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implement MATCH-VARS: in contrib/match

chris.double 2006-09-09 03:39:02 +00:00
parent 296e8ba0b3
commit f7e38fa8d4
2 changed files with 26 additions and 8 deletions
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14
contrib/match/match.factor
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@ -3,9 +3,19 @@
! !
! Based on pattern matching code from Paul Graham's book 'On Lisp'. ! Based on pattern matching code from Paul Graham's book 'On Lisp'.
IN: match IN: match
USING: kernel words sequences namespaces hashtables ; USING: kernel words sequences namespaces hashtables parser ;
SYMBOL: _ SYMBOL: _
USE: prettyprint
: define-match-var ( name -- )
create-in [ dup <wrapper> , \ get , ] [ ] make define-compound ;
: define-match-vars ( seq -- )
[ define-match-var ] each ;
: MATCH-VARS: ! vars ...
string-mode on [ string-mode off define-match-vars ] f ; parsing
: match-var? ( symbol -- bool ) : match-var? ( symbol -- bool )
dup word? [ dup word? [
@ -34,5 +44,3 @@ SYMBOL: result
[ [
[ first over match dup result set ] find 2nip dup [ result get [ second call ] bind ] [ no-cond ] if [ first over match dup result set ] find 2nip dup [ result get [ second call ] bind ] [ no-cond ] if
] with-scope ; ] with-scope ;

20
contrib/match/match.facts
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@ -7,16 +7,26 @@ HELP: match
} }
{ $description "Pattern match seq1 against seq2. The sequences can contain pattern variables, which are symbols that begin with '?'. The result is a hashtable of the bindings, mapping the pattern variables from one sequence to the equivalent value in the other sequence. The '_' symbol can be used to ignore the value at that point in the pattern for the match. " } { $description "Pattern match seq1 against seq2. The sequences can contain pattern variables, which are symbols that begin with '?'. The result is a hashtable of the bindings, mapping the pattern variables from one sequence to the equivalent value in the other sequence. The '_' symbol can be used to ignore the value at that point in the pattern for the match. " }
{ $examples { $examples
{ $example "SYMBOL: ?a\nSYMBOL: ?b\n{ ?a { 2 ?b } 5 } { 1 { 2 3 } _ } match\n => H{ { ?a 1 } { ?b 3 } }" } { $example "MATCH-VARS: ?a ?b ;\n{ ?a { 2 ?b } 5 } { 1 { 2 3 } _ } match\n => H{ { ?a 1 } { ?b 3 } }" }
} }
{ $see-also match-cond } ; { $see-also match-cond } ;
HELP: match-cond HELP: match-cond
{ $values { "seq" "A sequence" } { "assoc" "A sequence of quotation pairs" } { $values { "seq" "A sequence" } { "assoc" "A sequence of quotation pairs" } }
}
{ $description "Calls the second quotation in the first pair whose first sequence yields a successful " { $link match } " against seq. The second quotation, when called, has the hashtable returned from the " { $link match } " call bound as the top namespace so " { $link get } " can be used to retrieve the values. To have a fallthrough match clause use the '_' match variable." } { $description "Calls the second quotation in the first pair whose first sequence yields a successful " { $link match } " against seq. The second quotation, when called, has the hashtable returned from the " { $link match } " call bound as the top namespace so " { $link get } " can be used to retrieve the values. To have a fallthrough match clause use the '_' match variable." }
{ $examples { $examples
{ $example "SYMBOL: ?value\n{ increment ?value } {\n { { increment ?value } [ ?value get do-something ] }\n { { decrement ?value } [ ?value get do-something-else ] }\n { _ [ no-match-found ] }\n} match-cond" } { $example "MATCH-VARS: ?value ;\n{ increment ?value } {\n { { increment ?value } [ ?value do-something ] }\n { { decrement ?value } [ ?value do-something-else ] }\n { _ [ no-match-found ] }\n} match-cond" }
} }
{ $see-also match } ; { $see-also match } ;
HELP: MATCH-VARS:
{ $syntax "MATCH-VARS: var ... ;" }
{ $values { "var" "a match variable name beginning with '?'" } }
{ $description "Creates a symbol that can be used in " { $link match } " and " { $link match-cond } " for binding values in the matched sequence. The symbol name is created as a word that is defined to get the value of the symbol out of the current namespace. This can be used in " { $link match-cond } " to retrive the values in the quotation body." }
{ $examples
{ $example "MATCH-VARS: ?value ;\n{ increment ?value } {\n { { increment ?value } [ ?value do-something ] }\n { { decrement ?value } [ ?value do-something-else ] }\n { _ [ no-match-found ] }\n} match-cond" }
}
{ $see-also match match-cond } ;