chore(TypeScript): refactor objects into classes

fix: `Nil`(null, undefined) now renders as empty string
change: `parser.parseValue()` renamed to `parser.parseOutput`
change: registered tags/filters become static and shared across different liquid instances

src/parser/tokenizer.ts

@@ -0,0 +1,53 @@
+import whiteSpaceCtrl from './whitespace-ctrl'
+import HTMLToken from './html-token'
+import TagToken from './tag-token'
+import OutputToken from './output-token'
+
+enum ParseState { HTML, OUTPUT, TAG }
+
+export function parse (input: string, file?: string, options?) {
+  const tokens = []
+  let p = 0
+  let line = 1
+  let state = ParseState.HTML
+  let buffer = ''
+  let bufferBegin = 0
+
+  while(p < input.length) {
+    if (input[p] === '\n') line++
+    const bin = input.substr(p, 2)
+    if (state === ParseState.HTML) {
+      if (bin === '{{' || bin === '{%') {
+        if (buffer) tokens.push(new HTMLToken(buffer, bufferBegin, input, file, line))
+        buffer = bin
+        bufferBegin = p
+        p += 2
+        state = bin === '{{' ? ParseState.OUTPUT : ParseState.TAG
+        continue
+      }
+    }
+    else if (state === ParseState.OUTPUT && bin === '}}') {
+      buffer += '}}'
+      tokens.push(new OutputToken(buffer, bufferBegin, input, file, line))
+      p += 2
+      buffer = ''
+      bufferBegin = p
+      state = ParseState.HTML
+      continue
+    }
+    else if (bin === '%}') {
+      buffer += '%}'
+      tokens.push(new TagToken(buffer, bufferBegin, input, file, line))
+      p += 2
+      buffer = ''
+      bufferBegin = p
+      state = ParseState.HTML
+      continue
+    }
+    buffer += input[p++]
+  }
+  if (buffer) tokens.push(new HTMLToken(buffer, bufferBegin, input, file, line))
+
+  whiteSpaceCtrl(tokens, options)
+  return tokens
+}