From 38aab563d45c1e932c0be5135e6231a13f7ee8ce Mon Sep 17 00:00:00 2001
From: Max Horn <max@quendi.de>
Date: Sat, 21 Sep 2024 00:40:34 +0200
Subject: [PATCH] Add unsafe operations for FinGenAbGroupElem (#1619)

---
 src/GrpAb/Elem.jl  | 54 ++++++++++++++++++++++++++++++++++++++++++++++
 test/GrpAb/Elem.jl | 47 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/src/GrpAb/Elem.jl b/src/GrpAb/Elem.jl
index 8874317c3a..ec0d97fe54 100644
--- a/src/GrpAb/Elem.jl
+++ b/src/GrpAb/Elem.jl
@@ -224,6 +224,60 @@ end
 
 *(x::FinGenAbGroupElem, y::Integer) = y*x
 
+###############################################################################
+#
+#   Unsafe operators
+#
+###############################################################################
+
+function reduce!(x::FinGenAbGroupElem)
+  assure_reduced!(parent(x), x.coeff)
+  return x
+end
+
+function zero!(x::FinGenAbGroupElem)
+  zero!(x.coeff)
+  # no reduction necessary
+  return x
+end
+
+function neg!(x::FinGenAbGroupElem)
+  neg!(x.coeff)
+  return reduce!(x)
+end
+
+# TODO: set! for ZZMatrix not yet implemented, hence this is not yet implemented
+#function set!(x::FinGenAbGroupElem, y::FinGenAbGroupElem)
+#  set!(x.coeff, y.coeff)
+#  # no reduction necessary
+#  return x
+#end
+
+function add!(x::FinGenAbGroupElem, y::FinGenAbGroupElem, z::FinGenAbGroupElem)
+  add!(x.coeff, y.coeff, z.coeff)
+  return reduce!(x)
+end
+
+function sub!(x::FinGenAbGroupElem, y::FinGenAbGroupElem, z::FinGenAbGroupElem)
+  sub!(x.coeff, y.coeff, z.coeff)
+  return reduce!(x)
+end
+
+function mul!(x::FinGenAbGroupElem, y::FinGenAbGroupElem, z::Union{Int,ZZRingElem})
+  mul!(x.coeff, y.coeff, z)
+  return reduce!(x)
+end
+
+function addmul!(x::FinGenAbGroupElem, y::FinGenAbGroupElem, z::Union{Int,ZZRingElem})
+  addmul!(x.coeff, y.coeff, z)
+  return reduce!(x)
+end
+
+function addmul_delayed_reduction!(x::FinGenAbGroupElem, y::FinGenAbGroupElem, z::Union{Int,ZZRingElem})
+  addmul!(x.coeff, y.coeff, z)
+  return x
+end
+
 ################################################################################
 #
 #  Neutral element
diff --git a/test/GrpAb/Elem.jl b/test/GrpAb/Elem.jl
index d1002c5103..2e33680942 100644
--- a/test/GrpAb/Elem.jl
+++ b/test/GrpAb/Elem.jl
@@ -93,6 +93,53 @@
     @test aa == G([2, 0, 0])
   end
 
+  @testset "Unsafe operators" begin
+    G = abelian_group([3, 3, 0])
+
+    a = G([1, 2, 3])
+    @test zero!(a) == G([0, 0, 0])
+    @test a == G([0, 0, 0])
+
+    a = G([1, 2, 3])
+    @test neg!(a) == G([-1, -2, -3])
+    @test a == G([-1, -2, -3])
+
+    # TODO: set! not yet implemented
+    #a = G([1, 2, 3])
+    #@test Hecke.set!(a, G[1]) == G([1, 0, 0])
+    #@test a == G([1, 0, 0])
+
+    a = G([1, 2, 3])
+    @test add!(a, a) == G([2, 1, 6])
+    @test a == G([2, 1, 6])
+
+    a = G([1, 2, 3])
+    @test sub!(a, G([4, 4, 4])) == G([-3, -2, -1])
+    @test a == G([-3, -2, -1])
+
+    a = G([1, 2, 3])
+    @test mul!(a, 4) == G([1, 2, 12])
+    @test a == G([1, 2, 12])
+
+    a = G([1, 2, 3])
+    @test mul!(a, ZZ(4)) == G([1, 2, 12])
+    @test a == G([1, 2, 12])
+
+    a = G([1, 2, 3])
+    @test addmul!(a, G([1,1,1]), 4) == G([2, 0, 7])
+    @test a == G([2, 0, 7])
+
+    a = G([1, 2, 3])
+    @test addmul!(a, G([1,1,1]), ZZ(4)) == G([2, 0, 7])
+    @test a == G([2, 0, 7])
+
+    a = G([1, 2, 3])
+    @test Hecke.addmul_delayed_reduction!(a, G([1,1,1]), ZZ(4)) != G([2, 0, 7])
+    reduce!(a)
+    @test a == G([2, 0, 7])
+
+  end
+
   @testset "Neutral element" begin
     G = abelian_group([3, 3, 3])
     a = G[1]