External strings

Strings can use external buffers to store their contents.

testes/strings.lua

@@ -157,6 +157,12 @@ else   -- compatible coercion
   assert(tostring(-1203 + 0.0) == "-1203")
 end
 
+
+local function topointer (s)
+  return string.format("%p", s)
+end
+
+
 do  -- tests for '%p' format
   -- not much to test, as C does not specify what '%p' does.
   -- ("The value of the pointer is converted to a sequence of printing
@@ -180,18 +186,18 @@ do  -- tests for '%p' format
 
   do
     local t1 = {}; local t2 = {}
-    assert(string.format("%p", t1) ~= string.format("%p", t2))
+    assert(topointer(t1) ~= topointer(t2))
   end
 
   do     -- short strings are internalized
     local s1 = string.rep("a", 10)
     local s2 = string.rep("aa", 5)
-  assert(string.format("%p", s1) == string.format("%p", s2))
+  assert(topointer(s1) == topointer(s2))
   end
 
   do     -- long strings aren't internalized
     local s1 = string.rep("a", 300); local s2 = string.rep("a", 300)
-    assert(string.format("%p", s1) ~= string.format("%p", s2))
+    assert(topointer(s1) ~= topointer(s2))
   end
 end
 
@@ -521,6 +527,20 @@ else
   testpfs("P", str, {})
 end
 
+if T == nil then
+  (Message or print)('\n >>> testC not active: skipping external strings tests <<<\n')
+else
+  print("testing external strings")
+  local x = T.externKstr("hello")   -- external fixed short string
+  assert(x == "hello")
+  local x = T.externstr("hello")   -- external allocated short string
+  assert(x == "hello")
+  x = string.rep("a", 100)   -- long string
+  local y = T.externKstr(x)   -- external fixed long string
+  assert(y == x)
+  local z = T.externstr(x)   -- external allocated long string
+  assert(z == y)
+end
 
 print('OK')