[r2004-07-07 01:24:40 by beppe] added select and projections

Original author: beppe
Date: 2004-07-07 01:24:40+00:00

web/memento.xml

@@ -114,6 +114,11 @@ _" character,  starting by a capitalized letter or underscore.</li>
 <li>Transform: <code>transform e with p1 -> e1 | ... | pn -> en</code>. 
     Unmatched elements are discarded; each branch returns a sequence
     and all the resulting sequences are concatenated together. </li>
+<li>Selection: : <code>select %%e%% from %%p1%% in  %%e1%%  ...  %%pn%%
+    in %%en%% where %%e'%%</code>. SQL-like selection with the possibility 
+    of using CDuce patterns instead of variables. <code>%%e1%%  ...
+    %%en%%</code> must be sequences and <code>%%e'%%</code> a boolean
+     expression.</li>
 <li>Operators: concatenation <code>e1 @ e2 = [ !e1 !e2 ]</code>,
               flattening <code>flatten e = transform e with x -> x</code>.
 </li>
@@ -122,7 +127,7 @@ _" character,  starting by a capitalized letter or underscore.</li>
 
 <box title="Record" link="record">
 <ul>
-<li>Records litteral <code>{ l1 = e1; ...; ln = en }</code></li>
+<li>Records literal <code>{ l1 = e1; ...; ln = en }</code></li>
 <li>Types: <code>{| l1 = t1; ...; ln = tn |}</code> (closed, no more
 fields allowed), <code>>{ l1 = t1; ...; ln = tn }</code> (open,
 any other field allowed). Optional fields: <code>li =? ti</code>
@@ -156,6 +161,9 @@ field <code>l</code> is not present)</li>
       (semicolon can also be omitted in this case).
       E.g: <code>&lt;a href="abc">[ 'abc' ]</code>.</li>
  <li>Types and patterns: same notations.</li>
+ <li>XPath like projection: <code>%%e%%/%%t%%</code>. For every
+     XML tree in  <code>%%e%%</code> it returns the sequence of children
+     of type  <code>%%t%%</code></li>
 <li>Tree transformation: <code>xtransform e with p1 -> e1 | ... | pn -> en</code>. 
     Applies to sequences of XML trees. Unmatched elements are left unchanged and the
     transformation is recursively applied to the sequence of children of the unmatched