Updates for Julia 0.6 and 0.7 (#62)

Also includes general stylistic cleanup and an overhaul of the Young
diagram functionality to avoid type piracy.

Fixes #61.

.travis.yml

@@ -2,15 +2,14 @@ language: julia
 os:
     - linux
 julia:
-    - 0.5
     - 0.6
     - nightly
 sudo: false
 notifications:
     email: false
-script:
-    - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
-    - julia -e 'Pkg.clone(pwd())'
-    - julia -e 'Pkg.test("Combinatorics", coverage=true)'
+#script:
+#    - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
+#    - julia -e 'Pkg.clone(pwd())'
+#    - julia -e 'Pkg.test("Combinatorics", coverage=true)'
 after_success:
     - julia -e 'Pkg.add("Coverage"); cd(Pkg.dir("Combinatorics")); using Coverage; Coveralls.submit(Coveralls.process_folder()); Codecov.submit(process_folder())'

README.md

@@ -1,7 +1,7 @@
 # Combinatorics
 
-[![Combinatorics](http://pkg.julialang.org/badges/Combinatorics_0.5.svg)](http://pkg.julialang.org/?pkg=Combinatorics)
 [![Combinatorics](http://pkg.julialang.org/badges/Combinatorics_0.6.svg)](http://pkg.julialang.org/?pkg=Combinatorics)
+[![Combinatorics](http://pkg.julialang.org/badges/Combinatorics_0.7.svg)](http://pkg.julialang.org/?pkg=Combinatorics)
 [![Build Status](https://travis-ci.org/JuliaMath/Combinatorics.jl.svg?branch=master)](https://travis-ci.org/JuliaMath/Combinatorics.jl)
 [![Coverage Status](https://coveralls.io/repos/github/JuliaMath/Combinatorics.jl/badge.svg?branch=master)](https://coveralls.io/github/JuliaMath/Combinatorics.jl?branch=master)
 [![Codecov](https://codecov.io/gh/JuliaMath/Combinatorics.jl/branch/master/graph/badge.svg)](https://codecov.io/gh/JuliaMath/Combinatorics.jl)

REQUIRE

@@ -1,4 +1,4 @@
-julia 0.5
-Compat 0.18.0
+julia 0.6
+Compat 0.59.0
 Polynomials
 IterTools

src/Combinatorics.jl

@@ -2,17 +2,9 @@ __precompile__(true)
 
 module Combinatorics
 
-using Compat, Polynomials, IterTools
-
-import Base: start, next, done, length, eltype
-
-#These 8 functions were removed from Julia 0.5 as part of JuliaLang/julia#13897,
-#so check if it's necessary to import them to overload the stub methods left in
-#Base. Only do this if on a version of Julia post-combinatorics removal.
-if isdefined(Base, :combinations) && VERSION >= v"0.5.0-dev+1204"
-    import Base: combinations, partitions, prevprod, levicivita, nthperm,
-                 nthperm!, parity, permutations
-end
+using Compat
+using Polynomials
+using IterTools
 
 include("numbers.jl")
 include("factorials.jl")

src/combinations.jl

@@ -5,92 +5,93 @@ export combinations,
 
 #The Combinations iterator
 
-immutable Combinations{T}
+struct Combinations{T}
     a::T
     t::Int
 end
 
-start(c::Combinations) = [1:c.t;]
-function next(c::Combinations, s)
+Base.start(c::Combinations) = collect(1:c.t)
+function Base.next(c::Combinations, s)
     comb = [c.a[si] for si in s]
     if c.t == 0
         # special case to generate 1 result for t==0
-        return (comb,[length(c.a)+2])
+        return (comb, [length(c.a)+2])
     end
     s = copy(s)
     for i = length(s):-1:1
         s[i] += 1
-        if s[i] > (length(c.a) - (length(s)-i))
+        if s[i] > (length(c.a) - (length(s) - i))
             continue
         end
-        for j = i+1:endof(s)
+        for j = i+1:lastindex(s)
             s[j] = s[j-1]+1
         end
         break
     end
-    (comb,s)
+    (comb, s)
 end
-done(c::Combinations, s) = !isempty(s) && s[1] > length(c.a)-c.t+1
+Base.done(c::Combinations, s) = !isempty(s) && s[1] > length(c.a) - c.t + 1
+
+Base.length(c::Combinations) = binomial(length(c.a), c.t)
 
-length(c::Combinations) = binomial(length(c.a),c.t)
+Base.eltype(::Type{Combinations{T}}) where {T} = Vector{eltype(T)}
 
-eltype{T}(::Type{Combinations{T}}) = Vector{eltype(T)}
+"""
+    combinations(a, n)
 
-"Generate all combinations of `n` elements from an indexable object. Because the number of combinations can be very large, this function returns an iterator object. Use `collect(combinations(array,n))` to get an array of all combinations.
-"
+Generate all combinations of `n` elements from an indexable object `a`. Because the number
+of combinations can be very large, this function returns an iterator object.
+Use `collect(combinations(a, n))` to get an array of all combinations.
+"""
 function combinations(a, t::Integer)
     if t < 0
         # generate 0 combinations for negative argument
-        t = length(a)+1
+        t = length(a) + 1
     end
     Combinations(a, t)
 end
 
 
 """
-generate combinations of all orders, chaining of order iterators is eager,
-but sequence at each order is lazy
+    combinations(a)
+
+Generate combinations of the elements of `a` of all orders. Chaining of order iterators
+is eager, but the sequence at each order is lazy.
 """
-combinations(a) = chain([combinations(a,k) for k=1:length(a)]...)
+combinations(a) = IterTools.chain([combinations(a, k) for k = 1:length(a)]...)
 
 
 
 # cool-lex combinations iterator
 
 """
-Produces (n,k)-combinations in cool-lex order
-
-Implements the cool-lex algorithm to generate (n,k)-combinations
-@article{Ruskey:2009fk,
-	Author = {Frank Ruskey and Aaron Williams},
-	Doi = {10.1016/j.disc.2007.11.048},
-	Journal = {Discrete Mathematics},
-	Month = {September},
-	Number = {17},
-	Pages = {5305-5320},
-	Title = {The coolest way to generate combinations},
-	Url = {http://www.sciencedirect.com/science/article/pii/S0012365X07009570},
-	Volume = {309},
-	Year = {2009}}
+    CoolLexCombinations
+
+Produce ``(n,k)``-combinations in cool-lex order.
+
+# Reference
+
+Ruskey, F., & Williams, A. (2009). The coolest way to generate combinations.
+*Discrete Mathematics*, 309(17), 5305-5320.
 """
-immutable CoolLexCombinations
-    n :: Int
-    t :: Int
+struct CoolLexCombinations
+    n::Int
+    t::Int
 end
 
-immutable CoolLexIterState{T<:Integer}
-    R0:: T
-    R1:: T
-    R2:: T
-    R3:: T
+struct CoolLexIterState{T<:Integer}
+    R0::T
+    R1::T
+    R2::T
+    R3::T
 end
 
-function start(C::CoolLexCombinations)
+function Base.start(C::CoolLexCombinations)
     if C.n < 0
-        throw(DomainError())
+        throw(DomainError(C.n))
     end
     if C.t ≤ 0
-        throw(DomainError())
+        throw(DomainError(C.t))
     end
 
     #What integer size should I use?
@@ -103,7 +104,7 @@ function start(C::CoolLexCombinations)
     CoolLexIterState{T}(0, 0, T(1) << C.n, (T(1) << C.t) - 1)
 end
 
-function next(C::CoolLexCombinations, S::CoolLexIterState)
+function Base.next(C::CoolLexCombinations, S::CoolLexIterState)
     R0 = S.R0
     R1 = S.R1
     R2 = S.R2
@@ -122,36 +123,36 @@ end
 #Converts an integer bit pattern X into a subset
 #If X & 2^k == 1, then k is in the subset
 function _cool_lex_visit(X::Integer)
-  subset = Int[]
-  n=1
-  while X != 0
-    if X & 1 == 1 push!(subset, n) end
-    X >>= 1
-    n += 1
-  end
-  subset
+    subset = Int[]
+    n = 1
+    while X != 0
+        X & 1 == 1 && push!(subset, n)
+        X >>= 1
+        n += 1
+    end
+    subset
 end
 
-done(C::CoolLexCombinations, S::CoolLexIterState) = (S.R3 & S.R2 != 0)
+Base.done(C::CoolLexCombinations, S::CoolLexIterState) = (S.R3 & S.R2 != 0)
 
-length(C::CoolLexCombinations) = max(0, binomial(C.n, C.t))
+Base.length(C::CoolLexCombinations) = max(0, binomial(C.n, C.t))
 
 
-immutable MultiSetCombinations{T}
+struct MultiSetCombinations{T}
     m::T
     f::Vector{Int}
     t::Int
     ref::Vector{Int}
 end
 
-eltype{T}(::Type{MultiSetCombinations{T}}) = Vector{eltype(T)}
+Base.eltype(::Type{MultiSetCombinations{T}}) where {T} = Vector{eltype(T)}
 
-function length(c::MultiSetCombinations)
+function Base.length(c::MultiSetCombinations)
     t = c.t
     if t > length(c.ref)
         return 0
     end
-    p = [1; zeros(Int,t)]
+    p = [1; zeros(Int, t)]
     for i in 1:length(c.f)
         f = c.f[i]
         if i == 1
@@ -167,7 +168,7 @@ function length(c::MultiSetCombinations)
     return p[t+1]
 end
 
-function multiset_combinations{T<:Integer}(m, f::Vector{T}, t::Integer)
+function multiset_combinations(m, f::Vector{<:Integer}, t::Integer)
     length(m) == length(f) || error("Lengths of m and f are not the same.")
     ref = length(f) > 0 ? vcat([[i for j in 1:f[i] ] for i in 1:length(f)]...) : Int[]
     if t < 0
@@ -176,15 +177,19 @@ function multiset_combinations{T<:Integer}(m, f::Vector{T}, t::Integer)
     MultiSetCombinations(m, f, t, ref)
 end
 
-"generate all combinations of size t from an array a with possibly duplicated elements."
-function multiset_combinations{T}(a::T, t::Integer)
+"""
+    multiset_combinations(a, t)
+
+Generate all combinations of size `t` from an array `a` with possibly duplicated elements.
+"""
+function multiset_combinations(a, t::Integer)
     m = unique(collect(a))
     f = Int[sum([c == x for c in a]) for x in m]
     multiset_combinations(m, f, t)
 end
 
-start(c::MultiSetCombinations) = c.ref
-function next(c::MultiSetCombinations, s)
+Base.start(c::MultiSetCombinations) = c.ref
+function Base.next(c::MultiSetCombinations, s)
     ref = c.ref
     n = length(ref)
     t = c.t
@@ -195,7 +200,9 @@ function next(c::MultiSetCombinations, s)
         for i in t:-1:1
             if s[i] < ref[i + (n - t)]
                 j = 1
-                while ref[j] <= s[i]; j += 1; end
+                while ref[j] <= s[i]
+                    j += 1
+                end
                 s[i] = ref[j]
                 for l in (i+1):t
                     s[l] = ref[j+=1]
@@ -210,23 +217,27 @@ function next(c::MultiSetCombinations, s)
     end
     (comb, s)
 end
-done(c::MultiSetCombinations, s) =
-    (!isempty(s) && max(s[1], c.t) > length(c.ref)) ||  (isempty(s) && c.t > 0)
+Base.done(c::MultiSetCombinations, s) =
+    (!isempty(s) && max(s[1], c.t) > length(c.ref)) || (isempty(s) && c.t > 0)
 
-immutable WithReplacementCombinations{T}
+struct WithReplacementCombinations{T}
     a::T
     t::Int
 end
 
-eltype{T}(::Type{WithReplacementCombinations{T}}) = Vector{eltype(T)}
+Base.eltype(::Type{WithReplacementCombinations{T}}) where {T} = Vector{eltype(T)}
+
+Base.length(c::WithReplacementCombinations) = binomial(length(c.a) + c.t - 1, c.t)
 
-length(c::WithReplacementCombinations) = binomial(length(c.a)+c.t-1, c.t)
+"""
+    with_replacement_combinations(a, t)
 
-"generate all combinations with replacement of size t from an array a."
+Generate all combinations with replacement of size `t` from an array `a`.
+"""
 with_replacement_combinations(a, t::Integer) = WithReplacementCombinations(a, t)
 
-start(c::WithReplacementCombinations) = [1 for i in 1:c.t]
-function next(c::WithReplacementCombinations, s)
+Base.start(c::WithReplacementCombinations) = [1 for i in 1:c.t]
+function Base.next(c::WithReplacementCombinations, s)
     n = length(c.a)
     t = c.t
     comb = [c.a[si] for si in s]
@@ -249,4 +260,4 @@ function next(c::WithReplacementCombinations, s)
     end
     (comb, s)
 end
-done(c::WithReplacementCombinations, s) = !isempty(s) && s[1] > length(c.a) || c.t < 0
+Base.done(c::WithReplacementCombinations, s) = !isempty(s) && s[1] > length(c.a) || c.t < 0