feat: add is module and typings

Author: haithium

spec/is_spec.lua

@@ -0,0 +1,67 @@
+---@diagnostic disable: undefined-field, param-type-mismatch, need-check-nil
+
+local is = require("mods.is")
+local fmt = string.format
+
+describe("mods.is", function()
+  local f = function() end
+  local co = coroutine.create(f)
+  local ct = setmetatable({}, { __call = f })
+  local nct = setmetatable({}, { __call = true })
+
+  it("is is callable via __call", function()
+    assert.is_callable(is)
+  end)
+
+  -- stylua: ignore
+  local tests = {
+    -----type----|----ok-----|-not-ok---
+    { "Boolean"  , false     , 123   },
+    { "Boolean"  , true      , nil   },
+    { "Callable" , ct        , nct   },
+    { "Callable" , f         , {}    },
+    { "False"    , false     , true  },
+    { "Falsy"    , false     , true  },
+    { "Falsy"    , nil       , 123   },
+    { "Function" , f         , "abc" },
+    { "Integer"  , 123       , 13.4  },
+    { "Integer"  , 123       , nil   },
+    { "Nil"      , nil       , 123   },
+    { "Number"   , 123       , "123" },
+    { "String"   , "abc"     , true  },
+    { "Table"    , {}        , false },
+    { "Thread"   , co        , f     },
+    { "True"     , true      , false },
+    { "Truthy"   , 123       , nil   },
+    { "Truthy"   , true      , false },
+    { "Userdata" , io.stdout , {}    },
+  }
+
+  for i = 1, #tests do
+    local tp, v1, v2 = unpack(tests[i], 1, 3)
+
+    it(fmt("exposes is.%s", tp), function()
+      assert.is_function(is[tp])
+    end)
+
+    it(fmt("exposes is.%s", tp:lower()), function()
+      assert.is_function(is[tp:lower()])
+    end)
+
+    it(fmt("is.%s returns true for %s", tp, pretty(v1)), function()
+      assert.is_true(is[tp](v1))
+    end)
+
+    it(fmt("is.%s returns false for %s", tp, pretty(v2)), function()
+      assert.is_false(is[tp](v2))
+    end)
+
+    it(fmt("is(%q, %s) returns true", tp, pretty(v1)), function()
+      assert.is_true(is(v1, tp))
+    end)
+
+    it(fmt("is(%q, %s) returns false", tp, pretty(v2)), function()
+      assert.is_false(is(v2, tp))
+    end)
+  end
+end)

src/mods/init.lua

@@ -1,5 +1,12 @@
 local mods = {}
-for _, name in ipairs({ "List", "Set", "str", "stringcase", "tbl" }) do
+for _, name in ipairs({
+  "is",
+  "List",
+  "Set",
+  "str",
+  "stringcase",
+  "tbl",
+}) do
   mods[name] = "mods." .. name
 end
 

src/mods/is.lua

@@ -0,0 +1,104 @@
+local type = type
+local getmt = getmetatable
+local gsub = string.gsub
+local upper = string.upper
+
+local lfs
+
+local function require_lfs()
+  if lfs then
+    return lfs
+  end
+  local ok, mod = pcall(require, "lfs")
+  if not ok then
+    error("lfs is required for path-type checks", 2)
+  end
+  lfs = mod
+  return lfs
+end
+
+local function attrs(...)
+  local mod = require_lfs()
+  attrs = mod.attributes
+  return attrs(...)
+end
+
+local function symlinkattrs(...)
+  local mod = require_lfs()
+  symlinkattrs = mod.symlinkattributes
+  return symlinkattrs(...)
+end
+
+---@type mods.is
+local M = {}
+
+function M.callable(v)
+  if type(v) == "function" then
+    return true
+  end
+  local mt = getmt(v)
+  if mt and type(mt.__call) == "function" then
+    return true
+  end
+  return false
+end
+
+function M.device(v)
+  if type(v) ~= "string" then
+    return false
+  end
+  local mode = attrs(v, "mode")
+  return mode == "char device" or mode == "block device"
+end
+
+
+-- stylua: ignore start
+function M.boolean(v) return type(v) == "boolean" end
+function M.Function(v) return type(v) == "function" end
+function M.Nil(v) return type(v) == "nil" end
+function M.number(v) return type(v) == "number" end
+function M.string(v) return type(v) == "string" end
+function M.table(v) return type(v) == "table" end
+function M.thread(v) return type(v) == "thread" end
+function M.userdata(v) return type(v) == "userdata" end
+
+function M.False(v) return v == false  end
+function M.falsy(v) return not v and true or false end
+function M.integer(v) return type(v) == "number" and v % 1 == 0 end
+function M.True(v) return v == true end
+function M.truthy(v) return v and true or false end
+
+function M.block(v) return type(v) == "string" and attrs(v, "mode") == "block device" end
+function M.char(v) return type(v) == "string" and attrs(v, "mode") == "char device" end
+function M.dir(v) return type(v) == "string" and attrs(v, "mode") == "directory" end
+function M.fifo(v) return type(v) == "string" and attrs(v, "mode") == "named pipe" end
+function M.file(v) return type(v) == "string" and attrs(v, "mode") == "file" end
+function M.link(v) return type(v) == "string" and symlinkattrs(v, "mode") == "link" end
+function M.socket(v) return type(v) == "string" and attrs(v, "mode") == "socket" end
+-- stylua: ignore end
+
+local function capitalize(s)
+  return gsub(s, "^%l", upper)
+end
+
+local aliases = {}
+for k in pairs(M) do
+  aliases[#aliases + 1] = k
+end
+
+for _, v in ipairs(aliases) do
+  M[v:lower()] = M[v]
+  M[capitalize(v)] = M[v]
+end
+
+return setmetatable(M, {
+  __call = function(_, v, tp)
+    local fn = M[tp]
+    if fn then
+      return fn(v)
+    elseif type(v) == tp then
+      return true
+    end
+    return false
+  end,
+})