Started refactor

src_v2/utils/parser.nim

@@ -0,0 +1,28 @@
+import std/parseutils
+
+proc fastSubstr(s: string; token: var string; start, length: int) =
+  token.setLen length
+  for i in 0 ..< length: token[i] = s[i+start]
+
+proc parseUntilBackwards*(s: string, token: var string, until: string,
+                 start = 0): int {.inline.} =
+  ## Parses a token and stores it in ``token``. Returns
+  ## the number of the parsed characters or 0 in case of an error. A token
+  ## consists of any character that comes before the `until`  token.
+  runnableExamples:
+    var myToken: string
+    doAssert parseUntil("Hello World", myToken, "Wor") == 6
+    doAssert myToken == "Hello "
+    doAssert parseUntil("Hello World", myToken, "Wor", 2) == 4
+    doAssert myToken == "llo "
+  var i = s.len
+  while i > 0:
+    if until.len > 0 and s[i] == until[until.len - 1]:
+      var u = 1
+      while i+u < s.len and u < until.len and s[i+u] == until[u]:
+        inc u
+      if u >= until.len: break
+    dec(i)
+  result = i-start
+  fastSubstr(s, token, start, result)
+  #token = substr(s, start, i-1)