PTTextSearch

@interface PTTextSearch : NSObject

TextSearch searches through a PDF document for a user-given search pattern. The current implementation supports both verbatim search and the search using regular expressions, whose detailed syntax can be found at:

http://www.boost.org/doc/libs/release/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html

TextSearch also provides users with several useful search modes and extra information besides the found string that matches the pattern. TextSearch can either keep running until a matched string is found or be set to return periodically in order for the caller to perform any necessary updates (e.g., UI updates). It is also worth mentioning that the search modes can be changed on the fly while searching through a document.

Possible use case scenarios for TextSearch include:

  • Guide users of a PDF viewer (e.g. implemented by PDFViewCtrl) to places where they are intersted in;
  • Find interested PDF documents which contain certain patterns;
  • Extract interested information (e.g., credit card numbers) from a set of files;
  • Extract Highlight information (refer to the Highlights class for details) from files for external use.

Note:

Since

Since hyphens (‘-’) are frequently used in PDF documents to concatenate the two broken pieces of a word at the end of a line, for example

“TextSearch is powerful for finding patterns in PDF files; yes, it is really pow- erful.”

a search for “powerful” should return both instances. However, not all end-of-line hyphens are hyphens added to connect a broken word; some of them could be “real” hyphens. In addition, an input search pattern may also contain hyphens that complicate the situation. To tackle this problem, the following conventions are adopted:

a)When in the verbatim search mode and the pattern contains no hyphen, a matching string is returned if it is exactly the same or it contains end-of-line or start-of-line hyphens. For example, as mentioned above, a search for “powerful” would return both instances. b)When in verbatim search mode and the pattern contains one or multiple hyphens, a matching string is returned only if the string matches the pattern exactly. For example, a search for “pow-erful” will only return the second instance, and a search for “power-ful” will return nothing. c)When searching using regular expressions, hyphens are not taken care implicitly. Users should take care of it themselves. For example, in order to find both the “powerful” instances, the input pattern can be “pow-;erful”.

A sample use case (in C++):

 //... Initialize PDFNet ...
 PDFDoc doc(filein);
 doc.InitSecurityHandler();
 int page_num;
 char buf[32];
 UString result_str, ambient_string;
 Highlights hlts;
 TextSearch txt_search;
 TextSearch::Mode mode = TextSearch::e_whole_word | TextSearch::e_page_stop;
 UString pattern( "joHn sMiTh" );

 //PDFDoc doesn't allow simultaneous access from different threads. If this
 //document could be used from other threads (e.g., the rendering thread inside
 //PDFView/PDFViewCtrl, if used), it is good practice to lock it.
 //Notice: don't forget to call doc.Unlock() to avoid deadlock.
 doc.Lock();

 txt_search.Begin( doc, pattern, mode );
 while ( true )
 ;

 //unlock the document to avoid deadlock.
 doc.UnLock();

For a full sample, please take a look at the TextSearch sample project.

  • Constructor and destructor.

    Declaration

    Objective-C

    - (instancetype)init;

    Swift

    init!()
  • Initialize for search process. This should be called before starting the actual search with method Run().

    Declaration

    Objective-C

    - (BOOL)Begin:(PTPDFDoc *)doc
           pattern:(NSString *)pattern
              mode:(unsigned int)mode
        start_page:(int)start_page
          end_page:(int)end_page;

    Swift

    func begin(_ doc: PTPDFDoc!, pattern: String!, mode: UInt32, start_page: Int32, end_page: Int32) -> Bool

    Parameters

    doc

    the PDF document to search in.

    pattern

    the pattern to search for. When regular expression is used, it contains the expression, and in verbatim mode, it is the exact string to search for.

    mode

    the mode of the search process.

    start_page

    the start page of the page range to search in. The default value is -1 indicating the range starts from the first page.

    end_page

    the end page of the page range to search in. The default value is -1 indicating the range ends at the last page.

    Return Value

    true if the initialization has succeeded.

  • Search the document and returns upon the following circumstances: a)Reached the end of the document; b)Reached the end of a page (if set to return by specifying mode ‘e_page_stop’ ); c)Found an instance matching the search pattern.

    Note that this method should be called in a loop in order to find all matching instances; in other words, the search is conducted in an incremental fashion.

    Declaration

    Objective-C

    - (PTSearchResult *)Run;

    Swift

    func run() -> PTSearchResult!
  • Set the current search pattern. Note that it is not necessary to call this method since the search pattern is already set when calling the Begin() method. This method is provided for users to change the search pattern while searching through a document.

    Declaration

    Objective-C

    - (BOOL)SetPattern:(NSString *)pattern;

    Swift

    func setPattern(_ pattern: String!) -> Bool

    Parameters

    pattern

    the search pattern to set.

    Return Value

    true if the setting has succeeded.

  • Retrieve the current search mode.

    Declaration

    Objective-C

    - (unsigned int)GetMode;

    Swift

    func getMode() -> UInt32

    Return Value

    the current search mode.

  • Set the current search mode. For example, the following code turns on the regular expressions:

    TextSearch ts;
    

    … TextSearch::Mode mode = ts.GetMode(); mode |= TextSearch::e_reg_expression; ts.SetMode(mode); …

    Declaration

    Objective-C

    - (void)SetMode:(unsigned int)mode;

    Swift

    func setMode(_ mode: UInt32)

    Parameters

    mode

    the search mode to set.

  • Tells TextSearch that language is from right to left.

    Declaration

    Objective-C

    - (void)SetRightToLeftLanguage:(BOOL)flag;

    Swift

    func setRightToLeftLanguage(_ flag: Bool)

    Parameters

    flag

    Set to true if the language is right to left.

  • Retrieve the number of the current page that is searched in. If the returned value is -1, it indicates the search process has not been initialized (e.g., Begin() is not called yet); if the returned value is 0, it indicates the search process has finished, and if the returned value is positive, it is a valid page number.

    Declaration

    Objective-C

    - (int)GetCurrentPage;

    Swift

    func getCurrentPage() -> Int32

    Return Value

    the current page number.

  • Sets the Optional Content Group (OCG) context that should be used when processing the document. This function can be used to change the current OCG context. Optional content (such as PDF layers) will be selectively processed based on the states of optional content groups in the given context.

    Declaration

    Objective-C

    - (void)SetOCGContext:(PTContext *)context;

    Swift

    func setOCGContext(_ context: PTContext!)

    Parameters

    ctx

    Optional Content Group (OCG) context, or NULL if TextSearch should process all content on the page.