From 26acf1752df58c565b349cf4c6963a2d18950a36 Mon Sep 17 00:00:00 2001
From: Max Cahill <1bardesign@gmail.com>
Date: Fri, 17 Apr 2020 10:35:00 +1000
Subject: [PATCH] [added] stringx module (just split for now) and overlay to
 string on export

---
 init.lua    | 10 +++++++++-
 stringx.lua | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 stringx.lua

diff --git a/init.lua b/init.lua
index 1afd3b3..349b690 100644
--- a/init.lua
+++ b/init.lua
@@ -34,6 +34,8 @@ local _stable_sort = require_relative("stable_sort")
 local _functional = require_relative("functional")
 local _sequence = require_relative("sequence")
 
+local _stringx = require_relative("stringx")
+
 local _vec2 = require_relative("vec2")
 local _vec3 = require_relative("vec3")
 local _intersect = require_relative("intersect")
@@ -59,6 +61,9 @@ local _batteries = {
 	--
 	table = _tablex,
 	tablex = _tablex,
+	--
+	string = _stringx,
+	stringx = _stringx,
 	--sorting routines
 	stable_sort = _stable_sort,
 	sort = _stable_sort,
@@ -66,7 +71,7 @@ local _batteries = {
 	functional = _functional,
 	--
 	sequence = _sequence,
-	--
+	--geom
 	vec2 = _vec2,
 	vec3 = _vec3,
 	intersect = _intersect,
@@ -98,6 +103,9 @@ function _batteries:export(self)
 	--overlay onto math
 	_tablex.overlay(math, _mathx)
 
+	--overlay onto string
+	_tablex.overlay(string, _stringx)
+
 	--export geom
 	vec2 = _vec2
 	vec3 = _vec3
diff --git a/stringx.lua b/stringx.lua
new file mode 100644
index 0000000..e98ece1
--- /dev/null
+++ b/stringx.lua
@@ -0,0 +1,53 @@
+--[[
+	extra string routines
+]]
+
+local stringx = setmetatable({}, {
+	__index = string
+})
+
+--split a string on a delimiter into an ordered table
+function stringx:split(delim)
+	--try to create as little garbage as possible!
+	--one table to contain the result, plus the split strings should be all we need
+	--as such we work with the bytes underlying the string, as string.find is not compiled on older luajit :)
+	local length = self:len()
+	--
+	local delim_length = delim:len()
+	local delim_start = delim:byte(1)
+	--iterate through and collect split sites
+	local res = {}
+	local i = 1
+	while i <= length do
+		--scan for delimiter
+		if self:byte(i) == delim_start then
+			local has_whole_delim = true
+			for j = 2, delim_length do
+				if self:byte(i + j - 1) ~= delim:byte(j) then
+					has_whole_delim = false
+					break
+				end
+			end
+			if has_whole_delim then
+				table.insert(res, i)
+			end
+			--iterate forward
+			i = i + delim_length
+		else
+			--iterate forward
+			i = i + 1
+		end
+	end
+	--re-iterate, collecting substrings
+	i = 1
+	for si, j in ipairs(res) do
+		res[si] = self:sub(i, j-1)
+		i = j + delim_length
+	end
+	--add the final section
+	table.insert(res, self:sub(i, -1))
+	--return the collection
+	return res
+end
+
+return stringx