From 9da4ba3b74d5725160831cce8ec94e5e2f47daf7 Mon Sep 17 00:00:00 2001
From: Dennis Neufeld <dennis.neufeld@students.bfh.ch>
Date: Fri, 23 Oct 2020 19:50:33 +0200
Subject: anastasis reducer

---
 anastasis.rst | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

(limited to 'anastasis.rst')

diff --git a/anastasis.rst b/anastasis.rst
index 355d0d7a..f7232c59 100644
--- a/anastasis.rst
+++ b/anastasis.rst
@@ -815,10 +815,79 @@ Anastasis Reducer API
 
 This section describes the Anastasis Reducer API which is used by client applications
 to store or load the different states the client application can have.
+The reducer takes a state_ in JSON syntax and returns the new state in JSON syntax.
+
+For example a **state** may take the following structure:
+::
+
+    {
+      "backup_state": "CONTINENT_SELECTING",
+      "continents": [
+        "Europe",
+        "North_America"
+      ]
+    }
+
+The new state depends on the previous one and on the transition action_ with its
+arguments given to the reducer. A **transition argument** also is a statement in JSON syntax:
+::
+
+    {
+      "continent": "Europe"
+    }
+
+The new state returned by the reducer with the state and transition argument defined
+above would look like following for the transition action_ "select_continent":
+::
+
+  {
+    "backup_state": "COUNTRY_SELECTING",
+    "continents": [
+      "Europe",
+      "North_America"
+    ],
+    "selected_continent": "Europe",
+    "countries": [
+      {
+        "code": "ch",
+        "name": "Switzerland",
+        "continent": "Europe",
+        "name_i18n": {
+          "de_DE": "Schweiz",
+          "de_CH": "Schwiiz",
+          "fr": "Suisse",
+          "en": "Swiss"
+        },
+        "currency": "CHF"
+      },
+      {
+        "code": "de",
+        "name": "Germany",
+        "continent": "Europe",
+        "continent_i18n": {
+          "de": "Europa"
+        },
+        "name_i18n": {
+          "de_DE": "Deutschland",
+          "de_CH": "Deutschland",
+          "fr": "Allemagne",
+          "en": "Germany"
+        },
+        "currency": "EUR"
+      }
+    ]
+  }
+
+**State**:
+  - In SELECTING-States the user has to choose one value out of a predefined set of values (for example a continent out of a set of continents).
+  - In COLLECTING-States the user has to give certain values.
+  - In EDITING-States the user is free to choose which values he wants to give.
 
 
 Backup Reducer
 ^^^^^^^^^^^^^^
+.. _state:
+.. _action:
 .. figure:: anastasis_reducer_backup.png
     :name: fig-anastasis_reducer_backup
     :alt: fig-anastasis_reducer_backup
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