Реализация String.Format() в VB6
Можно String.Format() быть реализован в VB6, по крайней мере, достаточно близкая его версия, которая может быть полезна при программировании в хорошем старом VB6?
Хороший ресурс по производительности манипуляции со строками VB6: http://www.aivosto.com/vbtips/stringopt2.html
Что касается не связанных, я также придумал пару функций сравнения строк, найти их здесь на CodeReview.SE
Эти функции чрезвычайно полезны для улучшения читабельности VB6, особенно если вы в последнее время были испорчены кодом.net и внезапно должны погрузиться в базу кода VB6... Наслаждайтесь!
1 ответ
Решение
Я не мог найти нигде, поэтому я сделал свой собственный:
Public PADDING_CHAR As String
Public Function StringFormat(format_string As String, ParamArray values()) As String
'VB6 implementation of .net String.Format(), slightly customized.
'Tested with Office 2010 VBA (x64)
Dim return_value As String
Dim values_count As Integer
'some error-handling constants:
Const ERR_FORMAT_EXCEPTION As Long = vbObjectError Or 9001
Const ERR_ARGUMENT_NULL_EXCEPTION As Long = vbObjectError Or 9002
Const ERR_SOURCE As String = "StringFormat"
Const ERR_MSG_INVALID_FORMAT_STRING As String = "Invalid format string."
Const ERR_MSG_FORMAT_EXCEPTION As String = "The number indicating an argument to format is less than zero, or greater than or equal to the length of the args array."
'use SPACE as default padding character
If PADDING_CHAR = vbNullString Then PADDING_CHAR = Chr$(32)
'figure out number of passed values:
values_count = UBound(values) + 1
Dim regex As RegExp
Dim matches As MatchCollection
Dim thisMatch As Match
Dim thisString As String
Dim thisFormat As String
'when format_string starts with "@", escapes are not replaced
'(string is treated as a literal string with placeholders)
Dim useLiteral As Boolean
Dim escapeHex As Boolean 'indicates whether HEX specifier "0x" is to be escaped or not
'validate string_format:
Set regex = New RegExp
regex.Pattern = "{({{)*(\w+)(,-?\d+)?(:[^}]+)?}(}})*"
regex.IgnoreCase = True
regex.Global = True
Set matches = regex.Execute(format_string)
'determine if values_count matches number of unique regex matches:
Dim uniqueCount As Integer
Dim tmpCSV As String
For Each thisMatch In matches
If Not StringContains(tmpCSV, thisMatch.SubMatches(1)) Then
uniqueCount = uniqueCount + 1
tmpCSV = tmpCSV & thisMatch.SubMatches(1) & ","
End If
Next
'unique indices count must match values_count:
If matches.Count > 0 And uniqueCount <> values_count Then _
Err.Raise ERR_FORMAT_EXCEPTION, _
ERR_SOURCE, ERR_MSG_FORMAT_EXCEPTION
useLiteral = StringStartsWith("@", format_string)
'remove the "@" literal specifier
If useLiteral Then format_string = Right(format_string, Len(format_string) - 1)
If Not useLiteral And StringContains(format_string, "\\") Then _
format_string = Replace(format_string, "\\", Chr$(27))
If StringContains(format_string, "\\") Then _
format_string = Replace(format_string, "\\", Chr$(27))
If matches.Count = 0 And format_string <> vbNullString And UBound(values) = -1 Then
'only format_string was specified: skip to checking escape sequences:
return_value = format_string
GoTo checkEscapes
ElseIf UBound(values) = -1 And matches.Count > 0 Then
Err.Raise ERR_ARGUMENT_NULL_EXCEPTION, _
ERR_SOURCE, ERR_MSG_FORMAT_EXCEPTION
End If
return_value = format_string
'dissect format_string:
Dim i As Integer, v As String, p As String 'i: iterator; v: value; p: placeholder
Dim alignmentGroup As String, alignmentSpecifier As String
Dim formattedValue As String, alignmentPadding As Integer
'iterate regex matches (each match is a placeholder):
For i = 0 To matches.Count - 1
'get the placeholder specified index:
Set thisMatch = matches(i)
p = thisMatch.SubMatches(1)
'if specified index (0-based) > uniqueCount (1-based), something's wrong:
If p > uniqueCount - 1 Then _
Err.Raise ERR_FORMAT_EXCEPTION, _
ERR_SOURCE, ERR_MSG_FORMAT_EXCEPTION
v = values(p)
'get the alignment specifier if it is specified:
alignmentGroup = thisMatch.SubMatches(2)
If alignmentGroup <> vbNullString Then _
alignmentSpecifier = Right$(alignmentGroup, LenB(alignmentGroup) / 2 - 1)
'get the format specifier if it is specified:
thisString = thisMatch.Value
If StringContains(thisString, ":") Then
Dim formatGroup As String, precisionSpecifier As Integer
Dim formatSpecifier As String, precisionString As String
'get the string between ":" and "}":
formatGroup = Mid$(thisString, InStr(1, thisString, ":") + 1, (LenB(thisString) / 2) - 2)
formatGroup = Left$(formatGroup, LenB(formatGroup) / 2 - 1)
precisionString = Right$(formatGroup, LenB(formatGroup) / 2 - 1)
formatSpecifier = Mid$(thisString, InStr(1, thisString, ":") + 1, 1)
'applicable formatting depends on the type of the value (yes, GOTO!!):
If TypeName(values(p)) = "Date" Then GoTo DateTimeFormatSpecifiers
If v = vbNullString Then GoTo ApplyStringFormat
NumberFormatSpecifiers:
If precisionString <> vbNullString And Not IsNumeric(precisionString) Then _
Err.Raise ERR_FORMAT_EXCEPTION, _
ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING
If precisionString = vbNullString Then precisionString = 0
Select Case formatSpecifier
Case "C", "c" 'CURRENCY format, formats string as currency.
'Precision specifier determines number of decimal digits.
'This implementation ignores regional settings
'(hard-coded group separator, decimal separator and currency sign).
precisionSpecifier = CInt(precisionString)
thisFormat = "#,##0.$"
If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then
'if a non-zero precision is specified...
thisFormat = _
Replace$(thisFormat, ".", "." & String$(precisionString, Chr$(48)))
End If
Case "D", "d" 'DECIMAL format, formats string as integer number.
'Precision specifier determines number of digits in returned string.
precisionSpecifier = CInt(precisionString)
thisFormat = "0"
thisFormat = Right$(String$(precisionSpecifier, "0") & thisFormat, _
IIf(precisionSpecifier = 0, Len(thisFormat), precisionSpecifier))
Case "E", "e" 'EXPONENTIAL NOTATION format (aka "Scientific Notation")
'Precision specifier determines number of decimals in returned string.
'This implementation ignores regional settings'
'(hard-coded decimal separator).
precisionSpecifier = CInt(precisionString)
thisFormat = "0.00000#" & formatSpecifier & "-#" 'defaults to 6 decimals
If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then
'if a non-zero precision is specified...
thisFormat = "0." & String$(precisionSpecifier - 1, Chr$(48)) & "#" & formatSpecifier & "-#"
ElseIf LenB(formatGroup) > 2 And precisionSpecifier = 0 Then
Err.Raise ERR_FORMAT_EXCEPTION, _
ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING
End If
Case "F", "f" 'FIXED-POINT format
'Precision specifier determines number of decimals in returned string.
'This implementation ignores regional settings'
'(hard-coded decimal separator).
precisionSpecifier = CInt(precisionString)
thisFormat = "0"
If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then
'if a non-zero precision is specified...
thisFormat = (thisFormat & ".") & String$(precisionSpecifier, Chr$(48))
Else
'no precision specified - default to 2 decimals:
thisFormat = "0.00"
End If
Case "G", "g" 'GENERAL format (recursive)
'returns the shortest of either FIXED-POINT or SCIENTIFIC formats in case of a Double.
'returns DECIMAL format in case of a Integer or Long.
Dim eNotation As String, ePower As Integer, specifier As String
precisionSpecifier = IIf(CInt(precisionString) > 0, CInt(precisionString), _
IIf(StringContains(v, "."), Len(v) - InStr(1, v, "."), 0))
'track character case of formatSpecifier:
specifier = IIf(formatSpecifier = "G", "D", "d")
If TypeName(values(p)) = "Integer" Or TypeName(values(p)) = "Long" Then
'Integer types: use {0:D} (recursive call):
formattedValue = StringFormat("{0:" & specifier & "}", values(p))
ElseIf TypeName(values(p)) = "Double" Then
'Non-integer types: use {0:E}
specifier = IIf(formatSpecifier = "G", "E", "e")
'evaluate the exponential notation value (recursive call):
eNotation = StringFormat("{0:" & specifier & "}", v)
'get the power of eNotation:
ePower = Mid$(eNotation, InStr(1, UCase$(eNotation), "E-") + 1, Len(eNotation) - InStr(1, UCase$(eNotation), "E-"))
If ePower > -5 And Abs(ePower) < precisionSpecifier Then
'use {0:F} when ePower > -5 and abs(ePower) < precisionSpecifier:
'evaluate the floating-point value (recursive call):
specifier = IIf(formatSpecifier = "G", "F", "f")
formattedValue = StringFormat("{0:" & formatSpecifier & _
IIf(precisionSpecifier <> 0, precisionString, vbNullString) & "}", values(p))
Else
'fallback to {0:E} if previous rule didn't apply:
formattedValue = eNotation
End If
End If
GoTo AlignFormattedValue 'Skip the "ApplyStringFormat" step, it's applied already.
Case "N", "n" 'NUMERIC format, formats string as an integer or decimal number.
'Precision specifier determines number of decimal digits.
'This implementation ignores regional settings'
'(hard-coded group and decimal separators).
precisionSpecifier = CInt(precisionString)
If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then
'if a non-zero precision is specified...
thisFormat = "#,##0"
thisFormat = (thisFormat & ".") & String$(precisionSpecifier, Chr$(48))
Else 'only the "D" is specified
thisFormat = "#,##0"
End If
Case "P", "p" 'PERCENT format. Formats string as a percentage.
'Value is multiplied by 100 and displayed with a percent symbol.
'Precision specifier determines number of decimal digits.
thisFormat = "#,##0%"
precisionSpecifier = CInt(precisionString)
If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then
'if a non-zero precision is specified...
thisFormat = "#,##0"
thisFormat = (thisFormat & ".") & String$(precisionSpecifier, Chr$(48))
Else 'only the "P" is specified
thisFormat = "#,##0"
End If
'Append the percentage sign to the format string:
thisFormat = thisFormat & "%"
Case "R", "r" 'ROUND-TRIP format (a string that can round-trip to an identical number)
'example: ?StringFormat("{0:R}", 0.0000000001141596325677345362656)
' ...returns "0.000000000114159632567735"
'convert value to a Double (chop off overflow digits):
v = CDbl(v)
Case "X", "x" 'HEX format. Formats a string as a Hexadecimal value.
'Precision specifier determines number of total digits.
'Returned string is prefixed with "&H" to specify Hex.
v = Hex(v)
precisionSpecifier = CInt(precisionString)
If LenB(precisionString) > 0 Then 'precision here stands for left padding
v = Right$(String$(precisionSpecifier, "0") & v, IIf(precisionSpecifier = 0, Len(v), precisionSpecifier))
End If
'add C# hex specifier, apply specified casing:
'(VB6 hex specifier would cause Format() to reverse the formatting):
v = "0x" & IIf(formatSpecifier = "X", UCase$(v), LCase$(v))
Case Else
If IsNumeric(formatSpecifier) And val(formatGroup) = 0 Then
formatSpecifier = formatGroup
v = Format(v, formatGroup)
Else
Err.Raise ERR_FORMAT_EXCEPTION, _
ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING
End If
End Select
GoTo ApplyStringFormat
DateTimeFormatSpecifiers:
Select Case formatSpecifier
Case "c", "C" 'CUSTOM date/time format
'let VB Format() parse precision specifier as is:
thisFormat = precisionString
Case "d" 'SHORT DATE format
thisFormat = "ddddd"
Case "D" 'LONG DATE format
thisFormat = "dddddd"
Case "f" 'FULL DATE format (short)
thisFormat = "dddddd h:mm AM/PM"
Case "F" 'FULL DATE format (long)
thisFormat = "dddddd ttttt"
Case "g"
thisFormat = "ddddd hh:mm AM/PM"
Case "G"
thisFormat = "ddddd ttttt"
Case "s" 'SORTABLE DATETIME format
thisFormat = "yyyy-mm-ddThh:mm:ss"
Case "t" 'SHORT TIME format
thisFormat = "hh:mm AM/PM"
Case "T" 'LONG TIME format
thisFormat = "ttttt"
Case Else
Err.Raise ERR_FORMAT_EXCEPTION, _
ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING
End Select
GoTo ApplyStringFormat
End If
ApplyStringFormat:
'apply computed format string:
formattedValue = Format(v, thisFormat)
AlignFormattedValue:
'apply specified alignment specifier:
If alignmentSpecifier <> vbNullString Then
alignmentPadding = Abs(CInt(alignmentSpecifier))
If CInt(alignmentSpecifier) < 0 Then
'negative: left-justified alignment
If alignmentPadding - Len(formattedValue) > 0 Then _
formattedValue = formattedValue & _
String$(alignmentPadding - Len(formattedValue), PADDING_CHAR)
Else
'positive: right-justified alignment
If alignmentPadding - Len(formattedValue) > 0 Then _
formattedValue = String$(alignmentPadding - Len(formattedValue), PADDING_CHAR) & formattedValue
End If
End If
'Replace C# hex specifier with VB6 hex specifier,
'only if hex specifier was introduced in this function:
If (Not useLiteral And escapeHex) And _
StringContains(formattedValue, "0x") Then _
formattedValue = Replace$(formattedValue, "0x", "&H")
'replace all occurrences of placeholder {i} with their formatted values:
return_value = Replace(return_value, thisString, formattedValue, Count:=1)
'reset before reiterating:
thisFormat = vbNullString
Next
checkEscapes:
'if there's no more backslashes, don't bother checking for the rest:
If useLiteral Or Not StringContains(return_value, "\") Then GoTo normalExit
Dim escape As New EscapeSequence
Dim escapes As New Collection
escapes.Add escape.Create("\n", vbNewLine), "0"
escapes.Add escape.Create("\q", Chr$(34)), "1"
escapes.Add escape.Create("\t", vbTab), "2"
escapes.Add escape.Create("\a", Chr$(7)), "3"
escapes.Add escape.Create("\b", Chr$(8)), "4"
escapes.Add escape.Create("\v", Chr$(13)), "5"
escapes.Add escape.Create("\f", Chr$(14)), "6"
escapes.Add escape.Create("\r", Chr$(15)), "7"
For i = 0 To escapes.Count - 1
Set escape = escapes(CStr(i))
If StringContains(return_value, escape.EscapeString) Then _
return_value = Replace(return_value, escape.EscapeString, escape.ReplacementString)
If Not StringContains(return_value, "\") Then _
GoTo normalExit
Next
'replace "ASCII (oct)" escape sequence
Set regex = New RegExp
regex.Pattern = "\\(\d{3})"
regex.IgnoreCase = True
regex.Global = True
Set matches = regex.Execute(format_string)
Dim char As Long
If matches.Count <> 0 Then
For Each thisMatch In matches
p = thisMatch.SubMatches(0)
'"p" contains the octal number representing the ASCII code we're after:
p = "&O" & p 'prepend octal prefix
char = CLng(p)
return_value = Replace(return_value, thisMatch.Value, Chr$(char))
Next
End If
'if there's no more backslashes, don't bother checking for the rest:
If Not StringContains("\", return_value) Then GoTo normalExit
'replace "ASCII (hex)" escape sequence
Set regex = New RegExp
regex.Pattern = "\\x(\w{2})"
regex.IgnoreCase = True
regex.Global = True
Set matches = regex.Execute(format_string)
If matches.Count <> 0 Then
For Each thisMatch In matches
p = thisMatch.SubMatches(0)
'"p" contains the hex value representing the ASCII code we're after:
p = "&H" & p 'prepend hex prefix
char = CLng(p)
return_value = Replace(return_value, thisMatch.Value, Chr$(char))
Next
End If
normalExit:
Set escapes = Nothing
Set escape = Nothing
If Not useLiteral And StringContains(return_value, Chr$(27)) Then _
return_value = Replace(return_value, Chr$(27), "\")
StringFormat = return_value
End Function
Обратите внимание на ParamArray в сигнатуре метода (спасибо @wqw): это избавляет от использования нескольких необязательных параметров (и от ошибок использования с возможностью назначать value2 без назначения value1 при именовании параметров в операторе вызова). Потому что это ParamArray, отдельные значения Variant это означает, что каждый параметр может быть другого типа, VB выполняет преобразование строк за кулисами.
Функция может быть использована следующим образом:
?StringFormat("(C) Currency: . . . . . . . . {0:C}\n" & _
"(D) Decimal:. . . . . . . . . {0:D}\n" & _
"(E) Scientific: . . . . . . . {1:E}\n" & _
"(F) Fixed point:. . . . . . . {1:F}\n" & _
"(N) Number: . . . . . . . . . {0:N}\n" & _
"(P) Percent:. . . . . . . . . {1:P}\n" & _
"(R) Round-trip: . . . . . . . {1:R}\n" & _
"(X) Hexadecimal:. . . . . . . {0:X}\n",-123, -123.45)
Выход:
(C) Currency: . . . . . . . . -123.00$
(D) Decimal:. . . . . . . . . -123
(E) Scientific: . . . . . . . -1.23450E2
(F) Fixed point:. . . . . . . -123
(N) Number: . . . . . . . . . -123
(P) Percent:. . . . . . . . . -12,345%
(R) Round-trip: . . . . . . . -123.45
(X) Hexadecimal:. . . . . . . &HFFFFFF85
А также вот так:
?StringFormat("(c) Custom format: . . . . . .{0:cYYYY-MM-DD (MMMM)}\n" & _
"(d) Short date: . . . . . . . {0:d}\n" & _
"(D) Long date:. . . . . . . . {0:D}\n" & _
"(T) Long time:. . . . . . . . {0:T}\n" & _
"(f) Full date/short time: . . {0:f}\n" & _
"(F) Full date/long time:. . . {0:F}\n" & _
"(s) Sortable: . . . . . . . . {0:s}\n", Now())
Выход:
(c) Custom format: . . . . . .2013-01-26 (January)
(d) Short date: . . . . . . . 1/26/2013
(D) Long date:. . . . . . . . Saturday, January 26, 2013
(T) Long time:. . . . . . . . 8:28:11 PM
(f) Full date/short time: . . 1/26/2013 8:28:11 PM
(F) Full date/long time:. . . Saturday, January 26, 2013 8:28:11 PM
(s) Sortable: . . . . . . . . 2013-01-26T20:28:11
Также возможно указать выравнивание (/padding) и использовать escape-последовательности:
?StringFormat ("\q{0}, {1}!\x20\n'{2,10:C2}'\n'{2,-10:C2}'", "hello", "world", 100)
"hello, world!"
' 100.00$'
'100.00$ '
Глядя на примеры из http://msdn.microsoft.com/fr-fr/library/b1csw23d(v=vs.80).aspx, только несколько спецификаторов формата не реализованы, в основном, указатели даты / времени... но я подумал бы, что спецификатор формата даты / времени "c" делает это.
Функция использует прямую реализацию String.Contains():
Public Function StringContains(string_source As String, find_text As String, _
Optional ByVal caseSensitive As Boolean = True) As Boolean
StringContains = StringContainsAny(string_source, caseSensitive, find_text)
End Function
РЕДАКТИРОВАТЬ: этот код теперь правильно обрабатывает экранирование "\\", как указано в комментариях. Кроме того, в то время как StringContains конечно практично и дает более комфортное чтение, чем InStr() позвоните, ниже StringContainsAny функция еще лучше:
Public Function StringContainsAny(string_source As String, ByVal caseSensitive As Boolean, _
ParamArray find_values()) As Boolean
Dim i As Integer, found As Boolean
If caseSensitive Then
For i = LBound(find_values) To UBound(find_values)
found = (InStr(1, string_source, _
find_values(i), vbBinaryCompare) <> 0)
If found Then Exit For
Next
Else
For i = LBound(find_values) To UBound(find_values)
StringContainsAny = (InStr(1, LCase$(string_source), _
LCase$(find_values(i)), vbBinaryCompare) <> 0)
If found Then Exit For
Next
End If
StringContainsAny = found
End Function
Учтите следующее:
foo = Instr(1, source, "value1") > 0 Or Instr(1, source, "value2") > 0 _
Or Instr(1, source, "value3") > 0 Or Instr(1, source, "value4") > 0 _
Or Instr(1, source, "value5") > 0 Or Instr(1, source, "value6") > 0 _
Прежде чем VB сможет определить, foo является TRUE или же FALSE, каждый InStr() звонок сделан. Однако с StringContainsAny()условие удовлетворяется первым найденным значением, что делает его более быстрым.
РЕДАКТИРОВАТЬ: Предыдущее редактирование в значительной степени уничтожены escape-последовательности; восстановил их, используя небольшой класс EscapeSequence, выставляющий два свойства и фабричный метод - это позволяет сохранить цикл for-each и обрабатывать все простые escape-коды без дублирования большого количества кода.
Этот код также использует StringStartsWith функция, реализованная так:
Public Function StringStartsWith(ByVal find_text As String, ByVal string_source As String, Optional ByVal caseSensitive As Boolean = True) As Boolean
If caseSensitive Then
StringStartsWith = (Left$(string_source, LenB(find_text) / 2) = find_text)
Else
StringStartsWith = (Left$(LCase(string_source), LenB(find_text) / 2) = LCase$(find_text))
End If
End Function