Architecture

Architecture

plantuml.rs preserves the architecture of the Java original, mapping Java packages to Rust crates in the workspace.

Pipeline

Source text
  │
  ▼
BlockUmlBuilder          Splits input into @start/@end blocks
  │
  ▼
BlockUml                 One per @start/@end block. Lazy: TimLoader
  │                      preprocesses (!include, !define, variables)
  ▼
PSystemBuilder           createPSystem() dispatches to the
  │                      diagram-type factory (Sequence, Class,
  │                      Activity, UseCase, etc.)
  ▼
Diagram object           The in-memory diagram model
  │
  ▼
Diagram.exportDiagram()  Renders via FileFormat-specific StringBinder
  │                      to SVG / PNG / PDF / LaTeX / EPS / etc.
  ▼
Output bytes

Java Package → Rust Crate

Java Package(s)	Rust Crate	Responsibility
klimt	plantuml-klimt	2D graphics: shapes, geometry, fonts, StringBounder, UGraphic, TextBlock
com.plantuml.ubrex	plantuml-regex	Custom regex engine
preproc / tim	plantuml-preproc	Preprocessor: !include, !define, variables, conditionals
command	plantuml-command	Command / CommandFactory parsing framework
abel / cucadiagram	plantuml-model	Entity/relationship model: Entity, Link, LeafType
sequencediagram	plantuml-sequence	Sequence diagram
skin / style / theme	plantuml-skin	Skin / style / theme system
real	plantuml-real	1D constraint solver for layout positioning
svg	plantuml-svg	SVG rendering backend
root (partial)	plantuml-engine	BlockUml, BlockUmlBuilder, PSystemBuilder, SourceStringReader, unified render API
root (partial)	plantuml-core	Diagram, TextBlock, StringBounder, FileFormat, FileFormatOption
—	plantuml-ffi	C FFI shared library for language bindings
—	plantuml-wasm	WASM module (wasm-bindgen) for TypeScript binding

Design Patterns

The Rust port preserves the key design patterns from the Java original:

1. Factory + Registry — PSystemBuilder dispatches to per-type *DiagramFactory implementations via a trait-based registry.
2. Command pattern — Each source-line parser is a Command registered in a CommandFactory; mapped to a Command trait with implementations.
3. Strategy — FileFormat selects the rendering backend; layout backend selection (Graphviz vs ELK) is also a strategy, using trait objects or enums.
4. Lazy initialization — BlockUml.getDiagram() builds the model on demand via OnceCell<T> or explicit build() calls.
5. Template method — TitledDiagram / Diagram define base behavior extended by subclasses; mapped to traits with default methods and composition.

Workspace Structure

plantuml.rs/
├── crates/
│   ├── plantuml-core/         # Diagram, TextBlock, StringBounder, FileFormat
│   ├── plantuml-klimt/        # 2D graphics: shapes, geometry, fonts
│   ├── plantuml-regex/        # Custom regex engine
│   ├── plantuml-preproc/      # Preprocessor: !include, !define, variables
│   ├── plantuml-command/      # Command / CommandFactory parsing framework
│   ├── plantuml-model/        # Entity/relationship model
│   ├── plantuml-engine/       # Top-level pipeline and unified render API
│   ├── plantuml-svg/          # SVG rendering backend
│   ├── plantuml-skin/         # Skin / style / theme system
│   ├── plantuml-real/         # 1D constraint solver for layout
│   ├── plantuml-sequence/     # Sequence diagram
│   ├── plantuml-ffi/          # C FFI shared library
│   └── plantuml-wasm/         # WASM module (wasm-bindgen)
├── bindings/
│   ├── plantuml-java/         # Java binding (JNI)
│   └── plantuml-ts/           # TypeScript binding (WASM)
└── Cargo.toml                # Workspace manifest