thisind(s, i): return ncodeunits(s) + 1 if i > ncodeunits(s)

Author: StefanKarpinski

base/strings/basic.jl

@@ -237,11 +237,11 @@ end
 ## Generic indexing functions ##
 
 """
-    thisind(str::AbstractString, i::Integer)
+    thisind(s::AbstractString, i::Integer)
 
-Get the largest valid string index at or before `i`.
-Returns `0` if there is no valid string index at or before `i`.
-Returns `endof(str)` if `i≥endof(str)`.
+If `i` is the index into a character in `s` then `thisind` returns the index of the
+start of that character. If `i < start(s)` then it returns `start(s) - 1`.
+If `i > ncodeunits(s)` then it returns `ncodeunits(s) + 1`.
 
 # Examples
 ```jldoctest
@@ -257,15 +257,21 @@ julia> thisind("αβγdef", 3)
 julia> thisind("αβγdef", 4)
 3
 
-julia> thisind("αβγdef", 20)
+julia> thisind("αβγdef", 9)
 9
+
+julia> thisind("αβγdef", 10)
+10
+
+julia> thisind("αβγdef", 20)
+10
 """
 function thisind(s::AbstractString, i::Integer)
     j = Int(i)
     isvalid(s, j) && return j
     j < start(s) && return 0
-    e = endof(s)
-    j >= endof(s) && return e
+    n = ncodeunits(s)
+    j > n && return n + 1
     prevind(s, j)
 end
 

base/strings/string.jl

@@ -123,8 +123,8 @@ end
 function thisind(s::String, i::Integer)
     j = Int(i)
     j < 1 && return 0
-    e = endof(s)
-    j >= e && return e
+    n = ncodeunits(s)
+    j > n && return n + 1
     @inbounds while j > 0 && is_valid_continuation(codeunit(s,j))
         j -= 1
     end

base/strings/types.jl

@@ -88,16 +88,16 @@ end
 
 function thisind(s::SubString{String}, i::Integer)
     j = Int(i)
-    j < 1 && return 0
-    e = endof(s)
-    j >= e && return e
+    j < start(s) && return 0
+    n = ncodeunits(s)
+    j > n && return n + 1
     offset = s.offset
     str = s.string
     j += offset
     @inbounds while j > offset && is_valid_continuation(codeunit(str, j))
         j -= 1
     end
-    j-offset
+    j - offset
 end
 
 nextind(s::SubString, i::Integer) = nextind(s.string, i+s.offset)-s.offset

test/strings/basic.jl

@@ -580,13 +580,14 @@ end
             @test thisind(s, 6) == 6
             @test thisind(s, 15) == 15
             @test thisind(s, 16) == 15
-            @test thisind(s, 30) == 15
+            @test thisind(s, 17) == 17
+            @test thisind(s, 30) == 17
         end
     end
 
     let strs = Any["", s"", SubString("123", 2, 1), SubString(s"123", 2, 1)]
         for s in strs, i in -2:2
-            @test thisind(s, i) == 0
+            @test thisind(s, i) == (i > 0)
         end
     end
 end