PTL

Pharo transformation Language is a transformation model language like ALT tefkat.

state of the project , in developement

For now there is only a pattern matching implemented.

how to use it as a client

install it

execute this.

Metacello
	new
		repository: 'github://CafeKrem/PTL:main';
		baseline: 'PTL';
		onConflictUseIncoming;
		load.

how to write pattern

LiteralMatcher

we can match some Literal:

numberMatcher

stringMatcher := 100 asMatcher. 
stringMatcher2 := PTLMatcherInteger named: #int asMatcher. 
(stringMatcher match: 100) isMatch. "true"
(stringMatcher match: 50) isMatch. "false"
(stringMatcher2 match: 200) at: #int. "200"

StringMatcher

stringMatcher := 'klm' asMatcher. 
stringMatcher2 := PTLMatcherString named: #str asMatcher. 
(stringMatcher match: 'klm') isMatch. "true"
(stringMatcher match: 'patrick') isMatch. "false"
(stringMatcher2 match: 'anything') at: #str. "anything"

match a compose String

pattern := { 'set' , #'*aName'} asMatcher.
(pattern match: 'setLabel') at: #aName. "Label"

#* this match a collection of ellement. #* it's equivalent to a kleen star.

pattern := {#'@first' . #'*' . #'@last' } asMatcher.
matchResult := pattern match: {1 .2 .3 .4 .5 .6}.
matchResult at: #first."1"
matchResult at: #last. "6"

#@aName will store only one element.

match an Object or an element of your model.

pattern := { (RBSequenceNode suchAs: { (#statements -> { 
			             (RBAssignmentNode suchAs: { (#variable -> #'@x') }).
			             (RBAssignmentNode suchAs: { (#variable -> #'@y') }).
			             ((RBMessageNode suchAs: { 
					               (#receiver -> #'@x').
					               (#arguments -> #'@y') }) named: #message) }) }) }
		           asMatcher.
	rbAST := RBParser parseExpression: 'a := 5. b:= 5. a + b'.
	matchResult := pattern match: rbAST.
	matchResult isMatch. "true"
	matchResult at: #x. "RBVariableNode ..."
	matchResult at: #y ."RBVariableNode ..."
	matchResult at: #message.

so to summarize , in order to write pattern matching on Object/element of your metaModel. you have to write something like this.

pattern := {MyObject suchAs: {#attribut1 -> "ShouldBeLike" MyObjectB } } asMatcher

and in 'a := 5. b:= 5. a + b' expression there is another concept in our pattern. it's the fact that we can express that we want to match element that we matched.

(RBMessageNode suchAs: { 
	(#receiver -> #'@x').
	(#arguments -> #'@y') }) named: #message) })

in this part , there is #'@x' and #'@y' x and y are already used in asignementNode. Thanks to this it will only match if the value matched in x and y are equals to the current node.

match a range of value

I match if the matched value is in my range.

pattern := #'16..31' asMatcher.  ""
(pattern match: 16 ) isMatch" true"
(pattern match: 31 ) isMatch" true"
(pattern match: 18 ) isMatch" true"
(pattern match: 0 ) isMatch" false"

how to use it as maintener

I modelise on GenMyModel the class hierarchy.

https://app.genmymodel.com/api/repository/Clement%20Dutriez/PTLPatternMatchingModelUML

root of the model

This picture contains 2 important Object , MatcherModelEntity the root of the metaModel of pattern matching , and MatcherResult the Object return by the pattern when it match.

MatcherResult

It return by the pattern when it match. It will contains every matched Object.

MatcherModelEntity

MatcherModelEntity define many operations:

match: anObjectToMatch

it's the entry point of the API it will be use by the client. t's return a MatcherResult anObjectToMatch is convert as collection in order to be able to iterate on it.

match: anObjectToMatch withContext: aMatcherResult

aMatcherResult is transmit by parameter in order to store matched object. return a Boolean.

this method is responsible of asking if it's match. If it match so it will store the the matched value and pop from the collection.

### hasMatch: anObjectToMatch withContext: aMatcherResult

return a boolean true if it match else false. my subclasses have to implement me.

save: aValue inContext: aMatcherResult

this method is responsible of saving aValue if there is a selector into aMatcherResult.

how to add a new matcher

in order to do this you just have to create an object subclass of MatcherModelEntity.

hierarchy