fix(mason-lspconfig): deduplicate :LspInstall completion items (#88)

4 files changed, 26 insertions, 2 deletions

diff --git a/lua/mason-core/functional/init.lua b/lua/mason-core/functional/init.lua
index a7b0a369..97865f05 100644
--- a/lua/mason-core/functional/init.lua
+++ b/lua/mason-core/functional/init.lua
@@ -38,6 +38,7 @@ _.head = list.head
 _.length = list.length
 _.flatten = list.flatten
 _.sort_by = list.sort_by
+_.uniq_by = list.uniq_by
 _.join = list.join
 
 -- relation
diff --git a/lua/mason-core/functional/list.lua b/lua/mason-core/functional/list.lua
index c3aaecd8..f30dd13d 100644
--- a/lua/mason-core/functional/list.lua
+++ b/lua/mason-core/functional/list.lua
@@ -172,4 +172,22 @@ _.join = fun.curryN(function(sep, list)
     return table.concat(list, sep)
 end, 2)
 
+---@generic T
+---@param fun (item: T): any
+---@param list T[]
+---@return T[]
+_.uniq_by = fun.curryN(function(comp, list)
+    local set = {}
+    local result = {}
+    for i = 1, #list do
+        local item = list[i]
+        local uniq_key = comp(item)
+        if not set[uniq_key] then
+            set[uniq_key] = true
+            table.insert(result, item)
+        end
+    end
+    return result
+end, 2)
+
 return _
diff --git a/lua/mason-lspconfig/api/command.lua b/lua/mason-lspconfig/api/command.lua
index 5f0da4bf..a782ac08 100644
--- a/lua/mason-lspconfig/api/command.lua
+++ b/lua/mason-lspconfig/api/command.lua
@@ -124,8 +124,8 @@ _G.mason_lspconfig_completion = {
         local package_names = _.filter_map(function(pkg_name)
             return Optional.of_nilable(server_mapping.package_to_lspconfig[pkg_name])
         end, registry.get_all_package_names())
-        local completion = _.concat(package_names, _.keys(language_mapping))
-        table.sort(completion)
+        local completion =
+            _.compose(_.sort_by(_.identity), _.uniq_by(_.identity), _.concat(_.keys(language_mapping)))(package_names)
         return table.concat(completion, "\n")
     end,
     installed_server_completion = function()
diff --git a/tests/mason-core/functional/list_spec.lua b/tests/mason-core/functional/list_spec.lua
index 999b3625..ce0c285f 100644
--- a/tests/mason-core/functional/list_spec.lua
+++ b/tests/mason-core/functional/list_spec.lua
@@ -190,4 +190,9 @@ describe("functional: list", function()
     it("joins lists", function()
         assert.equals("Hello, John", _.join(", ", { "Hello", "John" }))
     end)
+
+    it("should uniq_by lists", function()
+        local list = { "Person.", "Woman.", "Man.", "Person.", "Woman.", "Camera.", "TV." }
+        assert.same({ "Person.", "Woman.", "Man.", "Camera.", "TV." }, _.uniq_by(_.identity, list))
+    end)
 end)