From a5c540608c469a2797262facb766e175b932f0e2 Mon Sep 17 00:00:00 2001
From: Andinus <andinus@nand.sh>
Date: Tue, 19 Jan 2021 21:53:16 +0530
Subject: Re-structure for CPAN upload, include a dictionary file

bin/octans calls lib/Octans/CLI.rakumod which has the MAIN subroutine.
---
 lib/Octans/Neighbors.rakumod | 53 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 lib/Octans/Neighbors.rakumod

(limited to 'lib/Octans/Neighbors.rakumod')

diff --git a/lib/Octans/Neighbors.rakumod b/lib/Octans/Neighbors.rakumod
new file mode 100644
index 0000000..c6f1c00
--- /dev/null
+++ b/lib/Octans/Neighbors.rakumod
@@ -0,0 +1,53 @@
+unit module Octans::Neighbors;
+
+# neighbors returns the neighbors of given index. Neighbors are cached
+# in @neighbors array. This way we don't have to compute them
+# everytime neighbors subroutine is called for the same position.
+sub neighbors (
+    @puzzle, Int $y, Int $x --> List
+) is export {
+    # @directions is holding a list of directions we can move in. It's
+    # used later for neighbors subroutine.
+    state List @directions = (
+        # $y, $x
+        ( +1, +0 ), # bottom
+        ( -1, +0 ), # top
+        ( +0, +1 ), # left
+        ( +0, -1 ), # right
+    );
+
+    # @neighbors holds the neighbors of given position.
+    state Array @neighbors;
+
+    if @puzzle[$y][$x] {
+
+        # If we've already computed the neighbors then no need to do
+        # it again.
+        unless @neighbors[$y][$x] {
+            my Int $pos-x;
+            my Int $pos-y;
+
+            # Starting from the intital position of $y, $x we move to
+            # each direction according to the values specified in
+            # @directions array. In this case we're just trying to
+            # move in 4 directions (top, bottom, left & right).
+            DIRECTION: for @directions -> $direction {
+                $pos-y = $y + $direction[0];
+                $pos-x = $x + $direction[1];
+
+                # If movement in this direction is out of puzzle grid
+                # boundary then move on to next direction.
+                next DIRECTION unless @puzzle[$pos-y][$pos-x];
+
+                # If neighbors exist in this direction then add them
+                # to @neighbors[$y][$x] array.
+                push @neighbors[$y][$x], [$pos-y, $pos-x];
+            }
+        }
+    } else {
+        # If it's out of boundary then return no neighbor.
+        @neighbors[$y][$x] = [];
+    }
+
+    return @neighbors[$y][$x];
+}
-- 
cgit 1.4.1-2-gfad0