added filter option

inspect.lua

@@ -136,10 +136,20 @@ local function countTableAppearances(t, tableAppearances)
   return tableAppearances
 end
 
+local function parse_filter(filter)
+  if type(filter) == 'function' then return filter end
+  -- not a function, so it must be a table or table-like
+  filter = type(filter) == 'table' and filter or {filter}
+  local dictionary = {}
+  for _,v in pairs(filter) do dictionary[v] = true end
+  return function(x) return dictionary[x] end
+end
+
 -------------------------------------------------------------------
 function inspect.inspect(rootObject, options)
-  options = options or {}
-  depth   = options.depth or math.huge
+  options       = options or {}
+  local depth   = options.depth or math.huge
+  local filter  = parse_filter(options.filter or {})
 
   local tableAppearances = countTableAppearances(rootObject)
 
@@ -252,16 +262,20 @@ function inspect.inspect(rootObject, options)
 
   -- putvalue is forward-declared before putTable & putKey
   putValue = function(v)
-    local tv = type(v)
-
-    if tv == 'string' then
-      puts(smartQuote(unescape(v)))
-    elseif tv == 'number' or tv == 'boolean' or tv == 'nil' then
-      puts(tostring(v))
-    elseif tv == 'table' then
-      putTable(v)
+    if filter(v) then
+      puts('<filtered>')
     else
-      puts('<',tv,' ',getId(v),'>')
+      local tv = type(v)
+
+      if tv == 'string' then
+        puts(smartQuote(unescape(v)))
+      elseif tv == 'number' or tv == 'boolean' or tv == 'nil' then
+        puts(tostring(v))
+      elseif tv == 'table' then
+        putTable(v)
+      else
+        puts('<',tv,' ',getId(v),'>')
+      end
     end
   end
 

spec/inspect_spec.lua

@@ -166,6 +166,63 @@ describe( 'inspect', function()
       end)
     end)
 
+    describe('The filter option', function()
+
+      it('filters hash values', function()
+        local a = {'this is a'}
+        local b = {x = 1, a = a}
+
+        assert.equals(inspect(b, {filter = {a}}), [[{
+  a = <filtered>,
+  x = 1
+}]])
+      end)
+
+      it('filtereds hash keys', function()
+        local a = {'this is a'}
+        local b = {x = 1, [a] = 'a is used as a key here'}
+
+        assert.equals(inspect(b, {filter = {a}}), [[{
+  x = 1,
+  [<filtered>] = "a is used as a key here"
+}]])
+      end)
+
+      it('filtereds array values', function()
+        assert.equals(inspect({10,20,30}, {filter = {20}}), "{ 10, <filtered>, 30 }")
+      end)
+
+      it('filtereds metatables', function()
+        local a = {'this is a'}
+        local b = setmetatable({x = 1}, a)
+        assert.equals(inspect(b, {filter = {a}}), [[{
+  x = 1,
+  <metatable> = <filtered>
+}]])
+
+      end)
+
+      it('does not increase the table ids', function()
+        local a = {'this is a'}
+        local b = {}
+        local c = {a, b, b}
+        assert.equals(inspect(c, {filter = {a}}), "{ <filtered>, <1>{}, <table 1> }")
+      end)
+
+      it('can be a non table (gets interpreted as a table with one element)', function()
+        assert.equals(inspect({'foo', 'bar', 'baz'}, {filter = "bar"}), '{ "foo", <filtered>, "baz" }')
+      end)
+
+      it('can be a function which returns true for the elements that needs to be filtered', function()
+        local msg = inspect({1,2,3,4,5}, { filter = function(x)
+          return type(x) == 'number' and x % 2 == 0
+        end })
+
+        assert.equals(msg, '{ 1, <filtered>, 3, <filtered>, 5 }')
+      end)
+
+    end)
+
     describe('metatables', function()
 
       it('includes the metatable as an extra hash attribute', function()