added count routine

docs/moonpie.tables.rst

@@ -3,6 +3,18 @@ moonpie.tables
 
 The tables utilities provides various mini-functions for helpful operations.
 
+tables.count(set, func)
+  Returns the count of items that match the comparison function passed in.
+
+.. code-block:: lua
+
+  local set = { 1, 2, 3, 4, 5, 6 }
+  local compare = function(v) return v % 2 == 0 end
+
+  print(tables.count(set, compare))
+  -- 3
+
+
 tables.deepCompare(tbl1, tbl2, ignoreMT)
   Tests the values in the the 2 tables to see if they look the same without having to be the same table instance.
 

moonpie/tables/count.lua

@@ -0,0 +1,14 @@
+-- Copyright (c) 2021 Trevor Redfern
+--
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
+
+return function(set, func)
+  if func == nil then return #set end
+
+  local c = 0
+  for _, v in ipairs(set) do
+    if func(v) then c = c + 1 end
+  end
+  return c
+end

moonpie/tables/count_spec.lua

@@ -0,0 +1,19 @@
+-- Copyright (c) 2021 Trevor Redfern
+--
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
+
+describe("moonpie.tables.count", function()
+  local count = require "moonpie.tables.count"
+
+  it("returns the number of items matching a function", function()
+    local set = { 1, 2, 3, 4, 5, 6 }
+
+    assert.equals(3, count(set, function(i) return i % 2 == 0 end))
+  end)
+
+  it("just returns the number of items if no function provided", function()
+    local set = { 1, 2, 3, 4, 5, 6 }
+    assert.equals(6, count(set))
+  end)
+end)

moonpie/tables/init.lua

@@ -9,6 +9,7 @@ return {
   assign = require "moonpie.tables.assign",
   concatArray = require "moonpie.tables.concat_array",
   copyKeys = require "moonpie.tables.copy_keys",
+  count = require "moonpie.tables.count",
   countBy = require "moonpie.tables.count_by",
   countKeys = require "moonpie.tables.count_keys",
   deepCompare = require "moonpie.tables.deep_compare",

moonpie/tables/init_spec.lua

@@ -24,6 +24,7 @@ describe("moonpie.tables", function()
     assert.is_function(tables.assign)
     assert.is_function(tables.concatArray)
     assert.is_function(tables.copyKeys)
+    assert.is_function(tables.count)
     assert.is_function(tables.countBy)
     assert.is_function(tables.countKeys)
     assert.is_function(tables.deepCompare)