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--- lam.read
local read = {}
local types = require "types"
local util = require "util"
function read.tokenize (str)
--[[ Convert a string of characters into a list of tokens ]]
assert(str, "No program given")
local tbl = {}
local word = ""
local push_word =
function ()
if word:len() > 0 then
table.insert(tbl, word)
word = ""
end
end
for c = 1, #str do
char = string.char(str:byte(c))
if char == " " or char == "\t" or char == "\n" then
push_word()
elseif char == "(" then
push_word()
table.insert(tbl, "(")
elseif char == ")" then
push_word()
table.insert(tbl, ")")
else
word = word .. char
end
end
push_word()
return tbl
end
function read.read (str)
-- [[ Read a scheme expression from a string ]]
local function Atom (token)
local n = tonumber(token)
if n then return n
else return tostring(token)
end
end
local function read_tokens (tokens)
--[[ Read a list of tokens from `tokenize' ]]
assert(next(tokens), "Unexpected EOF")
token = util.pop(tokens)
if token == "(" then
local L = {}
while tokens[1] ~= ")" do
table.insert(L, read_tokens(tokens))
end
util.pop(tokens) -- remove ")"
return L
elseif token == ")" then
error("Unexpected ')'")
else
return Atom(token)
end
end
return read_tokens(read.tokenize(str))
end
return setmetatable(read, { __call =
function(_, str)
return read.read(str)
end,
})
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