ExpressionScript Engine roadmap

This page is for tracking the development status and TODO lists for ExpressionScript Engine

Status

EM was introduced in version 1.92+ (released in March 2012). Since then it is a part of every LimeSurvey distribution.

Wish List for EM-Related Enhancements

• Enhance Expression Manager
• Optimize LimeSurvey for Long Surveys and better performance and maintenance in general

Performance Tuning Notes

ExpressionScript Engine can be called dozens to hundreds of times per page. Instead, it should be possible to concatenate together the roughly tailored parts of the survey page and call Expression Manager once per page (or at least fewer times).

To accomplish this, two things are needed:

1. Ensure that all replacement values are correct when called. Some values like {QUESTION} change multiple times per page. Others are constant across all pages.
2. Find a way to concatenate together all page components prior to calling ExpressionScript Engine.

For values that change multiple times per page (like {QUESTION}), I'd like to replace calls to templatereplace(), replaceTokens(), insertAnsReplace(), dTexts, and replaceFields() (several of which call ExpressionScript Engine) as follows:

• Templates: (except for Group and Question) - return as they are so they get processed at the end;
• Group Template: Replace {GROUP} with something like {GROUP_N} which ExpressionScript Engine would then substitute at the end;
• Question Template: Replace {QUESTION} and {ANSWER} with something like {QUESTION_N} and {ANSWER_N} which would also get replaced after the whole page was composed.

When are each of the following attributes changed?

Here are the possibilities:

• global - means that the value is global for the LimeSurvey instance (across all surveys and sessions);
• survey - means each survey might have a different value;
• session - means the value should be static across a given session
• page - means that the value on each page might differ
• group - means might differ for each group
• questions - means might differ for each question
• answer - means  might differ for each answer option
• no processing needed - means EM should only do a plain replace on these, no processing of the contents

Attribute	When Changed
AID	answer
ANSWER	answer
ANSWERSCLEARED	survey
ASSESSMENTS	page
ASSESSMENT_CURRENT_TOTAL	page
ASSESSMENT_HEADING	survey
CHECKJAVASCRIPT	survey - no processing needed
CLEARALL	survey
CLOSEWINDOW	survey
COMPLETED	session
DATESTAMP	page - no processing needed
EXPIRY	survey - no processing needed
GID	group
GROUPDESCRIPTION	group
GROUPNAME	group
LANG	page
LANGUAGECHANGER	page
LOADERROR	survey
LOADFORM	survey
LOADHEADING	survey
LOADMESSAGE	survey
NAVIGATOR	page
NOSURVEYID	survey - no processing needed
NUMBEROFQUESTIONS	survey
PERCENTCOMPLETE	page
PRIVACY	survey
PRIVACYMESSAGE	survey
QID	question
QUESTION	question
QUESTIONHELP	question
QUESTIONHELPPLAINTEXT	question
QUESTION_CLASS	question
QUESTION_CODE	question
QUESTION_ESSENTIALS	question
QUESTION_FILE_VALID_MESSAGE	question
QUESTION_HELP	question
QUESTION_INPUT_ERROR_CLASS	question
QUESTION_MANDATORY	question
QUESTION_MAN_CLASS	question
QUESTION_MAN_MESSAGE	question
QUESTION_NUMBER	question
QUESTION_TEXT	question
QUESTION_VALID_MESSAGE	question
REGISTERERROR	survey
REGISTERFORM	survey
REGISTERMESSAGE1	survey
REGISTERMESSAGE2	survey
RESTART	survey
RETURNTOSURVEY	survey
SAVE	survey
SAVEALERT	survey
SAVEDID	survey
SAVEERROR	survey
SAVEFORM	survey
SAVEHEADING	survey
SAVEMESSAGE	survey
SGQ	question
SID	survey
SITENAME	global
SUBMITBUTTON	survey
SUBMITCOMPLETE	survey
SUBMITREVIEW	survey
SURVEYCONTACT	survey
SURVEYDESCRIPTION	survey
SURVEYFORMAT	survey
SURVEYLANGAGE	survey
SURVEYLIST	survey
SURVEYLISTHEADING	survey
SURVEYNAME	survey
TEMPLATECSS	survey
TEMPLATEURL	survey
THEREAREXQUESTIONS	suvey
TOKEN	session - no processing needed
URL	survey
WELCOME	survey

Where within LimeSurvey is each Keyword Used?

A green 1 means that the keyword is used in that file at least once.