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import { ParseErr } from './err.ts'import { trimWS } from './utils.ts'
/* TYPES */
import type { EtaConfig } from './config.ts'
export type TagType = 'r' | 'e' | 'i' | ''
export interface TemplateObject {  t: TagType  val: string}
export type AstObject = string | TemplateObject
/* END TYPES */
const templateLitReg = /`(?:\\[\s\S]|\${(?:[^{}]|{(?:[^{}]|{[^}]*})*})*}|(?!\${)[^\\`])*`/g
const singleQuoteReg = /'(?:\\[\s\w"'\\`]|[^\n\r'\\])*?'/g
const doubleQuoteReg = /"(?:\\[\s\w"'\\`]|[^\n\r"\\])*?"/g
/** Escape special regular expression characters inside a string */
function escapeRegExp(string: string) {  // From MDN  return string.replace(/[.*+\-?^${}()|[\]\\]/g, '\\$&') // $& means the whole matched string}
export default function parse(str: string, config: EtaConfig): Array<AstObject> {  let buffer: Array<AstObject> = []  let trimLeftOfNextStr: string | false = false  let lastIndex = 0  const parseOptions = config.parse
  if (config.plugins) {    for (let i = 0; i < config.plugins.length; i++) {      const plugin = config.plugins[i]      if (plugin.processTemplate) {        str = plugin.processTemplate(str, config)      }    }  }
  /* Adding for EJS compatibility */  if (config.rmWhitespace) {    // Code taken directly from EJS    // Have to use two separate replaces here as `^` and `$` operators don't    // work well with `\r` and empty lines don't work well with the `m` flag.    // Essentially, this replaces the whitespace at the beginning and end of    // each line and removes multiple newlines.    str = str.replace(/[\r\n]+/g, '\n').replace(/^\s+|\s+$/gm, '')  }  /* End rmWhitespace option */
  templateLitReg.lastIndex = 0  singleQuoteReg.lastIndex = 0  doubleQuoteReg.lastIndex = 0
  function pushString(strng: string, shouldTrimRightOfString?: string | false) {    if (strng) {      // if string is truthy it must be of type 'string'
      strng = trimWS(        strng,        config,        trimLeftOfNextStr, // this will only be false on the first str, the next ones will be null or undefined        shouldTrimRightOfString      )
      if (strng) {        // replace \ with \\, ' with \'        // we're going to convert all CRLF to LF so it doesn't take more than one replace
        strng = strng.replace(/\\|'/g, '\\$&').replace(/\r\n|\n|\r/g, '\\n')
        buffer.push(strng)      }    }  }
  const prefixes = [parseOptions.exec, parseOptions.interpolate, parseOptions.raw].reduce(function (    accumulator,    prefix  ) {    if (accumulator && prefix) {      return accumulator + '|' + escapeRegExp(prefix)    } else if (prefix) {      // accumulator is falsy      return escapeRegExp(prefix)    } else {      // prefix and accumulator are both falsy      return accumulator    }  },  '')
  const parseOpenReg = new RegExp(    '([^]*?)' + escapeRegExp(config.tags[0]) + '(-|_)?\\s*(' + prefixes + ')?\\s*',    'g'  )
  const parseCloseReg = new RegExp(    '\'|"|`|\\/\\*|(\\s*(-|_)?' + escapeRegExp(config.tags[1]) + ')',    'g'  )  // TODO: benchmark having the \s* on either side vs using str.trim()
  let m
  while ((m = parseOpenReg.exec(str))) {    lastIndex = m[0].length + m.index
    const precedingString = m[1]    const wsLeft = m[2]    const prefix = m[3] || '' // by default either ~, =, or empty
    pushString(precedingString, wsLeft)
    parseCloseReg.lastIndex = lastIndex    let closeTag    let currentObj: AstObject | false = false
    while ((closeTag = parseCloseReg.exec(str))) {      if (closeTag[1]) {        let content = str.slice(lastIndex, closeTag.index)
        parseOpenReg.lastIndex = lastIndex = parseCloseReg.lastIndex
        trimLeftOfNextStr = closeTag[2]
        const currentType: TagType =          prefix === parseOptions.exec            ? 'e'            : prefix === parseOptions.raw            ? 'r'            : prefix === parseOptions.interpolate            ? 'i'            : ''
        currentObj = { t: currentType, val: content }        break      } else {        const char = closeTag[0]        if (char === '/*') {          const commentCloseInd = str.indexOf('*/', parseCloseReg.lastIndex)
          if (commentCloseInd === -1) {            ParseErr('unclosed comment', str, closeTag.index)          }          parseCloseReg.lastIndex = commentCloseInd        } else if (char === "'") {          singleQuoteReg.lastIndex = closeTag.index
          const singleQuoteMatch = singleQuoteReg.exec(str)          if (singleQuoteMatch) {            parseCloseReg.lastIndex = singleQuoteReg.lastIndex          } else {            ParseErr('unclosed string', str, closeTag.index)          }        } else if (char === '"') {          doubleQuoteReg.lastIndex = closeTag.index          const doubleQuoteMatch = doubleQuoteReg.exec(str)
          if (doubleQuoteMatch) {            parseCloseReg.lastIndex = doubleQuoteReg.lastIndex          } else {            ParseErr('unclosed string', str, closeTag.index)          }        } else if (char === '`') {          templateLitReg.lastIndex = closeTag.index          const templateLitMatch = templateLitReg.exec(str)          if (templateLitMatch) {            parseCloseReg.lastIndex = templateLitReg.lastIndex          } else {            ParseErr('unclosed string', str, closeTag.index)          }        }      }    }    if (currentObj) {      buffer.push(currentObj)    } else {      ParseErr('unclosed tag', str, m.index + precedingString.length)    }  }
  pushString(str.slice(lastIndex, str.length), false)
  if (config.plugins) {    for (let i = 0; i < config.plugins.length; i++) {      const plugin = config.plugins[i]      if (plugin.processAST) {        buffer = plugin.processAST(buffer, config)      }    }  }
  return buffer}