"

 COPYRIGHT (c) 1995 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

Object subclass:#PrintConverter 

	 instanceVariableNames:'valueToStringBlock stringToValueBlock'

	 classVariableNames:''

	 poolDictionaries:''

	 category:'Interface-Support'

!

!PrintConverter class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1995 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

version 

"

"

!

documentation

"

    printConverters can be used with labels and editFields to convert 

    an object to/from some printed representation.

    Conversion is done via two blocks which can be set at instance

    creation time - either as custom blocks ot to one of the

    standard conversions. There are a number of standard setups, for

    common conversions; if none of them fits your needs, create a custom

    converter, by defining its two conversion blocks.

    Notice: this class was implemented using protocol information

    from alpha testers - it may not be complete or compatible to

    the corresponding ST-80 class. If you encounter any incompatibilities,

    please forward a note to the ST/X team.

"

!

examples 

"

  stupid examples:

    convert date <-> string:

      |conv|

      conv := (PrintConverter new)

		  toPrint:[:date | date printString]

		  toRead:[:string | Date readFromString:string].

      (conv printStringFor:(Date today)) inspect.

      (conv readValueFrom:(Date today printString)) inspect

    convert number <-> string:

      |conv|

      conv := (PrintConverter new) initForNumber.

      (conv printStringFor:12345) inspect.

      (conv readValueFrom:'12345') inspect

    convert boolean <-> string:

      |conv|

      conv := (PrintConverter new) initForYesNo.

      (conv printStringFor:true).  

      (conv printStringFor:false).    

      (conv readValueFrom:'yes').  

      (conv readValueFrom:'no').  

      'if language is german:'.

      (conv readValueFrom:'ja').    

      (conv readValueFrom:'nein')  

  concrete examples: 

    convert in an inputField:

      |dialog field|

      dialog := Dialog new.

      dialog addTextLabel:'a number (and only numbers):'.

      dialog addVerticalSpace.

      field := dialog addInputFieldOn:(0 asValue).

      field converter:(PrintConverter new initForNumber).

      field immediateAccept:true.

      dialog addOkButton.

      dialog open.

      dialog accepted ifTrue:[

	  Transcript showCr:field editValue

      ]

    convert a models value for a label:

      |top v1 v2 l1 l2|

      v1 := 0 asValue.

      v2 := Date today asValue.

      top := StandardSystemView new.

      top extent:200@200.

      l1 := Label origin:0.0@0.0 corner:1.0@0.5 in:top.

      l1 converter:(PrintConverter new initForInteger).

      l1 model:v1; labelMessage:#value; aspect:#value.

      l1 level:-1; inset:10.

      l2 := Label origin:0.0@0.5 corner:1.0@1.0 in:top.

      l2 converter:(PrintConverter new initForDate).

      l2 model:v2; labelMessage:#value; aspect:#value.

      l2 level:-1; inset:10.

      top open.

      'now, change the values ...'.

      [

	1 to:50 do:[:i|

	    v1 value:(v1 value + 1).

	    v2 value:(v2 value addDays:1).

	    (Delay forSeconds:0.5) wait

	]

      ] fork

    convert a models value for a label with limited precision

    float conversion:

      |top v l1 l2|

      v := 0.0 asValue.

      top := StandardSystemView new.

      top extent:200@200.

      l1 := Label origin:0.0@0.0 corner:1.0@0.5 in:top.

      l1 converter:(PrintConverter new initForFloat).

      l1 model:v; labelMessage:#value; aspect:#value.

      l1 level:-1; inset:10.

      l2 := Label origin:0.0@0.5 corner:1.0@1.0 in:top.

      l2 converter:(PrintConverter new initForFloatWithPrecision:2).

      l2 model:v; labelMessage:#value; aspect:#value.

      l2 level:-1; inset:10.

      top open.

      'now, change the values ...'.

      [

	1 to:100 do:[:i|

	    v value:(v value + 0.005).

	    (Delay forSeconds:0.5) wait

	]

      ] fork

    a custom converter, converting a number to either 'odd'

    or 'even' strings (we only need a one-way converter for labels):

      |top v l1 l2|

      v := 0 asValue.

      top := StandardSystemView new.

      top extent:200@200.

      l1 := Label origin:0.0@0.0 corner:1.0@0.5 in:top.

      l1 converter:(PrintConverter new initForInteger).

      l1 model:v; labelMessage:#value; aspect:#value.

      l1 level:-1; inset:10.

      l2 := Label origin:0.0@0.5 corner:1.0@1.0 in:top.

      l2 converter:(PrintConverter 

		      new 

			  toPrint:[:num | num even ifTrue:['even'] 

						   ifFalse:['odd']]

			  toRead:[:string | ]).

      l2 model:v; labelMessage:#value; aspect:#value.

      l2 level:-1; inset:10.

      top open.

      'now, change the values ...'.

      [

	1 to:100 do:[:i|

	    v value:(v value + 1).

	    (Delay forSeconds:0.5) wait

	]

      ] fork

    see more examples in the EditField examples.

"

! !

!PrintConverter class methodsFor:'instance creation'!

new

    ^ (super new) 

	toPrint:[:val | val]

	toRead:[:string | string]

! !

!PrintConverter class methodsFor:'utilities'!

print:aNumber formattedBy:formatString

    "take the digits of aNumbers printString, and squash them

     into formatString, where #-characters are replaced by

     successive characters from the printString.

     Warning: use with care - it does not check for decimal points etc.

	      the printString of aNumber must have enough digits for all

	      #-characters to be replaced.

	      Therefore, precheck the numbers value and use appropriate format

	      strings then.

     For number formatting, see also: printfPrintString: implementations."

    |pS fS out|

    pS := ReadStream on:aNumber printString.

    fS := ReadStream on:formatString.

    out := WriteStream on:String new.

    [fS atEnd] whileFalse:[

	|c|

	c := fS next.

	c == $# ifTrue:[

	    c := pS next

	].

	out nextPut:c

    ].

    ^ out contents

    "

     PrintConverter print:'123456789' formattedBy:'US$ ###,###.##' 

    fails for:

     PrintConverter print:'1234' formattedBy:'US$ ###,###.##' 

    invalid string for:

     PrintConverter print:'123456789' formattedBy:'US$ ###' 

    "

! !

!PrintConverter methodsFor:'initialization'!

toPrint:printBlock toRead:readBlock

    "initialize to convert using two custom blocks.

     printBlock is supposed to get the objects value as argument,

     and to return a string.

     readBlock is supposed to get a string as argument, and return

     the corresponding object."

    valueToStringBlock := printBlock.

    stringToValueBlock := readBlock.

!

initForInteger

    "initialize to convert to/from an integer 

     - if the string is empty or invalid, convert to 0"

    valueToStringBlock := [:num | num truncated printString].

    stringToValueBlock := [:string | Integer readFromString:string onError:0]

!

initForIntegerOrNil

    "initialize to convert to/from an integer 

     - if the string is empty or invalid, convert to nil"

    valueToStringBlock := [:num | 

	num isNil ifTrue:[''] 

		  ifFalse:[num printString]].

    stringToValueBlock := [:string | 

	Integer readFromString:string onError:nil]

!

initForFloat

    "initialize to convert to/from an float 

     - if the string is empty or invalid, convert to 0"

    valueToStringBlock := [:num | num asFloat printString].

    stringToValueBlock := [:string | Float readFromString:string onError:0]

!

initForFloatWithPrecision:nDigits

    "initialize to convert to/from an float with nDigits after the decimal point

     (truncating remaining digits).

     - if the string is empty or invalid, convert to 0"

    |conv|

    conv := '%.' , nDigits printString , 'f'.

    valueToStringBlock := [:num | num asFloat printfPrintString:conv].

    stringToValueBlock := [:string | Float readFromString:string onError:0]

!

initForNumber

    "initialize to convert to/from a number 

     - if the string is empty or invalid, convert to 0"

    valueToStringBlock := [:num | num printString].

    stringToValueBlock := [:string | Number readFromString:string onError:0]

!

initForNumberOrNil

    "initialize to convert to/from a number 

     - if the string is empty or invalid, convert to nil"

    valueToStringBlock := [:num | 

	num isNil ifTrue:[''] 

		  ifFalse:[num printString]].

    stringToValueBlock := [:string | 

	Number readFromString:string onError:nil]

!

initForString

    "initialize for a string - this is trivial"

    valueToStringBlock := [:val | val isNil ifTrue:[''] ifFalse:[val]].

    stringToValueBlock := [:string | string]

!

initForDate

    "initialize to convert to/from a date 

     - if the string is empty or invalid, convert to the current date"

    valueToStringBlock := [:date | date printString].

    stringToValueBlock := [:string | Date readFromString:string onError:[Date today]]

!

initForDateOrNil

    "initialize to convert to/from a date 

     - if the string is empty or invalid, convert to nil"

    valueToStringBlock := [:date | date printString].

    stringToValueBlock := [:string | Date readFromString:string onError:nil]

!

initForYesNo

    "initialize to convert a 'yes'/'no' string to/from a boolean 

     The string is supposed to be in the current Language

     (i.e. if german, ja/nein has to be enterred.

     Invalid entries are converted to false."

    valueToStringBlock := [:bool | bool ifTrue:[ApplicationModel classResources string:'yes']

					ifFalse:[ApplicationModel classResources string:'no']].

    stringToValueBlock := [:string | string = (ApplicationModel classResources string:'yes')]

! !

!PrintConverter methodsFor:'converting'!

printStringFor:aValue

    ^ valueToStringBlock value:aValue

!

readValueFrom:aString

    ^ stringToValueBlock value:aString

! !