overleaf/services/document-updater/app/coffee/sharejs/text-tp2-api.js

/*
 * decaffeinate suggestions:
 * DS101: Remove unnecessary use of Array.from
 * DS102: Remove unnecessary code created because of implicit returns
 * DS205: Consider reworking code to avoid use of IIFEs
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
// Text document API for text-tp2

let type;
if (typeof WEB !== 'undefined' && WEB !== null) {
  type = exports.types['text-tp2'];
} else {
  type = require('./text-tp2');
}

const {_takeDoc:takeDoc, _append:append} = type;

const appendSkipChars = (op, doc, pos, maxlength) => (() => {
  const result = [];
  while (((maxlength === undefined) || (maxlength > 0)) && (pos.index < doc.data.length)) {
    const part = takeDoc(doc, pos, maxlength, true);
    if ((maxlength !== undefined) && (typeof part === 'string')) { maxlength -= part.length; }
    result.push(append(op, (part.length || part)));
  }
  return result;
})();

type['api'] = {
  'provides': {'text':true},

  // The number of characters in the string
  'getLength'() { return this.snapshot.charLength; },

  // Flatten a document into a string
  'getText'() {
    const strings = (Array.from(this.snapshot.data).filter((elem) => typeof elem === 'string'));
    return strings.join('');
  },

  'insert'(pos, text, callback) {
    if (pos === undefined) { pos = 0; }

    const op = [];
    const docPos = {index:0, offset:0};

    appendSkipChars(op, this.snapshot, docPos, pos);
    append(op, {'i':text});
    appendSkipChars(op, this.snapshot, docPos);
    
    this.submitOp(op, callback);
    return op;
  },
  
  'del'(pos, length, callback) {
    const op = [];
    const docPos = {index:0, offset:0};

    appendSkipChars(op, this.snapshot, docPos, pos);
    
    while (length > 0) {
      const part = takeDoc(this.snapshot, docPos, length, true);
      if (typeof part === 'string') {
        append(op, {'d':part.length});
        length -= part.length;
      } else {
        append(op, part);
      }
    }
    
    appendSkipChars(op, this.snapshot, docPos);

    this.submitOp(op, callback);
    return op;
  },

  '_register'() {
    // Interpret recieved ops + generate more detailed events for them
    return this.on('remoteop', function(op, snapshot) {
      let textPos = 0;
      const docPos = {index:0, offset:0};

      for (let component of Array.from(op)) {
        var part, remainder;
        if (typeof component === 'number') {
          // Skip
          remainder = component;
          while (remainder > 0) {
            part = takeDoc(snapshot, docPos, remainder);
            if (typeof part === 'string') {
              textPos += part.length;
            }
            remainder -= part.length || part;
          }
        } else if (component.i !== undefined) {
          // Insert
          if (typeof component.i === 'string') {
            this.emit('insert', textPos, component.i);
            textPos += component.i.length;
          }
        } else {
          // Delete
          remainder = component.d;
          while (remainder > 0) {
            part = takeDoc(snapshot, docPos, remainder);
            if (typeof part === 'string') {
              this.emit('delete', textPos, part);
            }
            remainder -= part.length || part;
          }
        }
      }

    });
  }
};