From 8c290732607692cd94247f7e3e9c80fad1dfe516 Mon Sep 17 00:00:00 2001
From: Jules Aguillon
Date: Sun, 11 Feb 2024 20:46:36 +0100
Subject: Compose key

The COMPOSE_PENDING modifier indicate whether a compose sequence is in
progress. The new key of kind Compose_pending sets the current state of
the sequence.

The compose sequences are compiled into a state machine by a python
script into a compact encoding.

The state of the pending compose is determined by the index of a state.
---
 srcs/juloo.keyboard2/ComposeKey.java | 55 ++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 srcs/juloo.keyboard2/ComposeKey.java

(limited to 'srcs/juloo.keyboard2/ComposeKey.java')

diff --git a/srcs/juloo.keyboard2/ComposeKey.java b/srcs/juloo.keyboard2/ComposeKey.java
new file mode 100644
index 0000000..5b89560
--- /dev/null
+++ b/srcs/juloo.keyboard2/ComposeKey.java
@@ -0,0 +1,55 @@
+package juloo.keyboard2;
+
+import java.util.Arrays;
+
+public final class ComposeKey
+{
+  /** Apply the pending compose sequence to [kv]. Returns [null] if [kv] is not
+      part of the pending sequence. */
+  public static KeyValue apply(int state, KeyValue kv)
+  {
+    switch (kv.getKind())
+    {
+      case Char: return apply(state, kv.getChar());
+      /* These keys must not be removed. */
+      case Event: return kv;
+      case Modifier: return kv;
+      /* These keys cannot be part of sequences. */
+      case String: return null;
+      case Keyevent: return null;
+      case Editing: return null;
+      case Placeholder: return null;
+      case Compose_pending: return null;
+    }
+    return null;
+  }
+
+  /** Apply the pending compose sequence to char [c]. */
+  static KeyValue apply(int state, char c)
+  {
+    char[] states = ComposeKeyData.states;
+    short[] edges = ComposeKeyData.edges;
+    int length = edges[state];
+    int next = Arrays.binarySearch(states, state + 1, state + length, c);
+    if (next < 0)
+      return null;
+    next = edges[next];
+    // The next state is the end of a sequence, show the result.
+    if (edges[next] == 1)
+      return KeyValue.makeCharKey(states[next]);
+    return KeyValue.makeComposePending(String.valueOf(c), next, 0);
+  }
+
+  /** The [states] array represents the different states and their transition.
+      A state occupies one or several cells of the array:
+      - The first cell is the result of the conpose sequence if the state is of
+        size 1, [0] otherwise.
+      - The remaining cells are the transitions, sorted alphabetically.
+
+      The [edges] array represents the transition state corresponding to each
+      accepted inputs.
+      Id [states[i]] is the first cell of a state, [edges[i]] is the number of
+      cells occupied by the state [i].
+      If [states[i]] is a transition, [edges[i]] is the index of the state to
+      jump into. */
+}
-- 
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