From b38df089cc2c4694c542e97e9b990a6fda65643b Mon Sep 17 00:00:00 2001
From: Alexander Pickering <alex@cogarr.net>
Date: Fri, 21 Aug 2020 12:45:19 -0400
Subject: Add rockspec

Add a rockspec for easy packaging
---
 src/ast_opts.lua | 251 +++++++++++++++++++++++++++++++++----------------------
 1 file changed, 151 insertions(+), 100 deletions(-)

(limited to 'src/ast_opts.lua')

diff --git a/src/ast_opts.lua b/src/ast_opts.lua
index de49932..060c0ac 100644
--- a/src/ast_opts.lua
+++ b/src/ast_opts.lua
@@ -1,100 +1,151 @@
---[[
-	Optimizatoins for abstract syntax trees
-]]
-local msg = io.write
---A debugging function, a replacement for glua PrintTable
-local function printtable(tbl, tabset)
-    tabset = tabset or 0
-    for k,v in pairs(tbl) do
-        for i = 0,tabset do msg("\t") end
-        msg(k .. ":")
-        if type(v) == "table" then
-            msg("\n")
-            printtable(v, tabset + 1)
-        else
-            msg(tostring(v) .. "\n")
-        end
-    end
-end
-
---A function to see if two ast's are equal-ish (does not compare position)
-local function deepcompare(tbl1, tbl2)
-	if type(tbl1) ~= type(tbl2) then return false end
-    for k,v in pairs(tbl1) do
-		print("Checking ", k, " from tbl1")
-		if k == "pos" then goto cont end
-        if type(v) == "table" then
-			print("It is a table! going deeper")
-            if not deepcompare(v,tbl2[k]) then
-                return false
-            end
-        else
-			print("Checking ", v , " against ", tbl2[k])
-            if v ~= tbl2[k] then
-                return false
-            end
-        end
-		::cont::
-    end
-	return true
-end
-
-local opts = {}
-
---Optimization 1
---Folds things with an operator when the fold results in a smaller string
-local foldables = {
-	["add"] = function(a,b) return a + b end,
-	["mul"] = function(a,b) return a * b end,
-	["mod"] = function(a,b) return a % b end,
-	["sub"] = function(a,b) return a - b end,
-	--["div"] = function(a,b) return a / b end, division has the chance to give us really long strings!
-}
-opts[1] = function(ast)
-	if ast.tag ~= "Op" then return false end
-	local opname = ast[1]
-	local func = foldables[opname]
-	if ast[3] ~= nil and func ~= nil and ast[2].tag == "Number" and ast[3].tag == "Number" then
-		ast.tag = "Number"
-		ast[1] = func(ast[2][1],ast[3][1])
-		for i = 2,#ast do
-			ast[i] = nil
-		end
-		return true
-	end
-	return false
-end
-
---Optimization 2
---Find places where we can replace calls with invokes.
-opts[2] = function(ast)
-	if ast.tag == "Call" and ast.pos == 160 then
-		print("Ast:")
-		printtable(ast)
-		print("ast[1][1]")
-		printtable(ast[1][1])
-		print("ast[2]")
-		printtable(ast[2])
-		local dcr = deepcompare(ast[1][1],ast[2])
-		print("Deepcompare:",dcr)
-		--error("stopping")
-	end
-	if ast.tag == "Call" and deepcompare(ast[1][1][1], ast[2][1]) then
-		print("Before correcting for invoke, ast is")
-		printtable(ast)
-		for i = 2,#ast[2] do
-			ast[i] = ast[i+1]
-		end
-		ast.tag = "Invoke"
-		ast[2] = ast[1][2]
-		ast[1] = ast[1][1]
-		print("After correcting for invoke, ast is")
-		printtable(ast)
-
-		--error("Call that should be invoke detected")
-		return true
-	end
-
-end
-
-return opts
+--[[
+	Optimizatoins for abstract syntax trees
+]]
+local msg = io.write
+
+--A debugging function, a replacement for glua PrintTable
+local function printtable(tbl, tabset)
+    tabset = tabset or 0
+    for k,v in pairs(tbl) do
+        for i = 0,tabset do msg("\t") end
+        msg(k .. ":")
+        if type(v) == "table" then
+            msg("\n")
+            printtable(v, tabset + 1)
+        else
+            msg(tostring(v) .. "\n")
+        end
+    end
+end
+
+--A function to see if two tables are equal-ish
+local function deepcompare(tbl1, tbl2)
+	if type(tbl1) ~= type(tbl2) then return false end
+    for k,v in pairs(tbl1) do
+		print("Checking ", k, " from tbl1")
+		if k == "pos" then goto cont end
+        if type(v) == "table" then
+			print("It is a table! going deeper")
+            if not deepcompare(v,tbl2[k]) then
+                return false
+            end
+        else
+			print("Checking ", v , " against ", tbl2[k])
+            if v ~= tbl2[k] then
+                return false
+            end
+        end
+		::cont::
+    end
+	return true
+end
+
+--Makes sure 2 things are refrenceing the same index
+local function indexcompare(tbl1,tbl2)
+	if type(tbl1) ~= "table" or type(tbl2) ~= "table" then return false end
+	--print("indexcompare is checking ",tbl1,tbl2)
+	--printtable(tbl1)
+	--print("is the same as")
+	--printtable(tbl2)
+	if tbl1.tag == "Id" and tbl2.tag == "Id" then
+		return tbl1[1] == tbl2[1]
+	elseif tbl1.tag == "Index" and tbl2.tag == "Index" then
+		return indexcompare(tbl1[1],tbl2[1]) and indexcompare(tbl1[2],tbl2[2])
+	elseif tbl1.tag == "String" and tbl2.tag == "String" then
+		return tbl1[1] == tbl2[1]
+	else
+		return false
+	end
+end
+
+local opts = {}
+
+--Optimization 1
+--Folds things with an operator when we have numbers on both sides, and the fold results in a smaller string
+local foldables = {
+	["add"] = function(a,b) return a + b end,
+	["mul"] = function(a,b) return a * b end,
+	["mod"] = function(a,b) return a % b end,
+	["sub"] = function(a,b) return a - b end,
+	--["div"] = function(a,b) return a / b end,-- division has the chance to give us really long strings!
+}
+opts[1] = function(ast)
+	if ast.tag ~= "Op" then return false end
+	local opname = ast[1]
+	local func = foldables[opname]
+	if ast[3] ~= nil and func ~= nil and ast[2].tag == "Number" and ast[3].tag == "Number" then
+		ast.tag = "Number"
+		ast[1] = func(ast[2][1],ast[3][1])
+		for i = 2,#ast do
+			ast[i] = nil
+		end
+		return true
+	end
+	return false
+end
+
+--Optimization 2
+--Find places where we can replace calls with invokes.
+--Lua provides syntax sugar where 
+--	table.method(table,arg1,arg2,...) 
+--is the same as
+--	table:method(arg1,arg2,...)
+opts[2] = function(ast)
+	--[[for debugging
+	if ast.tag == "Call" then
+		--print("Ast:")
+		--printtable(ast)
+		--print("ast[1][1]")
+		--printtable(ast[1][1])
+		--print("ast[2]")
+		--printtable(ast[2])
+		--local dcr = indexcompare(ast[1][1],ast[2])
+		--print("indexcompare:",dcr)
+		--error("stopping")
+	end
+	]]
+
+	--The ands are to make sure we short circut before indexing a nil
+	if ast.tag == "Call" and ast[1][1] and ast[2] and indexcompare(ast[1][1][1], ast[2][1]) then
+		--print("Before correcting for invoke, ast is")
+		--printtable(ast)
+		for i = 2,#ast[2] do
+			ast[i] = ast[i + 1]
+		end
+		ast.tag = "Invoke"
+		ast[2] = ast[1][2]
+		ast[1] = ast[1][1]
+
+		return true
+	end
+	return false
+end
+
+--Find places where we have multiple variables declared, but not initalized
+--and turn it into a 1-liner
+--so local a local b local c
+--becomes
+--local a,b,c
+--TODO: This can be done faster and in 1 pass with a little extra complexity
+opts[3] = function(ast)
+	if ast.tag == "Block" then
+		for i = 1,#ast do
+			if ast[i].tag == "Local" and next(ast[i][2]) == nil then
+				local cursor = ast[i]
+				local r
+				i = i + 1
+				while ast[i].tag == "Local" and next(ast[i][2]) == nil do
+					table.insert(cursor[1],ast[i][1][1])
+					table.remove(ast,i)
+					i = i + 1
+					r = true
+				end
+				if r then return true end
+			end
+		end
+		return false
+	end
+	return false
+end
+
+return opts
-- 
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