TokenNext()

Posted on February 8, 2014 by vivaclipper

TokenNext()

Successivly obtains tokens from a string

Syntax

      TokenNext( <[@]cString>, [<nToken>],
                 [<@cTokenEnvironment>] ) -> cToken

Arguments

<[@]cString> the processed string <nToken> a token number

<@cTokenEnvironment> a token environment

Returns

<cToken> a token from <cString>

Description

With TokenNext(), the tokens determined with the TOKENINIT() functions can be retrieved. To do this, TokenNext() uses the information stored in either the global token environment or the local one supplied by <cTokenEnvironment>. Note that, is supplied, this 3rd parameter has always to be passed by reference.

If the 2nd parameter, <nToken> is given, TokenNext() simply returns the <nToken>th token without manipulating the TE counter. Otherwise the token pointed to by the TE counter is returned and the counter is incremented by one. Like this, a simple loop with TOKENEND() can be used to retrieve all tokens of a string successivly.

Note that <cString> does not have to be the same used in TOKENINIT(), so that one can do a “correlational tokenization”, i.e. tokenize a string as if it was another! E.G. using TOKENINIT() with the string “AA, BBB” but calling TokenNext() with “CCCEE” would give first “CC” and then “EE” (because “CCCEE” is not long enough).

Examples

      // default behavhiour
      tokeninit( cString ) // initialize a token environment
      DO WHILE ! tokenend()
         ? TokenNext( cString )  // get all tokens successivly
      ENDDO
      ? TokenNext( cString, 3 )  // get the 3rd token, counter will remain 
                                 // the same
      tokenexit()                // free the memory used for the global 
                                 // token environment

Compliance

TokenNext() is compatible with CT3’s TokenNext(), but there are two additional parameters featuring local token environments and optional access to tokens.

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKENINIT(), TOKENEXIT(), TOKENNUM(), TOKENAT(), SAVETOKEN(), RESTTOKEN(), TOKENEND()

TokenInit()

Posted on February 8, 2014 by vivaclipper

TokenInit()

Initializes a token environment

Syntax

      TokenInit( <[@]cString>], [<cTokenizer>], [<nSkipWidth>],
                 [<@cTokenEnvironment>] ) -> lState

Arguments

<[@]cString> is the processed string

<cTokenizer> is a list of characters separating the tokens in <cString> Default: chr(0) + chr(9) + chr(10) + chr(13) + chr(26) + chr(32) + chr(32) + chr(138) + chr(141) + “, .;:!\?/\\<>()#&%+-*”

<nSkipWidth> specifies the maximum number of successive tokenizing characters that are combined as ONE token stop, e.g. specifying 1 can yield to empty token Default: 0, any number of successive tokenizing characters are combined as ONE token stop

<@cTokenEnvironment> is a token environment stored in a binary encoded string

Returns

<lState> success of the initialization

Description

The TokenInit() function initializes a token environment. A token environment is the information about how a string is to be tokenized. This information is created in the process of tokenization of the string <cString> – equal to the one used in the TOKEN() function with the help of the <cTokenizer> and <nSkipWidth> parameters.

This token environment can be very useful when large strings have to be tokenized since the tokenization has to take place only once whereas the TOKEN() function must always start the tokenizing process from scratch.

Unlike CT3, this function provides two mechanisms of storing the resulting token environment. If a variable is passed by reference as 4th parameter, the token environment is stored in this variable, otherwise the global token environment is used. Do not modify the token environment string directly !

Additionally, a counter is stored in the token environment, so that the tokens can successivly be obtained. This counter is first set to 1. When the TokenInit() function is called without a string a tokenize, the counter of either the global environment or the environment given by reference in the 4th parameter is rewind to 1.

Additionally, unlike CT3, TokenInit() does not need the string <cString> to be passed by reference, since one must provide the string in calls to TOKENNEXT() again.

Examples

  TokenInit( cString )             // tokenize the string <cString> with 
                                   // default rules and store the token 
                                   // environment globally and eventually 
                                   // delete an old global token environment
  TokenInit( @cString )            // no difference in result, but eventually 
                                   // faster, since the string must not be 
  TokenInit()                      // copied rewind counter of global TE to 1
  TokenInit( "1,2,3", "," , 1 )    // tokenize constant string, store in 
                                   // global token environment  
  TokenInit( cString, , 1, @cTE1)  // tokenize cString and store token 
                                   // environment in cTE1 only without 
                                   // overriding global token environment
  TokenInit( cString, , 1, cTE1 )  // tokenize cString and store token 
                                   // environment in GLOBAL token environment 
                                   // since 4th parameter is not given by 
                                   // reference !!!
  TokenInit( ,,, @cTE1 )           // set counter in TE stored in cTE1 to 1

Compliance

TokenInit() is compatible with CT3’s TokenInit(), but there is an additional parameter featuring local token environments.

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKEN(), TOKENEXIT(), TOKENNEXT(), TOKENNUM(), TOKENAT(), SAVETOKEN(), RESTTOKEN(), TOKENEND()

TokenExit()

Posted on February 8, 2014 by vivaclipper

TokenExit()

Release global token environment

Syntax

      TokenExit() -> lStaticEnvironmentReleased

Returns

<lStaticEnvironmentReleased> .T., if global token environment is successfully released

Description

The TokenExit() function releases the memory associated with the global token environment. One should use it for every tokeninit() using the global token environment. Additionally, TokenExit() is implicitly called from CTEXIT() to free the memory at library shutdown.

Examples

      tokeninit( cString ) // initialize a token environment
      DO WHILE ! tokenend()
         ? tokennext( cString )  // get all tokens successivly
      ENDDO
      ? tokennext( cString, 3 )  // get the 3rd token, counter 
                                 // will remain the same
      TokenExit()                // free the memory used for the 
                                 // global token environment

Compliance

TokenExit() is a new function in Harbour’s CT3 library.

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKENINIT(), TOKENNEXT(), TOKENNUM(), TOKENAT(), SAVETOKEN(), RESTTOKEN(), TOKENEND()

TokenEnd()

Posted on February 8, 2014 by vivaclipper

TokenEnd()

Check whether additional tokens are available with TOKENNEXT()

Syntax

      TokenEnd( [<@cTokenEnvironment>] ) -> lTokenEnd

Arguments

<@cTokenEnvironment> a token environment

Returns

<lTokenEnd> .T., if additional tokens are available

Description

The TokenEnd() function can be used to check whether the next call to TOKENNEXT() would return a new token. This can not be decided with TOKENNEXT() alone, since an empty token cannot be distinguished from a “no more” tokens.

If the parameter <@cTokenEnvironment> is supplied (must be by reference), the information from this token environment is used, otherwise the global TE is used.

With a combination of TokenEnd() and TOKENNEXT(), all tokens from a string can be retrieved successivly (see example).

Examples

      tokeninit( "a.b.c.d", ".", 1 )  // initialize global token environment
      DO WHILE ! TokenEnd()
         ? tokennext( "a.b.c.d" )     // get all tokens successivly
      ENDDO

Compliance

TokenEnd() is compatible with CT3’s TokenEnd(), but there are is an additional parameter featuring local token environments.

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKENINIT(), TOKENEXIT(), TOKENNEXT(), TOKENNUM(), TOKENAT(), SAVETOKEN(), RESTTOKEN()

TokenAt()

Posted on February 8, 2014 by vivaclipper

TOKENAT()

Get start and end positions of tokens in a token environment

Syntax

      TOKENAT( [<lSeparatorPositionBehindToken>], [<nToken>],
               [<@cTokenEnvironment>] ) -> nPosition

Arguments

<lSeparatorPositionBehindToken> .T., if TOKENAT() should return the position of the separator character BEHIND the token. Default: .F., return start position of a token.

<nToken> a token number <@cTokenEnvironment> a token environment

Returns

<nPosition> See description

Description

The TOKENAT() function is used to retrieve the start and end position of the tokens in a token environment. Note however that the position of last character of a token is given by tokenat (.T.)-1 !!

If the 2nd parameter, <nToken> is given, TOKENAT() returns the positions of the <nToken>th token. Otherwise the token pointed to by the TE counter, i.e. the token that will be retrieved by TOKENNEXT() _NEXT_ is used.

If the parameter <@cTokenEnvironment> is supplied (must be by reference), the information from this token environment is used, otherwise the global TE is used.

Tests

      tokeninit( cString ) // initialize a token environment
      DO WHILE ! tokenend()
         ? "From", tokenat(), "to", tokenat( .T. ) - 1
         ? tokennext( cString )  // get all tokens successivly
      ENDDO
      ? tokennext( cString, 3 )  // get the 3rd token, 
                                 // counter will remain the same
      tokenexit()                // free the memory used for the 
                                 // global token environment

Compliance

TOKENAT() is compatible with CT3’s TOKENAT(), but there are two additional parameters featuring local token environments and optional access to tokens.

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKENINIT(), TOKENEXIT(), TOKENNEXT(), TOKENNUM(), SAVETOKEN(), RESTTOKEN(), TOKENEND()

SaveToken()

Posted on February 8, 2014 by vivaclipper

SaveToken()

Save the global token environment

Syntax

      SaveToken() -> cStaticTokenEnvironment

Returns

<cStaticTokenEnvironment> a binary string encoding the global token environment

Description

The SaveToken() function can be used to store the global token environment for future use or when two or more incremental tokenizers must the nested. Note however that the latter can now be solved with locally stored token environments.

Compliance

SaveToken() is compatible with CT3’s SaveToken(),

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKENINIT(), TOKENEXIT(), TOKENNEXT(), TOKENNUM(), TOKENAT(), RESTTOKEN(), TOKENEND()

RestToken()

Posted on February 8, 2014 by vivaclipper

RestToken()

Restore global token environment

Syntax

      RestToken( <cStaticTokenEnvironment> ) -> cOldStaticEnvironment

Arguments

<cStaticTokenEnvironment> a binary string encoding a token environment

Returns

<cOldStaticEnvironment> a string encoding the old global token environment

Description

The RESTTOKEN() function restores the global token environment to the one encoded in <cStaticTokenEnvironment>. This can either be the return value of SAVETOKEN() or the value stored in the 4th parameter in a TOKENINIT() call.

Compliance

RestToken() is compatible with CT3’s RestToken(),

Platforms

All

Files

Source is token2.c, library is libct.

Seealso

TOKENINIT(), TOKENEXIT(), TOKENNEXT(), TOKENNUM(), TOKENAT(), SAVETOKEN(), TOKENEND()