Esla scripting language

Embeddable Scripting LAnguage

NEW: Qt support

Esla is a very simple scripting language that can be embedded within C++ applications. It comprises a set of global actions, such as for, forall, while, do-while loops, try-catch statements, if-elseif-else conditional tests, and encapsulates the notion of namespace. The namespace allows the wrapping of different actions specialized for a numerical code or other applications, without interfering with other action's name.

Esla does not produced byte code and there's no compilation. Sentences are executed as they are read.
It doesn't use Lex and Yacc because of the special definition and reference to user variables.
It can be easily extended as shown in the following code (interface and implementation of the prompt command):

The intent of this language is to be able to write repetitive tasks for numerical codes (see for example http://pangea.stanford.edu/research/geomech/Software/Software.htm), or to create macro within a graphical interface.

For more information about the syntax or how to extend and embed Esla within a C++ code, read this file.

Esla can be downloaded under the GPL license at http://sourceforge.net/projects/esla/

You can aslo read the code documentation here.

Thanks to the following contributors:

Bruno Levy at INRIA (France)

Example 1: Script to test the tokenizer

% ======================================================= % This script test the token actions: % token_size % get_token % ======================================================= set $s hello c'est juste un test set $nbr token_size $nbr $(s) println the line '$(s)' got $(nbr) tokens set $token get_token $token 1 $(s) println The first token is: [$(token)] get_token $token $(nbr) $(s) println And the last one is: [$(token)] println println Printing all tokens: for $i=1:$(nbr) get_token $token $(i) $(s) print [$(token)] end println println println Reverse the sentense: set $reverse "" for $i=$(nbr):-1:1 get_token $token $(i) $(s) $reverse = $(reverse) $(token) end println $(reverse) println println ========================================================== % Test the tokenizer with user defined separators % The action is: tokenize set $s hello c'est juste un test set $c tokenize $c " e" $(s) token_size $nbr $(c) println Tokenize sentense using separators 'e' and space println INIT : $(s) println FINAL: $(c) println println Printing all tokens: for $i=1:$(nbr) get_token $token $(i) $(c) print "[$(token)] " end println println

Example 2: Script to test the for loop and if statement

% *********************************** % This a simple test of 2 loops % with a flag for the second one % *********************************** set $q set $activate 1 for $i=1:10 set $a set $b cos($(i)) set $c sin($(i)+10/100) eval $a $(b) >= $(c) println i gives: $(b) >= $(c) ? $(a) if $(activate)=1 for $j=3:-1:$(i) println $(i) $(j) eval $a cos($(j)) * sin($(i)+10/100) / 100 println --> $(j) gives: $(a) if $(i)=$(j) println at this line, we have i equals j end rand $q println random = $(q) end end end

Example 3: Script to test the switch statement and the function definition

% ======================================================= % This script test the switch statement % ======================================================= % Local function to prompt a value function AskMe $message $val % Embedded function to exit if user pressed q or Q function TestQuit $c if $(c)=q | $(c)=Q println "Exising now." exit end end print $(message) prompt $val TestQuit $val end % Main program start here % ----------------------- println "-- Test switch statement --" println " (q or Q to quit)" println while 1 set $c AskMe "Enter a value: " $c switch $(c) case 1 2 3 4 5 6 7 8 9 println "******** You typed the "$(c)" character" end case 0 println "!!!!!!!! This is the ZERO character" end case hello println "Hello to you too" end default println "---Nothing to say---" end end end println

Example 4: Script to compute Pi

% ----------------------------------------------------------------------- % Algorithm to compute pi % ======================= % % | y[0] = sqrt(2) - 1 % init | % | x[0] = 6 - 4 * sqrt(2) % % y[n] = (1 - sqrt(sqrt(1 - y[n-1]^4))) / (1 + sqrt(sqrt(1 - y[n-1]^4))) % x[n] = ((1 + y[n])^4 * x[n-1]) - 2^(2n+1) * y[n] * (1 + y[n] + y[n]^2) % ----------------------------------------------------------------------- function computePi $nbr $p set $x 6-4*sqrt(2) set $y sqrt(2)-1 for $i=1:$(nbr) $y = (1 - sqrt(sqrt(1 - $(y)^4))) / (1 + sqrt(sqrt(1 - $(y)^4))) $x = ((1 + $(y))^4 * $(x)) - 2^(2*$(i)+1) * $(y) * (1 + $(y) + $(y)^2) end $p = 1/$(x) end set $p 0 computePi 5 $p println "pi = $(p)" println

Example 5: Script to convert a netgen file to a gocad file. This script uses some binded Qt commands, accessible with the namespace 'qt'

% ********************************************************** % This script converts a netgen file % into a Gocad Volume file. % ********************************************************** % % -------------------------------------------------- % Choose the file to convert % -------------------------------------------------- set $filter NetGen (*.vol) set $in println "Enter the NetGen file name" qt.open $(filter) $in if $(in)=NULL println "Exiting (No input file selected)" exit end % -------------------------------------------------- %choose the name of the so file % -------------------------------------------------- set $out $(in).so println Output file will be '$(out)' % -------------------------------------------------- % Define some variables, open the files and % start the timer. % -------------------------------------------------- timer.start open r $(in) open w $(out) set $line set $is_eof 0 set $index 0 % ----- TMP FILE set $tmpf tmp open w $(tmpf) % -------------- % -------------------------------------------------- % Object name % -------------------------------------------------- set $name object % -------------------------------------------------- % Write the Gocad hearder % -------------------------------------------------- writeln $(out) GOCAD TSolid 1.0 writeln $(out) HEARDER { writeln $(out) name: $(name) writeln $(out) } % -------------------------------------------------- % Main loop to read, parse and write % -------------------------------------------------- inc $index read $(in) $line read $(in) $line set $nbr_tetra read $(in) $nbr_tetra println "Reading temporary tetraherons..." for $i=1:$(nbr_tetra) { set $tok1 set $tok2 set $tok3 set $tok4 read $(in) $line tokenizer.get $tok1 3 $(line) $tok1 = $(tok1)-1 tokenizer.get $tok2 4 $(line) $tok2 = $(tok2)-1 tokenizer.get $tok3 5 $(line) $tok3 = $(tok3)-1 tokenizer.get $tok4 6 $(line) $tok4 = $(tok4)-1 writeln $(tmpf) TETRA $(tok1) $(tok2) $(tok3) $(tok4) } end close $(tmpf) while $(is_eof)=0 { set $tok set $nbr 0 read $(in) $line tokenizer.size $nbr $(line) if $(nbr)>0 tokenizer.get $tok 1 $(line) if $(tok)=points break end end eof $(in) $is_eof } end println "Writting vertices..." set $nbr_vert read $(in) $nbr_vert set $indexV 0 for $i=1:$(nbr_vert) { set $x set $y set $z read $(in) $line tokenizer.get $x 1 $(line) tokenizer.get $y 2 $(line) tokenizer.get $z 3 $(line) writeln $(out) VRTX $(indexV) $(x) $(y) $(z) $indexV = $(indexV)+1 } end set $is_eof 0 open r $(tmpf) println "Writting tetraherons..." while $(is_eof)=0 { set $line read $(tmpf) $line writeln $(out) $(line) eof $(tmpf) $is_eof } end writeln $(out) END % -------------------------------------------------- % Finish the script % -------------------------------------------------- close $(in) close $(out) close $(tmpf) timer.stop set $t timer.get $t qt.message Vertices: $(nbr_vert) Tetrahedrons: $(nbr_tetra) Time: $(t) seconds println "\n\nDone." println "Your input file was: $(in)" println "The result was saved as: $(out)" println "Read $(nbr_vert) vertices" println "Read $(nbr_tetra) tetrahedrons" println "Elasped time for the conversion: $(t) second(s)"