1 files changed, 100 insertions, 0 deletions
diff --git a/src/ast_opts.lua b/src/ast_opts.lua
new file mode 100644
index 0000000..de49932
--- /dev/null
+++ b/src/ast_opts.lua
@@ -0,0 +1,100 @@
+--[[
+	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