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| -rw-r--r-- | doc/gf-history.html | 58 | ||||
| -rw-r--r-- | src/GF/Grammar/PatternMatch.hs | 2 |
2 files changed, 44 insertions, 16 deletions
diff --git a/doc/gf-history.html b/doc/gf-history.html index 7b4e1091c..c58d39fa5 100644 --- a/doc/gf-history.html +++ b/doc/gf-history.html @@ -14,26 +14,54 @@ Changes in functionality since May 17, 2005, release of GF Version 2.2 <p> -5/1 (BB) New grammar printers <tt>slf_sub</tt> and <tt>slf_sub_graphviz</tt> -for creating SLF networks with sub-automata. - -<hr> - -6/1/2006 (AR) Concatenative string patterns to help morphology definitions. -The pattern <tt>Predef.CC p1 p2</tt> matches a string literal <tt>s</tt> -with the first (i.e. shortest-prefix) division <tt>s1 + s2 = s</tt> such that -<tt>p1</tt> matches <tt>s1</tt> and <tt>p2</tt> matches <tt>s2</tt>. For example, -the following expression produces the English plural forms -<i>boy-boys, play-plays, fly-flies, dog-dogs</i>: +7/1 (AR) Full set of regular expression patterns, with +as-patterns to enable variable bindings to matched expressions: +<ul> + <li> <i>p</i> <tt>+</tt> <i>q</i> : token consisting of <i>p</i> followed by <i>q</i> + <li> <i>p</i> <tt>*</tt> : token <i>p</i> repeated 0 or more times + (max the length of the strin to be matched) + <li> <tt>-</tt> <i>p</i> : matches anything that <i>p</i> does not match + <li> <i>x</i> <tt>@</tt> <i>p</i> : bind to <i>x</i> what <i>p</i> matches + <li> <i>p</i> <tt>|</tt> <i>q</i> : matches what either <i>p</i> or <i>q</i> matches +</ul> +The last three apply to all types of patterns, the first two only to token strings. +Example: plural formation in Swedish 2nd declension +(<i>pojke-pojkar, nyckel-nycklar, seger-segrar, bil-bilar</i>): <pre> - plur : Str -> Str = \s -> case s of { - CC x (CC ("a" | "o") "y") => s + "s" ; - CC x "y" => x + "ies" ; - _ => s + "s" + plural2 : Str -> Str = \w -> case w of { + pojk + "e" => pojk + "ar" ; + nyck + "e" + l@("l" | "r" | "n") => nyck + l + "ar" ; + bil => bil + "ar" } ; </pre> +Semantics: variables are always bound to the <b>first match</b>, in the sequence defined +as the list <tt>Match p v</tt> as follows: +<pre> + Match (p1|p2) v = Match p1 v ++ Match p2 v + Match (p1+p2) s = [Match p1 s1 ++ Match p2 s2 | i <- [0..length s], (s1,s2) = splitAt i s] + Match p* s = Match "" s ++ Match p s ++ Match (p + p) s ++ ... + Match c v = [[]] if c == v -- for constant patterns c + Match x v = [[(x,v)]] -- for variable patterns x + Match x@p v = [[(x,v)]] + M if M = Match p v /= [] + Match p v = [] otherwise -- failure +</pre> +Examples: +<ul> +<li> <tt>x + "e" + y</tt> matches <tt>"peter"</tt> with <tt>x = "p", y = "ter"</tt> +<li> <tt>x@("foo"*)</tt> matches any token with <tt>x = ""</tt> +<li> <tt>x + y@("er"*)</tt> matches <tt>"burgerer"</tt> with <tt>x = "burg", y = "erer"</tt> +</ul> +<p> + +6/1 (AR) Concatenative string patterns to help morphology definitions... This can be seen as a step towards regular expression string patterns. The natural notation <tt>p1 + p2</tt> will be considered later. +<b>Note</b>. This was done on 7/1. + +<p> + +5/1/2006 (BB) New grammar printers <tt>slf_sub</tt> and <tt>slf_sub_graphviz</tt> +for creating SLF networks with sub-automata. <hr> diff --git a/src/GF/Grammar/PatternMatch.hs b/src/GF/Grammar/PatternMatch.hs index f850981f0..2724bd263 100644 --- a/src/GF/Grammar/PatternMatch.hs +++ b/src/GF/Grammar/PatternMatch.hs @@ -105,7 +105,7 @@ tryMatch (p,t) = do return (concat matches) (PRep p1, ([],K s, [])) -> checks [ - trym (foldr (const (PSeq p1)) (PString "") [0..n]) t' | n <- [1 .. length s] + trym (foldr (const (PSeq p1)) (PString "") [1..n]) t' | n <- [0 .. length s] ] _ -> prtBad "no match in case expr for" t |