Problème
Trouvez les positions de toutes les occurrences d'un motif dans une chaîne. (Merci @DonMcCormack )
Solution
Utiliser les fonctions de correspondance de motifs
source = "this is a racecar and ere noon stressed desserts for Stanley Yelnats saw Anna was there";
palindrome = (Pat Regex( "[a-zA-Z][a-zA-Z ]{0,999}" )) >> firstpart + // one or more first letters
(Pat Regex( "[a-zA-Z ]{0,1}" )) + // optional middle letter
Expr( Reverse( firstpart ) ); // the tail
list = {}; // places to
positions = {}; // keep results
Pat Match(
source,
Pat Repeat( // repeat *is* a loop, within the source string
(Pat Pos() >> location + // capture current position in string
palindrome >> another + // capture the text of the palindrome match
Pat Test( // this function runs some JSL to see if the current position matches
Insert Into( list, another );// the JSL saves
Insert Into( positions, location );// two answers
1 // pattest returns 1(OK) because we are not actually testing anything...just wanted to run some JSL
)//
)
| // above adds to list, below skips forward a letter to try again
Pat Len( 1 ) // this bit is more important than it looks; it matches all the text that isn't interesting
)
);
Show( list, positions );
list = {"une voiture de course a", "ere", "midi", "desserts stressés", "Stanley Yelnats", "vit Anna était", "ere"};
positions = {8, 22, 26, 31, 53, 69, 84};
Discussion
PatRepeat est une fonction de correspondance de motif qui répète son motif aussi longtemps que possible. Il ne peut pas ignorer le texte indésirable sans l'alternative PatLen (1) qui lui permet d'ignorer un caractère à la fois jusqu'à ce qu'une autre instance du motif souhaité soit trouvée.
Vous pouvez aussi utiliser un modèle très simple:
source = "this is a racecar and ere noon stressed desserts for Stanley Yelnats saw Anna was there";
reallysimple = "is";
list = {}; // places to
positions = {}; // keep results
Pat Match(
source,
Pat Repeat( // repeat *is* a loop, within the source string
(Pat Pos() >> location + // capture current position in string
reallysimple >> another + // capture the text of the match
Pat Test( // this function runs some JSL to see if the current position matches
Insert Into( list, another );// the JSL saves
Insert Into( positions, location );// two answers
1 // pattest returns 1(OK) because we are not actually testing anything...just wanted to run some JSL
)//
)
| // above adds to list, below skips forward a letter to try again
Pat Len( 1 ) // this bit is more important than it looks; it matches all the text that isn't interesting
)
);
Show( list, positions );
list = {"est", "est"};
positions = {2, 5};
