Pharo transformation Language is a transformation model language like ALT tefkat.
# PTL [](https://coveralls.io/github/CafeKrem/PTL?branch=main)
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.
```smalltalk
Metacello
new
repository: 'github://CafeKrem/PTL:main';
baseline: 'PTL';
onConflictUseIncoming;
load.
```
### how to write pattern
#### LiteralMatcher
we can match some Literal:
##### numberMatcher
```smalltalk
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
```smalltalk
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
```smalltalk
pattern := { 'set' , #'*aName'} asMatcher.
(pattern match: 'setLabel') at: #aName. "Label"
```
#* this match a collection of ellement.
#* it's equivalent to a kleen star.
```smalltalk
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.
```smalltalk
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.
```smalltalk
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.
```smalltalk
(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.
```smalltalk
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
