Actually show glyphs for latex or emoji shortcodes being suggested in the REPL (JuliaLang#54800)

When a user requests a completion for a backslash shortcode, this PR
adds the glyphs for all the suggestions to the output. This makes it
much easier to find the result one is looking for, especially if the
user doesn't know all latex and emoji specifiers by heart.

Before:

<img width="813" alt="image"
src="https://github.com/JuliaLang/julia/assets/22495855/bf651399-85a6-4677-abdc-c66a104e3b89">

After:

<img width="977" alt="image"
src="https://github.com/JuliaLang/julia/assets/22495855/04c53ea2-318f-4888-96eb-0215b49c10f3">

---------

Co-authored-by: Dilum Aluthge <dilum@aluthge.com>

Author: jkrumbiegel

stdlib/REPL/src/LineEdit.jl

@@ -181,7 +181,18 @@ struct EmptyHistoryProvider <: HistoryProvider end
 
 reset_state(::EmptyHistoryProvider) = nothing
 
-complete_line(c::EmptyCompletionProvider, s; hint::Bool=false) = String[], "", true
+# Before, completions were always given as strings. But at least for backslash
+# completions, it's nice to see what glyphs are available in the completion preview.
+# To separate between what's shown in the preview list of possible matches, and what's
+# actually completed, we introduce this struct.
+struct NamedCompletion
+    completion::String # what is actually completed, for example "\trianglecdot"
+    name::String # what is displayed in lists of possible completions, for example "◬ \trianglecdot"
+end
+
+NamedCompletion(completion::String) = NamedCompletion(completion, completion)
+
+complete_line(c::EmptyCompletionProvider, s; hint::Bool=false) = NamedCompletion[], "", true
 
 # complete_line can be specialized for only two arguments, when the active module
 # doesn't matter (e.g. Pkg does this)
@@ -308,6 +319,7 @@ end
 
 set_action!(s, command::Symbol) = nothing
 
+common_prefix(completions::Vector{NamedCompletion}) = common_prefix(map(x -> x.completion, completions))
 function common_prefix(completions::Vector{String})
     ret = ""
     c1 = completions[1]
@@ -330,6 +342,8 @@ end
 # does not restrict column length when multiple columns are used.
 const MULTICOLUMN_THRESHOLD = 5
 
+show_completions(s::PromptState, completions::Vector{NamedCompletion}) = show_completions(s, map(x -> x.name, completions))
+
 # Show available completions
 function show_completions(s::PromptState, completions::Vector{String})
     # skip any lines of input after the cursor
@@ -374,6 +388,18 @@ function complete_line(s::MIState)
     end
 end
 
+# due to close coupling of the Pkg ReplExt `complete_line` can still return a vector of strings,
+# so we convert those in this helper
+function complete_line_named(args...; kwargs...)::Tuple{Vector{NamedCompletion},String,Bool}
+    result = complete_line(args...; kwargs...)::Union{Tuple{Vector{NamedCompletion},String,Bool},Tuple{Vector{String},String,Bool}}
+    if result isa Tuple{Vector{NamedCompletion},String,Bool}
+        return result
+    else
+        completions, partial, should_complete = result
+        return map(NamedCompletion, completions), partial, should_complete
+    end
+end
+
 function check_for_hint(s::MIState)
     st = state(s)
     if !options(st).hint_tab_completes || !eof(buffer(st))
@@ -383,12 +409,14 @@ function check_for_hint(s::MIState)
         return clear_hint(st)
     end
 
-    completions, partial, should_complete = try
-        complete_line(st.p.complete, st, s.active_module; hint = true)::Tuple{Vector{String},String,Bool}
+    named_completions, partial, should_complete = try
+        complete_line_named(st.p.complete, st, s.active_module; hint = true)
     catch
         @debug "error completing line for hint" exception=current_exceptions()
         return clear_hint(st)
     end
+    completions = map(x -> x.completion, named_completions)
+
     isempty(completions) && return clear_hint(st)
     # Don't complete for single chars, given e.g. `x` completes to `xor`
     if length(partial) > 1 && should_complete
@@ -425,7 +453,7 @@ function clear_hint(s::ModeState)
 end
 
 function complete_line(s::PromptState, repeats::Int, mod::Module; hint::Bool=false)
-    completions, partial, should_complete = complete_line(s.p.complete, s, mod; hint)::Tuple{Vector{String},String,Bool}
+    completions, partial, should_complete = complete_line_named(s.p.complete, s, mod; hint)
     isempty(completions) && return false
     if !should_complete
         # should_complete is false for cases where we only want to show
@@ -435,7 +463,7 @@ function complete_line(s::PromptState, repeats::Int, mod::Module; hint::Bool=fal
         # Replace word by completion
         prev_pos = position(s)
         push_undo(s)
-        edit_splice!(s, (prev_pos - sizeof(partial)) => prev_pos, completions[1])
+        edit_splice!(s, (prev_pos - sizeof(partial)) => prev_pos, completions[1].completion)
     else
         p = common_prefix(completions)
         if !isempty(p) && p != partial

stdlib/REPL/src/REPL.jl

@@ -843,22 +843,22 @@ function complete_line(c::REPLCompletionProvider, s::PromptState, mod::Module; h
     full = LineEdit.input_string(s)
     ret, range, should_complete = completions(full, lastindex(partial), mod, c.modifiers.shift, hint)
     c.modifiers = LineEdit.Modifiers()
-    return unique!(String[completion_text(x) for x in ret]), partial[range], should_complete
+    return unique!(LineEdit.NamedCompletion[named_completion(x) for x in ret]), partial[range], should_complete
 end
 
 function complete_line(c::ShellCompletionProvider, s::PromptState; hint::Bool=false)
     # First parse everything up to the current position
     partial = beforecursor(s.input_buffer)
     full = LineEdit.input_string(s)
     ret, range, should_complete = shell_completions(full, lastindex(partial), hint)
-    return unique!(String[completion_text(x) for x in ret]), partial[range], should_complete
+    return unique!(LineEdit.NamedCompletion[named_completion(x) for x in ret]), partial[range], should_complete
 end
 
 function complete_line(c::LatexCompletions, s; hint::Bool=false)
     partial = beforecursor(LineEdit.buffer(s))
     full = LineEdit.input_string(s)::String
     ret, range, should_complete = bslash_completions(full, lastindex(partial), hint)[2]
-    return unique!(String[completion_text(x) for x in ret]), partial[range], should_complete
+    return unique!(LineEdit.NamedCompletion[named_completion(x) for x in ret]), partial[range], should_complete
 end
 
 with_repl_linfo(f, repl) = f(outstream(repl))

stdlib/REPL/src/REPLCompletions.jl

@@ -2,7 +2,7 @@
 
 module REPLCompletions
 
-export completions, shell_completions, bslash_completions, completion_text
+export completions, shell_completions, bslash_completions, completion_text, named_completion
 
 using Core: Const
 # We want to insulate the REPLCompletion module from any changes the user may
@@ -13,6 +13,8 @@ using Base.Meta
 using Base: propertynames, something, IdSet
 using Base.Filesystem: _readdirx
 
+using ..REPL.LineEdit: NamedCompletion
+
 abstract type Completion end
 
 struct TextCompletion <: Completion
@@ -57,8 +59,10 @@ struct MethodCompletion <: Completion
 end
 
 struct BslashCompletion <: Completion
-    bslash::String
+    completion::String # what is actually completed, for example "\trianglecdot"
+    name::String # what is displayed, for example "◬ \trianglecdot"
 end
+BslashCompletion(completion::String) = BslashCompletion(completion, completion)
 
 struct ShellCompletion <: Completion
     text::String
@@ -114,13 +118,21 @@ _completion_text(c::PackageCompletion) = c.package
 _completion_text(c::PropertyCompletion) = sprint(Base.show_sym, c.property)
 _completion_text(c::FieldCompletion) = sprint(Base.show_sym, c.field)
 _completion_text(c::MethodCompletion) = repr(c.method)
-_completion_text(c::BslashCompletion) = c.bslash
 _completion_text(c::ShellCompletion) = c.text
 _completion_text(c::DictCompletion) = c.key
 _completion_text(c::KeywordArgumentCompletion) = c.kwarg*'='
 
 completion_text(c) = _completion_text(c)::String
 
+named_completion(c::BslashCompletion) = NamedCompletion(c.completion, c.name)
+
+function named_completion(c)
+    text = completion_text(c)::String
+    return NamedCompletion(text, text)
+end
+
+named_completion_completion(c) = named_completion(c).completion::String
+
 const Completions = Tuple{Vector{Completion}, UnitRange{Int}, Bool}
 
 function completes_global(x, name)
@@ -984,12 +996,10 @@ function bslash_completions(string::String, pos::Int, hint::Bool=false)
         end
         # return possible matches; these cannot be mixed with regular
         # Julian completions as only latex / emoji symbols contain the leading \
-        if startswith(s, "\\:") # emoji
-            namelist = Iterators.filter(k -> startswith(k, s), keys(emoji_symbols))
-        else # latex
-            namelist = Iterators.filter(k -> startswith(k, s), keys(latex_symbols))
-        end
-        return (true, (Completion[BslashCompletion(name) for name in sort!(collect(namelist))], slashpos:pos, true))
+        symbol_dict = startswith(s, "\\:") ? emoji_symbols : latex_symbols
+        namelist = Iterators.filter(k -> startswith(k, s), keys(symbol_dict))
+        completions = Completion[BslashCompletion(name, "$(symbol_dict[name]) $name") for name in sort!(collect(namelist))]
+        return (true, (completions, slashpos:pos, true))
     end
     return (false, (Completion[], 0:-1, false))
 end
@@ -1099,7 +1109,7 @@ function complete_keyword_argument(partial::String, last_idx::Int, context_modul
         complete_keyval!(suggestions, last_word)
     end
 
-    return sort!(suggestions, by=completion_text), wordrange
+    return sort!(suggestions, by=named_completion_completion), wordrange
 end
 
 function get_loading_candidates(pkgstarts::String, project_file::String)
@@ -1298,7 +1308,7 @@ function completions(string::String, pos::Int, context_module::Module=Main, shif
         complete_identifiers!(suggestions, context_module, string, name,
                               pos, separatorpos, startpos;
                               shift)
-        return sort!(unique!(completion_text, suggestions), by=completion_text), (separatorpos+1):pos, true
+        return sort!(unique!(named_completion, suggestions), by=named_completion_completion), (separatorpos+1):pos, true
     elseif inc_tag === :cmd
         # TODO: should this call shell_completions instead of partially reimplementing it?
         let m = match(r"[\t\n\r\"`><=*?|]| (?!\\)", reverse(partial)) # fuzzy shell_parse in reverse
@@ -1496,7 +1506,7 @@ function completions(string::String, pos::Int, context_module::Module=Main, shif
     complete_identifiers!(suggestions, context_module, string, name,
                           pos, separatorpos, startpos;
                           comp_keywords, complete_modules_only, shift)
-    return sort!(unique!(completion_text, suggestions), by=completion_text), namepos:pos, true
+    return sort!(unique!(named_completion, suggestions), by=named_completion_completion), namepos:pos, true
 end
 
 function shell_completions(string, pos, hint::Bool=false)

stdlib/REPL/test/replcompletions.jl

@@ -170,17 +170,23 @@ end
 
 function map_completion_text(completions)
     c, r, res = completions
-    return map(completion_text, c), r, res
+    return map(x -> named_completion(x).completion, c), r, res
+end
+
+function map_named_completion(completions)
+    c, r, res = completions
+    return map(named_completion, c), r, res
 end
 
 test_complete(s) = map_completion_text(@inferred(completions(s, lastindex(s))))
 test_scomplete(s) =  map_completion_text(@inferred(shell_completions(s, lastindex(s))))
-test_bslashcomplete(s) =  map_completion_text(@inferred(bslash_completions(s, lastindex(s)))[2])
 test_complete_context(s, m=@__MODULE__; shift::Bool=true) =
     map_completion_text(@inferred(completions(s,lastindex(s), m, shift)))
 test_complete_foo(s) = test_complete_context(s, Main.CompletionFoo)
 test_complete_noshift(s) = map_completion_text(@inferred(completions(s, lastindex(s), Main, false)))
 
+test_bslashcomplete(s) =  map_named_completion(@inferred(bslash_completions(s, lastindex(s)))[2])
+
 test_methods_list(@nospecialize(f), tt) = map(x -> string(x.method), Base._methods_by_ftype(Base.signature_type(f, tt), 10, Base.get_world_counter()))
 
 
@@ -350,36 +356,43 @@ end
 # test latex symbol completions
 let s = "\\alpha"
     c, r = test_bslashcomplete(s)
-    @test c[1] == "α"
+    @test c[1].completion == "α"
+    @test c[1].name == "α"
     @test r == 1:lastindex(s)
     @test length(c) == 1
 end
 
 # test latex symbol completions after unicode #9209
 let s = "α\\alpha"
     c, r = test_bslashcomplete(s)
-    @test c[1] == "α"
+    @test c[1].completion == "α"
+    @test c[1].name == "α"
     @test r == 3:sizeof(s)
     @test length(c) == 1
 end
 
 # test emoji symbol completions
 let s = "\\:koala:"
     c, r = test_bslashcomplete(s)
-    @test c[1] == "🐨"
+    @test c[1].completion == "🐨"
+    @test c[1].name == "🐨"
     @test r == 1:sizeof(s)
     @test length(c) == 1
 end
 
 let s = "\\:ko"
     c, r = test_bslashcomplete(s)
-    @test "\\:koala:" in c
+    ko = only(filter(c) do namedcompletion
+        namedcompletion.completion == "\\:koala:"
+    end)
+    @test ko.name == "🐨 \\:koala:"
 end
 
 # test emoji symbol completions after unicode #9209
 let s = "α\\:koala:"
     c, r = test_bslashcomplete(s)
-    @test c[1] == "🐨"
+    @test c[1].name == "🐨"
+    @test c[1].completion == "🐨"
     @test r == 3:sizeof(s)
     @test length(c) == 1
 end
@@ -1069,8 +1082,8 @@ let s, c, r
     # Issue #8047
     s = "@show \"/dev/nul\""
     c,r = completions(s, 15)
-    c = map(completion_text, c)
-    @test "null\"" in c
+    c = map(named_completion, c)
+    @test "null\"" in [_c.completion for _c in c]
     @test r == 13:15
     @test s[r] == "nul"
 
@@ -1476,7 +1489,7 @@ function test_dict_completion(dict_name)
     @test c == Any["\"abcd\"]"]
     s = "$dict_name[\"abcd]"  # trailing close bracket
     c, r = completions(s, lastindex(s) - 1)
-    c = map(completion_text, c)
+    c = map(x -> named_completion(x).completion, c)
     @test c == Any["\"abcd\""]
     s = "$dict_name[:b"
     c, r = test_complete(s)