From afec5a7e05a9960b1f60be44a77fda8f771c9504 Mon Sep 17 00:00:00 2001
From: Tyler Wardhaugh <tyler.wardhaugh@gmail.com>
Date: Sat, 10 Oct 2020 22:58:01 -0700
Subject: Ch81 [Lua]: Tasks 1 & 2

I used LPeg for both of these solutions, which is surely overkill. But I
wanted to experiment with it.
---
 challenge-081/tyler-wardhaugh/lua/ch-2.lua | 73 ++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100755 challenge-081/tyler-wardhaugh/lua/ch-2.lua

(limited to 'challenge-081/tyler-wardhaugh/lua/ch-2.lua')

diff --git a/challenge-081/tyler-wardhaugh/lua/ch-2.lua b/challenge-081/tyler-wardhaugh/lua/ch-2.lua
new file mode 100755
index 0000000000..49b5732fb1
--- /dev/null
+++ b/challenge-081/tyler-wardhaugh/lua/ch-2.lua
@@ -0,0 +1,73 @@
+#!/usr/bin/env lua
+
+--[[
+   An iterator over a table yielding keys (and their corresponding values) in
+   sorted order.
+
+   source: ideas from "keysToList" (and others) in:
+      http://lua-users.org/wiki/SortedIteration
+]]--
+function ordered_pairs(tbl, cmp)
+  local o = {}
+  for k, _ in pairs(tbl) do table.insert(o, k) end
+  table.sort(o, cmp)
+
+  local i = 0
+  return function()
+    i = i + 1
+    return o[i], tbl[o[i]]
+  end
+end
+
+local t2 = {}
+
+do
+  local lpeg = require'lpeg'
+  lpeg.locale(lpeg)
+  local C, Cs, Ct, P, S = lpeg.C, lpeg.Cs, lpeg.Ct, lpeg.P, lpeg.S
+
+  local strip = (S[[."(),]] + P"'s" + P"--" + P"\n")
+  t2.sanitizer = Cs((strip / " " + 1)^0)
+
+  local space = lpeg.space^1
+  local word = C((1 - space)^1)
+  t2.wordify = Ct(word * (space * word)^0)
+end
+
+function t2.frequency_sort(text)
+  local sanitized = t2.sanitizer:match(text)
+  local words = t2.wordify:match(sanitized)
+
+  local count = {}
+  for _, v in ipairs(words) do count[v] = (count[v] or 0) + 1 end
+
+  local invert = {}
+  for k, v in pairs(count) do
+    if invert[v] then
+      table.insert(invert[v], k)
+    else
+      invert[v] = {k}
+    end
+  end
+
+  for _, v in pairs(invert) do table.sort(v) end
+
+  return invert
+end
+
+function t2.slurp(input)
+  local fh = assert(io.open(input, "r"))
+  local text = fh:read("*all")
+  fh:close()
+  return text
+end
+
+function t2.run(args)
+  local input = args[1]
+  local results = t2.frequency_sort(t2.slurp(input))
+  for k, v in ordered_pairs(results) do
+    print(k, table.concat(v, " "), "\n")
+  end
+end
+
+return t2
-- 
cgit