imag/doc/src/04000-lib-store.md

# libstore {#sec:libstore}

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    Store functionality
-->

The "libstore" MUST define the programming-language level interface to the
store on the file system.
The library therefor MUST define and export types which can be used to get data
from the filesystem.

## Types {#sec:libstore:types}

The types in @tbl:libstore:types are exported by the library.

| Type          | Meaning                                          |
| :------------ | :----------------------------------------------- |
| Entry         | Entity on the Filesystem, File                   |
| EntryContent  | User-Content of the Entry                        |
| EntryHeader   | Header of the Entry                              |
| Store         | Store interface                                  |
| FileLockEntry | Handle to an Entry                               |

Table: Types the store library exports {#tbl:libstore:types}

Each of these types MUST export functions to work with the data the objects of
the types contain.

### Entry {#sec:libstore:types:entry}

The `Entry` type MUST hold the following content:

- A path where on the filesystem the acutal file lives
- An instance of `EntryContent` as interface to the content of the file
  (@sec:libstore:types:entrycontent).
- An instance of `EntryHeader` as interface to the header of the file
  (@sec:libstore:types:entryheader).

The entry type MUST export functions to get

- The content object
- The header object
- The path of the actual file

The entry type MUST export functions to set

- The header object
- The content object

### EntryContent {#sec:libstore:types:entrycontent}

The `EntryContent` type is an type-alias for `String`.

### EntryHeader {#sec:libstore:types:entryheader}

The `EntryHeader` type is an wrapper around the type, the TOML-Parser library
exports.

It SHOULD contain utility functions to work with the header in a convenient way.

### Store {#sec:libstore:types:store}

The `Store` type MUST represent the interface to the store on the filesystem.
It MUST contain CRUD-functionality to work with the entries in the store.
It MUST contain a variable which contains the path of the store on the
filesystem which is represented by an object of this type.
It also MUST contain a getter for this variable.
It MUST NOT contain a setter for this variable, as changing the store while the
programm is running is not allowed.