avoid potential under/overflows

JuliaLang · Mar 16, 2019 · 807a0c8 · 807a0c8
1 parent 447de54
commit 807a0c8
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Showing 2 changed files with 30 additions and 14 deletions.
diff --git a/base/array.jl b/base/array.jl
@@ -1604,10 +1604,11 @@ CartesianIndex(2, 1)
 function findnext(A, start)
     l = last(keys(A))
     i = start
-    while i <= l
-        if A[i]
-            return i
-        end
+    i > l && return nothing
+    while true
+        A[i] && return i
+        i == l && break
+        # nextind(A, l) can throw/overflow
         i = nextind(A, i)
     end
     return nothing
@@ -1685,10 +1686,11 @@ CartesianIndex(1, 1)
 function findnext(testf::Function, A, start)
     l = last(keys(A))
     i = start
-    while i <= l
-        if testf(A[i])
-            return i
-        end
+    i > l && return nothing
+    while true
+        testf(A[i]) && return i
+        i == l && break
+        # nextind(A, l) can throw/overflow
         i = nextind(A, i)
     end
     return nothing
@@ -1781,8 +1783,12 @@ CartesianIndex(2, 1)
 """
 function findprev(A, start)
     i = start
-    while i >= first(keys(A))
+    f = first(keys(A))
+    i < f && return nothing
+    while true
         A[i] && return i
+        i == f && break
+        # prevind(A, l) can throw/underflow
         i = prevind(A, i)
     end
     return nothing
@@ -1868,8 +1874,12 @@ CartesianIndex(2, 1)
 """
 function findprev(testf::Function, A, start)
     i = start
-    while i >= first(keys(A))
+    f = first(keys(A))
+    i < f && return nothing
+    while true
         testf(A[i]) && return i
+        i == f && break
+        # prevind(A, l) can throw/underflow
         i = prevind(A, i)
     end
     return nothing

diff --git a/base/multidimensional.jl b/base/multidimensional.jl
@@ -145,13 +145,19 @@ module IteratorsMD
     # nextind and prevind with CartesianIndex
     function Base.nextind(a::AbstractArray{<:Any,N}, i::CartesianIndex{N}) where {N}
         iter = CartesianIndices(axes(a))
-        _, I = inc((), i.I, first(iter).I, last(iter).I)
-        return I
+        I = inc((), i.I, first(iter).I, last(iter).I)
+        if I === nothing
+            throw(BoundsError(a, i))
+        else
+        return I[2]
     end
     function Base.prevind(a::AbstractArray{<:Any,N}, i::CartesianIndex{N}) where {N}
         iter = CartesianIndices(axes(a))
-        _, I = dec((), i.I, first(iter).I, last(iter).I)
-        return I
+        I = dec((), i.I, first(iter).I, last(iter).I)
+        if I === nothing
+            throw(BoundsError(a, i))
+        else
+        return I[2]
     end
 
     # Iteration over the elements of CartesianIndex cannot be supported until its length can be inferred,