Access cached values when available (#227)

* Access cached values when available

For LorentzVectorBase accessors use cached values in PseudoJet and
EEJet when these exist.

For LorentzVectorBase.phi(::PseudoJet) there is no use of the cached
value because of the different range conventions in LorentzVectorBase,
[-pi, pi], vs. JetReconstruction, which uses [0, 2pi].

* Add tests for LVB accessors

Author: graeme-a-stewart

src/CommonJet.jl

@@ -120,6 +120,9 @@ const m = mass
     phi(j::FourMomentum)
 
 Return the azimuthal angle, ϕ, of the four momentum `j` in the range [0, 2π).
+
+Note that the range [0, 2π) differs from the convention in LorentzVectorBase,
+which is [-π, π].
 """
 function phi(j::FourMomentum)
     phi = LorentzVectorBase.phi(j)

src/EEJet.jl

@@ -128,6 +128,7 @@ Return the squared momentum of the `EEJet` object `eej`. This accessor uses the
 pre-calculated value that the struct has.
 """
 p2(eej::EEJet) = eej._p2
+LorentzVectorBase.spatial_magnitude2(eej::EEJet) = eej._p2
 
 """
     nx(eej::EEJet)

src/PseudoJet.jl

@@ -177,6 +177,9 @@ isvalid(j::PseudoJet) = !(j === invalid_pseudojet)
 
 Return the azimuthal angle, ϕ, of a `PseudoJet` object `p` in the range
 [0, 2π). This accessor uses the pre-calculated value that the struct has.
+
+Note that the range [0, 2π) differs from the convention in LorentzVectorBase,
+which is [-π, π].
 """
 phi(p::PseudoJet) = p._phi
 
@@ -187,6 +190,7 @@ Return the rapidity of a `PseudoJet` object. This accessor uses the
 pre-calculated value that the struct has.
 """
 rapidity(p::PseudoJet) = p._rap
+LorentzVectorBase.rapidity(p::PseudoJet) = p._rap
 
 """
     pt2(p::PseudoJet)
@@ -195,6 +199,7 @@ Return the squared transverse momentum of a `PseudoJet`. This accessor uses the
 pre-calculated value that the struct has.
 """
 pt2(p::PseudoJet) = p._pt2
+LorentzVectorBase.pt2(p::PseudoJet) = p._pt2
 
 """
     pt(p::PseudoJet)
@@ -203,3 +208,4 @@ Return the scalar transverse momentum (pt) of a PseudoJet. This accessor uses
 the precalculated value that the struct has.
 """
 pt(p::PseudoJet) = sqrt(p._pt2)
+LorentzVectorBase.pt(p::PseudoJet) = sqrt(p._pt2)

test/test-jet-types.jl

@@ -26,6 +26,11 @@ pj_beam = PseudoJet(0.0, 0.0, 5.0, 5.0)
     @test LorentzVectorBase.spatial_magnitude2(pj) ≈ JetReconstruction.p2(pj)
     @test LorentzVectorBase.cos_theta(pj) ≈ JetReconstruction.CosTheta(pj)
 
+    # These accessors should compare exactly as they use cached values
+    @test LorentzVectorBase.rapidity(pj) == JetReconstruction.rapidity(pj)
+    @test LorentzVectorBase.pt2(pj) == JetReconstruction.pt2(pj)
+    @test LorentzVectorBase.pt(pj) == JetReconstruction.pt(pj)
+
     # This isn't really a test of the output, but rather that the object
     # can be printed without error
     @test string(pj) == "PseudoJet(px: 1.0 py: 2.0 pz: 3.0 E: 10.0 cluster_hist_index: 7)"