Add trim methods on String:

- trim()
- trim(chars)
- trimEnd()
- trimEnd(chars)
- trimStart()
- trimStart(chars)

src/vm/wren_core.wren

@@ -236,6 +236,48 @@ class String is Sequence {
     return result
   }
 
+  trim() { trim_("\t\r\n ", true, true) }
+  trim(chars) { trim_(chars, true, true) }
+  trimEnd() { trim_("\t\r\n ", false, true) }
+  trimEnd(chars) { trim_(chars, false, true) }
+  trimStart() { trim_("\t\r\n ", true, false) }
+  trimStart(chars) { trim_(chars, true, false) }
+
+  trim_(chars, trimStart, trimEnd) {
+    if (!(chars is String)) {
+      Fiber.abort("Characters must be a string.")
+    }
+
+    var codePoints = chars.codePoints.toList
+
+    var start
+    if (trimStart) {
+      while (start = iterate(start)) {
+        if (!codePoints.contains(codePointAt_(start))) break
+      }
+
+      if (start == false) return ""
+    } else {
+      start = 0
+    }
+
+    var end
+    if (trimEnd) {
+      end = byteCount_ - 1
+      while (end >= start) {
+        var codePoint = codePointAt_(end)
+        if (codePoint != -1 && !codePoints.contains(codePoint)) break
+        end = end - 1
+      }
+
+      if (end < start) return ""
+    } else {
+      end = -1
+    }
+
+    return this[start..end]
+  }
+
   *(count) {
     if (!(count is Num) || !count.isInteger || count < 0) {
       Fiber.abort("Count must be a non-negative integer.")

src/vm/wren_core.wren.inc

@@ -238,6 +238,56 @@ static const char* coreModuleSource =
 "    return result\n"
 "  }\n"
 "\n"
+"  trim() { trim_(\"\t\r\n \", true, true) }\n"
+"\n"
+"  trim(chars) { trim_(chars, true, true) }\n"
+"\n"
+"  trimEnd() { trim_(\"\t\r\n \", false, true) }\n"
+"\n"
+"  trimEnd(chars) { trim_(chars, false, true) }\n"
+"\n"
+"  trimStart() { trim_(\"\t\r\n \", true, false) }\n"
+"\n"
+"  trimStart(chars) { trim_(chars, true, false) }\n"
+"\n"
+"  trim_(chars, trimStart, trimEnd) {\n"
+"    if (!(chars is String)) {\n"
+"      Fiber.abort(\"Characters must be a string.\")\n"
+"    }\n"
+"\n"
+"    var codePoints = chars.codePoints.toList\n"
+"//     System.print(\"code points %(codePoints)\")\n"
+"\n"
+"    var start\n"
+"    if (trimStart) {\n"
+"      while (start = iterate(start)) {\n"
+"        if (!codePoints.contains(codePointAt_(start))) break\n"
+"      }\n"
+"\n"
+"      if (start == false) return \"\"\n"
+"    } else {\n"
+"      start = 0\n"
+"    }\n"
+"\n"
+"    var end\n"
+"    if (trimEnd) {\n"
+"      end = byteCount_ - 1\n"
+"      while (end >= start) {\n"
+"        var codePoint = codePointAt_(end)\n"
+"//         System.print(\"test %(end) : %(codePoint)\")\n"
+"        if (codePoint != -1 && !codePoints.contains(codePoint)) break\n"
+"        end = end - 1\n"
+"      }\n"
+"\n"
+"//       System.print(\"range %(start) %(end)\")\n"
+"      if (end < start) return \"\"\n"
+"    } else {\n"
+"      end = -1\n"
+"    }\n"
+"\n"
+"    return this[start..end]\n"
+"  }\n"
+"\n"
 "  *(count) {\n"
 "    if (!(count is Num) || !count.isInteger || count < 0) {\n"
 "      Fiber.abort(\"Count must be a non-negative integer.\")\n"