# Generating include diagrams

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* [Tracking system headers directly included by project sources](#tracking-system-headers-directly-included-by-project-sources)

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Include diagrams allow to document the include dependencies among different parts of the project. This can be very useful
for instance to detect that a file was included from a module directory, on which specific part of the project
should not ever depend.

The minimal config required to generate an include diagram is presented below:
```yaml
# Path to the directory where `compile_commands.json` can be found
compilation_database_dir: _build
# Output directory for the diagrams
output_directory: puml
# Diagrams definitions
diagrams:
  # Diagram name
  my_class_diagram:
    # Type of diagram (has to be `include`)
    type: include
    # Include only translation units matching the following patterns
    glob:
      - src/*.cc
    # Render the paths relative to this directory
    relative_to: src
    # Include also external system headers
    generate_system_headers: true
    # Include only classes and functions from files in `src` directory
    include:
      # Include only files belonging to these paths
      paths:
        - src
```

One distinctive option in `include` diagrams is `relative_to`, which tells `clang-uml` to render all filename
paths relative to this directory.

The following table presents the PlantUML arrows representing relationships in the include diagrams.

| UML                                    | PlantUML   |
| ----                                   | ---        |
| Include (local)                        | ![association](img/puml_association.png) |
| Include (system)                       | ![dependency](img/puml_dependency.png) |

## Tracking system headers directly included by project sources

In case you would like to include the information about what system headers your projects file include simply add
the following option to the diagram:

```yaml
generate_system_headers: true
```

This will include only system headers directly included from the projects source files (matched by `glob`) and not
their dependencies, for example:

![t40001_include](./test_cases/t40001_include.svg)

Please note that generating include diagram, which contains third party and system library headers will result
in a huge diagram that will be unlikely to be useful.