From 8a81ff2f6337b45b948cd2b7a524d87c57dbc45c Mon Sep 17 00:00:00 2001
From: Nicholas Dunn <nexela@gmail.com>
Date: Sun, 19 May 2019 20:29:36 -0400
Subject: [PATCH] Add Vendor pulsar A* pathfinding

---
 stdlib/vendor/pulsar.lua | 163 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 163 insertions(+)
 create mode 100644 stdlib/vendor/pulsar.lua

diff --git a/stdlib/vendor/pulsar.lua b/stdlib/vendor/pulsar.lua
new file mode 100644
index 00000000..2bd815ae
--- /dev/null
+++ b/stdlib/vendor/pulsar.lua
@@ -0,0 +1,163 @@
+-- pulsar.lua - v1.0 (2011-11)
+-- Copyright (c) 2011 Enrique García Cota
+-- Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+-- The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+local Path = {}
+
+local pathmt = {
+
+  __tostring = function(self)
+
+    local buffer = {}
+    for i=1,#self do
+      buffer[#buffer+1] = tostring(self[i])
+    end
+    return ("{ %s }"):format(table.concat(buffer, ', '))
+
+  end,
+
+  __eq = function(self, other)
+
+    local myLength, otherLength = #self, #other
+    if myLength ~= otherLength then return false end
+
+    for i=1, myLength do
+      if self[i] ~= other[i] then return false end
+    end
+
+    return true
+  end
+}
+
+function Path:new(...)
+  return setmetatable({...}, pathmt)
+end
+
+----------------------------------------------------------------------------
+
+local Node = {}
+
+function Node:new(location, parent, g, h)
+  local node = {
+    parent = parent,
+    location = location,
+    g = g,
+    h = h,
+    f = g + h
+  }
+  return node
+end
+
+----------------------------------------------------------------------------
+
+local Finder = {}
+local findermt = { __index = Finder }
+
+local function sortByf(a,b)
+  return a.f < b.f
+end
+
+local function sortOpenIfNeeded(self)
+  if not self.openIsSorted then
+    table.sort(self.open, sortByf)
+    self.openIsSorted = true
+  end
+end
+
+local function createNode(self, location, parent, g, h)
+  parent = parent or self.bestNode
+  local parentLocation = parent and parent.location or self.origin
+  g = g or self.cost(parentLocation, location)
+  h = h or self.heuristic(parentLocation, location)
+
+  local node = Node:new(location, parent, g, h)
+  self.nodes[location] = node
+  return node
+end
+
+local function checkAndSetParam(finder, value, name)
+  assert(value, ("%s expected. Was (%s)"):format(name, tostring(value)))
+  finder[name] = value
+end
+
+function Finder:findPath()
+  local result = Path:new()
+
+  while self.bestLocation ~= self.destination do
+    self:findNext()
+    table.insert(result, self.bestLocation)
+  end
+
+  return result
+end
+
+function Finder:findNext()
+  local neighbors = self.neighbors(self.bestLocation)
+  table.sort(neighbors, self.sort)
+  self.bestLocation = neighbors[1]
+end
+
+function Finder:getOrCreateNode(location, parent, g, h)
+  return self.nodes[location] or createNode(self, location, parent, g, h)
+end
+
+function Finder:new(origin, destination, neighbors, cost, heuristic)
+  local finder = {}
+  checkAndSetParam(finder, origin, "origin")
+  checkAndSetParam(finder, destination, "destination")
+  checkAndSetParam(finder, neighbors, "neighbors")
+  checkAndSetParam(finder, cost, "cost")
+  checkAndSetParam(finder, heuristic, "heuristic")
+
+  finder.bestLocation = origin
+  finder.sort = function(node1, node2) return heuristic(node1, destination) < heuristic(node2, destination) end
+
+  finder.nodes = {}
+  finder.open = {}
+
+  setmetatable(finder, findermt)
+  local initialNode = finder:getOrCreateNode(origin, nil, 0, heuristic(origin, destination))
+  finder:openNode(initialNode)
+  finder.bestNode=initialNode
+  return finder
+end
+
+
+function Finder:openNode(node)
+  node.open = true
+  table.insert(self.open, node)
+  self.openIsSorted = false
+end
+
+function Finder:closeNode(node)
+  node.open = false
+end
+
+function Finder:pickNextBestNode()
+  sortOpenIfNeeded(self)
+  local node = self.open[1]
+  if node then
+    table.remove(self.open, 1)
+    return node
+  end
+end
+
+function Finder:openNeighbors()
+  local neighbors = self.neighbors(self.bestLocation)
+  for i=1, #neighbors do
+    self:openNode(self:getOrCreateNode(neighbors[i]))
+  end
+end
+
+----------------------------------------------------------------------------
+
+local pulsar = {}
+
+pulsar.Path = Path
+pulsar.Node = Node
+pulsar.Finder = Finder
+
+
+return pulsar