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/lexical.ts

@@ -0,0 +1,86 @@
+// quote related
+const singleQuoted = /'[^']*'/
+const doubleQuoted = /"[^"]*"/
+export const quoted = new RegExp(`${singleQuoted.source}|${doubleQuoted.source}`)
+export const quoteBalanced = new RegExp(`(?:${quoted.source}|[^'"])*`)
+
+// basic types
+export const integer = /-?\d+/
+export const number = /-?\d+\.?\d*|\.?\d+/
+export const bool = /true|false/
+
+// property access
+export const identifier = /[\w-]+[?]?/
+export const subscript = new RegExp(`\\[(?:${quoted.source}|[\\w-\\.]+)\\]`)
+export const literal = new RegExp(`(?:${quoted.source}|${bool.source}|${number.source})`)
+export const variable = new RegExp(`${identifier.source}(?:\\.${identifier.source}|${subscript.source})*`)
+
+// range related
+export const rangeLimit = new RegExp(`(?:${variable.source}|${number.source})`)
+export const range = new RegExp(`\\(${rangeLimit.source}\\.\\.${rangeLimit.source}\\)`)
+export const rangeCapture = new RegExp(`\\((${rangeLimit.source})\\.\\.(${rangeLimit.source})\\)`)
+
+export const value = new RegExp(`(?:${variable.source}|${literal.source}|${range.source})`)
+
+// hash related
+export const hash = new RegExp(`(?:${identifier.source})\\s*:\\s*(?:${value.source})`)
+export const hashCapture = new RegExp(`(${identifier.source})\\s*:\\s*(${value.source})`, 'g')
+
+// full match
+export const tagLine = new RegExp(`^\\s*(${identifier.source})\\s*([\\s\\S]*?)\\s*$`)
+export const literalLine = new RegExp(`^${literal.source}$`, 'i')
+export const variableLine = new RegExp(`^${variable.source}$`)
+export const numberLine = new RegExp(`^${number.source}$`)
+export const boolLine = new RegExp(`^${bool.source}$`, 'i')
+export const quotedLine = new RegExp(`^${quoted.source}$`)
+export const rangeLine = new RegExp(`^${rangeCapture.source}$`)
+export const integerLine = new RegExp(`^${integer.source}$`)
+
+// filter related
+export const valueDeclaration = new RegExp(`(?:${identifier.source}\\s*:\\s*)?${value.source}`)
+export const valueList = new RegExp(`${valueDeclaration.source}(\\s*,\\s*${valueDeclaration.source})*`)
+export const filter = new RegExp(`${identifier.source}(?:\\s*:\\s*${valueList.source})?`, 'g')
+export const filterCapture = new RegExp(`(${identifier.source})(?:\\s*:\\s*(${valueList.source}))?`)
+export const filterLine = new RegExp(`^${filterCapture.source}$`)
+
+export const operators = [
+  /\s+or\s+/,
+  /\s+and\s+/,
+  /==|!=|<=|>=|<|>|\s+contains\s+/
+]
+
+export function isInteger (str) {
+  return integerLine.test(str)
+}
+
+export function isLiteral (str) {
+  return literalLine.test(str)
+}
+
+export function isRange (str) {
+  return rangeLine.test(str)
+}
+
+export function isVariable (str) {
+  return variableLine.test(str)
+}
+
+export function matchValue (str) {
+  return value.exec(str)
+}
+
+export function parseLiteral (str) {
+  let res = str.match(numberLine)
+  if (res) {
+    return Number(str)
+  }
+  res = str.match(boolLine)
+  if (res) {
+    return str.toLowerCase() === 'true'
+  }
+  res = str.match(quotedLine)
+  if (res) {
+    return str.slice(1, -1)
+  }
+  throw new TypeError(`cannot parse '${str}' as literal`)
+}