Experimentations with pointer types.

cdata.lua

@@ -2,6 +2,7 @@
 -- Import
 
 local ffi = require 'ffi'
+local bit = require 'bit'
 
 -- Constants
 
@@ -14,18 +15,22 @@ local NUMBER_TO_HEX = {
 	[12] = 'C', [13] = 'D', [14] = 'E', [15] = 'F',
 }
 
-local function to_hex (str)
+local function to_hex (val, nr_elements, element_size)
 	local l = {}
-	for i = 1, #str do
-		local v = str:byte(i)
-		l[#l+1] = NUMBER_TO_HEX[math.floor(v / 16)]
-		l[#l+1] = NUMBER_TO_HEX[v % 16]
+	for i = 0, nr_elements - 1 do
+		local v = val[i]
+		l[#l+1] = bit.tohex(v, -2*element_size)
 		l[#l+1] = ' '
 	end
 	l[#l] = nil
 	return table.concat(l, '')
 end
 
+local function is_nice_unicode_string (str)
+	-- TODO... Maybe also look into a purely binary oriented representation.
+	return false
+end
+
 local function is_nice_ascii_string (str)
 	for i = 1, #str do
 		local byte = str:byte(i)
@@ -35,24 +40,45 @@ local function is_nice_ascii_string (str)
 end
 
 local function get_type_and_size_of_singular ( ctype )
-	local nr_elements  =  1
+	local nr_elements, layers  =  1, 0
 	while true do
 		local etype, elements  =  ctype:match('(.+)%[(%d*)%]$')
 		if not elements then  break  end
 		ctype, nr_elements  =  etype, nr_elements * elements
+		layers = layers + 1
 	end
-	return ctype, nr_elements
+	return ctype, nr_elements, layers
 end
 
 --------------------------------------------------------------------------------
 
 local CDATA_REPR_MATCHER = 'cdata<(.+)>: (0x%w+)'
 
-return function (value, options, depth, l)
+local function format_cdata (value, options, depth, l, format_value)
+
 	local native_repr  =  tostring(value)
 	local data_length  =  ffi.sizeof(value)
 	local ctype, addr  =  native_repr:match(CDATA_REPR_MATCHER)
 
+	-- Is void  pointer?
+	if ctype == 'void *' then
+		local address_pointing_at = tonumber(ffi.cast('int', value))
+		l[#l+1] = 'void pointer to ' .. addr
+		return ;
+	end
+
+	-- Is normal pointer?
+	if ctype:match('%*$') then
+		if type(value[0]) ~= 'cdata' then
+			-- Data presentable in Lua, refered to by pointers?
+			l[#l+1] = 'pointer to '
+			return format_value(value[0], options, depth, l)
+		else
+			l[#l+1] = '* '
+			return format_cdata(value[0], options, depth, l, format_value)
+		end
+	end
+
 	l[#l+1] = 'cdata {'
 	--l[#l+1] = '\n\tnative = \''   .. native_repr .. '\','
 	l[#l+1] = '\n\ttype   = '   .. ctype .. ','
@@ -63,21 +89,25 @@ return function (value, options, depth, l)
 		l[#l+1] = '\n\tsize   = '   .. data_length .. ','
 
 		-- Element size and type
-		local element_type, nr_elements  =  get_type_and_size_of_singular(ctype)
+		local element_type, nr_elements, nr_layers  =  get_type_and_size_of_singular(ctype)
 		local element_size = data_length / nr_elements
 		l[#l+1] = '\n\tnr_e   = ' .. nr_elements .. ','
 		l[#l+1] = '\n\ttype_e = '   .. element_type .. ','
 		l[#l+1] = '\n\tsize_e = '   .. element_size .. ','
 
-		--
-		if is_nice_ascii_string(str) then
-			l[#l+1] = '\n\tstr    = ' .. str .. ','
+		-- If can be expressed as string, express it as string.
+		if is_nice_ascii_string(str) or is_nice_unicode_string(str) then
+			local string_or_unicode = is_nice_ascii_string(str) and 'ascii' or 'utf8 '
+			l[#l+1] = '\n\t'..string_or_unicode..'    = ' .. str .. ','
+		end
+		--
+		if nr_layers == 1 then
+			-- Only a single level of arrays
+			l[#l+1] = '\n\thex    = ' .. to_hex(value, nr_elements, element_size) .. ','
 		end
-		l[#l+1] = '\n\tbin    = ' .. to_hex(str) .. ','
-
-
-
 
 	end
 	l[#l+1] = '\n}'
 end
+
+return format_cdata

test/test_pretty.lua

@@ -19,15 +19,12 @@ local function format_test (t)
     if t.longterm     then return  end
     if t.adv_getlocal and not HAS_ADV_GETLOCAL then return  end
     SUITE:addTest(t.expect, function ()
-    	local input_value      =  t.input
-        local input_options    =  t.options
-        local expected_result  =  t.expect
-    	local actual_result    =  format(input_value, input_options)
+    	local actual_result    =  format(t.input, t.options)
         if not t.approx or type(actual_result) ~= 'string' then
-            assert_equal(expected_result, actual_result)
+            assert_equal(t.expect, actual_result)
         else
-            if not actual_result:match(expected_result) then
-                error(ASSERT_ERROR_APPROX:format(expected_result, actual_result))
+            if not actual_result:match(t.expect) then
+                error(ASSERT_ERROR_APPROX:format(t.expect, actual_result))
             end
         end
     end)
@@ -372,6 +369,10 @@ if type(jit) == 'table' then
 
     local ffi = require('ffi')
     ffi.cdef[[
+        typedef struct foo { int a, b; } foo_t;
+
+        void free(void *ptr);
+        void *malloc(size_t size);
         int poll(struct pollfd *fds, unsigned long nfds, int timeout);
     ]]
 
@@ -389,6 +390,15 @@ if type(jit) == 'table' then
         }
     end
 
+    do
+        local list = ffi.new('int [17]')
+        for i = 0, 16 do  list[i] = i end
+        format_test {
+            input  = list,
+            expect = 'cdata<.+>: 0x%x+',
+        }
+    end
+
     do
         local list = ffi.new('char [10]')
         for i = 0, 10-1 do  list[i] = i + 65 end
@@ -406,6 +416,31 @@ if type(jit) == 'table' then
             expect = 'cdata<.+>: 0x%x+',
         }
     end
+
+    do
+        local p = ffi.gc(ffi.C.malloc(1), ffi.C.free)
+        format_test {
+            input  = p,
+            expect = 'cdata<.+>: 0x%x+',
+        }
+    end
+
+    SUITE:addTest('a_very_small_part_of_math', function ()
+        local p = ffi.new('char[1]')
+              p[0] = 27
+        local actual_result  =  format(p + 0, {})
+        assert_equal('Derp', actual_result)
+    end)
+
+    do
+        local p = ffi.new('foo_t[1]')
+              p[0].a = 27
+              p[0].b = 27
+        format_test {
+            input  = p + 0,
+            expect = 'cdata<.+>: 0x%x+',
+        }
+    end
 end
 
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