compile-string.ts

import Parse from './parse'

/* TYPES */

import type { EtaConfig } from './config'
import type { AstObject } from './parse'

/* END TYPES */

/**
 * Compiles a template string to a function string. Most often users just use `compile()`, which calls `compileToString` and creates a new function using the result
 *
 * **Example**
 *
 * ```js
 * compileToString("Hi <%= it.user %>", eta.config)
 * // "var tR='',include=E.include.bind(E),includeFile=E.includeFile.bind(E);tR+='Hi ';tR+=E.e(it.user);if(cb){cb(null,tR)} return tR"
 * ```
 */

export default function compileToString(str: string, config: EtaConfig): string {
  const buffer: Array<AstObject> = Parse(str, config)

  let res =
    "var tR='',__l,__lP" +
    (config.include ? ',include=E.include.bind(E)' : '') +
    (config.includeFile ? ',includeFile=E.includeFile.bind(E)' : '') +
    '\nfunction layout(p,d){__l=p;__lP=d}\n' +
    (config.useWith ? 'with(' + config.varName + '||{}){' : '') +
    compileScope(buffer, config) +
    (config.includeFile
      ? 'if(__l)tR=' +
        (config.async ? 'await ' : '') +
        `includeFile(__l,Object.assign(${config.varName},{body:tR},__lP))\n`
      : config.include
      ? 'if(__l)tR=' +
        (config.async ? 'await ' : '') +
        `include(__l,Object.assign(${config.varName},{body:tR},__lP))\n`
      : '') +
    'if(cb){cb(null,tR)} return tR' +
    (config.useWith ? '}' : '')

  if (config.plugins) {
    for (let i = 0; i < config.plugins.length; i++) {
      const plugin = config.plugins[i]
      if (plugin.processFnString) {
        res = plugin.processFnString(res, config)
      }
    }
  }

  return res
}

/**
 * Loops through the AST generated by `parse` and transform each item into JS calls
 *
 * **Example**
 *
 * ```js
 * // AST version of 'Hi <%= it.user %>'
 * let templateAST = ['Hi ', { val: 'it.user', t: 'i' }]
 * compileScope(templateAST, eta.config)
 * // "tR+='Hi ';tR+=E.e(it.user);"
 * ```
 */

function compileScope(buff: Array<AstObject>, config: EtaConfig) {
  let i = 0
  const buffLength = buff.length
  let returnStr = ''

  for (i; i < buffLength; i++) {
    const currentBlock = buff[i]
    if (typeof currentBlock === 'string') {
      const str = currentBlock

      // we know string exists
      returnStr += "tR+='" + str + "'\n"
    } else {
      const type = currentBlock.t // ~, s, !, ?, r
      let content = currentBlock.val || ''

      if (type === 'r') {
        // raw

        if (config.filter) {
          content = 'E.filter(' + content + ')'
        }

        returnStr += 'tR+=' + content + '\n'
      } else if (type === 'i') {
        // interpolate

        if (config.filter) {
          content = 'E.filter(' + content + ')'
        }

        if (config.autoEscape) {
          content = 'E.e(' + content + ')'
        }
        returnStr += 'tR+=' + content + '\n'
        // reference
      } else if (type === 'e') {
        // execute
        returnStr += content + '\n' // you need a \n in case you have <% } %>
      }
    }
  }

  return returnStr
}