[spec/*,*] Split library in submodules.

strings.lua

@@ -0,0 +1,28 @@
+local strings = {}
+
+
+--- Test whether a string starts with a prefix.
+function strings.startswith(s, prefix)
+    -- optimized version of: return s:sub(1, #prefix) == prefix
+    for i = 1,#prefix do
+        if s:byte(i) ~= prefix:byte(i) then
+            return false
+        end
+    end
+    return true
+end
+
+--- Test whether a string ends with a trailing suffix.
+function strings.endswith(s, trailing)
+    -- optimized version of: return trailing == "" or s:sub(-#trailing) == trailing
+    local n1,n2 = #s,#trailing
+
+    for i = 0,n2-1 do
+        if s:byte(n1-i) ~= trailing:byte(n2-i) then
+            return false
+        end
+    end
+    return true
+end
+
+return strings