Lax parent checks in isequal methods

Since isequal is called for e.g. keys in dictionaries, it
makes sense to allow comparing rings with different parents,
and reporting them as being non-equal

Author: fingolfin

docs/src/ring_interface.md

@@ -900,7 +900,7 @@ function ==(f::ConstPoly{T}, g::ConstPoly{T}) where T <: RingElement
 end
 
 function isequal(f::ConstPoly{T}, g::ConstPoly{T}) where T <: RingElement
-   check_parent(f, g)
+   parent(f) == parent(g) || return false
    return isequal(f.c, g.c)
 end
 

src/AbsSeries.jl

@@ -522,9 +522,8 @@ power series are precisely the same, to the same precision, are they declared
 equal by this function.
 """
 function isequal(x::AbsPowerSeriesRingElem{T}, y::AbsPowerSeriesRingElem{T}) where T <: RingElement
-   if parent(x) != parent(y)
-      return false
-   end
+   parent(x) == parent(y) || return false
+
    if precision(x) != precision(y) || length(x) != length(y)
       return false
    end

src/Fraction.jl

@@ -436,9 +436,7 @@ inexact, e.g. power series. Only if the power series are precisely the same,
 to the same precision, are they declared equal by this function.
 """
 function isequal(x::FracElem{T}, y::FracElem{T}) where {T <: RingElem}
-   if parent(x) != parent(y)
-      return false
-   end
+   parent(x) == parent(y) || return false
    return isequal(numerator(x, false)*denominator(y, false),
                   denominator(x, false)*numerator(y, false))
 end

src/Matrix.jl

@@ -1286,8 +1286,7 @@ series. Only if the power series are precisely the same, to the same precision,
 are they declared equal by this function.
 """
 function isequal(x::MatrixElem{T}, y::MatrixElem{T}) where {T <: NCRingElement}
-   b = check_parent(x, y, false)
-   !b && return false
+   parent(x) == parent(y) || return false
    for i = 1:nrows(x)
       for j = 1:ncols(x)
          if !isequal(x[i, j], y[i, j])

src/NCPoly.jl

@@ -361,9 +361,7 @@ power series. Only if the power series are precisely the same, to the same
 precision, are they declared equal by this function.
 """
 function isequal(x::NCPolyRingElem{T}, y::NCPolyRingElem{T}) where T <: NCRingElem
-   if parent(x) != parent(y)
-      return false
-   end
+   parent(x) == parent(y) || return false
    if length(x) != length(y)
       return false
    end

src/Poly.jl

@@ -859,9 +859,8 @@ power series. Only if the power series are precisely the same, to the same
 precision, are they declared equal by this function.
 """
 function isequal(x::PolyRingElem{T}, y::PolyRingElem{T}) where T <: RingElement
-   if parent(x) != parent(y)
-      return false
-   end
+   parent(x) == parent(y) || return false
+
    if length(x) != length(y)
       return false
    end

src/RelSeries.jl

@@ -761,9 +761,8 @@ power series are precisely the same, to the same precision, are they declared
 equal by this function.
 """
 function isequal(x::RelPowerSeriesRingElem{T}, y::RelPowerSeriesRingElem{T}) where T <: RingElement
-   if parent(x) != parent(y)
-      return false
-   end
+   parent(x) == parent(y) || return false
+
    if precision(x) != precision(y) || pol_length(x) != pol_length(y) ||
       valuation(x) != valuation(y)
       return false

src/Residue.jl

@@ -256,8 +256,7 @@ Only if the power series are precisely the same, to the same precision, are
 they declared equal by this function.
 """
 function isequal(a::ResElem{T}, b::ResElem{T}) where {T <: RingElement}
-   fl = check_parent(a, b, false)
-   !fl && return false
+   parent(a) == parent(b) || return false
    return isequal(data(a), data(b))
 end
 

src/generic/LaurentSeries.jl

@@ -1093,9 +1093,7 @@ power series are precisely the same, to the same precision, are they declared
 equal by this function.
 """
 function isequal(x::LaurentSeriesElem{T}, y::LaurentSeriesElem{T}) where {T <: RingElement}
-   if parent(x) != parent(y)
-      return false
-   end
+   parent(x) == parent(y) || return false
    if precision(x) != precision(y) || pol_length(x) != pol_length(y) ||
       valuation(x) != valuation(y) || scale(x) != scale(y)
       return false

src/generic/PuiseuxSeries.jl

@@ -564,6 +564,7 @@ function ==(a::PuiseuxSeriesElem{T}, b::PuiseuxSeriesElem{T}) where T <: RingEle
 end
 
 function isequal(a::PuiseuxSeriesElem{T}, b::PuiseuxSeriesElem{T}) where T <: RingElement
+   parent(a) == parent(b) || return false
    return a.scale == b.scale && isequal(a.data, b.data)
 end