User:Shainasabarwal/ScadLexer for ScintillaEditor


Personal Information[edit]

  • Name: Shaina Sabarwal
  • Email-address:
  • IRC username: shaina
  • Contact Number: +917837091321
  • Blog:

Background Information[edit]

  • Computer Science Engineering student at Guru Nanak Dev Engineering College, Ludhiana, Punjab, India. Presently studying in 4th year.
  • I have worked in C++, Qt, Wt, HTML, CSS, Javascript, Ruby on rails, flex and Bison and Wordpress.
  • Have worked with OpenSCAD in 2014 on project UI Brushup of OpenSCAD that was about enhancing the interface for users of OpenSCAD by adding QScintilla Editor and its various features, Toolbars with small 2D icons. Options to choose color scheme of the solid models, and launching screen of OpenSCAD.
  • I am active member of Linux User Group, Ludhiana where the students are made aware about the open source technologies and motivated to contribute in them.

Project Information[edit]

Title: SCAD lexer for QScintilla Editor[edit]

This project aims to make lexer specifically for SCAD language. Currently, QScintilla is using CPP lexer, which cause syntax problem as CPP language is very large as compared to SCAD language of OpenSCAD. With this, some scintilla and GUI related issues will also be solved.

QsciLexerCustom inherited lexer In my project UI brushup of OpenSCAD, I added QScintilla editor and used its CPP lexer class QsciLexerCPP for syntax highlighting. It worked fine. But after testing, some issues arises as SCAD is small and simple language as compared to CPP. In this project, we found the solution of the problem - Writing a lexer specifically for SCAD language. QScintilla library has a class QsciLexerCustom ( which can be used as a base class for new language lexers. The advantage of using this class is that it doesn't require to make any change in QScintilla code or to re-compile it. This will be inherited by our new class for Scad lexer and its virtual functions will be redefined.

Defining style index for SCAD language SCAD language includes various categories of keywords including mathematical functions, solid primitives as defined: ,Operators, Numbers, Comments - single line as well as multiline, single quoted and double quoted strings, parenthesis and variable names. The lexer firstly requires to index the styles of different keywords for the purpose of syntax highlighting using functions of qsciLexerCustom. This indexing can be done using an enum as

enum {
       Default = 0
       Keyword = 1
       Comment = 2
       Operator = 3

Syntax Highlighting Syntax highlighting is very important feature of an editor as it improves the readability of the code and context of text. QScintilla editor in OpenSCAD as used CPP lexer, caused problems in highlighting as Writing lexer for SCAD language will solve such problems. For this, different functions for highlighting of keywords, operators, numbers, mathematical functions etc will be defined in the lexer.
For Example
void highlightKeywords(const QString &source, int start){

   foreach(QString word, keywordsList) {    //iterate keywords
       if(source.contains(word)) {
int p = source.count(word);    // consider joining
           int index = 0;    // begin to consider the indices 
           while(p != 0) {
               int begin = source.indexOf(word, index);    //consider an index entry
               index = begin+1;    //give point of reference for next iteration
               startStyling(start + begin);    //begin to style with an index entry
               setStyling(word.length(), Keyword);    //for the length of a given style word.length Keyword
               startStyling(start + begin);    //finish styling


As shown, the function is using respective style index 'Keyword' for styling. The complete DEMO for keyword highlighting is:

Different Color scheme Not every color suits to everyone. People like to have choices specially in case of colors, so it is very important to have different color schemes as options in preferences to be selected by the user. This feature helps to improve the usability of software a lot. It will require checking the selected scheme and define style index accordingly.

Issue #1108 Customizable Icon set I liked the idea that user may add its own icon set for toolbars. It will require user to add his/her icons in a file such as icons/icon.svg and openscad will fetch and put them onto toolbar instead adding them into code directly.

Issue #1056 Toolbar Buttons Toolbars requires more icons as demanded here

Issue #1172 Syntax highlighting: # affects the whole line As presently, qscintilla uses CPP lexer, so it takes the whole line as preprocessor directive, started with #. With writing lexer specifically for SCAD language, this problem will be tackled.

Issue #905 AutoComplete/ Calltips for QScintilla Editor Many times, a programmer makes mistakes while writing syntax which can cause irritable errors and reduce productivity. In this case, auto completion or call tips helps a lot, which is considered as a great feature of an editor. As a first step, only the functions defined in the scad language will be added to be shown in call tips. Further after the feedback of the community, names of the modules related to current project can be added.

Issue #1075 Add multi-line, nested list '[' ']' indentation and tree folding to QScintilla Editor The feature of multi line, nested indentation and folding can be added into the scad lexer using functions like setFoldAtElse(), setFoldComments() etc.

Issue #915 Scintilla Editor issues The remaining issues such as auto scroll to error line after compilation, convert tab into spaces and highlighting the folded region will be solved.


Community Bonding Period

  • Talk to the community Members
  • Start reading understand existing code of scintillalexer of openscad

Week 1(25th May)

  • Get started and solving issue #1056 Toolbar buttons

Week 2(1 june)

  • Read and get confortable of qscilexercustom and its base class qscilexer to understand its virtual functions that will be defined in scad lexer
  • Start writing scad lexer

Week 3(8 june)

  • List all keywords, operators, mathematical functions, solid primitive functions

etc of the SCAD language and define their style index.

Week 4(15 june)

  • Start redefining the functions of qscilexercustom in scad lexer
  • Define function to color keywords.
  • Define function to color comments.

Week 5(22 june)

  • Define function to color Operators.
  • Define function to color solid primitive functions
  • Define function to color mathematical functions

Week 6(29 june)

  • Define function to color transformation functions.
  • Read about existing color scheme code in scintilla editor code in openscad and try to understand how to add those color scheme option through new scad lexer.

Week 7(6 july)

  • Define various color scheme options for users.
  • Read and improve code.

Week 8(13 july)

  • Solve scintilla related issues listed in issue #915
  • Add autocomplete feature solving issue #905

Week 9, 10(20 july)

  • Find a way to fetch icons from a icons file rather than directly coded in
  • Solve issue #1108 i.e. allow users to add its own icon set.

Week 11, 12(23 july)

  • Solve issues #1075 and #1172

Week 13(6 August)

  • Solve the remaining errors.
  • Get feedback by mentors and other community members
  • Test on various platforms

Week 14(20 August)

  • Improve code and testing before final submission of code.


  • A special lexer for SCAD language with syntax highlighting and other features.
  • A file to add custom icons by users.
  • More icons for toolbar
  • Improvement of scintilla editor by removing its issues.


Time Availability[edit]

I will be available for 40 to 48 hours / week, can spend more, if required.

Email/Mailing list[edit]

My email address is, I have subscribed to both brlcad and openscad mailing lists. I have been in contact through these mailing lists with other community members.

Real-Time Contact[edit]

I can interact with the mentors through OpenSCAD's IRC channel(#openscad) on freenode. My nickname on IRC is shaina. I am also comfortable with talking to my mentor via telephone if need arises. Contact Number: +91 7837091321

Code Review[edit]

I already has commit access to openscad respository at I will push my code in separate branch of same repository and send pull request so that mentors can review my code and then merge it up in master branch after testing.

Why OpenSCAD?[edit]

OpenSCAD is an open source CAD software application used to make 3D solid models. It has various applications in mechanical, civil, electronics and designing hardware tools for research and education purposes. The software has potential to be used by the large number of professionals and hardware developers. I have already contributed in this community and worked in UI brushup of OpenSCAD as my last year GSOC project. I have very good interaction with mentors and community members of the community as I also attended Reunion at California in 2014. I feel very confortable to discuss and come up with new ideas.

Why SCAD lexer project?[edit]

I came up with this idea of adding scad lexer as gsoc project, because last time, I, in my project 'UI brushup of OpenSCAD' used QsciLexerCPP as a base class for SCAD lexer class. But as the CPP is very large language as compared to SCAD so it is causing various issues, which I came to know later. In this year, I want to solve all those issues by writing a lexer specifically for scad lexer.

Why Me?[edit]

As we have very less number of women in technical study as compared to men, I want to be the part of technical community and spread awareness about women in tech in our society. I learnt a lot being the part of this community and want to contribute more through this program and afterwards. I also shared idea of improving the website of OpenSCAD but that couldn't be the part of this project, so I have plans to do so after completion of this project.