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Merge pull request #52 from odanoburu/doc-pre

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(refman) update pre syntax
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Inari Listenmaa
2018-05-24 23:10:17 +01:00
committed by GitHub
parent 19c6090e85 2ae44902e1
commit a2f9d9d8d5
1 changed files with 12 additions and 4 deletions
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doc/gf-refman.html
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@@ -1834,7 +1834,7 @@ Some expressions are moreover left- or right-associative.
</TR>
<TR>
<TD>5</TD>
<TD><CODE>pre {"a" ; "an"/vowel}</CODE></TD>
<TD><CODE>pre {vowel => "an" ; _ => "a"}</CODE></TD>
<TD>prefix-dependent choice</TD>
</TR>
<TR>
@@ -2264,7 +2264,7 @@ Expressions of type <CODE>Str</CODE> have the following canonical forms:
<LI><B>the empty token list</B>, <CODE>[]</CODE>
<LI><B>concatenation</B>, <I>s</I> <CODE>++</CODE> <I>t</I>, where <I>s,t</I> : <CODE>Str</CODE>
<LI><B>prefix-dependent choice</B>,
<CODE>pre {</CODE> <I>s</I> ; <i>s</i><sub>1</sub> <CODE>/</CODE> <i>p</i><sub>1</sub> ; ... ; <i>s</i><sub>n</sub> <CODE>/</CODE> <i>p</i><sub>n</sub>}, where
<CODE>pre {p<sub>1</sub> => s<sub>1</sub> ; ... ; p<sub>n</sub> => s<sub>n</sub> ; _ => s }, where
<UL>
<LI><I>s</I>, <i>s</i><sub>1</sub>,...,<i>s</i><sub>n</sub>, <i>p</i><sub>1</sub>,...,<i>p</i><sub>n</sub> : <CODE>Str</CODE>
</UL>
@@ -2344,13 +2344,16 @@ A prime example of prefix-dependent choice operation is the following
approximative expression for the English indefinite article:
</P>
<PRE>
pre {"a" ; "an" / variants {"a" ; "e" ; "i" ; "o"}}
pre {
("a" | "e" | "i" | "o") => "an" ;
_ => "a"
} ;
</PRE>
<P>
This expression can be computed in the context of a subsequent token:
</P>
<UL>
<LI><CODE>pre {</CODE> <I>s</I> ; <i>s</i><sub>1</sub> <CODE>/</CODE> <i>p</i><sub>1</sub> ; ... ; <i>s</i><sub>n</sub> <CODE>/</CODE> <i>p</i><sub>n</sub><CODE>} ++</CODE> <I>t</I>
<LI><CODE>pre {p<sub>1</sub> => s<sub>1</sub> ; ... ; p<sub>n</sub> => s<sub>n</sub> ; _ => s } ++ t</CODE>
==>
<UL>
<LI><i>s</i><sub>i</sub> for the first <I>i</I> such that the prefix <i>p</i><sub>i</sub>
@@ -2374,6 +2377,11 @@ subsequent token depends on a run-time variable.
The prefix-dependent choice expression itself may not depend on run-time
variables.
</P>
<P>
<I>There is an older syntax for prefix-dependent choice,
namely: <code>pre { s ; s1 / p1 ; ... ; sn / pn}</code>. This syntax
will not accept strings as patterns.</I>
</P>
<P>
<I>In GF prior to 3.0, a specific type</I> <CODE>Strs</CODE>
<I>is used for defining prefixes,</I>