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handle boundary cases better in suffix-arrays. more unit tests

db4
Doug Coleman 2008-10-01 16:00:23 -05:00
parent 4c502165e7
commit 64af1a9e67
3 changed files with 32 additions and 14 deletions
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8
extra/suffix-arrays/suffix-arrays-docs.factor
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@ -8,7 +8,7 @@ HELP: >suffix-array
{ $values
{ "seq" sequence }
{ "array" array } }
{ $description "Creates a suffix array from the input sequence." } ;
{ $description "Creates a suffix array from the input sequence. Suffix arrays are arrays of slices." } ;
HELP: SA{
{ $description "Creates a new literal suffix array at parse-time." } ;
@ -21,15 +21,15 @@ HELP: suffixes
HELP: from-to
{ $values
{ "index" integer } { "suffix-array" "a suffix-array" } { "begin" string }
{ "index" integer } { "suffix-array" "a suffix-array" } { "begin" sequence }
{ "from" integer } { "to" integer } }
{ $notes "Slices are [m,n) and we want (m,n) so we increment." } ;
HELP: query
{ $values
{ "begin" string } { "suffix-array" "a suffix-array" }
{ "begin" sequence } { "suffix-array" "a suffix-array" }
{ "matches" array } }
{ $description "Returns " } ;
{ $description "Returns a sequence of sequences from the suffix-array that contain the input sequence. An empty array is returned when there are no matches." } ;
ARTICLE: "suffix-arrays" "Suffix arrays"
"The " { $vocab-link "suffix-arrays" } " vocabulary implements the suffix array data structure for efficient lookup of subsequences. This suffix array implementation is a sorted array of suffixes. Querying it for matches uses binary search for efficiency." $nl

16
extra/suffix-arrays/suffix-arrays-tests.factor
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@ -5,7 +5,7 @@ IN: suffix-arrays.tests
! built from [ all-words 10 head [ name>> ] map ]
[ ] [
SA{
{
"run-tests"
"must-fail-with"
"test-all"
@ -16,15 +16,23 @@ IN: suffix-arrays.tests
"this-test"
"(unit-test)"
"unit-test"
} "suffix-array" set
} >suffix-array "suffix-array" set
] unit-test
[ "suffix-array" get "" swap query ] must-fail
[ t ]
[ "suffix-array" get "" swap query empty? not ] unit-test
[ SA{ } "something" swap query ] must-fail
[ { } ]
[ SA{ } "something" swap query ] unit-test
[ V{ "unit-test" "(unit-test)" } ]
[ "suffix-array" get "unit-test" swap query ] unit-test
[ t ]
[ "suffix-array" get "something else" swap query empty? ] unit-test
[ V{ "rofl" } ] [ SA{ "rofl" } "r" swap query ] unit-test
[ V{ "rofl" } ] [ SA{ "rofl" } "o" swap query ] unit-test
[ V{ "rofl" } ] [ SA{ "rofl" } "f" swap query ] unit-test
[ V{ "rofl" } ] [ SA{ "rofl" } "l" swap query ] unit-test
[ V{ } ] [ SA{ "rofl" } "t" swap query ] unit-test

20
extra/suffix-arrays/suffix-arrays.factor
View File

@ -11,13 +11,22 @@ IN: suffix-arrays
: prefix<=> ( begin seq -- <=> )
[ <=> ] [ swap head? ] 2bi [ drop +eq+ ] when ;
: find-index ( begin suffix-array -- index )
: find-index ( begin suffix-array -- index/f )
[ prefix<=> ] with search drop ;
: from-to ( index begin suffix-array -- from to )
: from-to ( index begin suffix-array -- from/f to/f )
swap '[ _ head? not ]
[ find-last-from drop 1+ ]
[ find-last-from drop dup [ 1+ ] when ]
[ find-from drop ] 3bi ;
: <funky-slice> ( from/f to/f seq -- slice )
[
tuck
[ drop [ 0 ] unless* ]
[ dupd length ? ] 2bi*
[ min ] keep
] keep <slice> ;
PRIVATE>
: >suffix-array ( seq -- array )
@ -26,5 +35,6 @@ PRIVATE>
: SA{ \ } [ >suffix-array ] parse-literal ; parsing
: query ( begin suffix-array -- matches )
[ [ find-index ] 2keep from-to [ min ] keep ] keep
<slice> [ seq>> ] map prune ;
2dup find-index
[ -rot [ from-to ] keep <funky-slice> [ seq>> ] map prune ]
[ 2drop { } ] if* ;