From ffe969afa75d874d71fb8a9f3819fdded1d0f3f6 Mon Sep 17 00:00:00 2001
From: Stefan Krastanov <stefan@krastanov.org>
Date: Thu, 24 Mar 2022 18:27:01 -0400
Subject: [PATCH] Val{Bool} keywords for `generate!`

---
 CHANGELOG.md               |  5 +++--
 src/project_trace_reset.jl | 19 ++++++++++++-------
 test/test_allocations.jl   |  4 ++--
 3 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e852ce0c..7179c9c35 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,13 +4,14 @@
 
 - Implement `trusted_rank` that returns `rank` for states that support it and `length` for others (e.g. `Stabilizer`).
 - Implement `length` for `[Mixed]Destabilizer`.
-- Clean up code repetition between `project!` and `projectX/Y/Z!`.
+- Clean up code repetition between `project!` and `projectX/Y/Z!`. Issue `#40`
 - More conversion constructors between different tableau types.
 - Implement pre-compilation examples (again) for julia 1.9+.
+- `generate!` does not needlessly allocate anymore, helping `project!` on `Stabilizer`. Issue `#39`
 
 ## v0.4.2
 
-- `project!` does not needlessly allocate anymore on `MixedDestabilizer`. PR `#41`
+- `project!` does not needlessly allocate anymore on `MixedDestabilizer`. Issue `#39`, PR `#41`
 
 ## v0.4.1
 
diff --git a/src/project_trace_reset.jl b/src/project_trace_reset.jl
index 75a69e7b9..1582ccb6f 100644
--- a/src/project_trace_reset.jl
+++ b/src/project_trace_reset.jl
@@ -33,8 +33,13 @@ julia> generate!(P"XII",canonicalize!(S"XII")) === nothing
 false
 ```
 """
-function generate!(pauli::PauliOperator{Tz,Tv}, stabilizer::Stabilizer{Tzv,Tm}; phases::Bool=true, saveindices::Bool=true) where {Tz<:AbstractArray{UInt8,0}, Tzv<:AbstractVector{UInt8}, Tme<:Unsigned, Tv<:AbstractVector{Tme}, Tm<:AbstractMatrix{Tme}} # TODO there is stuff that can be abstracted away here and in canonicalize!
+function generate!(pauli::PauliOperator, stabilizer::Stabilizer; phases::Bool=true, saveindices::Bool=true)
     _phases = Val(phases)
+    _saveindices = Val(saveindices)
+    _generate!(pauli, stabilizer; phases=_phases, saveindices=_saveindices)
+end
+
+function _generate!(pauli::PauliOperator{Tz,Tv}, stabilizer::Stabilizer{Tzv,Tm}; phases::Val{PHASES}=Val(true), saveindices::Val{SAVEIDX}=Val(true)) where {Tz<:AbstractArray{UInt8,0}, Tzv<:AbstractVector{UInt8}, Tme<:Unsigned, Tv<:AbstractVector{Tme}, Tm<:AbstractMatrix{Tme}, PHASES, SAVEIDX} # TODO there is stuff that can be abstracted away here and in canonicalize!
     xzs = stabilizer.xzs
     xs = @view xzs[1:end÷2,:]
     zs = @view xzs[end÷2+1:end,:]
@@ -54,8 +59,8 @@ function generate!(pauli::PauliOperator{Tz,Tv}, stabilizer::Stabilizer{Tzv,Tm};
         else
             used += candidate
         end
-        mul_left!(pauli, stabilizer, used, phases=_phases)
-        saveindices && push!(used_indices, used)
+        mul_left!(pauli, stabilizer, used, phases=phases)
+        SAVEIDX && push!(used_indices, used)
     end
     # remove Zs
     while (i=unsafe_bitfindnext_(pz,1)) !== nothing
@@ -68,11 +73,11 @@ function generate!(pauli::PauliOperator{Tz,Tv}, stabilizer::Stabilizer{Tzv,Tm};
         else
             used += candidate
         end
-        mul_left!(pauli, stabilizer, used, phases=_phases)
-        saveindices && push!(used_indices, used)
+        mul_left!(pauli, stabilizer, used, phases=phases)
+        SAVEIDX && push!(used_indices, used)
     end
     all(iszero, pauli.xz) || return nothing # Need to check due to cases like generate!(P"_Z", S"XZ") that bypass the X checks # TODO do this better, without this extra loop through p.xz
-    if saveindices
+    if SAVEIDX
         return pauli, used_indices
     else
         return pauli
@@ -282,7 +287,7 @@ function _project!(stabilizer::Stabilizer,pauli::PauliOperator;keep_result::Bool
     if anticommutes == 0
         if keep_result
             _,_,r = canonicalize!(stabilizer; phases=B, ranks=true) # O(n^3)
-            gen = generate!(copy(pauli), stabilizer, phases=B) # O(n^2)
+            gen = _generate!(copy(pauli), stabilizer, phases=phases) # O(n^2)
             if isnothing(gen)
                 result = nothing
                 anticommutes = r+1
diff --git a/test/test_allocations.jl b/test/test_allocations.jl
index 5ec8ef662..600e77de0 100644
--- a/test/test_allocations.jl
+++ b/test/test_allocations.jl
@@ -51,8 +51,8 @@ function test_allocations()
             f3()
             f4() = project!(md,p)
             f4()
-            @test_broken allocated(f1) < 300
-            @test_broken allocated(f2) < 300
+            @test allocated(f1) < 1600
+            @test allocated(f2) < 1500
             @test allocated(f3) < 400
             @test allocated(f4) < 450
             for p! in [projectX!, projectY!, projectZ!]