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Add initial C# vector of unions support to the documentation. (#6880)

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* Add initial C# vector of unions support to the documentation.

* Add notes about missing documentation for vector of unions.
This commit is contained in:
Richard A Hofer
2022-01-14 01:15:35 -05:00
committed by GitHub
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commit 3250a1f8dd
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docs/source/Tutorial.md
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@@ -3392,6 +3392,125 @@ decimals in the JSON document.*
## Advanced Features for Each Language
### Vector of Unions
Some languages support storing unions directly in a vector.
~~~
// File found in tests/union_vector/union_vector.fbs
namespace Example.VectorOfUnions;
// Demonstrates the ability to have vectors of unions, and also to
// store structs and strings in unions.
table Attacker {
sword_attack_damage: int;
}
struct Rapunzel {
hair_length: int;
}
struct BookReader {
books_read: int;
}
union Character {
MuLan: Attacker, // Can have name be different from type.
Rapunzel, // Or just both the same, as before.
Belle: BookReader,
BookFan: BookReader,
Other: string,
Unused: string
}
table Movie {
main_character: Character;
characters: [Character];
}
~~~
#### Creating
Analagously to how a union adds two fields to a table a vector of unions creates two different vectors:
one for the union data and one for the data types.
<div class="language-cpp">
C++ supports vectors of unions, but it isn't currently documented.
</div>
<div class="language-typescript">
Typescript supports vectors of unions, but it isn't currently documented.
</div>
<div class="language-php">
PHP supports vectors of unions, but it isn't currently documented.
</div>
<div class="language-java">
Java supports vectors of unions, but it isn't currently documented.
</div>
<div class="language-csharp">
~~~{.cs}
using FlatBuffers;
using Example.VectorOfUnions;
var fbb = new FlatBufferBuilder(100);
var characterTypes = new[]
{
Character.MuLan,
Character.Belle,
Character.Other,
};
var characterTypesOffset = Movie.CreateCharactersTypeVector(fbb, characterTypes);
var characters = new[]
{
Attacker.CreateAttacker(fbb, 10).Value,
BookReader.CreateBookReader(fbb, 20).Value,
fbb.CreateSharedString("Chip").Value,
};
var charactersOffset = Movie.CreateCharactersVector(fbb, characters);
var movieOffset = Movie.CreateMovie(
fbb,
Character.Rapunzel,
rapunzel,
characterTypesOffset,
charactersOffset);
Movie.FinishMovieBuffer(fbb, movieOffset);
~~~
</div>
<div class="language-kotlin">
Kotlin supports vectors of unions, but it isn't currently documented.
</div>
<div class="language-swift">
Swift supports vectors of unions, but it isn't currently documented.
</div>
#### Reading
<div class="language-csharp">
~~~{.cs}
var movie = Movie.GetRootAsMovie(fbb.DataBuffer);
for (var i = 0; i <= movie.CharactersLength; i++)
{
if (movie.CharactersType(i) == Character.MuLan)
{
var mulanSwordDamage = movie.Characters<Attacker>(i).Value.SwordAttackDamage;
}
else if (movie.CharactersType(i) == Character.Belle)
{
var belleBooksRead = movie.Characters<BookReader>(i).Value.BooksRead;
}
else if (movie.CharactersType(i) == Character.Other)
{
var otherStr = movie.CharactersAsString(i);
}
}
~~~
</div>
### Further Reading
Each language has a dedicated `Use in XXX` page in the Programmer's Guide
to cover the nuances of FlatBuffers in that language.