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Merged
JesseHerrick merged 4 commits into from
Jun 12, 2026
+637 −45
Merged

Add do snippet, structural snippets, and use-injection dedup (#73) #76

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73362a7
Add do snippet, structural snippets, and use-injection dedup (#73)
JesseHerrick Jun 7, 2026
cf0b685
Add defstruct/defexception/defprotocol/defimpl snippets, parser fix, …
JesseHerrick Jun 7, 2026
c66c424
Fix some weird paren stuff with VS Code
JesseHerrick Jun 8, 2026
05352d4
Fix do-block snippets for ordinary functions
JesseHerrick Jun 11, 2026
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150 changes: 124 additions & 26 deletions internal/lsp/server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1535,7 +1535,7 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
Kind: protocol.CompletionItemKindFunction,
Detail: fmt.Sprintf(":%s.%s/%d", erlModule, e.Function, e.Arity),
}
applySnippet(&item, e.Function, e.Arity, e.Params, inPipe, s.snippetSupport)
applySnippet(&item, e.Function, e.Arity, e.Params, "", inPipe, s.snippetSupport)
items = append(items, item)
}
}
Expand Down Expand Up @@ -1597,7 +1597,7 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
"line": r.Line,
},
}
applySnippet(&item, r.Function, r.Arity, r.Params, inPipe, s.snippetSupport)
applySnippet(&item, r.Function, r.Arity, r.Params, r.Kind, inPipe, s.snippetSupport)
items = append(items, item)
}

Expand Down Expand Up @@ -1685,7 +1685,7 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
Kind: kindToCompletionItemKind(bf.Kind),
Detail: bf.Kind,
}
applySnippet(&item, bf.Name, bf.Arity, bf.Params, inPipe, s.snippetSupport)
applySnippet(&item, bf.Name, bf.Arity, bf.Params, bf.Kind, inPipe, s.snippetSupport)
items = append(items, item)
}
}
Expand Down Expand Up @@ -1713,7 +1713,7 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
"line": r.Line,
},
}
applySnippet(&item, r.Function, r.Arity, r.Params, inPipe, s.snippetSupport)
applySnippet(&item, r.Function, r.Arity, r.Params, r.Kind, inPipe, s.snippetSupport)
items = append(items, item)
}
}
Expand Down Expand Up @@ -1758,6 +1758,21 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
}
}
}
// Plain keyword completions (e.g., "do", "end"). These don't
// expand to snippets; they just insert the keyword itself so
// that pressing Enter doesn't replace the keyword with a
// VS Code word-based suggestion.
for _, kw := range elixirKeywords {
if strings.HasPrefix(kw, funcPrefix) && !seen[kw] {
seen[kw] = true
items = append(items, protocol.CompletionItem{
Label: kw,
Kind: protocol.CompletionItemKindKeyword,
Detail: "keyword",
Preselect: true,
})
}
}
}

if len(items) == 0 {
Expand Down Expand Up @@ -2110,6 +2125,9 @@ func (s *Server) addCompletionsFromUsing(moduleName, funcPrefix string, seen map
if !strings.HasPrefix(funcName, funcPrefix) {
continue
}
if useSnippets && elixirFormSnippets[funcName] != "" {
continue
}
for _, d := range defs {
key := funcKey(funcName, d.arity)
if !seen[key] {
Expand All @@ -2123,7 +2141,7 @@ func (s *Server) addCompletionsFromUsing(moduleName, funcPrefix string, seen map
"line": d.line,
},
}
applySnippet(&item, funcName, d.arity, d.params, inPipe, useSnippets)
applySnippet(&item, funcName, d.arity, d.params, d.kind, inPipe, useSnippets)
*items = append(*items, item)
}
}
Expand All @@ -2137,6 +2155,9 @@ func (s *Server) addCompletionsFromUsing(moduleName, funcPrefix string, seen map
for _, r := range results {
key := funcKey(r.Function, r.Arity)
if strings.HasPrefix(r.Function, funcPrefix) && !seen[key] {
if useSnippets && elixirFormSnippets[r.Function] != "" {
continue
}
seen[key] = true
item := protocol.CompletionItem{
Label: r.Function,
Expand All @@ -2147,7 +2168,7 @@ func (s *Server) addCompletionsFromUsing(moduleName, funcPrefix string, seen map
"line": r.Line,
},
}
applySnippet(&item, r.Function, r.Arity, r.Params, inPipe, useSnippets)
applySnippet(&item, r.Function, r.Arity, r.Params, r.Kind, inPipe, useSnippets)
*items = append(*items, item)
}
}
Expand Down Expand Up @@ -2298,23 +2319,84 @@ func funcKey(name string, arity int) string {
return name + "/" + strconv.Itoa(arity)
}

// elixirKeywords are plain keyword completions (no snippet expansion).
// They prevent VS Code from falling back to word-based completions when the
// user types a keyword like "do" or "end" and presses Enter.
var elixirKeywords = []string{"do", "end"}

var elixirFormSnippets = map[string]string{
"for": "for ${1:pattern} <- ${2:enumerable} do\n\t$0\nend",
"with": "with ${1:pattern} <- ${2:expression} do\n\t$0\nend",
"case": "case ${1:expression} do\n\t${2:pattern} ->\n\t\t$0\nend",
"cond": "cond do\n\t${1:condition} ->\n\t\t$0\nend",
"if": "if ${1:condition} do\n\t$0\nend",
"unless": "unless ${1:condition} do\n\t$0\nend",
"receive": "receive do\n\t${1:pattern} ->\n\t\t$0\nend",
"try": "try do\n\t$0\nrescue\n\t${1:exception} ->\n\t\t${2:handler}\nend",
"quote": "quote do\n\t$0\nend",
"fn": "fn ${1:args} -> $0 end",
}

func applySnippet(item *protocol.CompletionItem, name string, arity int, params string, inPipe bool, useSnippets bool) {
"do": "do\n\t$0\nend",
"defmodule": "defmodule ${1:Name} do\n\t$0\nend",
"def": "def ${1:name}$2 do\n\t$0\nend",
"defp": "defp ${1:name}$2 do\n\t$0\nend",
"defmacro": "defmacro ${1:name}$2 do\n\t$0\nend",
"defmacrop": "defmacrop ${1:name}$2 do\n\t$0\nend",
"defstruct": "defstruct [${1:fields}]$0",
"defexception": "defexception [${1:fields}]$0",
"defprotocol": "defprotocol ${1:Name} do\n\t$0\nend",
"defimpl": "defimpl ${1:Protocol}, for: ${2:Type} do\n\t$0\nend",
"defdelegate": "defdelegate ${1:func}$2, to: ${3:module}$0",
"defguard": "defguard ${1:name}$2 when ${3:condition}$0",
"defguardp": "defguardp ${1:name}$2 when ${3:condition}$0",
"defoverridable": "defoverridable ${1:name}: ${2:arity}$0",
"for": "for ${1:pattern} <- ${2:enumerable} do\n\t$0\nend",
"with": "with ${1:pattern} <- ${2:expression} do\n\t$0\nend",
"case": "case ${1:expression} do\n\t${2:pattern} ->\n\t\t$0\nend",
"cond": "cond do\n\t${1:condition} ->\n\t\t$0\nend",
"if": "if ${1:condition} do\n\t$0\nelse\n\t${2}\nend",
"unless": "unless ${1:condition} do\n\t$0\nend",
"receive": "receive do\n\t${1:pattern} ->\n\t\t$0\nend",
"try": "try do\n\t$0\nrescue\n\t${1:exception} ->\n\t\t${2:handler}\nend",
"quote": "quote do\n\t$0\nend",
"fn": "fn ${1:args} -> $0 end",
}

// noParenFuncs are macros conventionally written without parentheses in Elixir,
// such as ExUnit's test/describe. When generating completion snippets or plain
// call text, these names produce `name arg1, arg2` instead of `name(arg1, arg2)`.
var noParenFuncs = map[string]bool{
"test": true,
"describe": true,
"assert": true,
"refute": true,
"assert_raise": true,
"assert_receive": true,
"assert_received": true,
"refute_receive": true,
"refute_received": true,
"setup": true,
"setup_all": true,
"catch_error": true,
"catch_exit": true,
"catch_throw": true,
}

// doBlockSnippets provides custom snippet templates for functions that take
// do/end blocks. These are applied when the function is in scope via the
// import/use-chain (unlike elixirFormSnippets which are global special forms).
var doBlockSnippets = map[string]string{
"test": "test \"${1:description}\" do\n\t$0\nend",
"describe": "describe \"${1:description}\" do\n\t$0\nend",
"setup": "setup do\n\t$0\nend",
"setup_all": "setup_all do\n\t$0\nend",
"assert_raise": "assert_raise ${1:exception} do\n\t$0\nend",
}

func applySnippet(item *protocol.CompletionItem, name string, arity int, params string, kind string, inPipe bool, useSnippets bool) {
item.Label = fmt.Sprintf("%s/%d", name, arity)
item.FilterText = name

// Check for a do-block snippet template first. These provide full
// do/end block structure (e.g. `test "..." do ... end`) and take
// priority over auto-generated arg lists.
if useSnippets && isMacroKind(kind) {
if tmpl, ok := doBlockSnippets[name]; ok {
item.InsertTextFormat = protocol.InsertTextFormatSnippet
item.InsertText = tmpl
return
}
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}

snippetArity := arity
snippetParams := params
paramStartIndex := 1
Expand All @@ -2330,9 +2412,13 @@ func applySnippet(item *protocol.CompletionItem, name string, arity int, params
}
}

noParen := noParenFuncs[name]

if !useSnippets {
if snippetArity > 0 {
item.InsertText = functionCallText(name, snippetArity, snippetParams, paramStartIndex)
item.InsertText = functionCallText(name, snippetArity, snippetParams, paramStartIndex, noParen)
} else if noParen {
item.InsertText = name
} else {
item.InsertText = name + "()"
}
Expand All @@ -2341,21 +2427,27 @@ func applySnippet(item *protocol.CompletionItem, name string, arity int, params

if snippetArity > 0 {
item.InsertTextFormat = protocol.InsertTextFormatSnippet
item.InsertText = functionSnippet(name, snippetArity, snippetParams, paramStartIndex)
item.InsertText = functionSnippet(name, snippetArity, snippetParams, paramStartIndex, noParen)
} else if noParen {
item.InsertText = name
} else {
item.InsertText = name + "()"
}
}

func functionSnippet(name string, arity int, params string, paramStartIndex int) string {
return buildCallText(name, arity, params, true, paramStartIndex)
func isMacroKind(kind string) bool {
return kind == "defmacro" || kind == "defmacrop"
}

func functionCallText(name string, arity int, params string, paramStartIndex int) string {
return buildCallText(name, arity, params, false, paramStartIndex)
func functionSnippet(name string, arity int, params string, paramStartIndex int, noParen bool) string {
return buildCallText(name, arity, params, true, paramStartIndex, noParen)
}

func buildCallText(name string, arity int, params string, snippet bool, paramStartIndex int) string {
func functionCallText(name string, arity int, params string, paramStartIndex int, noParen bool) string {
return buildCallText(name, arity, params, false, paramStartIndex, noParen)
}

func buildCallText(name string, arity int, params string, snippet bool, paramStartIndex int, noParen bool) string {
if paramStartIndex < 1 {
paramStartIndex = 1
}
Expand All @@ -2375,6 +2467,12 @@ func buildCallText(name string, arity int, params string, snippet bool, paramSta
args = append(args, paramName)
}
}
if noParen {
if snippet {
return name + " " + strings.Join(args, ", ") + "$0"
}
return name + " " + strings.Join(args, ", ")
}
call := name + "(" + strings.Join(args, ", ") + ")"
if snippet {
call += "$0"
Expand Down
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