fixup! deprecate unsafe_length for length

Author: vtjnash

base/checked.jl

@@ -6,14 +6,14 @@ module Checked
 
 export checked_neg, checked_abs, checked_add, checked_sub, checked_mul,
        checked_div, checked_rem, checked_fld, checked_mod, checked_cld,
-       add_with_overflow, sub_with_overflow, mul_with_overflow
+       checked_length, add_with_overflow, sub_with_overflow, mul_with_overflow
 
 import Core.Intrinsics:
        checked_sadd_int, checked_ssub_int, checked_smul_int, checked_sdiv_int,
        checked_srem_int,
        checked_uadd_int, checked_usub_int, checked_umul_int, checked_udiv_int,
        checked_urem_int
-import ..no_op_err, ..@_inline_meta, ..@_noinline_meta
+import ..no_op_err, ..@_inline_meta, ..@_noinline_meta, ..checked_length
 
 # define promotion behavior for checked operations
 checked_add(x::Integer, y::Integer) = checked_add(promote(x,y)...)
@@ -349,4 +349,12 @@ The overflow protection may impose a perceptible performance penalty.
 """
 checked_cld(x::T, y::T) where {T<:Integer} = cld(x, y) # Base.cld already checks
 
+"""
+    Base.checked_length(r)
+
+Calculates `length(r)`, but may check for overflow errors where applicable when
+the result doesn't fit into `Union{eltype(r),Int}`.
+"""
+checked_length(r) = length(r) # for most things, length doesn't error
+
 end

base/deprecated.jl

@@ -240,8 +240,8 @@ end
 @deprecate cat_shape(dims, shape::Tuple{}, shapes::Tuple...) cat_shape(dims, shapes) false
 cat_shape(dims, shape::Tuple{}) = () # make sure `cat_shape(dims, ())` do not recursively calls itself
 
-@deprecate unsafe_indices(A) axes(A)
-@deprecate unsafe_length(r) length(r)
+@deprecate unsafe_indices(A) axes(A) false
+@deprecate unsafe_length(r) length(r) false
 
 # END 1.6 deprecations
 

base/range.jl

@@ -631,46 +631,100 @@ firstindex(::UnitRange) = 1
 firstindex(::StepRange) = 1
 firstindex(::LinRange) = 1
 
-length(r::AbstractUnitRange) = Integer(last(r) - first(r) + step(r))
+# n.b. checked_length for these is defined iff checked_add and checked_sub are
+# defined between the relevant types
+function checked_length(r::OrdinalRange{T}) where T
+    s = step(r)
+    # s != 0, by construction, but avoids the division error later
+    start = first(r)
+    if s == zero(s) || isempty(r)
+        return Integer(start - start + zero(s))
+    end
+    return Integer(div(checked_add(checked_sub(last(r), start), s, s)))
+end
+
+function checked_length(r::AbstractUnitRange{T}) where T
+    # compiler optimization: remove dead cases from above
+    if isempty(r)
+        return Integer(first(r) - first(r))
+    end
+    a = Integer(checked_add(checked_sub(last(r), first(r))))
+    return a + one(a)
+end
+
+function length(r::OrdinalRange{T}) where T
+    s = step(r)
+    # s != 0, by construction, but avoids the division error later
+    start = first(r)
+    if s == zero(s) || isempty(r)
+        return Integer(start - start + zero(s))
+    end
+    return Integer(div(last(r) - start + s, s))
+end
+
+function length(r::AbstractUnitRange{T}) where T
+    @_inline_meta
+    a = Integer(last(r) - first(r)) # even when isempty, by construction (with overflow)
+    return a + one(a)
+end
+
 length(r::OneTo) = Integer(r.stop - zero(r.stop))
 length(r::StepRangeLen) = r.len
 length(r::LinRange) = r.len
-length(r::StepRange) = Integer(div(r.stop - r.start + r.step, r.step))
 
-# compile optimizations for which promote_type(T, Int) = T
-let bigint = Union{Int,UInt,Int64,UInt64,Int128,UInt128}
+let bigints = Union{Int, UInt, Int64, UInt64, Int128, UInt128}
     global length
-    function length(r::StepRange{T}) where T<:bigint
-        step = r.step
-        diff = r.stop - r.start
-        step == 0 && return zero(T) # unreachable, by construction, but avoids the error case here later
+    # compile optimization for which promote_type(T, Int) == T
+    length(r::OneTo{T}) where {T<:bigints} = r.stop
+    # slightly more accurate length and checked_length in extreme cases
+    # (near typemax) for types with known `unsigned` functions
+    function length(r::OrdinalRange{T}) where T<:bigints
+        s = step(r)
+        s == zero(s) && return zero(T) # unreachable, by construction, but avoids the error case here later
         isempty(r) && return zero(T)
-        if -1 <= step <= 1 || step == -step || step isa Unsigned # n.b. !(step isa T)
-            # if |step| > 1, diff might have overflowed, but unsigned(diff)÷step should
-            # therefore still be valid (if the result is representable at all)
-            return div(diff, step) % T + one(T)
-        elseif step < 0
-            return div(unsigned(-diff), -step) % T + one(T)
+        diff = last(r) - first(r)
+        # if |s| > 1, diff might have overflowed, but unsigned(diff)÷s should
+        # therefore still be valid (if the result is representable at all)
+        # n.b. !(s isa T)
+        if s isa Unsigned || -1 <= s <= 1 || s == -s
+            a = div(diff, s)
+        elseif s < 0
+            a = div(unsigned(-diff), -s) % typeof(diff)
         else
-            return div(unsigned(diff), step) % T + one(T)
+            a = div(unsigned(diff), s) % typeof(diff)
         end
+        return Integer(a) + one(a)
     end
-
-    function length(r::AbstractUnitRange{T}) where T<:bigint
-        @_inline_meta
-        return last(r) - first(r) + one(T) # even when isempty, by construction (with overflow)
+    function checked_length(r::OrdinalRange{T}) where T<:bigints
+        s = step(r)
+        s == zero(s) && return zero(T) # unreachable, by construction, but avoids the error case here later
+        isempty(r) && return zero(T)
+        stop, start = last(r), first(r)
+        # n.b. !(s isa T)
+        if s > 1
+            diff = stop - start
+            a = convert(T, div(unsigned(diff), s))
+        elseif s < -1
+            diff = start - stop
+            a = convert(T, div(unsigned(diff), -s))
+        elseif s > 0
+            a = div(checked_sub(stop, start), s)
+        else
+            a = div(checked_sub(start, stop), -s)
+        end
+        return checked_add(a, one(a))
     end
-    length(r::OneTo{T}) where {T<:bigint} = r.stop
 end
 
 # some special cases to favor default Int type
-let smallint = (Int === Int64 ?
-                Union{Int8,UInt8,Int16,UInt16,Int32,UInt32} :
-                Union{Int8,UInt8,Int16,UInt16})
+let smallints = (Int === Int64 ?
+                Union{Int8, UInt8, Int16, UInt16, Int32, UInt32} :
+                Union{Int8, UInt8, Int16, UInt16})
     global length
-    length(r::StepRange{<:smallint}) = div(Int(r.stop) - Int(r.start) + r.step, r.step) # n.b. !(step isa T)
-    length(r::AbstractUnitRange{<:smallint}) = Int(last(r)) - Int(first(r)) + 1
-    length(r::OneTo{<:smallint}) = Int(r.stop)
+    # n.b. !(step isa T)
+    length(r::OrdinalRange{<:smallints}) = div(Int(last(r)) - Int(first(r)) + step(r), step(r))
+    length(r::AbstractUnitRange{<:smallints}) = Int(last(r)) - Int(first(r)) + 1
+    length(r::OneTo{<:smallints}) = Int(r.stop)
 end
 
 first(r::OrdinalRange{T}) where {T} = convert(T, r.start)

test/testhelpers/Furlongs.jl

@@ -20,7 +20,7 @@ Furlong{p}(x::Furlong{q}) where {p,q} = (@assert(p==q); Furlong{p,typeof(x.val)}
 Furlong{p,T}(x::Furlong{q}) where {T,p,q} = (@assert(p==q); Furlong{p,T}(T(x.val)))
 
 Base.promote_type(::Type{Furlong{p,T}}, ::Type{Furlong{p,S}}) where {p,T,S} =
-    (Base.@_pure_meta; Furlong{p,promote_type(T,S)})
+    Furlong{p,promote_type(T,S)}
 
 Base.one(x::Furlong{p,T}) where {p,T} = one(T)
 Base.one(::Type{Furlong{p,T}}) where {p,T} = one(T)
@@ -38,14 +38,12 @@ Base.floatmax(::Type{Furlong{p,T}}) where {p,T<:AbstractFloat} = Furlong{p}(floa
 Base.floatmax(::Furlong{p,T}) where {p,T<:AbstractFloat} = floatmax(Furlong{p,T})
 Base.conj(x::Furlong{p,T}) where {p,T} = Furlong{p,T}(conj(x.val))
 
-# convert Furlong exponent p to a canonical form.  This
-# is not type stable, but it doesn't matter since it is used
-# at compile time (in generated functions), not runtime
+# convert Furlong exponent p to a canonical form
 canonical_p(p) = isinteger(p) ? Int(p) : Rational{Int}(p)
 
 Base.abs(x::Furlong{p}) where {p} = Furlong{p}(abs(x.val))
-@generated Base.abs2(x::Furlong{p}) where {p} = :(Furlong{$(canonical_p(2p))}(abs2(x.val)))
-@generated Base.inv(x::Furlong{p}) where {p} = :(Furlong{$(canonical_p(-p))}(inv(x.val)))
+Base.abs2(x::Furlong{p}) where {p} = Furlong{canonical_p(2p)}(abs2(x.val))
+Base.inv(x::Furlong{p}) where {p} = Furlong{canonical_p(-p)}(inv(x.val))
 
 for f in (:isfinite, :isnan, :isreal, :isinf)
     @eval Base.$f(x::Furlong) = $f(x.val)
@@ -64,11 +62,10 @@ end
 for op in (:(==), :(!=), :<, :<=, :isless, :isequal)
     @eval $op(x::Furlong{p}, y::Furlong{p}) where {p} = $op(x.val, y.val)
 end
-# generated functions to allow type inference of the value of the exponent:
 for (f,op) in ((:_plus,:+),(:_minus,:-),(:_times,:*),(:_div,://))
-    @eval @generated function $f(v::T, ::Furlong{p}, ::Union{Furlong{q},Val{q}}) where {T,p,q}
+    @eval function $f(v::T, ::Furlong{p}, ::Union{Furlong{q},Val{q}}) where {T,p,q}
         s = $op(p, q)
-        :(Furlong{$(canonical_p(s)),$T}(v))
+        Furlong{canonical_p(s),T}(v)
     end
 end
 for (op,eop) in ((:*, :_plus), (:/, :_minus), (://, :_minus), (:div, :_minus))