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local rex = require('rex_pcre')
local string = require('string')
local table = require('table')
local types = require('types')
local throw, Nil, Symbol, List = types.throw, types.Nil,
types.Symbol, types.List
local M = {}
Reader = {}
function Reader:new(tokens)
local newObj = {tokens = tokens, position = 1}
self.__index = self
return setmetatable(newObj, self)
end
function Reader:next()
self.position = self.position + 1
return self.tokens[self.position-1]
end
function Reader:peek()
return self.tokens[self.position]
end
function M.tokenize(str)
local results = {}
local re_pos = 1
local re = rex.new("[\\s,]*(~@|[\\[\\]{}()'`~^@]|\"(?:\\\\.|[^\\\\\"])*\"|;[^\n]*|[^\\s\\[\\]{}('\"`,;)]*)", rex.flags().EXTENDED)
while true do
local s, e, t = re:exec(str, re_pos)
if not s or s > e then break end
re_pos = e + 1
local val = string.sub(str,t[1],t[2])
if string.sub(val,1,1) ~= ";" then
table.insert(results, val)
end
end
return results
end
function M.read_atom(rdr)
local int_re = rex.new("^-?[0-9]+$")
local float_re = rex.new("^-?[0-9][0-9.]*$")
local token = rdr:next()
if int_re:exec(token) then return tonumber(token)
elseif float_re:exec(token) then return tonumber(token)
elseif string.sub(token,1,1) == '"' then
local sval = string.sub(token,2,string.len(token)-1)
sval = string.gsub(sval, '\\"', '"')
sval = string.gsub(sval, '\\n', '\n')
return sval
elseif string.sub(token,1,1) == ':' then
return "\177" .. string.sub(token,2)
elseif token == "nil" then return Nil
elseif token == "true" then return true
elseif token == "false" then return false
else return Symbol:new(token)
end
end
function M.read_sequence(rdr, start, last)
local ast = {}
local token = rdr:next()
if token ~= start then throw("expected '"..start.."'") end
token = rdr:peek()
while token ~= last do
if not token then throw("expected '"..last.."', got EOF") end
table.insert(ast, M.read_form(rdr))
token = rdr:peek()
end
rdr:next()
return ast
end
function M.read_list(rdr)
return types.List:new(M.read_sequence(rdr, '(', ')'))
end
function M.read_vector(rdr)
return types.Vector:new(M.read_sequence(rdr, '[', ']'))
end
function M.read_hash_map(rdr)
local seq = M.read_sequence(rdr, '{', '}')
return types._assoc_BANG(types.HashMap:new(), unpack(seq))
end
function M.read_form(rdr)
local token = rdr:peek()
if "'" == token then
rdr:next()
return List:new({Symbol:new('quote'), M.read_form(rdr)})
elseif '`' == token then
rdr:next()
return List:new({Symbol:new('quasiquote'), M.read_form(rdr)})
elseif '~' == token then
rdr:next()
return List:new({Symbol:new('unquote'), M.read_form(rdr)})
elseif '~@' == token then
rdr:next()
return List:new({Symbol:new('splice-unquote'), M.read_form(rdr)})
elseif '^' == token then
rdr:next()
local meta = M.read_form(rdr)
return List:new({Symbol:new('with-meta'), M.read_form(rdr), meta})
elseif '@' == token then
rdr:next()
return List:new({Symbol:new('deref'), M.read_form(rdr)})
elseif ')' == token then throw("unexpected ')'")
elseif '(' == token then return M.read_list(rdr)
elseif ']' == token then throw("unexpected ']'")
elseif '[' == token then return M.read_vector(rdr)
elseif '}' == token then throw("unexpected '}'")
elseif '{' == token then return M.read_hash_map(rdr)
else return M.read_atom(rdr)
end
end
function M.read_str(str)
local tokens = M.tokenize(str)
if #tokens == 0 then error(nil) end
return M.read_form(Reader:new(tokens))
end
return M
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