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(**
* section: InputOutput
* synopsis: Example of custom Input/Output
* purpose: Demonstrate the use of xmlRegisterInputCallbacks
* to build a custom I/O layer, this is used in an
* XInclude method context to show how dynamic document can
* be built in a clean way.
* usage: io1
* test: io1 > io1.tmp ; diff io1.tmp io1.res ; rm -f io1.tmp
* author: Daniel Veillard
* copy: see Copyright for the status of this software.
*)
program io1;
{$mode objfpc}
uses
ctypes,
xml2,
exutils,
SysUtils;
const
include: pchar =
'<?xml version=''1.0''?>'#10+
'<document xmlns:xi="http://www.w3.org/2003/XInclude">'#10+
'<p>List of people:</p>'#10+
'<xi:include href="sql:select_name_from_people"/>'#10+
'</document>'#10;
var
res: pchar = '<list><people>a</people><people>b</people></list>';
cur: pchar = nil;
rlen: cint = 0;
(**
* sqlMatch:
* @URI: an URI to test
*
* Check for an sql: query
*
* Returns 1 if yes and 0 if another Input module should be used
*)
function sqlMatch(URI: pchar): cint; cdecl;
begin
if assigned(URI) and (strlcomp(URI, 'sql:', 4) = 0) then
result := 1
else
result := 0;
end;
(**
* sqlOpen:
* @URI: an URI to test
*
* Return a pointer to the sql: query handler, in this example simply
* the current pointer...
*
* Returns an Input context or NULL in case or error
*)
function sqlOpen(URI: pchar): pointer; cdecl;
begin
if not assigned(URI) or (strlcomp(URI, 'sql:', 4) <> 0) then
exit(nil);
cur := res;
rlen := strlen(res);
result := pointer(cur);
end;
(**
* sqlClose:
* @context: the read context
*
* Close the sql: query handler
*
* Returns 0 or -1 in case of error
*)
function sqlClose(context: pointer): cint; cdecl;
begin
if not assigned(context) then
exit(-1);
cur := nil;
rlen := 0;
result := 0;
end;
(**
* sqlRead:
* @context: the read context
* @buffer: where to store data
* @len: number of bytes to read
*
* Implement an sql: query read.
*
* Returns the number of bytes read or -1 in case of error
*)
function sqlRead(context: pointer; buffer: pchar; len: cint): cint; cdecl;
var
ptr: pchar;
begin
if not assigned(context) or not assigned(buffer) or (len < 0) then
exit(-1);
ptr := context;
if len > rlen then
len := rlen;
move(ptr^, buffer^, len);
rlen := rlen - len;
result := len;
end;
var
doc: xmlDocPtr;
begin
(*
* this initialize the library and check potential ABI mismatches
* between the version it was compiled for and the actual shared
* library used.
*)
LIBXML_TEST_VERSION;
(*
* register the new I/O handlers
*)
if xmlRegisterInputCallbacks(@sqlMatch, @sqlOpen, @sqlRead, @sqlClose) < 0 then
begin
printfn('failed to register SQL handler');
halt(1);
end;
(*
* parse include into a document
*)
doc := xmlReadMemory(include, strlen(include), 'include.xml', nil, 0);
if doc = nil then
begin
printfn('failed to parse the including file');
halt(1);
end;
(*
* apply the XInclude process, this should trigger the I/O just
* registered.
*)
if xmlXIncludeProcess(doc) <= 0 then
begin
printfn('XInclude processing failed');
halt(1);
end;
(*
* save the output for checking to stdout
*)
// xmlDocDump(stdout, doc);
(*
* Free the document
*)
//xmlDumpDoc(doc);
docdump(doc);
(*
* Cleanup function for the XML library.
*)
xmlCleanupParser();
end.
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