refactor

src/__comm__/_str_hash.scad

@@ -1,8 +1,20 @@
 use <../util/sum.scad>;
 
 function _str_hash(value) = 
-    let(s = str(value))
+    let(
-	sum([
+		chars = str(value),
-		for(i = len(s) - 1; i > -1; i = i - 1)
+		end = len(chars) - 1
-		ord(s[i]) * 31 ^ i
+	)
-	]);
+	end == 0 ? ord(chars[0]) :
+	let(cum_total = [for(i = 0, s = ord(chars[i]); i < end; i = i + 1, s = s + (ord(chars[i]) * 31 ^ i)) s])
+	cum_total[len(cum_total) - 1] + (ord(chars[end]) * 31 ^ i);
+
+	// sum([
+	// 	for(i = len(s) - 1; i > -1; i = i - 1)
+	// 	ord(s[i]) * 31 ^ i
+	// ]);
+
+    let(end = len(lt) - 1)
+    end == 0 ? lt[0] :
+    let(cum_total = [for(i = 0, s = lt[0]; i < end; i = i + 1, s = s + lt[i]) s])
+    cum_total[len(cum_total) - 1] + lt[end];