Add and use xpath_context()

[irspy-moved-to-github.git] / lib / ZOOM / IRSpy / Record.pm

diff --git a/lib/ZOOM/IRSpy/Record.pm b/lib/ZOOM/IRSpy/Record.pm
index 4f5ee82..4ba8bb6 100644 (file)
--- a/lib/ZOOM/IRSpy/Record.pm
+++ b/lib/ZOOM/IRSpy/Record.pm
@@ -1,13 +1,16 @@
-# $Id: Record.pm,v 1.5 2006-07-21 11:30:51 mike Exp $
+# $Id: Record.pm,v 1.25 2007-05-04 12:09:24 mike Exp $
 
 package ZOOM::IRSpy::Record;
+### I don't think there's any reason for this to be separate from
+#   ZOOM::IRSpy::Connection, now that the correspondence is always 1:1
 
 use 5.008;
 use strict;
 use warnings;
 
 use XML::LibXML;
-
+use XML::LibXML::XPathContext;
+use ZOOM::IRSpy::Utils qw(xml_encode isodate irspy_xpath_context);
 
 =head1 NAME
 
@@ -25,16 +28,19 @@ I<## To follow>
 
 sub new {
     my $class = shift();
-    my($target, $zeerex) = @_;
+    my($irspy, $target, $zeerex) = @_;
 
     if (!defined $zeerex) {
        $zeerex = _empty_zeerex_record($target);
     }
 
+    ### Parser should be in the IRSpy object
     my $parser = new XML::LibXML();
     return bless {
+       irspy => $irspy,
        target => $target,
-       zeerex => $parser->parse_string($zeerex),
+       parser => $parser,
+       zeerex => $parser->parse_string($zeerex)->documentElement(),
     }, $class;
 }
 
@@ -42,21 +48,124 @@ sub new {
 sub _empty_zeerex_record {
     my($target) = @_;
 
-    ### Doesn't recognise SRU/SRW URLs
-    my($host, $port, $db) = ZOOM::IRSpy::_parse_target_string($target);
+    my($protocol, $host, $port, $db) =
+       ZOOM::IRSpy::_parse_target_string($target);
 
+    my $xprotocol = xml_encode($protocol);
+    my $xhost = xml_encode($host);
+    my $xport = xml_encode($port);
+    my $xdb = xml_encode($db);
     return <<__EOT__;
 <explain xmlns="http://explain.z3950.org/dtd/2.0/">
- <serverInfo protocol="Z39.50" version="1995">
-  <host>$host</host>
-  <port>$port</port>
-  <database>$db</database>
+ <serverInfo protocol="$xprotocol">
+  <host>$xhost</host>
+  <port>$xport</port>
+  <database>$xdb</database>
  </serverInfo>
 </explain>
 __EOT__
 }
 
 
+sub append_entry {
+    my $this = shift();
+    my($xpath, $frag) = @_;
+
+    #print STDERR "this=$this, xpath='$xpath', frag='$frag'\n";
+    my $xc = $this->xpath_context();
+    $xc->registerNs(zeerex => "http://explain.z3950.org/dtd/2.0/");
+    $xc->registerNs(irspy => $ZOOM::IRSpy::Utils::IRSPY_NS);
+
+    my @nodes = $xc->findnodes($xpath);
+    if (@nodes == 0) {
+       # Make the node that we're inserting into, if possible.  A
+       # fully general version would work its way through each
+       # component of the XPath, but for now we just treat it as a
+       # single chunk to go inside the top-level node.
+       $this->_half_decent_appendWellBalancedChunk($xc, "<$xpath></$xpath>");
+       @nodes = $xc->findnodes($xpath);
+       die("still no matches for '$xpath' after creating: can't append")
+           if @nodes == 0;
+    }
+
+    $this->{irspy}->log("warn",
+                       scalar(@nodes), " matches for '$xpath': using first")
+       if @nodes > 1;
+
+    $this->_half_decent_appendWellBalancedChunk($nodes[0], $frag);
+}
+
+sub xpath_context {
+    my $this = shift();
+
+    return irspy_xpath_context($this->{zeerex});
+}
+
+sub store_result {
+    my ($this, $type, %info) = @_;
+    my $xml = "<irspy:$type";
+
+    foreach my $key (keys %info) {
+        $xml .= " $key=\"" . xml_encode($info{$key}) . "\"";
+    }
+
+    $xml .= ">" . isodate(time()) . "</irspy:$type>\n";
+
+    $this->append_entry('irspy:status', $xml);
+}
+
+
+# *sigh*
+#
+# _Clearly_ the right way to append a well-balanced chunk of XML to
+# a node's children is to call appendWellBalancedChunk() from the
+# XML::LibXML::Element class.  However, this fails in the common case
+# where the ZeeRex record we're working with doesn't declare the
+# "irspy" namespace that the inserted fragments use.
+#
+# To my utter astonishment it seems that XML::LibXML (as of version
+# 1.58, 31st March 2004) doesn't provide ANY way to register a
+# namespace for parsing, which makes the parse_balanced_chunk()
+# function that appendWellBalancedChunk() uses effectively useless.
+# It _is_ possible to use setNamespace() on a node, to register a new
+# namespace mapping for that node -- but that only affects pre-parsed
+# trees, and is no use for parsing.  Hence the following pair of lines
+# DOES NOT WORK:
+#      $node->setNamespace($ZOOM::IRSpy::Utils::IRSPY_NS, "irspy", 0);
+#      $node->appendWellBalancedChunk($frag);
+#
+# Instead I have to go the long way round, hence this method.  I have
+# two candidate re-implementations, of which the former is marginally
+# less loathsome, but does require that the excess namespace
+# declarations be factored out later -- as least, if you want neat
+# output.
+#
+sub _half_decent_appendWellBalancedChunk {
+    my $this = shift();
+    my($node, $frag) = @_;
+
+    if (1) {
+       $frag =~ s,>, xmlns:irspy="$ZOOM::IRSpy::Utils::IRSPY_NS">,;
+       $node->appendWellBalancedChunk($frag);
+       return;
+    }
+
+    # Instead -- and to call this brain-damaged would be an insult
+    # to all those fine people out there with actual brain damage
+    # -- I have to "parse" the XML fragment myself and insert the
+    # resulting hand-build DOM tree.  Someone shoot me now.
+    my($open, $content, $close) = $frag =~ /^<(.*?)>(.*)<\/(.*?)>$/;
+    die "can't 'parse' XML fragment '$frag'"
+       if !defined $open;
+    my($tag, $attrs) = $open =~ /(.*?)\s(.*)/;
+    $tag = $open if !defined $tag;
+    die "mismatched XML start/end <$open>...<$close>"
+       if $close ne $tag;
+    print STDERR "tag='$tag', attrs=[$attrs], content='$content'\n";
+    die "## no code yet to make DOM node";
+}
+
+
 =head1 SEE ALSO
 
 ZOOM::IRSpy