileOptions

#
CompileOptions::with_dark_theme_overrides

source
fn CompileOptions::with_dark_theme_overrides(self : CompileOptions, dark_theme_overrides : 
ThemeOverrides?) -> CompileOptions

#
CompileOptions::with_direction

source

#
CompileOptions::with_layout_engine

source
fn CompileOptions::with_layout_engine(self : CompileOptions, layout_engine : LayoutEngine) -> CompileOptions

#
CompileOptions::with_layout_plugin

source
fn CompileOptions::with_layout_plugin(self : CompileOptions, layout_plugin : LayoutPlugin?) -> CompileOptions

#
CompileOptions::with_no_xml_tag

source
fn CompileOptions::with_no_xml_tag(self : CompileOptions, no_xml_tag : Bool?) -> CompileOptions

#
CompileOptions::with_omit_version

source
fn CompileOptions::with_omit_version(self : CompileOptions, omit_version : Bool?) -> CompileOptions

#
CompileOptions::with_output_mode

source
fn CompileOptions::with_output_mode(self : CompileOptions, output_mode : OutputMode) -> CompileOptions

#
CompileOptions::with_pad

source
fn CompileOptions::with_pad(self : CompileOptions, pad : Double?) -> CompileOptions

#
CompileOptions::with_parse_options

source
fn CompileOptions::with_parse_options(self : CompileOptions, parse_options : ParseOptions) -> CompileOptions

#
CompileOptions::with_route_plugin

source
fn CompileOptions::with_route_plugin(self : CompileOptions, route_plugin : RoutePlugin?) -> CompileOptions

#
CompileOptions::with_salt

source
fn CompileOptions::with_salt(self : CompileOptions, salt : String?) -> CompileOptions

#
CompileOptions::with_scale

source
fn CompileOptions::with_scale(self : CompileOptions, scale : Double?) -> CompileOptions

#
CompileOptions::with_sketch

source
fn CompileOptions::with_sketch(self : CompileOptions, sketch : Bool?) -> CompileOptions

#
CompileOptions::with_target_spec

source
fn CompileOptions::with_target_spec(self : CompileOptions, target_spec : String?) -> CompileOptions

#
CompileOptions::with_theme_name

source
fn CompileOptions::with_theme_name(self : CompileOptions, theme_name : String?) -> CompileOptions

#
CompileOptions::with_theme_overrides

source

#
CompletionItem

source
pub struct CompletionItem {
  label : String
  kind : CompletionKind
  detail : String
  insert_text : String
} derive(Eq, 
Debug)

#
CompletionKind

source
pub(all) enum CompletionKind {
  Keyword
  Style
  Shape
  Value
} derive(Eq, 
Debug)

#
LayoutEngine

source
pub(all) enum LayoutEngine {
  Auto
  Dagre
  Elk
  Railway
} derive(Eq, 
Debug)

#
LayoutPlugin

source

#
OutputMode

source
pub(all) enum OutputMode {
  Svg
  Ascii
  Unicode
} derive(Eq, 
Debug)

#
ParseOptions

source
pub struct ParseOptions {
  import_resolver : 
ImportResolver?
}

#
ParseOptions::new

source

#
ParseOptions::with_import_resolver

source
fn ParseOptions::with_import_resolver(_self : ParseOptions, import_resolver : 
ImportResolver?) -> ParseOptions

#
RoutePlugin

source

#
SyntaxToken

source
pub struct SyntaxToken {
  start : Int
  end : Int
  kind : SyntaxTokenKind
} derive(Eq, 
Debug)

A highlighted source range.

start and end are zero-based Unicode code point offsets. The range is half-open: it includes start and excludes end.

#
SyntaxTokenKind

source
pub(all) enum SyntaxTokenKind {
  Comment
  String
  Number
  Boolean
  Keyword
  Identifier
  Operator
  Punctuation
} derive(Eq, 
Debug)

A lexical category used by source editors.

#
compile

source
fn compile(source : String, options? : CompileOptions) -> String raise DiagoError

#
compile_diagram

source
fn compile_diagram(source : String, options? : CompileOptions) -> 
Diagram raise DiagoError

#
get_board_path_at_position

source
fn get_board_path_at_position(source : String, line : Int, column : Int) -> Array[String]

#
get_completion_items

source
fn get_completion_items(source : String, line : Int, column : Int) -> Array[CompletionItem]

#
get_ref_ranges

source
fn get_ref_ranges(source : String, key : String, board_path? : Array[String], options? : ParseOptions) -> Array[
Range] raise DiagoError

#
get_syntax_tokens

source
fn get_syntax_tokens(source : String) -> Array[SyntaxToken]

Tokenize Diago source for syntax highlighting.

The result is available even when the source is incomplete or contains syntax errors.

#
parse

source
fn parse(source : String, options? : ParseOptions) -> 
Map raise DiagoError

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