promotion rules

src/CFTime.jl

@@ -16,8 +16,8 @@ The following types are supported `DateTime`,
 module CFTime
 
 using Printf
-using Dates
-import Dates: UTInstant, Millisecond
+import Dates
+import Dates: UTInstant, Millisecond, DateTime, DateFormat
 import Dates:
     year,
     month,
@@ -50,7 +50,7 @@ import Dates:
     yearmonth,
     yearmonthday
 
-import Base: +, -, isless, string, show, convert, reinterpret, ==
+import Base: +, -, isless, string, show, convert, reinterpret, ==, promote_rule
 
 include("constants.jl")
 include("types.jl")

src/datetime.jl

@@ -66,7 +66,7 @@ This type implements the calendar defined as "$($calendar)".
                              units = first(TIME_DIVISION[max(length(args),7)-2]),
                              )
             DT = $CFDateTime
-            factor, exponent = filter(td -> td[1] == units,TIME_DIVISION)[1][2:end]
+            factor, exponent = filter(td -> td[1] == Symbol(units),TIME_DIVISION)[1][2:end]
             T = Period{Ti,Val(factor), Val(exponent)}
             return DT{T,Val(origin)}(args...)
         end
@@ -182,27 +182,6 @@ pattern given in the `format` string.
     end
 end
 
-
-function +(p1::Period{T,Tfactor,Texponent},p2::Period{T,Tfactor,Texponent}) where {T, Tfactor, Texponent}
-    Period{T,Tfactor,Texponent}(p1.duration + p2.duration)
-end
-
-function +(p1::Period{T1},p2::Period{T2}) where {T1, T2}
-    T = promote_type(T1,T2)
-
-    # which is the smallest unit?
-    if _factor(p1) / 10^(-_exponent(p1)) <= _factor(p2) / 10^(-_exponent(p2))
-
-        duration = T(p1.duration) +
-                       (T(p2.duration) * _factor(p2) * 10^(_exponent(p2)-_exponent(p1))) ÷
-                       _factor(p1)
-        return Period(duration,_factor(p1),_exponent(p1))
-    else
-        return p2 + p1
-    end
-end
-
-
 +(dt::AbstractCFDateTime,p::Union{Dates.TimePeriod,Dates.Day}) = dt + convert(CFTime.Period,p)
 
 function -(dt1::AbstractCFDateTime,dt2::AbstractCFDateTime)

src/period.jl

@@ -5,6 +5,11 @@
 
 Period(duration::Number,factor,exponent=-3) = Period{typeof(duration),Val(factor),Val(exponent)}(duration)
 
+function Period(duration::Number,units::Union{Symbol,AbstractString})
+    factor, exponent = filter(td -> td[1] == Symbol(units),TIME_DIVISION)[1][2:end]
+    return Period(duration,factor,exponent)
+end
+
 _type(p::Period{T,factor,exponent}) where {T,factor,exponent} = T
 _factor(p::Period{T,factor,exponent}) where {T,factor,exponent} = unwrap(factor)
 _exponent(p::Period{T,factor,exponent}) where {T,factor,exponent} = unwrap(exponent)
@@ -67,6 +72,44 @@ function Period(T::DataType,tuf::Tuple,factor,exponent=-3)
     Period{typeof(duration),Val(factor),Val(exponent)}(duration)
 end
 
+function promote_rule(::Type{Period{T1,Tfactor1,Texponent1}},
+                      ::Type{Period{T2,Tfactor2,Texponent2}}) where
+    {T1,Tfactor1,Texponent1,T2,Tfactor2,Texponent2}
+
+    factor1 = unwrap(Tfactor1)
+    factor2 = unwrap(Tfactor2)
+    exponent1 = unwrap(Texponent1)
+    exponent2 = unwrap(Texponent2)
+    T = promote_type(T1,T2)
+
+    # which is the smallest unit?
+    if factor1 / 10^(-exponent1) <= factor2 / 10^(-exponent2)
+        return Period{T,Tfactor1,Texponent1}
+    else
+        return Period{T,Tfactor2,Texponent2}
+    end
+end
+
+function convert(::Type{Period{T1,Tfactor1,Texponent1}},
+                 p::Period{T2,Tfactor2,Texponent2}) where
+    {T1,Tfactor1,Texponent1,T2,Tfactor2,Texponent2}
+
+    factor1 = unwrap(Tfactor1)
+    factor2 = unwrap(Tfactor2)
+    exponent1 = unwrap(Texponent1)
+    exponent2 = unwrap(Texponent2)
+
+    duration = (T1(p.duration) * factor2 * 10^(exponent2-exponent1)) ÷
+        factor1
+
+    return Period{T1,Tfactor1,Texponent1}(duration)
+end
+
+function +(p1::Period{T,Tfactor,Texponent},p2::Period{T,Tfactor,Texponent}) where {T, Tfactor, Texponent}
+    Period{T,Tfactor,Texponent}(p1.duration + p2.duration)
+end
+
++(p1::Period,p2::Period) = +(promote(p1,p2)...)
 +(p1::Period,p2::Union{Dates.TimePeriod,Dates.Day}) = p1 + convert(CFTime.Period,p2)
 +(p1::Union{Dates.TimePeriod,Dates.Day},p2::Period) = p2 + p1
 

test/test_resolution.jl

@@ -5,11 +5,9 @@ using Pkg; Pkg.activate("CFTime-env",shared=true)
 using CFTime
 import CFTime: timetuplefrac, datetuple_ymd, timeunits, datetuple, datenum, AbstractCFDateTime, parseDT, datenum_
 import Dates
-import Dates: value, year,  month,  day, hour, minute, second, millisecond, microsecond, nanosecond
+import Dates: value, year,  month,  day, hour, minute, second, millisecond, microsecond, nanosecond, DateTime, @dateformat_str
 using Test
 import Base: +, -, *, zero, one, isless, rem, div, string, convert
-using Dates
-
 using CFTime: Period, DateTimeStandard
 
 # TEST
@@ -30,10 +28,7 @@ end
 
 factor = 1000
 
-#for tuf in (
-#    (2,3,4,5),
 tuf=    (2,3,4,5,6,7,8)
-#    )
 factor = 1e-6
 exponent = -3
 
@@ -47,8 +42,16 @@ exponent = -9
 p = Period(tuf,factor,exponent)
 @test timetuplefrac(p)[1:length(tuf)] == tuf
 
+# test promotion rules
+
+p1 = CFTime.Period(1,:second)
+p2 = CFTime.Period(1000,:millisecond)
+
+@test promote_type(typeof(p1),typeof(p2)) == typeof(p2)
+
+pp1,pp2 = promote(p1,p2)
+@test pp1 === pp2
 
-#end
 
 dt = DateTimeStandard(1000,"milliseconds since 2000-01-01");
 @test same_tuple((2000, 1, 1, 0, 0, 1),datetuple(dt))