From d53cd1d0ad4f729f50e3e15e330c10e10559c671 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sun, 9 Feb 2020 22:18:15 -0500
Subject: [PATCH] start on State class

---
 Rsconscript |  1 +
 src/main.d  |  2 ++
 src/state.d | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)
 create mode 100644 src/state.d

diff --git a/Rsconscript b/Rsconscript
index 433bebf..054b5e0 100644
--- a/Rsconscript
+++ b/Rsconscript
@@ -4,6 +4,7 @@ end
 
 build do
   Environment.new do |env|
+    env["D_IMPORT_PATH"] << "src"
     env.Program("peg-puzzle", glob("src/**/*.d"))
   end
 end
diff --git a/src/main.d b/src/main.d
index ed9b871..e0cdd77 100644
--- a/src/main.d
+++ b/src/main.d
@@ -1,7 +1,9 @@
 import std.stdio;
+import state;
 
 int main(string[] args)
 {
+    State s = new State(3);
     writeln("Peg Puzzle");
     return 0;
 }
diff --git a/src/state.d b/src/state.d
new file mode 100644
index 0000000..50a9b5e
--- /dev/null
+++ b/src/state.d
@@ -0,0 +1,36 @@
+class State
+{
+    private int m_size;
+    private bool[] m_pegs;
+
+    this(int size)
+    {
+        assert(size >= 3);
+        m_size = size;
+        const int n_pegs = (size * (size + 1)) / 2;
+        m_pegs = new bool[n_pegs];
+        m_pegs[] = true;
+        m_pegs[0] = false;
+    }
+
+    this(State s)
+    {
+        m_size = s.m_size;
+        m_pegs = s.m_pegs.dup;
+    }
+
+    private int peg_index(int row, int col)
+    {
+        return (row * (row + 1)) / 2 + col;
+    }
+
+    bool valid_position(int row, int col)
+    {
+        return (row >= 0) && (row < m_size) && (col >= 0) && (col <= row);
+    }
+
+    bool peg_present(int row, int col)
+    {
+        return m_pegs[peg_index(row, col)];
+    }
+}