Add hidden command and option aliases

Also auto-add an alias with dashes in place of underscores if an alias
has an underscore.

docsrc/messages.rst

@@ -39,6 +39,41 @@ it is not included into help and usage messages, but otherwise works normally.
       deprecated_option = "value"
    }
 
+Hiding option and command aliases
+---------------------------------
+
+Hidden aliases can be added to an option or command by setting the
+``hidden_name`` property. Its value is interpreted in the same way as the
+``name`` property.
+
+.. code-block:: lua
+   :linenos:
+
+   parser:option "--server"
+      :hidden_name "--from"
+
+.. code-block:: none
+
+   $ lua script.lua --help
+
+.. code-block:: none
+
+   Usage: script.lua [-h] [--server <server>]
+
+   Options:
+      -h, --help            Show this help message and exit.
+      --server <server>
+
+.. code-block:: none
+
+   $ lua script.lua --server foo
+   $ lua script.lua --from foo
+
+.. code-block:: lua
+
+   {
+      server = "foo"
+   }
 
 Setting argument placeholder
 ----------------------------

docsrc/misc.rst

@@ -200,6 +200,7 @@ Other properties:
 =========================== ==========================
 Property                    Type
 =========================== ==========================
+``hidden_name``             String
 ``summary``                 String
 ``target``                  String
 ``usage``                   String
@@ -269,6 +270,7 @@ Other properties:
 =================== ==================
 Property            Type
 =================== ==================
+``hidden_name``     String
 ``target``          String
 ``defmode``         String
 ``show_default``    Boolean

spec/help_spec.lua

@@ -311,6 +311,24 @@ Commands:
 Usage: foo]], parser:get_help())
    end)
 
+   it("does not mention hidden option and command aliases", function()
+      local parser = Parser "foo"
+      parser:option "--server"
+         :hidden_name "--from"
+      parser:command "newname"
+         :hidden_name "oldname"
+
+      assert.equal([[
+Usage: foo [-h] [--server <server>] <command> ...
+
+Options:
+   -h, --help            Show this help message and exit.
+   --server <server>
+
+Commands:
+   newname]], parser:get_help())
+   end)
+
    it("supports grouping options", function()
       local parser = Parser "foo"
          :add_help(false)

spec/options_spec.lua

@@ -57,14 +57,14 @@ describe("tests related to options", function()
          assert.same({server = {"foo", "bar"}}, args)
       end)
 
-      it("handles short option correclty", function()
+      it("handles short option correctly", function()
          local parser = Parser()
          parser:option "-s" "--server"
          local args = parser:parse({"-s", "foo"})
          assert.same({server = "foo"}, args)
       end)
 
-      it("handles flag correclty", function()
+      it("handles flag correctly", function()
          local parser = Parser()
          parser:flag "-q" "--quiet"
          local args = parser:parse({"--quiet"})
@@ -73,7 +73,7 @@ describe("tests related to options", function()
          assert.same({}, args)
       end)
 
-      it("handles combined flags correclty", function()
+      it("handles combined flags correctly", function()
          local parser = Parser()
          parser:flag "-q" "--quiet"
          parser:flag "-f" "--fast"
@@ -88,7 +88,7 @@ describe("tests related to options", function()
          assert.same({server = "foo"}, args)
       end)
 
-      it("handles flags combined with short option correclty", function()
+      it("handles flags combined with short option correctly", function()
          local parser = Parser()
          parser:flag "-q" "--quiet"
          parser:option "-s" "--server"
@@ -146,6 +146,14 @@ describe("tests related to options", function()
          assert.same({tail = {"foo", "--unrelated", "bar"}}, args)
       end)
 
+      it("handles hidden option aliases", function()
+         local parser = Parser()
+         parser:option "--server"
+            :hidden_name "--from"
+         local args = parser:parse{"--from", "foo"}
+         assert.same({server = "foo"}, args)
+      end)
+
       describe("Special chars set", function()
          it("handles windows-style options", function()
             local parser = Parser()

src/argparse.lua

@@ -130,12 +130,30 @@ local multiname = {"name", function(self, value)
    for alias in value:gmatch("%S+") do
       self._name = self._name or alias
       table.insert(self._aliases, alias)
+      table.insert(self._public_aliases, alias)
+      -- If alias contains '_', accept '-' also.
+      if alias:find("_", 1, true) then
+         table.insert(self._aliases, (alias:gsub("_", "-")))
+      end
    end
 
    -- Do not set _name as with other properties.
    return true
 end}
 
+local multiname_hidden = {"hidden_name", function(self, value)
+   typecheck("hidden_name", {"string"}, value)
+
+   for alias in value:gmatch("%S+") do
+      table.insert(self._aliases, alias)
+      if alias:find("_", 1, true) then
+         table.insert(self._aliases, (alias:gsub("_", "-")))
+      end
+   end
+
+   return true
+end}
+
 local function parse_boundaries(str)
    if tonumber(str) then
       return tonumber(str), tonumber(str)
@@ -257,12 +275,14 @@ local Parser = class({
 })
 
 local Command = class({
-   _aliases = {}
+   _aliases = {},
+   _public_aliases = {}
 }, {
    args = 3,
    multiname,
    typechecked("description", "string"),
    typechecked("epilog", "string"),
+   multiname_hidden,
    typechecked("summary", "string"),
    typechecked("target", "string"),
    typechecked("usage", "string"),
@@ -307,6 +327,7 @@ local Argument = class({
 
 local Option = class({
    _aliases = {},
+   _public_aliases = {},
    _mincount = 0,
    _overwrite = true
 }, {
@@ -317,6 +338,7 @@ local Option = class({
    typechecked("convert", "function", "table"),
    boundaries("args"),
    boundaries("count"),
+   multiname_hidden,
    typechecked("target", "string"),
    typechecked("defmode", "string"),
    typechecked("show_default", "boolean"),
@@ -505,22 +527,22 @@ function Option:_get_label_lines()
 
    if #argument_list == 0 then
       -- Don't put aliases for simple flags like `-h` on different lines.
-      return {table.concat(self._aliases, ", ")}
+      return {table.concat(self._public_aliases, ", ")}
    end
 
    local longest_alias_length = -1
 
-   for _, alias in ipairs(self._aliases) do
+   for _, alias in ipairs(self._public_aliases) do
       longest_alias_length = math.max(longest_alias_length, #alias)
    end
 
    local argument_list_repr = table.concat(argument_list, " ")
    local lines = {}
 
-   for i, alias in ipairs(self._aliases) do
+   for i, alias in ipairs(self._public_aliases) do
       local line = (" "):rep(longest_alias_length - #alias) .. alias .. " " .. argument_list_repr
 
-      if i ~= #self._aliases then
+      if i ~= #self._public_aliases then
          line = line .. ","
       end
 
@@ -531,7 +553,7 @@ function Option:_get_label_lines()
 end
 
 function Command:_get_label_lines()
-   return {table.concat(self._aliases, ", ")}
+   return {table.concat(self._public_aliases, ", ")}
 end
 
 function Argument:_get_description()
@@ -569,7 +591,7 @@ end
 function Option:_get_default_target()
    local res
 
-   for _, alias in ipairs(self._aliases) do
+   for _, alias in ipairs(self._public_aliases) do
       if alias:sub(1, 1) == alias:sub(2, 2) then
          res = alias:sub(3)
          break