Class TextSearch

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.
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:
1. 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.
2. 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.
3. 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-{0,1}erful".

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

//... Initialize PDFNet ...
PDFDoc doc = new PDFDoc(filein);
doc.initSecurityHandler();
int mode = TextSearch.e_whole_word | TextSearch.e_page_stop;
UString pattern( "joHn sMiTh" );
TextSearch txt_search = new TextSearch();
//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, -1, -1 );
while ( true )
{
TextSearch.ResultCode result = txt_search.Run();
if ( result.GetCode() == TextSearchResult.e_found )
{
Console.WriteLine("found one instance: " + result.GetResultStr());
}
else
{
break;
}
}
//unlock the document to avoid deadlock.
doc.UnLock();

Inheritance

object

TextSearch

Implements

IDisposable

Inherited Members

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

Namespace: pdftron.PDF

Assembly: PDFNet.dll

Syntax

public class TextSearch : IDisposable

Constructors

TextSearch()

Constructor and destructor.

Declaration

public TextSearch()

Methods

Begin(PDFDoc, string, int, int, int)

Initialize for the search process. This should be called before starting the actual search. with method run().

Declaration

public bool Begin(PDFDoc doc, string pattern, int mode, int start_page, int end_page)

Parameters

Type	Name	Description
PDFDoc	doc	the PDF document to search in.
string	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.
int	mode	the mode of the search process.
int	start_page	the start page of the page range to search in. -1 indicates the range starts from the first page.
int	end_page	the end page of the page range to search in. -1 indicates the range ends at the last page.

Returns

Type	Description
bool	true if the initialization has succeeded.

Dispose()

Releases all resources used by the TextSearch

Declaration

public override sealed void Dispose()

Dispose(bool)

Declaration

[HandleProcessCorruptedStateExceptions]
protected virtual void Dispose(bool A_0)

Parameters

Type	Name	Description
bool	A_0

~TextSearch()

Declaration

protected ~TextSearch()

GetCurrentPage()

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

public int GetCurrentPage()

Returns

Type	Description
int	the current page number.

GetMode()

Retrieve the current search mode.

Declaration

public int GetMode()

Returns

Type	Description
int	the current search mode.

Run(ref int, ref string, ref string, Highlights)

Search the document and returns upon the following circumstances:

Reached the end of the document
Reached the end of a page (if set to return by specifying mode 'e_page_stop' )
Found an instance matching the search pattern

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

Declaration

public TextSearch.ResultCode Run(ref int page_num, ref string result_str, ref string ambient_str, Highlights hlts)

Parameters

Type	Name	Description
int	page_num	the number of the page the found instance is on.
string	result_str	the found string that matches the search pattern.
string	ambient_str	the ambient string of the found string (computed if 'e_ambient_string' is set).
Highlights	hlts	the Highlights info associated with the found string (computed if 'e_highlight' is set).

Returns

Type	Description
TextSearch.ResultCode	the code indicating the reason of the return. Note that only when the returned code is 'e_found', the resulting information is meaningful.

SetAmbientLettersAfter(int)

Sets the maximum number of ambient string letters after the search term (default: 70). This should be called before starting the actual search with method Run().

Declaration

public void SetAmbientLettersAfter(int ambient_letters_after)

Parameters

Type	Name	Description
int	ambient_letters_after	maximum number of letters

SetAmbientLettersBefore(int)

Sets the maximum number of ambient string letters before the search term (default: 30). This should be called before starting the actual search with method Run().

Declaration

public void SetAmbientLettersBefore(int ambient_letters_before)

Parameters

Type	Name	Description
int	ambient_letters_before	maximum number of letters

SetAmbientWordsAfter(int)

Sets the maximum number of ambient string words after the search term (default: 10). This should be called before starting the actual search with method Run().

Declaration

public void SetAmbientWordsAfter(int ambient_words_after)

Parameters

Type	Name	Description
int	ambient_words_after	maximum number of words

SetAmbientWordsBefore(int)

Sets the maximum number of ambient string words before the search term (default: 1). This should be called before starting the actual search with method Run().

Declaration

public void SetAmbientWordsBefore(int ambient_words_before)

Parameters

Type	Name	Description
int	ambient_words_before	maximum number of words

SetMode(int)

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

TextSearch ts = new TextSearch(); ... int mode = ts.getMode(); mode |= TextSearch.e_reg_expression; ts.setMode(mode); ...

Declaration

public void SetMode(int mode)

Parameters

Type	Name	Description
int	mode	the search mode to set.

SetOCGContext(Context)

Declaration

public void SetOCGContext(Context ctx)

Parameters

Type	Name	Description
Context	ctx

SetPattern(string)

Sets 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

public bool SetPattern(string pattern)

Parameters

Type	Name	Description
string	pattern	the search pattern to set.

Returns

Type	Description
bool	true if the setting has succeeded.

SetRightToLeftLanguage(bool)

Tells TextSearch that reads from right to left.

Declaration

public void SetRightToLeftLanguage(bool flag)

Parameters

Type	Name	Description
bool	flag	True if the language is right to left.

Implements

IDisposable