recoll / Code / Diff of /src/internfile/mh

Diff of /src/internfile/mh_execm.h [29fe1e] .. [3736c0]

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...
 * This version uses persistent filters which can handle multiple requests 
 * without exiting (both multiple files and multiple documents per file), 
 * with a simple question/response protocol.
 *
 * The data is exchanged in TLV fashion, in a way that should be
 * usable in most script languages. The basic unit of data has one line 
 * with a data type and a count (both ASCII), followed by the data. A
 * 'message' is made of one or several units or tags and ends with one empty
 * line. 
 * 
 * Example from recollindex (the message begins before 'Filename' and has
 * 'Filename' and 'Ipath' tags):
 * 
Filename: 24
/my/home/mail/somefolderIpath: 2
22

<Message ends here: because of the empty line after '22'

 * 
 * Example answer, with 'Mimetype' and 'Data' tags
 * 
Mimetype: 10
text/plainData: 10
0123456789

<Message ends here because of empty line

 *        
 * This format is both extensible and reasonably easy to parse. 
 * While it's more fitted for python or perl on the script side, it
 * should even be sort of usable from the shell (e.g.: use dd to read
 * the counted data). Most alternatives would need data encoding in
 * some cases.
 *
 * Higher level dialog:
 * The C++ program is the master and sends request messages to the script. 
 * Both sides of the communication should be prepared to receive and discard 
 * unknown tags.
 * The messages normally have the following tags:
 *  - Filename: the file to process. This can be empty meaning that we 
 *      are requesting the next document in the current file.
 *  - Ipath: this will be present only if we are requesting a specific 
 *      subdocument inside a container file (typically for preview, at query 
 *      time). Absent during indexing (ipaths are generated and sent back from
 *      the script)
 *  - Mimetype: this is the mime type for the (possibly container) file. 
 *    Can be useful to filters which handle multiple types, like rclaudio.
 *      
 * The script answers with messages having the following fields:
 *   - Document: translated document data.
 *   - Ipath: ipath for the returned document. Can be used at query time to
 *     extract a specific subdocument for preview. Not present or empty for 
 *     non-container files and for the "self" document of a container.
 *   - Mimetype: mime type for the returned data.
 *     This is optional. For multi-document filters, if mimetype is
 *     not present in the answer, the ipath must be a file-name-like
 *     string which will be used to divine the mime type (this is used
 *     typically with archives like Zip or Tar). If this fails,
 *     the document will be handled as unknown type and the contents won't 
 *     be indexed. When neither ipath nor mimetype are present the default 
 *     is to attempt to treat the document as HTML.
 *   - Charset: for document types for which it makes sense, and if the filter
 *     has the information.
 *   - Eofnow: empty field: no document is returned and we're at eof.
 *   - Eofnext: empty field: file ends after the doc returned by this message.
 *   - SubdocError: no subdoc returned by this request, but file goes on.

 *   - FileError: error, stop for this file.
 */
class MimeHandlerExecMultiple : public MimeHandlerExec {
    /////////
    // Things not reset by "clear()", additionally to those in MimeHandlerExec

	a/src/internfile/mh_execm.h		b/src/internfile/mh_execm.h
	...		...
29	* This version uses persistent filters which can handle multiple requests	29	* This version uses persistent filters which can handle multiple requests
30	* without exiting (both multiple files and multiple documents per file),	30	* without exiting (both multiple files and multiple documents per file),
31	* with a simple question/response protocol.	31	* with a simple question/response protocol.
32	*	32	*
33	* The data is exchanged in TLV fashion, in a way that should be	33	* The data is exchanged in TLV fashion, in a way that should be
34	* usable in most script languages. The basic unit has one line with a	34	* usable in most script languages. The basic unit of data has one line
35	* data type and a count, followed by the data. A 'message' ends with	35	* with a data type and a count (both ASCII), followed by the data. A
36	* one empty line. A possible exchange:	36	* 'message' is made of one or several units or tags and ends with one empty
		37	* line.
37	*	38	*
38	* From recollindex (the message begins before 'Filename'):	39	* Example from recollindex (the message begins before 'Filename' and has
		40	* 'Filename' and 'Ipath' tags):
39	*	41	*
40	Filename: 24	42	Filename: 24
41	/my/home/mail/somefolderIpath: 2	43	/my/home/mail/somefolderIpath: 2
42	22	44	22
43		45
44	<Message ends here: because of the empty line after '22'	46	<Message ends here: because of the empty line after '22'
45		47
46	*	48	*
47	* Example answer:	49	* Example answer, with 'Mimetype' and 'Data' tags
48	*	50	*
49	Mimetype: 10	51	Mimetype: 10
50	text/plainData: 10	52	text/plainData: 10
51	0123456789	53	0123456789
52		54
53	<Message ends here because of empty line	55	<Message ends here because of empty line
54		56
55	*	57	*
56	* This format is both extensible and reasonably easy to parse.	58	* This format is both extensible and reasonably easy to parse.
57	* While it's more fitted for python or perl on the script side, it	59	* While it's more fitted for python or perl on the script side, it
58	* should even be sort of usable from the shell (ie: use dd to read	60	* should even be sort of usable from the shell (e.g.: use dd to read
59	* the counted data). Most alternatives would need data encoding in	61	* the counted data). Most alternatives would need data encoding in
60	* some cases.	62	* some cases.
61	*	63	*
62	* Higher level dialog:	64	* Higher level dialog:
63	* The c++ program is the master and sends request messages to the script. The	65	* The C++ program is the master and sends request messages to the script.
64	* requests have the following fields:	66	* Both sides of the communication should be prepared to receive and discard
		67	* unknown tags.
		68	* The messages normally have the following tags:
65	* - Filename: the file to process. This can be empty meaning that we	69	* - Filename: the file to process. This can be empty meaning that we
66	* are requesting the next document in the current file.	70	* are requesting the next document in the current file.
67	* - Ipath: this will be present only if we are requesting a specific	71	* - Ipath: this will be present only if we are requesting a specific
68	* subdocument inside a container file (typically for preview, at query	72	* subdocument inside a container file (typically for preview, at query
69	* time). Absent during indexing (ipaths are generated and sent back from	73	* time). Absent during indexing (ipaths are generated and sent back from
70	* the script	74	* the script)
71	* - Mimetype: this is the mime type for the (possibly container) file.	75	* - Mimetype: this is the mime type for the (possibly container) file.
72	* Can be useful to filters which handle multiple types, like rclaudio.	76	* Can be useful to filters which handle multiple types, like rclaudio.
73	*	77	*
74	* The script answers with messages having the following fields:	78	* The script answers with messages having the following fields:
75	* - Document: translated document data (typically, but not always, html)	79	* - Document: translated document data.
76	* - Ipath: ipath for the returned document. Can be used at query time to	80	* - Ipath: ipath for the returned document. Can be used at query time to
77	* extract a specific subdocument for preview. Not present or empty for	81	* extract a specific subdocument for preview. Not present or empty for
78	* non-container files.	82	* non-container files and for the "self" document of a container.
79	* - Mimetype: mime type for the returned data (ie: text/html, text/plain)	83	* - Mimetype: mime type for the returned data.
		84	* This is optional. For multi-document filters, if mimetype is
		85	* not present in the answer, the ipath must be a file-name-like
		86	* string which will be used to divine the mime type (this is used
		87	* typically with archives like Zip or Tar). If this fails,
		88	* the document will be handled as unknown type and the contents won't
		89	* be indexed. When neither ipath nor mimetype are present the default
		90	* is to attempt to treat the document as HTML.
		91	* - Charset: for document types for which it makes sense, and if the filter
		92	* has the information.
80	* - Eofnow: empty field: no document is returned and we're at eof.	93	* - Eofnow: empty field: no document is returned and we're at eof.
81	* - Eofnext: empty field: file ends after the doc returned by this message.	94	* - Eofnext: empty field: file ends after the doc returned by this message.
82	* - SubdocError: no subdoc returned by this request, but file goes on.	95	* - SubdocError: no subdoc returned by this request, but file goes on.
83	* (the indexer (1.14) treats this as a file-fatal error anyway).
84	* - FileError: error, stop for this file.	96	* - FileError: error, stop for this file.
85	*/	97	*/
86	class MimeHandlerExecMultiple : public MimeHandlerExec {	98	class MimeHandlerExecMultiple : public MimeHandlerExec {
87	/////////	99	/////////
88	// Things not reset by "clear()", additionally to those in MimeHandlerExec	100	// Things not reset by "clear()", additionally to those in MimeHandlerExec