GABC Generator

Backend of this experimental tool for generating GABC code from liturgical texts with a regular structure, starting with the prefaces of the Mass.

Structure tree

APP Diagram here

Kanban of the project here

Frontend page here

Architectural Decisions

This project follows a package-oriented design, where packages are the primary unit of responsibility and reuse.
The structure is designed to keep dependencies explicit and changes localized.

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Packages are organized by the stability of the concepts they represent:

• Core, stable concepts live in internal packages with no external dependencies.

• Context-specific and infrastructure concerns live at the edges.

• Imports always point inward.

• composition/phrases/words is dependency-free.

• preface depends on composition, not the other way around.

• Infrastructure packages depend on interfaces defined closer to the domain.

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Packages represent domain concepts, not technical layers.

• words, phrases, and paragraph model text structure.
• staff models musical notation.
• preface applies rules specific to the Preface.

Generic packages such as models or utils are intentionally avoided.

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Text is built through a clear dependency chain:

words → phrases → paragraph

Each package builds on the one below it and imports only what it directly needs, making the data flow easy to follow through imports and constructors.

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Core types are kept free of context-specific rules.

• composition defines physical text structures.
• preface applies behavior required by the Preface.

This allows new liturgical contexts to reuse the same core types without modification.

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External integrations are isolated under internal/platform.

• Interfaces are defined where they are used.
• Infrastructure provides concrete implementations.
• Domain packages never import infrastructure packages.

This keeps the domain testable and independent from external services.

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The service package coordinates application workflows:

• orchestrates calls between domain packages
• connects domain logic with infrastructure
• exposes entry points to the delivery layer

Low-level domain logic remains outside this package.

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All wiring happens in cmd/gabcgen.

This is the only place where concrete implementations are selected and the application is assembled.

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These decisions:

• makes dependencies visible through imports
• allows adding new liturgical parts without modifying existing packages
• keeps packages small and focused
• favors clarity over abstraction