rtf-parser/rtf-parser.js

This is a general RTF parser. It takes a text stream and produces a document object representing the parsed document. In and of itself, this isn't super useful but it's the building block for other tools to convert RTF into other formats.

'use strict'
const Transform = require('readable-stream').Transform

class RTFParser extends Transform {
  constructor () {
    super({objectMode: true})
    this.text = ''
    this.controlWord = ''
    this.controlWordParam = ''
    this.hexChar = ''
    this.parserState = this.parseText
    this.char = 0
    this.row = 1
    this.col = 1
  }
  _transform (buf, encoding, done) {
    const text = buf.toString('ascii')
    for (let ii = 0; ii < text.length; ++ii) {
      ++this.char
      if (text[ii] === '\n') {
        ++this.row
        this.col = 1
      } else {
        ++this.col
      }
      this.parserState(text[ii])
    }
    done()
  }
  _flush (done) {
    if (this.text !== '\u0000') this.emitText()
    done()
  }
  parseText (char) {
    if (char === '\\') {
      this.parserState = this.parseEscapes
    } else if (char === '{') {
      this.emitStartGroup()
    } else if (char === '}') {
      this.emitEndGroup()
    } else if (char === '\x0A' || char === '\x0D') {
      // cr/lf are noise chars
    } else {
      this.text += char
    }
  }

  parseEscapes (char) {
    if (char === '\\' || char === '{' || char === '}') {
      this.text += char
      this.parserState = this.parseText
    } else {
      this.parserState = this.parseControlSymbol
      this.parseControlSymbol(char)
    }
  }
  parseControlSymbol (char) {
    if (char === '~') {
      this.text += '\u00a0' // nbsp
      this.parserState = this.parseText
    } else if (char === '-') {
      this.text += '\u00ad' // soft hyphen
    } else if (char === '_') {
      this.text += '\u2011' // non-breaking hyphen
    } else if (char === '*') {
      this.emitIgnorable()
      this.parserState = this.parseText
    } else if (char === "'") {
      this.parserState = this.parseHexChar
    } else if (char === '|') { // formula character
      this.emitFormula()
      this.parserState = this.parseText
    } else if (char === ':') { // subentry in an index entry
      this.emitIndexSubEntry()
      this.parserState = this.parseText
    } else if (char === '\x0a') {
      this.emitEndParagraph()
      this.parserState = this.parseText
    } else if (char === '\x0d') {
      this.emitEndParagraph()
      this.parserState = this.parseText
    } else {
      this.parserState = this.parseControlWord
      this.parseControlWord(char)
    }
  }
  parseHexChar (char) {
    if (/^[A-Fa-f0-9]$/.test(char)) {
      this.hexChar += char
      if (this.hexChar.length >= 2) {
        this.emitHexChar()
        this.parserState = this.parseText
      }
    } else {
      this.emitError(`Invalid character "${char}" in hex literal.`)
      this.parserState = this.parseText
    }
  }
  parseControlWord (char) {
    if (char === ' ') {
      this.emitControlWord()
      this.parserState = this.parseText
    } else if (/^[-\d]$/.test(char)) {
      this.parserState = this.parseControlWordParam
      this.controlWordParam += char
    } else if (/^[A-Za-z]$/.test(char)) {
      this.controlWord += char
    } else {
      this.emitControlWord()
      this.parserState = this.parseText
      this.parseText(char)
    }
  }
  parseControlWordParam (char) {
    if (/^\d$/.test(char)) {
      this.controlWordParam += char
    } else if (char === ' ') {
      this.emitControlWord()
      this.parserState = this.parseText
    } else {
      this.emitControlWord()
      this.parserState = this.parseText
      this.parseText(char)
    }
  }
  emitText () {
    if (this.text === '') return
    this.push({type: 'text', value: this.text, pos: this.char, row: this.row, col: this.col})
    this.text = ''
  }
  emitControlWord () {
    this.emitText()
    if (this.controlWord === '') {
      this.emitError('empty control word')
    } else {
      this.push({
        type: 'control-word',
        value: this.controlWord,
        param: this.controlWordParam !== '' && Number(this.controlWordParam),
        pos: this.char,
        row: this.row,
        col: this.col
      })
    }
    this.controlWord = ''
    this.controlWordParam = ''
  }
  emitStartGroup () {
    this.emitText()
    this.push({type: 'group-start', pos: this.char, row: this.row, col: this.col})
  }
  emitEndGroup () {
    this.emitText()
    this.push({type: 'group-end', pos: this.char, row: this.row, col: this.col})
  }
  emitIgnorable () {
    this.emitText()
    this.push({type: 'ignorable', pos: this.char, row: this.row, col: this.col})
  }
  emitHexChar () {
    this.emitText()
    this.push({type: 'hexchar', value: this.hexChar, pos: this.char, row: this.row, col: this.col})
    this.hexChar = ''
  }
  emitError (message) {
    this.emitText()
    this.push({type: 'error', value: message, row: this.row, col: this.col, char: this.char, stack: new Error().stack})
  }
  emitEndParagraph () {
    this.emitText()
    this.push({type: 'end-paragraph', pos: this.char, row: this.row, col: this.col})
  }
}

module.exports = RTFParser