From 8ce2915e3c54598c2fda4fec0980ebfc2a3adf6e Mon Sep 17 00:00:00 2001
From: Case Duckworth
Date: Tue, 9 Apr 2024 21:04:17 -0500
Subject: Reorganization

---
 port.lua | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 port.lua

(limited to 'port.lua')

diff --git a/port.lua b/port.lua
new file mode 100644
index 0000000..812f05e
--- /dev/null
+++ b/port.lua
@@ -0,0 +1,103 @@
+--- lam.port --- port objects
+-- because the implementation for ports is fairly involved, they're in their own
+-- file outside of `type'.
+
+local m = {}
+local util = require("util")
+local error = util.error
+local tochars = util.tochars
+
+-- The EOF object is what the reader emits when it hits an end-of-file or use up
+-- a port.
+m.eof = setmetatable({}, {
+		__type = "eof",
+		__tostring = function () return "#<eof>" end,
+})
+
+---[[ INPUT PORTS ]]---
+
+-- return the next token from PORT, given READTABLE
+local function input_port_next_token (port, readtable)
+	repeat
+		if #port.buffer == 0 then
+			if port.file then
+				local ln = port.file:read()
+				if ln == nil then
+					return m.eof
+				end
+				port.buffer = tochars(ln)
+			else
+				return m.eof
+			end
+		end
+
+		local token, token_type
+		local c = port.buffer[1]
+		if readtable.chars[c] then
+			token, token_type, port.buffer =
+				readtable.chars[c](port.buffer)
+		else
+			for re, fn in pairs(readtable.regex) do
+				if c:match(re) then
+					token, token_type, port.buffer =
+						fn(port.buffer)
+					break
+				end
+			end
+			if token == nil then
+				token, token_type, port.buffer =
+					readtable.default(port.buffer)
+			end
+		end
+
+		port.buffer = port.buffer or {}
+		if token then
+			return token, token_type
+		end
+	until nil
+end
+
+function m.input_port (source, source_type)
+	-- SOURCE is the name of the file/string to read or nil; nil means
+	-- standard input.  SOURCE_TYPE is one of "file", "string"; "file" is
+	-- the default.
+	local f, b
+	source_type = source_type or "file"
+	if source then
+		if source_type == "file" then
+			f = io.open(source, "r")
+		elseif source_type == "string" then
+			b = tochars(source)
+		else
+			error("input-port: bad type", source_type)
+		end
+	else
+		f = io.input() -- ignore SOURCE_TYPE
+	end
+	local t = {
+		file = f,
+		name = f and source or "[string]",
+		type = source_type,
+		buffer = b or {},
+		flush = function (self) self.buffer = {} end,
+		next = input_port_next_token, -- port:next(readtable)
+		close =
+			function (self)
+				if self.file then self.file:close() end
+			end,
+	}
+	local mt = {
+		__type = "input-port",
+		__tostring =
+			function (self)
+				return string.format("#<port %s>", self.name)
+			end,
+	}
+	return setmetatable(t, mt)
+end
+
+---[[ OUTPUT PORTS ]]---
+-- TODO
+
+--------
+return m
-- 
cgit 1.4.1-21-gabe81