split next into nextval & nextstate

For example,

    for x in xs
        ...

now transforms into

    iter = start(xs)
    while !done(xs,iter)
        x = nextval(xs,iter)
        ...
        iter = nextstate(xs,iter)

base/abstractarray.jl

@@ -256,7 +256,8 @@ zero{T}(x::AbstractArray{T}) = fill!(similar(x), zero(T))
 
 start(A::AbstractArray) = _start(A,linearindexing(A))
 _start(::AbstractArray,::LinearFast) = 1
-next(a::AbstractArray,i) = (a[i],i+1)
+nextval(a::AbstractArray,i) = a[i]
+nextstate(a::AbstractArray,i) = i+1
 done(a::AbstractArray,i) = (i > length(a))
 isempty(a::AbstractArray) = (length(a) == 0)
 

base/bitarray.jl

@@ -197,7 +197,8 @@ end
 
 ## custom iterator ##
 start(B::BitArray) = 0
-next(B::BitArray, i::Int) = (B.chunks[@_div64(i)+1] & (uint64(1)<<@_mod64(i)) != 0, i+1)
+nextval(B::BitArray, i::Int) = B.chunks[@_div64(i)+1] & (uint64(1)<<@_mod64(i)) != 0
+nextstate(B::BitArray, i::Int) = i+1
 done(B::BitArray, i::Int) = i >= length(B)
 
 ## similar, fill!, copy! etc ##

base/char.jl

@@ -26,7 +26,8 @@ last(c::Char) = c
 eltype(c::Char) = Char
 
 start(c::Char) = false
-next(c::Char, state) = (c, true)
+nextval(c::Char, state) = c
+nextstate(c::Char, state) = true
 done(c::Char, state) = state
 isempty(c::Char) = false
 in(x::Char, y::Char) = x == y

base/collections.jl

@@ -1,6 +1,6 @@
 module Collections
 
-import Base: setindex!, done, get, hash, haskey, isempty, length, next, getindex, start
+import Base: setindex!, done, get, hash, haskey, isempty, length, nextstate, nextval, getindex, start
 import ..Order: Forward, Ordering, lt
 
 export
@@ -282,10 +282,11 @@ start(pq::PriorityQueue) = start(pq.index)
 
 done(pq::PriorityQueue, i) = done(pq.index, i)
 
-function next(pq::PriorityQueue, i)
-    (k, idx), i = next(pq.index, i)
-    return ((k, pq.xs[idx].second), i)
+function nextval(pq::PriorityQueue, i)
+    (k, idx) = nextval(pq.index, i)
+    (k, pq.xs[idx].second)
 end
+nextstate(pq::PriorityQueue, i) = nextstate(pq.index, i)
 
 
 end # module Collections

base/combinatorics.jl

@@ -256,11 +256,11 @@ function combinations(a, t::Integer)
 end
 
 start(c::Combinations) = [1:c.t]
-function next(c::Combinations, s)
-    comb = c.a[s]
+nextval(c::Combinations, s) = c.a[s]
+function nextstate(c::Combinations, s)
     if c.t == 0
         # special case to generate 1 result for t==0
-        return (comb,[length(c.a)+2])
+        return [length(c.a)+2]
     end
     s = copy(s)
     for i = length(s):-1:1
@@ -273,7 +273,7 @@ function next(c::Combinations, s)
         end
         break
     end
-    (comb,s)
+    s
 end
 done(c::Combinations, s) = !isempty(s) && s[1] > length(c.a)-c.t+1
 
@@ -290,13 +290,13 @@ length(c::Permutations) = factorial(length(c.a))
 permutations(a) = Permutations(a)
 
 start(p::Permutations) = [1:length(p.a)]
-function next(p::Permutations, s)
+nextval(p::Permutations, s) = length(p.a) == 0 ? p.a : p.a[s]
+function nextstate(p::Permutations, s)
     if length(p.a) == 0
         # special case to generate 1 result for len==0
-        return (p.a,[1])
+        return [1]
     end
     s = copy(s)
-    perm = p.a[s]
     k = length(s)-1
     while k > 0 && s[k] > s[k+1];  k -= 1;  end
     if k == 0
@@ -307,7 +307,7 @@ function next(p::Permutations, s)
         s[k],s[l] = s[l],s[k]
         reverse!(s,k+1)
     end
-    (perm,s)
+    s
 end
 done(p::Permutations, s) = !isempty(s) && s[1] > length(p.a)
 
@@ -324,7 +324,8 @@ partitions(n::Integer) = IntegerPartitions(n)
 
 start(p::IntegerPartitions) = Int[]
 done(p::IntegerPartitions, xs) = length(xs) == p.n
-next(p::IntegerPartitions, xs) = (xs = nextpartition(p.n,xs); (xs,xs))
+nextval(p::IntegerPartitions, xs) = nextpartition(p.n,xs)
+nextstate(p::IntegerPartitions, xs) = nextpartition(p.n,xs)
 
 function nextpartition(n, as)
     if isempty(as);  return Int[n];  end
@@ -394,7 +395,8 @@ function done(f::FixedPartitions, s::Vector{Int})
     isempty(s) && return false
     return f.m == 1 || s[1]-1 <= s[end]
 end
-next(f::FixedPartitions, s::Vector{Int}) = (xs = nextfixedpartition(f.n,f.m,s); (xs,xs))
+nextval(f::FixedPartitions, s::Vector{Int}) = nextfixedpartition(f.n,f.m,s)
+nextstate(f::FixedPartitions, s::Vector{Int}) = nextfixedpartition(f.n,f.m,s)
 
 function nextfixedpartition(n, m, bs)
     as = copy(bs)
@@ -452,21 +454,19 @@ partitions(s::AbstractVector) = SetPartitions(s)
 
 start(p::SetPartitions) = (n = length(p.s); (zeros(Int32, n), ones(Int32, n-1), n, 1))
 done(p::SetPartitions, s) = s[1][1] > 0
-next(p::SetPartitions, s) = nextsetpartition(p.s, s...)
 
-function nextsetpartition(s::AbstractVector, a, b, n, m)
-    function makeparts(s, a, m)
-        temp = [ similar(s,0) for k = 0:m ]
-        for i = 1:n
-            push!(temp[a[i]+1], s[i])
-        end
-        filter!(x->!isempty(x), temp)
+function nextval(p::SetPartitions, s)
+    a, _, n, m = s
+    temp = [ similar(p.s,0) for k = 0:m ]
+    for i = 1:n
+        push!(temp[a[i]+1], p.s[i])
     end
+    filter!(x->!isempty(x), temp)
+end
 
-    if isempty(s);  return ([s], ([1], Int[], n, 1));  end
-
-    part = makeparts(s,a,m)
-
+function nextstate(p::SetPartitions, s)
+    a, b, n, m = s
+    isempty(p.s) && return ([1], Int[], n, 1)
     if a[end] != m
         a[end] += 1
     else
@@ -484,9 +484,7 @@ function nextsetpartition(s::AbstractVector, a, b, n, m)
         end
         a[end] = 0
     end
-
-    return (part, (a,b,n,m))
-
+    (a,b,n,m)
 end
 
 let _nsetpartitions = Dict{Int,Int}()
@@ -528,22 +526,22 @@ end
 # integer n
 
 done(p::FixedSetPartitions, s) = length(s[1]) == 0 || s[1][1] > 1
-next(p::FixedSetPartitions, s) = nextfixedsetpartition(p.s,p.m, s...)
 
-function nextfixedsetpartition(s::AbstractVector, m, a, b, n)
-    function makeparts(s, a)
-        part = [ similar(s,0) for k = 1:m ]
-        for i = 1:n
-            push!(part[a[i]], s[i])
-        end
-        return part
+function nextval(p::FixedSetPartitions, s)
+    a, _, n = s
+    part = [ similar(p.s,0) for k = 1:p.m ]
+    for i = 1:n
+        push!(part[a[i]], p.s[i])
     end
+    part
+end
 
-    part = makeparts(s,a)
-
+function nextstate(p::FixedSetPartitions, s)
+    m = p.m
+    a, b, n = s
     if m == 1
         a[1] = 2
-        return (part, (a, b, n))
+        return (a, b, n)
     end
 
     if a[end] != m
@@ -574,8 +572,7 @@ function nextfixedsetpartition(s::AbstractVector, m, a, b, n)
             a[b]=1:m
         end
     end
-
-    return (part, (a,b,n))
+    (a,b,n)
 end
 
 function nfixedsetpartitions(n::Int,m::Int)

base/dates/ranges.jl

@@ -29,5 +29,6 @@ function in{T<:TimeType}(x::T, r::StepRange{T})
 end
 
 Base.start{T<:TimeType}(r::StepRange{T}) = 0
-Base.next{T<:TimeType}(r::StepRange{T}, i::Int) = (r.start+r.step*i,i+1)
+Base.nextval{T<:TimeType}(r::StepRange{T}, i::Int) = r.start+r.step*i
+Base.nextstate{T<:TimeType}(r::StepRange{T}, i::Int) = i+1
 Base.done{T<:TimeType,S<:Period}(r::StepRange{T,S}, i::Integer) = length(r) <= i

base/dict.jl

@@ -149,15 +149,11 @@ eltype(v::ValueIterator) = eltype(v.dict)[2]
 start(v::Union(KeyIterator,ValueIterator)) = start(v.dict)
 done(v::Union(KeyIterator,ValueIterator), state) = done(v.dict, state)
 
-function next(v::KeyIterator, state)
-    n = next(v.dict, state)
-    n[1][1], n[2]
-end
+nextval(v::KeyIterator, state) = nextval(v.dict, state)[1]
+nextstate(v::KeyIterator, state) = nextstate(v.dict, state)
 
-function next(v::ValueIterator, state)
-    n = next(v.dict, state)
-    n[1][2], n[2]
-end
+nextval(v::ValueIterator, state) = nextval(v.dict, state)[2]
+nextstate(v::ValueIterator, state) = nextstate(v.dict, state)
 
 in(k, v::KeyIterator) = !is(get(v.dict, k, secret_table_token),
                             secret_table_token)
@@ -300,7 +296,8 @@ _oidd_nextind(a, i) = reinterpret(Int,ccall(:jl_eqtable_nextind, Csize_t, (Any,
 
 start(t::ObjectIdDict) = _oidd_nextind(t.ht, 0)
 done(t::ObjectIdDict, i) = (i == -1)
-next(t::ObjectIdDict, i) = ((t.ht[i+1],t.ht[i+2]), _oidd_nextind(t.ht, i+2))
+nextval(t::ObjectIdDict, i) = (t.ht[i+1],t.ht[i+2])
+nextstate(t::ObjectIdDict, i) = _oidd_nextind(t.ht, i+2)
 
 function length(d::ObjectIdDict)
     n = 0
@@ -699,13 +696,17 @@ end
 
 start(t::Dict) = skip_deleted(t, 1)
 done(t::Dict, i) = done(t.vals, i)
-next(t::Dict, i) = ((t.keys[i],t.vals[i]), skip_deleted(t,i+1))
+nextval(t::Dict, i) = (t.keys[i],t.vals[i])
+nextstate(t::Dict, i) = skip_deleted(t,i+1)
 
 isempty(t::Dict) = (t.count == 0)
 length(t::Dict) = t.count
 
-next{T<:Dict}(v::KeyIterator{T}, i) = (v.dict.keys[i], skip_deleted(v.dict,i+1))
-next{T<:Dict}(v::ValueIterator{T}, i) = (v.dict.vals[i], skip_deleted(v.dict,i+1))
+nextval{T<:Dict}(v::KeyIterator{T}, i) = v.dict.keys[i]
+nextstate{T<:Dict}(v::KeyIterator{T}, i) = skip_deleted(v.dict,i+1)
+
+nextval{T<:Dict}(v::ValueIterator{T}, i) = v.dict.vals[i]
+nextstate{T<:Dict}(v::ValueIterator{T}, i) = skip_deleted(v.dict,i+1)
 
 # weak key dictionaries
 
@@ -774,8 +775,6 @@ isempty(wkh::WeakKeyDict) = isempty(wkh.ht)
 
 start(t::WeakKeyDict) = start(t.ht)
 done(t::WeakKeyDict, i) = done(t.ht, i)
-function next{K}(t::WeakKeyDict{K}, i)
-    kv, i = next(t.ht, i)
-    ((kv[1].value::K,kv[2]), i)
-end
+nextval{K}(t::WeakKeyDict{K}, i) = (kv = nextval(t.ht,i); (kv[1].value::K,kv[2]))
+nextstate(t::WeakKeyDict, i) = nextstate(t.ht, i)
 length(t::WeakKeyDict) = length(t.ht)

base/env.jl

@@ -117,7 +117,7 @@ push!(::EnvHash, k::AbstractString, v) = setindex!(ENV, v, k)
 start(::EnvHash) = 0
 done(::EnvHash, i) = (ccall(:jl_environ, Any, (Int32,), i) == nothing)
 
-function next(::EnvHash, i)
+function nextval(::EnvHash, i)
     env = ccall(:jl_environ, Any, (Int32,), i)
     if env == nothing
         error(BoundsError)
@@ -127,31 +127,40 @@ function next(::EnvHash, i)
     if m == nothing
         error("malformed environment entry: $env")
     end
-    (ByteString[convert(typeof(env),x) for x in m.captures], i+1)
+    ByteString[convert(typeof(env),x) for x in m.captures]
 end
+nextstate(::EnvHash, i) = i+1
 end
 
 @windows_only begin
-start(hash::EnvHash) = (pos = ccall(:GetEnvironmentStringsW,stdcall,Ptr{UInt16},()); (pos,pos))
-function done(hash::EnvHash, block::(Ptr{UInt16},Ptr{UInt16}))
-    if unsafe_load(block[1])==0
-        ccall(:FreeEnvironmentStringsW,stdcall,Int32,(Ptr{UInt16},),block[2])
+function start(hash::EnvHash)
+    pos = ccall(:GetEnvironmentStringsW, stdcall, Ptr{UInt16}, ())
+    nextstate(hash, (0,pos,pos))
+end
+function done(hash::EnvHash, state::(UInt,Ptr{UInt16},Ptr{UInt16}))
+    if unsafe_load(state[2]) == 0
+        ccall(:FreeEnvironmentStringsW,stdcall,Int32,(Ptr{UInt16},),state[3])
         return true
     end
     false
 end
-function next(hash::EnvHash, block::(Ptr{UInt16},Ptr{UInt16}))
-    pos = block[1]
-    blk = block[2]
-    len = ccall(:wcslen, UInt, (Ptr{UInt16},), pos)+1
+function nextval(hash::EnvHash, state::(UInt,Ptr{UInt16},Ptr{UInt16}))
+    len = state[1]
+    pos = state[2]
     buf = Array(UInt16, len)
     unsafe_copy!(pointer(buf), pos, len)
     env = utf8(UTF16String(buf))
     m = match(r"^(=?[^=]+)=(.*)$"s, env)
     if m == nothing
         error("malformed environment entry: $env")
     end
-    (ByteString[convert(typeof(env),x) for x in m.captures], (pos+len*2, blk))
+    ByteString[convert(typeof(env),x) for x in m.captures]
+end
+function nextstate(hash::EnvHash, state::(UInt,Ptr{UInt16},Ptr{UInt16}))
+    len,pos,blk = state
+    pos += 2len
+    len = ccall(:wcslen, UInt, (Ptr{UInt16},), pos) + 1
+    (len, pos, blk)
 end
 end
 

base/exports.jl

@@ -978,6 +978,8 @@ export
     done,
     enumerate,
     next,
+    nextstate,
+    nextval,
     start,
     zip,
 

base/inference.jl

@@ -2160,7 +2160,7 @@ function inlineable(f, e::Expr, atypes, sv, enclosing_ast)
     if incompletematch
         cost *= 4
     end
-    if is(f, next) || is(f, done)
+    if is(f, next) || is(f, nextstate) || is(f, nextval) || is(f, done)
         cost /= 4
     end
     if !inline_worthy(body, cost)

base/intset.jl

@@ -134,21 +134,22 @@ function in(n::Integer, s::IntSet)
 end
 
 start(s::IntSet) = int64(0)
-done(s::IntSet, i) = (!s.fill1s && next(s,i)[1] >= s.limit) || i == typemax(Int)
-function next(s::IntSet, i)
+done(s::IntSet, i) = (!s.fill1s && nextval(s,i) >= s.limit) || i == typemax(Int)
+function nextval(s::IntSet, i)
     if i >= s.limit
         n = int64(i)
     else
         n = int64(ccall(:bitvector_next, UInt64, (Ptr{UInt32}, UInt64, UInt64), s.bits, i, s.limit))
     end
-    (n, n+1)
+    n
 end
+nextstate(s::IntSet, i) = nextval(s,i)+1
 
 isempty(s::IntSet) =
     !s.fill1s && ccall(:bitvector_any1, UInt32, (Ptr{UInt32}, UInt64, UInt64), s.bits, 0, s.limit)==0
 
 function first(s::IntSet)
-    n = next(s,0)[1]
+    n = nextval(s,0)
     if n >= s.limit
         error("set must be non-empty")
     end

base/io.jl

@@ -265,7 +265,8 @@ function done(itr::EachLine, nada)
     itr.ondone()
     true
 end
-next(itr::EachLine, nada) = (readline(itr.stream), nothing)
+nextval(itr::EachLine, nada) = readline(itr.stream)
+nextstate(itr::EachLine, nada) = nothing
 eltype(itr::EachLine) = ByteString
 
 readlines(s=STDIN) = collect(eachline(s))