16815657215

Committed 07 Aug 2025 08:56PM UTC coverage: 88.858% (-0.01%) from 88.871%

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Tieske

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fix(*): some Lua 5.5 fixes for constant loop variables

see #497

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/lua/pl/seq.lua

--- Manipulating iterators as sequences.
-- See @{07-functional.md.Sequences|The Guide}
--
-- Dependencies: `pl.utils`, `pl.types`, `debug`
-- @module pl.seq

local next,assert,pairs,tonumber,type,setmetatable = next,assert,pairs,tonumber,type,setmetatable
local strfind,format = string.find,string.format
local mrandom = math.random
local tsort,tappend = table.sort,table.insert
local io = io
local utils = require 'pl.utils'
local callable = require 'pl.types'.is_callable
local function_arg = utils.function_arg
local assert_arg = utils.assert_arg
local debug = require 'debug'

local seq = {}

-- given a number, return a function(y) which returns true if y > x
-- @param x a number
function seq.greater_than(x)
  return function(v)
    return tonumber(v) > x
  end
end

-- given a number, returns a function(y) which returns true if y < x
-- @param x a number
function seq.less_than(x)
  return function(v)
    return tonumber(v) < x
  end
end

-- given any value, return a function(y) which returns true if y == x
-- @param x a value
function seq.equal_to(x)
  if type(x) == "number" then
    return function(v)
      return tonumber(v) == x
    end
  else
    return function(v)
      return v == x
    end
  end
end

--- given a string, return a function(y) which matches y against the string.
-- @param s a string
function seq.matching(s)
  return function(v)
     return strfind(v,s)
  end
end

local nexti

--- sequence adaptor for a table.   Note that if any generic function is
-- passed a table, it will automatically use seq.list()
-- @param t a list-like table
-- @usage sum(list(t)) is the sum of all elements of t
-- @usage for x in list(t) do...end
function seq.list(t)
  assert_arg(1,t,'table')
  if not nexti then
    nexti = ipairs{}
  end
  local key,value = 0
  return function()
    key,value = nexti(t,key)
    return value
  end
end

--- return the keys of the table.
-- @param t an arbitrary table
-- @return iterator over keys
function seq.keys(t)
  assert_arg(1,t,'table')
  local key
  return function()
    key = next(t,key)
    return key
  end
end

local list = seq.list
local function default_iter(iter)
  if type(iter) == 'table' then return list(iter)
  else return iter end
end

seq.iter = default_iter

--- create an iterator over a numerical range. Like the standard Python function xrange.
-- @param start a number
-- @param finish a number greater than start
function seq.range(start,finish)
  local i = start - 1
  return function()
      i = i + 1
      if i > finish then return nil
      else return i end
  end
end

-- count the number of elements in the sequence which satisfy the predicate
-- @param iter a sequence
-- @param condn a predicate function (must return either true or false)
-- @param optional argument to be passed to predicate as second argument.
-- @return count
function seq.count(iter,condn,arg)
  local i = 0
  seq.foreach(iter,function(val)
        if condn(val,arg) then i = i + 1 end
  end)
  return i
end

--- return the minimum and the maximum value of the sequence.
-- @param iter a sequence
-- @return minimum value
-- @return maximum value
function seq.minmax(iter)
  local vmin,vmax = 1e70,-1e70
  for val in default_iter(iter) do
    local v = tonumber(val)
    if v < vmin then vmin = v end
    if v > vmax then vmax = v end
  end
  return vmin,vmax
end

--- return the sum and element count of the sequence.
-- @param iter a sequence
-- @param fn an optional function to apply to the values
function seq.sum(iter,fn)
  local s = 0
  local i = 0
  for val in default_iter(iter) do
    local v
    if fn then
      v = fn(val)
    else
      v = val
    end
    s = s + v
    i = i + 1
  end
  return s,i
end

--- create a table from the sequence. (This will make the result a List.)
-- @param iter a sequence
-- @return a List
-- @usage copy(list(ls)) is equal to ls
-- @usage copy(list {1,2,3}) == List{1,2,3}
function seq.copy(iter)
    local res,k = {},1
    for v in default_iter(iter) do
        res[k] = v
        k = k + 1
    end
    setmetatable(res, require('pl.List'))
    return res
end

--- create a table of pairs from the double-valued sequence.
-- @param iter a double-valued sequence
-- @param i1 used to capture extra iterator values
-- @param i2 as with pairs & ipairs
-- @usage copy2(ipairs{10,20,30}) == {{1,10},{2,20},{3,30}}
-- @return a list-like table
function seq.copy2 (iter,i1,i2)
    local res,k = {},1
    for v1,v2 in iter,i1,i2 do
        res[k] = {v1,v2}
        k = k + 1
    end
    return res
end

--- create a table of 'tuples' from a multi-valued sequence.
-- A generalization of copy2 above
-- @param iter a multiple-valued sequence
-- @return a list-like table
function seq.copy_tuples (iter)
    iter = default_iter(iter)
    local res = {}
    local row = {iter()}
    while #row > 0 do
        tappend(res,row)
        row = {iter()}
    end
    return res
end

--- return an iterator of random numbers.
-- @param n the length of the sequence
-- @param l same as the first optional argument to math.random
-- @param u same as the second optional argument to math.random
-- @return a sequence
function seq.random(n,l,u)
  local rand
  assert(type(n) == 'number')
  if u then
     rand = function() return mrandom(l,u) end
  elseif l then
     rand = function() return mrandom(l) end
  else
     rand = mrandom
  end

  return function()
     if n == 0 then return nil
     else
       n = n - 1
       return rand()
     end
  end
end

--- return an iterator to the sorted elements of a sequence.
-- @param iter a sequence
-- @param comp an optional comparison function (comp(x,y) is true if x < y)
function seq.sort(iter,comp)
    local t = seq.copy(iter)
    tsort(t,comp)
    return list(t)
end

--- return an iterator which returns elements of two sequences.
-- @param iter1 a sequence
-- @param iter2 a sequence
-- @usage for x,y in seq.zip(ls1,ls2) do....end
function seq.zip(iter1,iter2)
    iter1 = default_iter(iter1)
    iter2 = default_iter(iter2)
    return function()
        return iter1(),iter2()
    end
end

--- Makes a table where the key/values are the values and value counts of the sequence.
-- This version works with 'hashable' values like strings and numbers.
-- `pl.tablex.count_map` is more general.
-- @param iter a sequence
-- @return a map-like table
-- @return a table
-- @see pl.tablex.count_map
function seq.count_map(iter)
    local t = {}
    local v
    for s in default_iter(iter) do
        v = t[s]
        if v then t[s] = v + 1
        else t[s] = 1 end
    end
    return setmetatable(t, require('pl.Map'))
end

-- given a sequence, return all the unique values in that sequence.
-- @param iter a sequence
-- @param returns_table true if we return a table, not a sequence
-- @return a sequence or a table; defaults to a sequence.
function seq.unique(iter,returns_table)
    local t = seq.count_map(iter)
    local res,k = {},1
    for key in pairs(t) do res[k] = key; k = k + 1 end
    table.sort(res)
    if returns_table then
        return res
    else
        return list(res)
    end
end

--- print out a sequence iter with a separator.
-- @param iter a sequence
-- @param sep the separator (default space)
-- @param nfields maximum number of values per line (default 7)
-- @param fmt optional format function for each value
function seq.printall(iter,sep,nfields,fmt)
  local write = io.write
  if not sep then sep = ' ' end
  if not nfields then
      if sep == '\n' then nfields = 1e30
      else nfields = 7 end
  end
  if fmt then
    local fstr = fmt
    fmt = function(v) return format(fstr,v) end
  end
  local k = 1
  for v in default_iter(iter) do
     if fmt then v = fmt(v) end
     if k < nfields then
       write(v,sep)
       k = k + 1
    else
       write(v,'\n')
       k = 1
    end
  end
  write '\n'
end

-- return an iterator running over every element of two sequences (concatenation).
-- @param iter1 a sequence
-- @param iter2 a sequence
function seq.splice(iter1,iter2)
  iter1 = default_iter(iter1)
  iter2 = default_iter(iter2)
  local iter = iter1
  return function()
    local ret = iter()
    if ret == nil then
      if iter == iter1 then
        iter = iter2
        return iter()
      else return nil end
   else
       return  ret
   end
 end
end

--- return a sequence where every element of a sequence has been transformed
-- by a function. If you don't supply an argument, then the function will
-- receive both values of a double-valued sequence, otherwise behaves rather like
-- tablex.map.
-- @param fn a function to apply to elements; may take two arguments
-- @param iter a sequence of one or two values
-- @param arg optional argument to pass to function.
function seq.map(fn,iter,arg)
    fn = function_arg(1,fn)
    iter = default_iter(iter)
    return function()
        local v1,v2 = iter()
        if v1 == nil then return nil end
        return fn(v1,arg or v2) or false
    end
end

--- filter a sequence using a predicate function.
-- @param iter a sequence of one or two values
-- @param pred a boolean function; may take two arguments
-- @param arg optional argument to pass to function.
function seq.filter (iter,pred,arg)
    pred = function_arg(2,pred)
    return function ()
        local v1,v2
        while true do
            v1,v2 = iter()
            if v1 == nil then return nil end
            if pred(v1,arg or v2) then return v1,v2 end
        end
    end
end

--- 'reduce' a sequence using a binary function.
-- @func fn a function of two arguments
-- @param iter a sequence
-- @param initval optional initial value
-- @usage seq.reduce(operator.add,seq.list{1,2,3,4}) == 10
-- @usage seq.reduce('-',{1,2,3,4,5}) == -13
function seq.reduce (fn,iter,initval)
   fn = function_arg(1,fn)
   iter = default_iter(iter)
   local val = initval or iter()
   if val == nil then return nil end
   for v in iter do
       val = fn(val,v)
   end
   return val
end

--- take the first n values from the sequence.
-- @param iter a sequence of one or two values
-- @param n number of items to take
-- @return a sequence of at most n items
function seq.take (iter,n)
    iter = default_iter(iter)
    return function()
        if n < 1 then return end
        local val1,val2 = iter()
        if not val1 then return end
        n = n - 1
        return val1,val2
    end
end

--- skip the first n values of a sequence
-- @param iter a sequence of one or more values
-- @param n number of items to skip
function seq.skip (iter,n)
    n = n or 1
    for i = 1,n do
        if iter() == nil then return list{} end
    end
    return iter
end

--- a sequence with a sequence count and the original value.
-- enum(copy(ls)) is a roundabout way of saying ipairs(ls).
-- @param iter a single or double valued sequence
-- @return sequence of (i,v), i = 1..n and v is from iter.
function seq.enum (iter)
    local i = 0
    iter = default_iter(iter)
    return function  ()
        local val1,val2 = iter()
        if not val1 then return end
        i = i + 1
        return i,val1,val2
    end
end

--- map using a named method over a sequence.
-- @param iter a sequence
-- @param name the method name
-- @param arg1 optional first extra argument
-- @param arg2 optional second extra argument
function seq.mapmethod (iter,name,arg1,arg2)
    iter = default_iter(iter)
    return function()
        local val = iter()
        if not val then return end
        local fn = val[name]
        if not fn then error(type(val).." does not have method "..name) end
        return fn(val,arg1,arg2)
    end
end

--- a sequence of (last,current) values from another sequence.
--  This will return S(i-1),S(i) if given S(i)
-- @param iter a sequence
function seq.last (iter)
    iter = default_iter(iter)
    local val, l = iter(), nil
    if val == nil then return list{} end
    return function ()
        val,l = iter(),val
        if val == nil then return nil end
        return val,l
    end
end

--- call the function on each element of the sequence.
-- @param iter a sequence with up to 3 values
-- @param fn a function
function seq.foreach(iter,fn)
    fn = function_arg(2,fn)
    for i1,i2,i3 in default_iter(iter) do fn(i1,i2,i3) end
end

---------------------- Sequence Adapters ---------------------

local SMT

local function SW (iter,...)
    if callable(iter) then
        return setmetatable({iter=iter},SMT)
    else
        return iter,...
    end
end


-- can't directly look these up in seq because of the wrong argument order...
local map,reduce,mapmethod = seq.map, seq.reduce, seq.mapmethod
local overrides = {
    map = function(self,fun,arg)
        return map(fun,self,arg)
    end,
    reduce = function(self,fun,initval)
        return reduce(fun,self,initval)
    end
}

SMT = {
    __index = function (tbl,key)
        local fn = overrides[key] or seq[key]
        if fn then
            return function(sw,...) return SW(fn(sw.iter,...)) end
        else
            return function(sw,...) return SW(mapmethod(sw.iter,key,...)) end
        end
    end,
    __call = function (sw)
        return sw.iter()
    end,
}

setmetatable(seq,{
    __call = function(tbl,iter,extra)
        if not callable(iter) then
            if type(iter) == 'table' then iter = seq.list(iter)
            else return iter
            end
        end
        if extra then
            return setmetatable({iter=function()
                return iter(extra)
            end},SMT)
        else
            return setmetatable({iter=iter},SMT)
        end
    end
})

--- create a wrapped iterator over all lines in the file.
-- @param f either a filename, file-like object, or 'STDIN' (for standard input)
-- @param ... for Lua 5.2 only, optional format specifiers, as in `io.read`.
-- @return a sequence wrapper
function seq.lines (f,...)
    local iter,obj
    if f == 'STDIN' then
        f = io.stdin
    elseif type(f) == 'string' then
        iter,obj = io.lines(f,...)
    elseif not f.read then
        error("Pass either a string or a file-like object",2)
    end
    if not iter then
        iter,obj = f:lines(...)
    end
    if obj then -- LuaJIT version returns a function operating on a file
        local lines,file = iter,obj
        iter = function() return lines(file) end
    end
    return SW(iter)
end

function seq.import ()
    debug.setmetatable(function() end,{
        __index = function(tbl,key)
            local s = overrides[key] or seq[key]
            if s then return s
            else
                return function(s,...) return seq.mapmethod(s,key,...) end
            end
        end
    })
end

return seq

1	--- Manipulating iterators as sequences.
2	-- See @{07-functional.md.Sequences\|The Guide}
3	--
4	-- Dependencies: `pl.utils`, `pl.types`, `debug`
5	-- @module pl.seq
6
7	local next,assert,pairs,tonumber,type,setmetatable = next,assert,pairs,tonumber,type,setmetatable	18✔
8	local strfind,format = string.find,string.format	18✔
9	local mrandom = math.random	18✔
10	local tsort,tappend = table.sort,table.insert	18✔
11	local io = io	18✔
12	local utils = require 'pl.utils'	18✔
13	local callable = require 'pl.types'.is_callable	18✔
14	local function_arg = utils.function_arg	18✔
15	local assert_arg = utils.assert_arg	18✔
16	local debug = require 'debug'	18✔
17
18	local seq = {}	18✔
19
20	-- given a number, return a function(y) which returns true if y > x
21	-- @param x a number
22	function seq.greater_than(x)	18✔
23	return function(v)
24	return tonumber(v) > x	150✔
25	end
26	end
27
28	-- given a number, returns a function(y) which returns true if y < x
29	-- @param x a number
30	function seq.less_than(x)	18✔
31	return function(v)
32	return tonumber(v) < x	150✔
33	end
34	end
35
36	-- given any value, return a function(y) which returns true if y == x
37	-- @param x a value
38	function seq.equal_to(x)	18✔
39	if type(x) == "number" then	12✔
40	return function(v)
41	return tonumber(v) == x	30✔
42	end
43	else
44	return function(v)
45	return v == x	30✔
46	end
47	end
48	end
49
50	--- given a string, return a function(y) which matches y against the string.
51	-- @param s a string
52	function seq.matching(s)	18✔
53	return function(v)
54	return strfind(v,s)	18✔
55	end
56	end
57
58	local nexti
59
60	--- sequence adaptor for a table. Note that if any generic function is
61	-- passed a table, it will automatically use seq.list()
62	-- @param t a list-like table
63	-- @usage sum(list(t)) is the sum of all elements of t
64	-- @usage for x in list(t) do...end
65	function seq.list(t)	18✔
66	assert_arg(1,t,'table')	234✔
67	if not nexti then	234✔
68	nexti = ipairs{}	6✔
69	end
70	local key,value = 0	234✔
71	return function()
72	key,value = nexti(t,key)	906✔
73	return value	906✔
74	end
75	end
76
77	--- return the keys of the table.
78	-- @param t an arbitrary table
79	-- @return iterator over keys
80	function seq.keys(t)	18✔
81	assert_arg(1,t,'table')	6✔
82	local key
83	return function()
84	key = next(t,key)	24✔
85	return key	24✔
86	end
87	end
88
89	local list = seq.list	18✔
90	local function default_iter(iter)
91	if type(iter) == 'table' then return list(iter)	342✔
92	else return iter end	282✔
93	end
94
95	seq.iter = default_iter	18✔
96
97	--- create an iterator over a numerical range. Like the standard Python function xrange.
98	-- @param start a number
99	-- @param finish a number greater than start
100	function seq.range(start,finish)	18✔
101	local i = start - 1	6✔
102	return function()
103	i = i + 1	30✔
104	if i > finish then return nil	30✔
105	else return i end	24✔
106	end
107	end
108
109	-- count the number of elements in the sequence which satisfy the predicate
110	-- @param iter a sequence
111	-- @param condn a predicate function (must return either true or false)
112	-- @param optional argument to be passed to predicate as second argument.
113	-- @return count
114	function seq.count(iter,condn,arg)	18✔
115	local i = 0	6✔
116	seq.foreach(iter,function(val)	12✔
117	if condn(val,arg) then i = i + 1 end	32✔
118	end)
119	return i	6✔
120	end
121
122	--- return the minimum and the maximum value of the sequence.
123	-- @param iter a sequence
124	-- @return minimum value
125	-- @return maximum value
126	function seq.minmax(iter)	18✔
127	local vmin,vmax = 1e70,-1e70	6✔
128	for val in default_iter(iter) do	90✔
129	local v = tonumber(val)	60✔
130	if v < vmin then vmin = v end	60✔
131	if v > vmax then vmax = v end	60✔
132	end
133	return vmin,vmax	6✔
134	end
135
136	--- return the sum and element count of the sequence.
137	-- @param iter a sequence
138	-- @param fn an optional function to apply to the values
139	function seq.sum(iter,fn)	18✔
140	local s = 0	6✔
141	local i = 0	6✔
142	for val in default_iter(iter) do	50✔
143	local v
144	if fn then	30✔
NEW 145	v = fn(val)	×
146	else
147	v = val	30✔
148	end
149	s = s + v	30✔
150	i = i + 1	30✔
151	end
152	return s,i	6✔
153	end
154
155	--- create a table from the sequence. (This will make the result a List.)
156	-- @param iter a sequence
157	-- @return a List
158	-- @usage copy(list(ls)) is equal to ls
159	-- @usage copy(list {1,2,3}) == List{1,2,3}
160	function seq.copy(iter)	18✔
161	local res,k = {},1	168✔
162	for v in default_iter(iter) do	920✔
163	res[k] = v	480✔
164	k = k + 1	480✔
165	end
166	setmetatable(res, require('pl.List'))	168✔
167	return res	168✔
168	end
169
170	--- create a table of pairs from the double-valued sequence.
171	-- @param iter a double-valued sequence
172	-- @param i1 used to capture extra iterator values
173	-- @param i2 as with pairs & ipairs
174	-- @usage copy2(ipairs{10,20,30}) == {{1,10},{2,20},{3,30}}
175	-- @return a list-like table
176	function seq.copy2 (iter,i1,i2)	18✔
177	local res,k = {},1	240✔
178	for v1,v2 in iter,i1,i2 do	1,104✔
179	res[k] = {v1,v2}	594✔
180	k = k + 1	594✔
181	end
182	return res	240✔
183	end
184
185	--- create a table of 'tuples' from a multi-valued sequence.
186	-- A generalization of copy2 above
187	-- @param iter a multiple-valued sequence
188	-- @return a list-like table
189	function seq.copy_tuples (iter)	18✔
190	iter = default_iter(iter)	8✔
191	local res = {}	6✔
192	local row = {iter()}	8✔
193	while #row > 0 do	36✔
194	tappend(res,row)	30✔
195	row = {iter()}	40✔
196	end
197	return res	6✔
198	end
199
200	--- return an iterator of random numbers.
201	-- @param n the length of the sequence
202	-- @param l same as the first optional argument to math.random
203	-- @param u same as the second optional argument to math.random
204	-- @return a sequence
205	function seq.random(n,l,u)	18✔
206	local rand
207	assert(type(n) == 'number')	18✔
208	if u then	18✔
209	rand = function() return mrandom(l,u) end	48✔
210	elseif l then	12✔
211	rand = function() return mrandom(l) end	48✔
212	else
213	rand = mrandom	6✔
214	end
215
216	return function()
217	if n == 0 then return nil	144✔
218	else
219	n = n - 1	126✔
220	return rand()	126✔
221	end
222	end
223	end
224
225	--- return an iterator to the sorted elements of a sequence.
226	-- @param iter a sequence
227	-- @param comp an optional comparison function (comp(x,y) is true if x < y)
228	function seq.sort(iter,comp)	18✔
229	local t = seq.copy(iter)	12✔
230	tsort(t,comp)	12✔
231	return list(t)	12✔
232	end
233
234	--- return an iterator which returns elements of two sequences.
235	-- @param iter1 a sequence
236	-- @param iter2 a sequence
237	-- @usage for x,y in seq.zip(ls1,ls2) do....end
238	function seq.zip(iter1,iter2)	18✔
239	iter1 = default_iter(iter1)	8✔
240	iter2 = default_iter(iter2)	8✔
241	return function()
242	return iter1(),iter2()	40✔
243	end
244	end
245
246	--- Makes a table where the key/values are the values and value counts of the sequence.
247	-- This version works with 'hashable' values like strings and numbers.
248	-- `pl.tablex.count_map` is more general.
249	-- @param iter a sequence
250	-- @return a map-like table
251	-- @return a table
252	-- @see pl.tablex.count_map
253	function seq.count_map(iter)	18✔
254	local t = {}	6✔
255	local v
256	for s in default_iter(iter) do	50✔
257	v = t[s]	30✔
258	if v then t[s] = v + 1	30✔
259	else t[s] = 1 end	18✔
260	end
261	return setmetatable(t, require('pl.Map'))	6✔
262	end
263
264	-- given a sequence, return all the unique values in that sequence.
265	-- @param iter a sequence
266	-- @param returns_table true if we return a table, not a sequence
267	-- @return a sequence or a table; defaults to a sequence.
268	function seq.unique(iter,returns_table)	18✔
269	local t = seq.count_map(iter)	6✔
270	local res,k = {},1	6✔
271	for key in pairs(t) do res[k] = key; k = k + 1 end	24✔
272	table.sort(res)	6✔
273	if returns_table then	6✔
274	return res	×
275	else
276	return list(res)	6✔
277	end
278	end
279
280	--- print out a sequence iter with a separator.
281	-- @param iter a sequence
282	-- @param sep the separator (default space)
283	-- @param nfields maximum number of values per line (default 7)
284	-- @param fmt optional format function for each value
285	function seq.printall(iter,sep,nfields,fmt)	18✔
286	local write = io.write	6✔
287	if not sep then sep = ' ' end	6✔
288	if not nfields then	6✔
289	if sep == '\n' then nfields = 1e30	6✔
290	else nfields = 7 end	6✔
291	end
292	if fmt then	6✔
293	local fstr = fmt	6✔
294	fmt = function(v) return format(fstr,v) end	66✔
295	end
296	local k = 1	6✔
297	for v in default_iter(iter) do	90✔
298	if fmt then v = fmt(v) end	80✔
299	if k < nfields then	60✔
300	write(v,sep)	54✔
301	k = k + 1	54✔
302	else
303	write(v,'\n')	6✔
304	k = 1	6✔
305	end
306	end
307	write '\n'	6✔
308	end
309
310	-- return an iterator running over every element of two sequences (concatenation).
311	-- @param iter1 a sequence
312	-- @param iter2 a sequence
313	function seq.splice(iter1,iter2)	18✔
314	iter1 = default_iter(iter1)	8✔
315	iter2 = default_iter(iter2)	8✔
316	local iter = iter1	6✔
317	return function()
318	local ret = iter()	30✔
319	if ret == nil then	30✔
320	if iter == iter1 then	12✔
321	iter = iter2	6✔
322	return iter()	6✔
323	else return nil end	6✔
324	else
325	return ret	18✔
326	end
327	end
328	end
329
330	--- return a sequence where every element of a sequence has been transformed
331	-- by a function. If you don't supply an argument, then the function will
332	-- receive both values of a double-valued sequence, otherwise behaves rather like
333	-- tablex.map.
334	-- @param fn a function to apply to elements; may take two arguments
335	-- @param iter a sequence of one or two values
336	-- @param arg optional argument to pass to function.
337	function seq.map(fn,iter,arg)	18✔
338	fn = function_arg(1,fn)	16✔
339	iter = default_iter(iter)	16✔
340	return function()
341	local v1,v2 = iter()	42✔
342	if v1 == nil then return nil end	42✔
343	return fn(v1,arg or v2) or false	40✔
344	end
345	end
346
347	--- filter a sequence using a predicate function.
348	-- @param iter a sequence of one or two values
349	-- @param pred a boolean function; may take two arguments
350	-- @param arg optional argument to pass to function.
351	function seq.filter (iter,pred,arg)	18✔
352	pred = function_arg(2,pred)	88✔
353	return function ()
354	local v1,v2
355	while true do
356	v1,v2 = iter()	592✔
357	if v1 == nil then return nil end	444✔
358	if pred(v1,arg or v2) then return v1,v2 end	504✔
359	end
360	end
361	end
362
363	--- 'reduce' a sequence using a binary function.
364	-- @func fn a function of two arguments
365	-- @param iter a sequence
366	-- @param initval optional initial value
367	-- @usage seq.reduce(operator.add,seq.list{1,2,3,4}) == 10
368	-- @usage seq.reduce('-',{1,2,3,4,5}) == -13
369	function seq.reduce (fn,iter,initval)	18✔
370	fn = function_arg(1,fn)	56✔
371	iter = default_iter(iter)	56✔
372	local val = initval or iter()	42✔
373	if val == nil then return nil end	42✔
374	for v in iter do	160✔
375	val = fn(val,v)	112✔
376	end
377	return val	36✔
378	end
379
380	--- take the first n values from the sequence.
381	-- @param iter a sequence of one or two values
382	-- @param n number of items to take
383	-- @return a sequence of at most n items
384	function seq.take (iter,n)	18✔
385	iter = default_iter(iter)	40✔
386	return function()
387	if n < 1 then return end	102✔
388	local val1,val2 = iter()	78✔
389	if not val1 then return end	78✔
390	n = n - 1	72✔
391	return val1,val2	72✔
392	end
393	end
394
395	--- skip the first n values of a sequence
396	-- @param iter a sequence of one or more values
397	-- @param n number of items to skip
398	function seq.skip (iter,n)	18✔
399	n = n or 1	12✔
400	for i = 1,n do	36✔
401	if iter() == nil then return list{} end	40✔
402	end
403	return iter	6✔
404	end
405
406	--- a sequence with a sequence count and the original value.
407	-- enum(copy(ls)) is a roundabout way of saying ipairs(ls).
408	-- @param iter a single or double valued sequence
409	-- @return sequence of (i,v), i = 1..n and v is from iter.
410	function seq.enum (iter)	18✔
411	local i = 0	6✔
412	iter = default_iter(iter)	8✔
413	return function ()
414	local val1,val2 = iter()	36✔
415	if not val1 then return end	36✔
416	i = i + 1	30✔
417	return i,val1,val2	30✔
418	end
419	end
420
421	--- map using a named method over a sequence.
422	-- @param iter a sequence
423	-- @param name the method name
424	-- @param arg1 optional first extra argument
425	-- @param arg2 optional second extra argument
426	function seq.mapmethod (iter,name,arg1,arg2)	18✔
427	iter = default_iter(iter)	8✔
428	return function()
429	local val = iter()	18✔
430	if not val then return end	18✔
431	local fn = val[name]	12✔
432	if not fn then error(type(val).." does not have method "..name) end	12✔
433	return fn(val,arg1,arg2)	12✔
434	end
435	end
436
437	--- a sequence of (last,current) values from another sequence.
438	-- This will return S(i-1),S(i) if given S(i)
439	-- @param iter a sequence
440	function seq.last (iter)	18✔
441	iter = default_iter(iter)	24✔
442	local val, l = iter(), nil	24✔
443	if val == nil then return list{} end	18✔
444	return function ()
445	val,l = iter(),val	32✔
446	if val == nil then return nil end	24✔
447	return val,l	12✔
448	end
449	end
450
451	--- call the function on each element of the sequence.
452	-- @param iter a sequence with up to 3 values
453	-- @param fn a function
454	function seq.foreach(iter,fn)	18✔
455	fn = function_arg(2,fn)	8✔
456	for i1,i2,i3 in default_iter(iter) do fn(i1,i2,i3) end	50✔
457	end
458
459	---------------------- Sequence Adapters ---------------------
460
461	local SMT
462
463	local function SW (iter,...)
464	if callable(iter) then	352✔
465	return setmetatable({iter=iter},SMT)	114✔
466	else
467	return iter,...	150✔
468	end
469	end
470
471
472	-- can't directly look these up in seq because of the wrong argument order...
473	local map,reduce,mapmethod = seq.map, seq.reduce, seq.mapmethod	18✔
474	local overrides = {	18✔
475	map = function(self,fun,arg)
476	return map(fun,self,arg)	6✔
477	end,
478	reduce = function(self,fun,initval)
479	return reduce(fun,self,initval)	36✔
480	end
481	}
482
483	SMT = {	18✔
484	__index = function (tbl,key)
485	local fn = overrides[key] or seq[key]	258✔
486	if fn then	258✔
487	return function(sw,...) return SW(fn(sw.iter,...)) end	588✔
488	else
489	return function(sw,...) return SW(mapmethod(sw.iter,key,...)) end	14✔
490	end
491	end,
492	__call = function (sw)
493	return sw.iter()	×
494	end,
495	}	18✔
496
497	setmetatable(seq,{	36✔
498	__call = function(tbl,iter,extra)
499	if not callable(iter) then	192✔
500	if type(iter) == 'table' then iter = seq.list(iter)	152✔
501	else return iter	×
502	end
503	end
504	if extra then	144✔
505	return setmetatable({iter=function()	10✔
506	return iter(extra)	24✔
507	end},SMT)	9✔
508	else
509	return setmetatable({iter=iter},SMT)	138✔
510	end
511	end
512	})
513
514	--- create a wrapped iterator over all lines in the file.
515	-- @param f either a filename, file-like object, or 'STDIN' (for standard input)
516	-- @param ... for Lua 5.2 only, optional format specifiers, as in `io.read`.
517	-- @return a sequence wrapper
518	function seq.lines (f,...)	18✔
519	local iter,obj
520	if f == 'STDIN' then	6✔
521	f = io.stdin	×
522	elseif type(f) == 'string' then	6✔
523	iter,obj = io.lines(f,...)	×
524	elseif not f.read then	6✔
525	error("Pass either a string or a file-like object",2)	×
526	end
527	if not iter then	6✔
528	iter,obj = f:lines(...)	8✔
529	end
530	if obj then -- LuaJIT version returns a function operating on a file	6✔
531	local lines,file = iter,obj	×
532	iter = function() return lines(file) end	×
533	end
534	return SW(iter)	6✔
535	end
536
537	function seq.import ()	18✔
538	debug.setmetatable(function() end,{	×
539	__index = function(tbl,key)
540	local s = overrides[key] or seq[key]	×
541	if s then return s	×
542	else
543	return function(s,...) return seq.mapmethod(s,key,...) end	×
544	end
545	end
546	})
547	end
548
549	return seq	18✔

lunarmodules / Penlight / 16815657215

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