Darta

Darta parses Dart source code through ANTLR and renders Nassi-Shneiderman diagrams as single-file HTML pages. The architecture is DDD-inspired with hexagonal boundaries so the ANTLR infrastructure stays behind ports and the domain layer stays independent.

Feature Matrix

Control Flow

Construct	Extracted	Diagram
if / else if / else	✅	✅ NS triangle with Yes/No branches
if (x case Pattern when guard) Dart 3	✅	✅ full pattern+guard in condition
while	✅	✅ loop block
do … while	✅	✅ body-first loop block
for (init; cond; incr)	✅	✅ for block
for (x in collection)	✅	✅ for block
await for (x in stream)	✅	✅ purple accent + "Await for" header
standalone { ... } block statement	✅	✅ nested block container
switch / case / default (classic)	✅	✅ side-by-side columns
switch with Dart 3 patterns & guards	✅	✅ pattern text in case label
switch(v) { p => e } expression (Dart 3)	✅	✅ teal accent + switch badge in standalone, return, and assignment/declaration forms
try / on / catch / finally	✅	✅ catch lanes + finally
throw expr	✅	✅ red accent + throw badge
await expr	✅	✅ purple accent + await badge in standalone, return, assignment, and nested expression forms
=> expr arrow body	✅	✅ semantic return / throw / await / switch extraction
yield / yield*	✅	✅ green accent + yield / yield* badge
return expr	✅	✅ teal accent + return badge
rethrow	✅	✅ red accent + rethrow badge
assert(cond, msg?)	✅	✅ amber accent + assert badge
break / break label	✅	✅ orange accent + break badge
continue / continue label	✅	✅ orange accent + continue badge
label: statement	✅	✅ labeled container around the target statement
var / final local declaration	✅	✅ blue declare badge instead of generic action
var (a, b) = expr pattern variable	✅	✅ blue accent + pattern destructuring

Function Discovery

Kind	Discovered	Notes
Top-level function	✅
Top-level getter	✅
Top-level setter	✅
Class method	✅	static, instance, abstract, and external declarations
Class getter	✅	concrete and abstract/external declarations
Class setter	✅	concrete and abstract/external declarations
Constructor (default)	✅	block-body and semicolon forms; diagrams include field and super(...) initializers
Constructor (named)	✅	block-body and semicolon forms; diagrams include field and super(...) initializers
Constructor (redirecting this(...))	✅	discovered structurally; no function body to diagram
Constructor (const)	✅	discovered structurally
Redirecting factory (= ClassName)	✅	discovered structurally; no function body to diagram
Factory constructor	✅	block-body and redirecting forms
Operator overload	✅
Mixin method / getter	✅
Extension method / getter	✅
Extension type method	✅
Enum method / getter	✅	via enumBody member declarations
Local function declaration	✅	discovered structurally inside enclosing function/method and diagrammed as nested local-function step

Grammar

Feature	Status
Grammar source	✅ dart-lang/sdk spec parser v0.60
Dart 2 syntax	✅
Dart 3 patterns & records	✅
Dart 3 sealed / base / final classes	✅ parsed, not specially rendered
String interpolation	✅ lexer brace-stack
async / async* / sync* functions	✅

Rendering

Feature	Status
Single-file HTML output	✅ inline CSS/markup; default theme requests Google Fonts
Dark Tokyo Night theme	✅
JetBrains Mono font	✅ via Google Fonts
Depth-coded nested ifs (50 levels)	✅ color cycling + Unicode badges ①–㊿
Switch — side-by-side columns	✅
await purple accent	✅
Responsive layout	✅
Directory index page	✅

Recent coverage additions include semantic arrow-body extraction, explicit embedded-await steps, nested local-function containers, declaration badges, labeled statement containers, standalone block steps, and constructor super(...) initializer steps.

---

Screenshots

Basic control flow — sequential actions and an if-block with Yes/No branches:

Deeper nesting and extracted members — nested conditionals, constructor/getter coverage, and local helper declarations represented alongside the main function flow:

---

Quick Start

1. Install dependencies:

uv sync --extra dev

2. Generate the Dart parser from the vendored grammar:

uv run python scripts/generate_dart_parser.py

3. Build a Nassi-Shneiderman diagram for one Dart file:

uv run darta nassi-file path/to/file.dart --out output/file.nassi.html

4. Build diagrams for an entire directory:

uv run darta nassi-dir path/to/project --out output/nassi-bundle

5. Parse a file and get a JSON structural report:

uv run darta parse-file path/to/file.dart

See examples/feature_tour.dart for a single file that exercises the main control-flow constructs and representative structural extraction edges, including semantic arrow bodies, labels, local functions, and constructor initializer steps.

---

Architecture

Four explicit layers:

Layer	Responsibility
domain	model, invariants, ports, domain events
application	use cases, DTOs
infrastructure	ANTLR adapter, filesystem, event publishing
presentation	CLI

---