forth-stuff/Interpreters.tl

local ds = require("DataStructures")
local Stack, Dictionary, WordInfo, Environment = ds.Stack, ds.Dictionary, ds.WordInfo, ds.Environment
local helpers = require("CoreHelpers")
local isNumber, skipWhitespace, parseToken = helpers.isNumber, helpers.skipWhitespace, helpers.parseToken
local istream = require("InputStream")
local CoreWords = require("CoreWords")
local Pointer = ds.Pointer
local type Interpreters = record
	inner: function(Environment)
	outer: function(Environment)
end

function Interpreters.start(env: Environment)
	table.insert(env.dictionaries, CoreWords)
	local interpreterInstructions = {}
	table.insert(interpreterInstructions, Interpreters.outer)
	table.insert(interpreterInstructions, helpers.reset)
	table.insert(env.recognizers, helpers.recNumber)
	table.insert(env.recognizers, helpers.recWord)
	local startPointer = Pointer:new()
	startPointer.referant = interpreterInstructions
	env.instructionPointer = startPointer
	Interpreters.inner(env)
end


function selectRecXT(env: Environment): function(Environment)
	local dataStack = env.activeDataStack
	if env.compileState then
		dataStack:pop()
		local selected = dataStack:pop()
		dataStack:pop()
		return selected as function(Environment)
	else
		dataStack:pop()
		dataStack:pop()
		return dataStack:pop() as function(Environment)
	end
end


function Interpreters.outer(env: Environment)
	local dataStack = env.activeDataStack
	skipWhitespace(env)
	local token: string | nil = parseToken(env)
	if not token then
		env.running = false
		return
	end
	for _, rec in ipairs(env.recognizers) do
		dataStack:push(token)
		rec(env)
		local result = dataStack:pop() as boolean
		if not result then
			token = dataStack:pop() as string
		end
		if result then
			(selectRecXT(env))(env)
			return
		end
	end
	
	-- We did not recognize the token.
	io.write("\""..token.."\"?\n")
end
			
function Interpreters.inner(env: Environment)
	while(env.running) do
		env.instructionPointer:deref() as function(Environment)(env)
		env.instructionPointer:inc()
	end
end

return Interpreters