open editor at correct column for edit_input

Author: KristofferC

stdlib/REPL/src/LineEdit.jl

@@ -1314,7 +1314,7 @@ function guess_current_mode_name(s)
 end
 
 # edit current input in editor
-function edit_input(s, f = (filename, line) -> InteractiveUtils.edit(filename, line))
+function edit_input(s, f = (filename, line, column) -> InteractiveUtils.edit(filename, line, column))
     mode_name = guess_current_mode_name(s)
     filename = tempname()
     if mode_name == :julia
@@ -1325,9 +1325,26 @@ function edit_input(s, f = (filename, line) -> InteractiveUtils.edit(filename, l
     buf = buffer(s)
     pos = position(buf)
     str = String(take!(buf))
-    line = 1 + count(==(_newline), view(str, 1:pos))
+    lines = readlines(IOBuffer(str); keep=true)
+
+    # Compute line
+    line_start_offset = 0
+    line = 1
+    while line < length(lines) && line_start_offset + sizeof(lines[line]) <= pos
+        line_start_offset += sizeof(lines[line])
+        line += 1
+    end
+
+    # Compute column
+    col = 0
+    off = line_start_offset
+    while off <= pos
+        off = nextind(str, off)
+        col += 1
+    end
+
     write(filename, str)
-    f(filename, line)
+    f(filename, line, col)
     str_mod = readchomp(filename)
     rm(filename)
     if str != str_mod # something was changed, run the input

stdlib/REPL/test/repl.jl

@@ -1506,11 +1506,10 @@ fake_repl() do stdin_write, stdout_read, repl
     end
     repl.interface = REPL.setup_interface(repl)
     s = LineEdit.init_state(repl.t, repl.interface)
-    LineEdit.edit_insert(s, "1234")
-    @show buffercontents(LineEdit.buffer(s))
-    input_f = function(filename, line)
-        write(filename, "123456\n")
+    LineEdit.edit_insert(s, "1234αβ")
+    input_f = function(filename, line, column)
+        write(filename, "1234αβ56γ\n")
     end
     LineEdit.edit_input(s, input_f)
-    @test buffercontents(LineEdit.buffer(s)) == "123456"
+    @test buffercontents(LineEdit.buffer(s)) == "1234αβ56γ"
 end