REPL: transpose words with Alt-t

Fixes part of #8447.

base/repl/LineEdit.jl

@@ -587,8 +587,9 @@ function edit_kill_line(s::MIState)
     refresh_line(s)
 end
 
-edit_transpose(s) = edit_transpose(buffer(s)) && refresh_line(s)
-function edit_transpose(buf::IOBuffer)
+edit_transpose_chars(s) = edit_transpose_chars(buffer(s)) && refresh_line(s)
+
+function edit_transpose_chars(buf::IOBuffer)
     position(buf) == 0 && return false
     eof(buf) && char_move_left(buf)
     char_move_left(buf)
@@ -599,6 +600,32 @@ function edit_transpose(buf::IOBuffer)
     return true
 end
 
+edit_transpose_words(s) = edit_transpose_words(buffer(s)) && refresh_line(s)
+
+function edit_transpose_words(buf::IOBuffer, mode=:readline)
+    mode in [:readline, :emacs] ||
+        throw(ArgumentError("`mode` must be `:readline` or `:emacs`"))
+    pos = position(buf)
+    if mode == :emacs
+        char_move_word_left(buf)
+        char_move_word_right(buf)
+    end
+    char_move_word_right(buf)
+    e2 = position(buf)
+    char_move_word_left(buf)
+    b2 = position(buf)
+    char_move_word_left(buf)
+    b1 = position(buf)
+    char_move_word_right(buf)
+    e1 = position(buf)
+    e1 >= b2 && (seek(buf, pos); return false)
+    word2 = splice!(buf.data, b2+1:e2, buf.data[b1+1:e1])
+    splice!(buf.data, b1+1:e1, word2)
+    seek(buf, e2)
+    true
+end
+
+
 edit_clear(buf::IOBuffer) = truncate(buf, 0)
 
 function edit_clear(s::MIState)
@@ -1492,7 +1519,8 @@ AnyDict(
         input = bracketed_paste(s)
         edit_insert(s, input)
     end,
-    "^T" => (s,o...)->edit_transpose(s)
+    "^T" => (s,o...)->edit_transpose_chars(s),
+    "\et" => (s,o...)->edit_transpose_words(s),
 )
 
 const history_keymap = AnyDict(

test/lineedit.jl

@@ -308,41 +308,77 @@ let buf = IOBuffer()
     @test String(buf.data[1:buf.size]) == "a"
 end
 
-## edit_transpose ##
+## edit_transpose_chars ##
 let buf = IOBuffer()
     LineEdit.edit_insert(buf, "abcde")
     seek(buf,0)
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "abcde"
     LineEdit.char_move_right(buf)
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "bacde"
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "bcade"
     seekend(buf)
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "bcaed"
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "bcade"
 
     seek(buf, 0)
     LineEdit.edit_clear(buf)
     LineEdit.edit_insert(buf, "αβγδε")
     seek(buf,0)
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "αβγδε"
     LineEdit.char_move_right(buf)
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "βαγδε"
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "βγαδε"
     seekend(buf)
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "βγαεδ"
-    LineEdit.edit_transpose(buf)
+    LineEdit.edit_transpose_chars(buf)
     @test String(buf.data[1:buf.size]) == "βγαδε"
 end
 
+@testset "edit_word_transpose" begin
+    buf = IOBuffer()
+    mode = Ref{Symbol}
+    function transpose!(i) # i: char indice
+        seek(buf, Base.unsafe_chr2ind(String(take!(copy(buf))), i+1)-1)
+        LineEdit.edit_transpose_words(buf, mode[])
+        str = String(take!(copy(buf)))
+        str, Base.unsafe_ind2chr(str, position(buf)+1)-1
+    end
+
+    mode[] = :readline
+    LineEdit.edit_insert(buf, "àbç def  gh ")
+    @test transpose!(0) == ("àbç def  gh ", 0)
+    @test transpose!(1) == ("àbç def  gh ", 1)
+    @test transpose!(2) == ("àbç def  gh ", 2)
+    @test transpose!(3) == ("def àbç  gh ", 7)
+    @test transpose!(4) == ("àbç def  gh ", 7)
+    @test transpose!(5) == ("def àbç  gh ", 7)
+    @test transpose!(6) == ("àbç def  gh ", 7)
+    @test transpose!(7) == ("àbç gh  def ", 11)
+    @test transpose!(10) == ("àbç def  gh ", 11)
+    @test transpose!(11) == ("àbç gh   def", 12)
+    LineEdit.edit_insert(buf, " ")
+    @test transpose!(13) == ("àbç def    gh", 13)
+
+    take!(buf)
+    mode[] = :emacs
+    LineEdit.edit_insert(buf, "àbç def  gh ")
+    @test transpose!(0) == ("def àbç  gh ", 7)
+    @test transpose!(4) == ("àbç def  gh ", 7)
+    @test transpose!(5) == ("àbç gh  def ", 11)
+    @test transpose!(10) == ("àbç def   gh", 12)
+    LineEdit.edit_insert(buf, " ")
+    @test transpose!(13) == ("àbç gh    def", 13)
+end
+
 let
     term = TestHelpers.FakeTerminal(IOBuffer(), IOBuffer(), IOBuffer())
     s = LineEdit.init_state(term, ModalInterface([Prompt("test> ")]))