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diff --git a/chromium/third_party/cygwin/lib/perl5/5.10/pods/perlunicode.pod b/chromium/third_party/cygwin/lib/perl5/5.10/pods/perlunicode.pod deleted file mode 100644 index 4e62fed0b51..00000000000 --- a/chromium/third_party/cygwin/lib/perl5/5.10/pods/perlunicode.pod +++ /dev/null @@ -1,1622 +0,0 @@ -=head1 NAME - -perlunicode - Unicode support in Perl - -=head1 DESCRIPTION - -=head2 Important Caveats - -Unicode support is an extensive requirement. While Perl does not -implement the Unicode standard or the accompanying technical reports -from cover to cover, Perl does support many Unicode features. - -People who want to learn to use Unicode in Perl, should probably read -L<the Perl Unicode tutorial, perlunitut|perlunitut>, before reading -this reference document. - -=over 4 - -=item Input and Output Layers - -Perl knows when a filehandle uses Perl's internal Unicode encodings -(UTF-8, or UTF-EBCDIC if in EBCDIC) if the filehandle is opened with -the ":utf8" layer. Other encodings can be converted to Perl's -encoding on input or from Perl's encoding on output by use of the -":encoding(...)" layer. See L<open>. - -To indicate that Perl source itself is in UTF-8, use C<use utf8;>. - -=item Regular Expressions - -The regular expression compiler produces polymorphic opcodes. That is, -the pattern adapts to the data and automatically switches to the Unicode -character scheme when presented with data that is internally encoded in -UTF-8 -- or instead uses a traditional byte scheme when presented with -byte data. - -=item C<use utf8> still needed to enable UTF-8/UTF-EBCDIC in scripts - -As a compatibility measure, the C<use utf8> pragma must be explicitly -included to enable recognition of UTF-8 in the Perl scripts themselves -(in string or regular expression literals, or in identifier names) on -ASCII-based machines or to recognize UTF-EBCDIC on EBCDIC-based -machines. B<These are the only times when an explicit C<use utf8> -is needed.> See L<utf8>. - -=item BOM-marked scripts and UTF-16 scripts autodetected - -If a Perl script begins marked with the Unicode BOM (UTF-16LE, UTF16-BE, -or UTF-8), or if the script looks like non-BOM-marked UTF-16 of either -endianness, Perl will correctly read in the script as Unicode. -(BOMless UTF-8 cannot be effectively recognized or differentiated from -ISO 8859-1 or other eight-bit encodings.) - -=item C<use encoding> needed to upgrade non-Latin-1 byte strings - -By default, there is a fundamental asymmetry in Perl's Unicode model: -implicit upgrading from byte strings to Unicode strings assumes that -they were encoded in I<ISO 8859-1 (Latin-1)>, but Unicode strings are -downgraded with UTF-8 encoding. This happens because the first 256 -codepoints in Unicode happens to agree with Latin-1. - -See L</"Byte and Character Semantics"> for more details. - -=back - -=head2 Byte and Character Semantics - -Beginning with version 5.6, Perl uses logically-wide characters to -represent strings internally. - -In future, Perl-level operations will be expected to work with -characters rather than bytes. - -However, as an interim compatibility measure, Perl aims to -provide a safe migration path from byte semantics to character -semantics for programs. For operations where Perl can unambiguously -decide that the input data are characters, Perl switches to -character semantics. For operations where this determination cannot -be made without additional information from the user, Perl decides in -favor of compatibility and chooses to use byte semantics. - -This behavior preserves compatibility with earlier versions of Perl, -which allowed byte semantics in Perl operations only if -none of the program's inputs were marked as being as source of Unicode -character data. Such data may come from filehandles, from calls to -external programs, from information provided by the system (such as %ENV), -or from literals and constants in the source text. - -The C<bytes> pragma will always, regardless of platform, force byte -semantics in a particular lexical scope. See L<bytes>. - -The C<utf8> pragma is primarily a compatibility device that enables -recognition of UTF-(8|EBCDIC) in literals encountered by the parser. -Note that this pragma is only required while Perl defaults to byte -semantics; when character semantics become the default, this pragma -may become a no-op. See L<utf8>. - -Unless explicitly stated, Perl operators use character semantics -for Unicode data and byte semantics for non-Unicode data. -The decision to use character semantics is made transparently. If -input data comes from a Unicode source--for example, if a character -encoding layer is added to a filehandle or a literal Unicode -string constant appears in a program--character semantics apply. -Otherwise, byte semantics are in effect. The C<bytes> pragma should -be used to force byte semantics on Unicode data. - -If strings operating under byte semantics and strings with Unicode -character data are concatenated, the new string will be created by -decoding the byte strings as I<ISO 8859-1 (Latin-1)>, even if the -old Unicode string used EBCDIC. This translation is done without -regard to the system's native 8-bit encoding. - -Under character semantics, many operations that formerly operated on -bytes now operate on characters. A character in Perl is -logically just a number ranging from 0 to 2**31 or so. Larger -characters may encode into longer sequences of bytes internally, but -this internal detail is mostly hidden for Perl code. -See L<perluniintro> for more. - -=head2 Effects of Character Semantics - -Character semantics have the following effects: - -=over 4 - -=item * - -Strings--including hash keys--and regular expression patterns may -contain characters that have an ordinal value larger than 255. - -If you use a Unicode editor to edit your program, Unicode characters may -occur directly within the literal strings in UTF-8 encoding, or UTF-16. -(The former requires a BOM or C<use utf8>, the latter requires a BOM.) - -Unicode characters can also be added to a string by using the C<\x{...}> -notation. The Unicode code for the desired character, in hexadecimal, -should be placed in the braces. For instance, a smiley face is -C<\x{263A}>. This encoding scheme only works for all characters, but -for characters under 0x100, note that Perl may use an 8 bit encoding -internally, for optimization and/or backward compatibility. - -Additionally, if you - - use charnames ':full'; - -you can use the C<\N{...}> notation and put the official Unicode -character name within the braces, such as C<\N{WHITE SMILING FACE}>. - -=item * - -If an appropriate L<encoding> is specified, identifiers within the -Perl script may contain Unicode alphanumeric characters, including -ideographs. Perl does not currently attempt to canonicalize variable -names. - -=item * - -Regular expressions match characters instead of bytes. "." matches -a character instead of a byte. - -=item * - -Character classes in regular expressions match characters instead of -bytes and match against the character properties specified in the -Unicode properties database. C<\w> can be used to match a Japanese -ideograph, for instance. - -=item * - -Named Unicode properties, scripts, and block ranges may be used like -character classes via the C<\p{}> "matches property" construct and -the C<\P{}> negation, "doesn't match property". - -See L</"Unicode Character Properties"> for more details. - -You can define your own character properties and use them -in the regular expression with the C<\p{}> or C<\P{}> construct. - -See L</"User-Defined Character Properties"> for more details. - -=item * - -The special pattern C<\X> matches any extended Unicode -sequence--"a combining character sequence" in Standardese--where the -first character is a base character and subsequent characters are mark -characters that apply to the base character. C<\X> is equivalent to -C<< (?>\PM\pM*) >>. - -=item * - -The C<tr///> operator translates characters instead of bytes. Note -that the C<tr///CU> functionality has been removed. For similar -functionality see pack('U0', ...) and pack('C0', ...). - -=item * - -Case translation operators use the Unicode case translation tables -when character input is provided. Note that C<uc()>, or C<\U> in -interpolated strings, translates to uppercase, while C<ucfirst>, -or C<\u> in interpolated strings, translates to titlecase in languages -that make the distinction. - -=item * - -Most operators that deal with positions or lengths in a string will -automatically switch to using character positions, including -C<chop()>, C<chomp()>, C<substr()>, C<pos()>, C<index()>, C<rindex()>, -C<sprintf()>, C<write()>, and C<length()>. An operator that -specifically does not switch is C<vec()>. Operators that really don't -care include operators that treat strings as a bucket of bits such as -C<sort()>, and operators dealing with filenames. - -=item * - -The C<pack()>/C<unpack()> letter C<C> does I<not> change, since it is often -used for byte-oriented formats. Again, think C<char> in the C language. - -There is a new C<U> specifier that converts between Unicode characters -and code points. There is also a C<W> specifier that is the equivalent of -C<chr>/C<ord> and properly handles character values even if they are above 255. - -=item * - -The C<chr()> and C<ord()> functions work on characters, similar to -C<pack("W")> and C<unpack("W")>, I<not> C<pack("C")> and -C<unpack("C")>. C<pack("C")> and C<unpack("C")> are methods for -emulating byte-oriented C<chr()> and C<ord()> on Unicode strings. -While these methods reveal the internal encoding of Unicode strings, -that is not something one normally needs to care about at all. - -=item * - -The bit string operators, C<& | ^ ~>, can operate on character data. -However, for backward compatibility, such as when using bit string -operations when characters are all less than 256 in ordinal value, one -should not use C<~> (the bit complement) with characters of both -values less than 256 and values greater than 256. Most importantly, -DeMorgan's laws (C<~($x|$y) eq ~$x&~$y> and C<~($x&$y) eq ~$x|~$y>) -will not hold. The reason for this mathematical I<faux pas> is that -the complement cannot return B<both> the 8-bit (byte-wide) bit -complement B<and> the full character-wide bit complement. - -=item * - -lc(), uc(), lcfirst(), and ucfirst() work for the following cases: - -=over 8 - -=item * - -the case mapping is from a single Unicode character to another -single Unicode character, or - -=item * - -the case mapping is from a single Unicode character to more -than one Unicode character. - -=back - -Things to do with locales (Lithuanian, Turkish, Azeri) do B<not> work -since Perl does not understand the concept of Unicode locales. - -See the Unicode Technical Report #21, Case Mappings, for more details. - -But you can also define your own mappings to be used in the lc(), -lcfirst(), uc(), and ucfirst() (or their string-inlined versions). - -See L</"User-Defined Case Mappings"> for more details. - -=back - -=over 4 - -=item * - -And finally, C<scalar reverse()> reverses by character rather than by byte. - -=back - -=head2 Unicode Character Properties - -Named Unicode properties, scripts, and block ranges may be used like -character classes via the C<\p{}> "matches property" construct and -the C<\P{}> negation, "doesn't match property". - -For instance, C<\p{Lu}> matches any character with the Unicode "Lu" -(Letter, uppercase) property, while C<\p{M}> matches any character -with an "M" (mark--accents and such) property. Brackets are not -required for single letter properties, so C<\p{M}> is equivalent to -C<\pM>. Many predefined properties are available, such as -C<\p{Mirrored}> and C<\p{Tibetan}>. - -The official Unicode script and block names have spaces and dashes as -separators, but for convenience you can use dashes, spaces, or -underbars, and case is unimportant. It is recommended, however, that -for consistency you use the following naming: the official Unicode -script, property, or block name (see below for the additional rules -that apply to block names) with whitespace and dashes removed, and the -words "uppercase-first-lowercase-rest". C<Latin-1 Supplement> thus -becomes C<Latin1Supplement>. - -You can also use negation in both C<\p{}> and C<\P{}> by introducing a caret -(^) between the first brace and the property name: C<\p{^Tamil}> is -equal to C<\P{Tamil}>. - -B<NOTE: the properties, scripts, and blocks listed here are as of -Unicode 5.0.0 in July 2006.> - -=over 4 - -=item General Category - -Here are the basic Unicode General Category properties, followed by their -long form. You can use either; C<\p{Lu}> and C<\p{UppercaseLetter}>, -for instance, are identical. - - Short Long - - L Letter - LC CasedLetter - Lu UppercaseLetter - Ll LowercaseLetter - Lt TitlecaseLetter - Lm ModifierLetter - Lo OtherLetter - - M Mark - Mn NonspacingMark - Mc SpacingMark - Me EnclosingMark - - N Number - Nd DecimalNumber - Nl LetterNumber - No OtherNumber - - P Punctuation - Pc ConnectorPunctuation - Pd DashPunctuation - Ps OpenPunctuation - Pe ClosePunctuation - Pi InitialPunctuation - (may behave like Ps or Pe depending on usage) - Pf FinalPunctuation - (may behave like Ps or Pe depending on usage) - Po OtherPunctuation - - S Symbol - Sm MathSymbol - Sc CurrencySymbol - Sk ModifierSymbol - So OtherSymbol - - Z Separator - Zs SpaceSeparator - Zl LineSeparator - Zp ParagraphSeparator - - C Other - Cc Control - Cf Format - Cs Surrogate (not usable) - Co PrivateUse - Cn Unassigned - -Single-letter properties match all characters in any of the -two-letter sub-properties starting with the same letter. -C<LC> and C<L&> are special cases, which are aliases for the set of -C<Ll>, C<Lu>, and C<Lt>. - -Because Perl hides the need for the user to understand the internal -representation of Unicode characters, there is no need to implement -the somewhat messy concept of surrogates. C<Cs> is therefore not -supported. - -=item Bidirectional Character Types - -Because scripts differ in their directionality--Hebrew is -written right to left, for example--Unicode supplies these properties in -the BidiClass class: - - Property Meaning - - L Left-to-Right - LRE Left-to-Right Embedding - LRO Left-to-Right Override - R Right-to-Left - AL Right-to-Left Arabic - RLE Right-to-Left Embedding - RLO Right-to-Left Override - PDF Pop Directional Format - EN European Number - ES European Number Separator - ET European Number Terminator - AN Arabic Number - CS Common Number Separator - NSM Non-Spacing Mark - BN Boundary Neutral - B Paragraph Separator - S Segment Separator - WS Whitespace - ON Other Neutrals - -For example, C<\p{BidiClass:R}> matches characters that are normally -written right to left. - -=item Scripts - -The script names which can be used by C<\p{...}> and C<\P{...}>, -such as in C<\p{Latin}> or C<\p{Cyrillic}>, are as follows: - - Arabic - Armenian - Balinese - Bengali - Bopomofo - Braille - Buginese - Buhid - CanadianAboriginal - Cherokee - Coptic - Cuneiform - Cypriot - Cyrillic - Deseret - Devanagari - Ethiopic - Georgian - Glagolitic - Gothic - Greek - Gujarati - Gurmukhi - Han - Hangul - Hanunoo - Hebrew - Hiragana - Inherited - Kannada - Katakana - Kharoshthi - Khmer - Lao - Latin - Limbu - LinearB - Malayalam - Mongolian - Myanmar - NewTaiLue - Nko - Ogham - OldItalic - OldPersian - Oriya - Osmanya - PhagsPa - Phoenician - Runic - Shavian - Sinhala - SylotiNagri - Syriac - Tagalog - Tagbanwa - TaiLe - Tamil - Telugu - Thaana - Thai - Tibetan - Tifinagh - Ugaritic - Yi - -=item Extended property classes - -Extended property classes can supplement the basic -properties, defined by the F<PropList> Unicode database: - - ASCIIHexDigit - BidiControl - Dash - Deprecated - Diacritic - Extender - HexDigit - Hyphen - Ideographic - IDSBinaryOperator - IDSTrinaryOperator - JoinControl - LogicalOrderException - NoncharacterCodePoint - OtherAlphabetic - OtherDefaultIgnorableCodePoint - OtherGraphemeExtend - OtherIDStart - OtherIDContinue - OtherLowercase - OtherMath - OtherUppercase - PatternSyntax - PatternWhiteSpace - QuotationMark - Radical - SoftDotted - STerm - TerminalPunctuation - UnifiedIdeograph - VariationSelector - WhiteSpace - -and there are further derived properties: - - Alphabetic = Lu + Ll + Lt + Lm + Lo + Nl + OtherAlphabetic - Lowercase = Ll + OtherLowercase - Uppercase = Lu + OtherUppercase - Math = Sm + OtherMath - - IDStart = Lu + Ll + Lt + Lm + Lo + Nl + OtherIDStart - IDContinue = IDStart + Mn + Mc + Nd + Pc + OtherIDContinue - - DefaultIgnorableCodePoint - = OtherDefaultIgnorableCodePoint - + Cf + Cc + Cs + Noncharacters + VariationSelector - - WhiteSpace - FFF9..FFFB (Annotation Characters) - - Any = Any code points (i.e. U+0000 to U+10FFFF) - Assigned = Any non-Cn code points (i.e. synonym for \P{Cn}) - Unassigned = Synonym for \p{Cn} - ASCII = ASCII (i.e. U+0000 to U+007F) - - Common = Any character (or unassigned code point) - not explicitly assigned to a script - -=item Use of "Is" Prefix - -For backward compatibility (with Perl 5.6), all properties mentioned -so far may have C<Is> prepended to their name, so C<\P{IsLu}>, for -example, is equal to C<\P{Lu}>. - -=item Blocks - -In addition to B<scripts>, Unicode also defines B<blocks> of -characters. The difference between scripts and blocks is that the -concept of scripts is closer to natural languages, while the concept -of blocks is more of an artificial grouping based on groups of 256 -Unicode characters. For example, the C<Latin> script contains letters -from many blocks but does not contain all the characters from those -blocks. It does not, for example, contain digits, because digits are -shared across many scripts. Digits and similar groups, like -punctuation, are in a category called C<Common>. - -For more about scripts, see the UAX#24 "Script Names": - - http://www.unicode.org/reports/tr24/ - -For more about blocks, see: - - http://www.unicode.org/Public/UNIDATA/Blocks.txt - -Block names are given with the C<In> prefix. For example, the -Katakana block is referenced via C<\p{InKatakana}>. The C<In> -prefix may be omitted if there is no naming conflict with a script -or any other property, but it is recommended that C<In> always be used -for block tests to avoid confusion. - -These block names are supported: - - InAegeanNumbers - InAlphabeticPresentationForms - InAncientGreekMusicalNotation - InAncientGreekNumbers - InArabic - InArabicPresentationFormsA - InArabicPresentationFormsB - InArabicSupplement - InArmenian - InArrows - InBalinese - InBasicLatin - InBengali - InBlockElements - InBopomofo - InBopomofoExtended - InBoxDrawing - InBraillePatterns - InBuginese - InBuhid - InByzantineMusicalSymbols - InCJKCompatibility - InCJKCompatibilityForms - InCJKCompatibilityIdeographs - InCJKCompatibilityIdeographsSupplement - InCJKRadicalsSupplement - InCJKStrokes - InCJKSymbolsAndPunctuation - InCJKUnifiedIdeographs - InCJKUnifiedIdeographsExtensionA - InCJKUnifiedIdeographsExtensionB - InCherokee - InCombiningDiacriticalMarks - InCombiningDiacriticalMarksSupplement - InCombiningDiacriticalMarksforSymbols - InCombiningHalfMarks - InControlPictures - InCoptic - InCountingRodNumerals - InCuneiform - InCuneiformNumbersAndPunctuation - InCurrencySymbols - InCypriotSyllabary - InCyrillic - InCyrillicSupplement - InDeseret - InDevanagari - InDingbats - InEnclosedAlphanumerics - InEnclosedCJKLettersAndMonths - InEthiopic - InEthiopicExtended - InEthiopicSupplement - InGeneralPunctuation - InGeometricShapes - InGeorgian - InGeorgianSupplement - InGlagolitic - InGothic - InGreekExtended - InGreekAndCoptic - InGujarati - InGurmukhi - InHalfwidthAndFullwidthForms - InHangulCompatibilityJamo - InHangulJamo - InHangulSyllables - InHanunoo - InHebrew - InHighPrivateUseSurrogates - InHighSurrogates - InHiragana - InIPAExtensions - InIdeographicDescriptionCharacters - InKanbun - InKangxiRadicals - InKannada - InKatakana - InKatakanaPhoneticExtensions - InKharoshthi - InKhmer - InKhmerSymbols - InLao - InLatin1Supplement - InLatinExtendedA - InLatinExtendedAdditional - InLatinExtendedB - InLatinExtendedC - InLatinExtendedD - InLetterlikeSymbols - InLimbu - InLinearBIdeograms - InLinearBSyllabary - InLowSurrogates - InMalayalam - InMathematicalAlphanumericSymbols - InMathematicalOperators - InMiscellaneousMathematicalSymbolsA - InMiscellaneousMathematicalSymbolsB - InMiscellaneousSymbols - InMiscellaneousSymbolsAndArrows - InMiscellaneousTechnical - InModifierToneLetters - InMongolian - InMusicalSymbols - InMyanmar - InNKo - InNewTaiLue - InNumberForms - InOgham - InOldItalic - InOldPersian - InOpticalCharacterRecognition - InOriya - InOsmanya - InPhagspa - InPhoenician - InPhoneticExtensions - InPhoneticExtensionsSupplement - InPrivateUseArea - InRunic - InShavian - InSinhala - InSmallFormVariants - InSpacingModifierLetters - InSpecials - InSuperscriptsAndSubscripts - InSupplementalArrowsA - InSupplementalArrowsB - InSupplementalMathematicalOperators - InSupplementalPunctuation - InSupplementaryPrivateUseAreaA - InSupplementaryPrivateUseAreaB - InSylotiNagri - InSyriac - InTagalog - InTagbanwa - InTags - InTaiLe - InTaiXuanJingSymbols - InTamil - InTelugu - InThaana - InThai - InTibetan - InTifinagh - InUgaritic - InUnifiedCanadianAboriginalSyllabics - InVariationSelectors - InVariationSelectorsSupplement - InVerticalForms - InYiRadicals - InYiSyllables - InYijingHexagramSymbols - -=back - -=head2 User-Defined Character Properties - -You can define your own character properties by defining subroutines -whose names begin with "In" or "Is". The subroutines can be defined in -any package. The user-defined properties can be used in the regular -expression C<\p> and C<\P> constructs; if you are using a user-defined -property from a package other than the one you are in, you must specify -its package in the C<\p> or C<\P> construct. - - # assuming property IsForeign defined in Lang:: - package main; # property package name required - if ($txt =~ /\p{Lang::IsForeign}+/) { ... } - - package Lang; # property package name not required - if ($txt =~ /\p{IsForeign}+/) { ... } - - -Note that the effect is compile-time and immutable once defined. - -The subroutines must return a specially-formatted string, with one -or more newline-separated lines. Each line must be one of the following: - -=over 4 - -=item * - -A single hexadecimal number denoting a Unicode code point to include. - -=item * - -Two hexadecimal numbers separated by horizontal whitespace (space or -tabular characters) denoting a range of Unicode code points to include. - -=item * - -Something to include, prefixed by "+": a built-in character -property (prefixed by "utf8::") or a user-defined character property, -to represent all the characters in that property; two hexadecimal code -points for a range; or a single hexadecimal code point. - -=item * - -Something to exclude, prefixed by "-": an existing character -property (prefixed by "utf8::") or a user-defined character property, -to represent all the characters in that property; two hexadecimal code -points for a range; or a single hexadecimal code point. - -=item * - -Something to negate, prefixed "!": an existing character -property (prefixed by "utf8::") or a user-defined character property, -to represent all the characters in that property; two hexadecimal code -points for a range; or a single hexadecimal code point. - -=item * - -Something to intersect with, prefixed by "&": an existing character -property (prefixed by "utf8::") or a user-defined character property, -for all the characters except the characters in the property; two -hexadecimal code points for a range; or a single hexadecimal code point. - -=back - -For example, to define a property that covers both the Japanese -syllabaries (hiragana and katakana), you can define - - sub InKana { - return <<END; - 3040\t309F - 30A0\t30FF - END - } - -Imagine that the here-doc end marker is at the beginning of the line. -Now you can use C<\p{InKana}> and C<\P{InKana}>. - -You could also have used the existing block property names: - - sub InKana { - return <<'END'; - +utf8::InHiragana - +utf8::InKatakana - END - } - -Suppose you wanted to match only the allocated characters, -not the raw block ranges: in other words, you want to remove -the non-characters: - - sub InKana { - return <<'END'; - +utf8::InHiragana - +utf8::InKatakana - -utf8::IsCn - END - } - -The negation is useful for defining (surprise!) negated classes. - - sub InNotKana { - return <<'END'; - !utf8::InHiragana - -utf8::InKatakana - +utf8::IsCn - END - } - -Intersection is useful for getting the common characters matched by -two (or more) classes. - - sub InFooAndBar { - return <<'END'; - +main::Foo - &main::Bar - END - } - -It's important to remember not to use "&" for the first set -- that -would be intersecting with nothing (resulting in an empty set). - -=head2 User-Defined Case Mappings - -You can also define your own mappings to be used in the lc(), -lcfirst(), uc(), and ucfirst() (or their string-inlined versions). -The principle is similar to that of user-defined character -properties: to define subroutines in the C<main> package -with names like C<ToLower> (for lc() and lcfirst()), C<ToTitle> (for -the first character in ucfirst()), and C<ToUpper> (for uc(), and the -rest of the characters in ucfirst()). - -The string returned by the subroutines needs now to be three -hexadecimal numbers separated by tabulators: start of the source -range, end of the source range, and start of the destination range. -For example: - - sub ToUpper { - return <<END; - 0061\t0063\t0041 - END - } - -defines an uc() mapping that causes only the characters "a", "b", and -"c" to be mapped to "A", "B", "C", all other characters will remain -unchanged. - -If there is no source range to speak of, that is, the mapping is from -a single character to another single character, leave the end of the -source range empty, but the two tabulator characters are still needed. -For example: - - sub ToLower { - return <<END; - 0041\t\t0061 - END - } - -defines a lc() mapping that causes only "A" to be mapped to "a", all -other characters will remain unchanged. - -(For serious hackers only) If you want to introspect the default -mappings, you can find the data in the directory -C<$Config{privlib}>/F<unicore/To/>. The mapping data is returned as -the here-document, and the C<utf8::ToSpecFoo> are special exception -mappings derived from <$Config{privlib}>/F<unicore/SpecialCasing.txt>. -The C<Digit> and C<Fold> mappings that one can see in the directory -are not directly user-accessible, one can use either the -C<Unicode::UCD> module, or just match case-insensitively (that's when -the C<Fold> mapping is used). - -A final note on the user-defined case mappings: they will be used -only if the scalar has been marked as having Unicode characters. -Old byte-style strings will not be affected. - -=head2 Character Encodings for Input and Output - -See L<Encode>. - -=head2 Unicode Regular Expression Support Level - -The following list of Unicode support for regular expressions describes -all the features currently supported. The references to "Level N" -and the section numbers refer to the Unicode Technical Standard #18, -"Unicode Regular Expressions", version 11, in May 2005. - -=over 4 - -=item * - -Level 1 - Basic Unicode Support - - RL1.1 Hex Notation - done [1] - RL1.2 Properties - done [2][3] - RL1.2a Compatibility Properties - done [4] - RL1.3 Subtraction and Intersection - MISSING [5] - RL1.4 Simple Word Boundaries - done [6] - RL1.5 Simple Loose Matches - done [7] - RL1.6 Line Boundaries - MISSING [8] - RL1.7 Supplementary Code Points - done [9] - - [1] \x{...} - [2] \p{...} \P{...} - [3] supports not only minimal list (general category, scripts, - Alphabetic, Lowercase, Uppercase, WhiteSpace, - NoncharacterCodePoint, DefaultIgnorableCodePoint, Any, - ASCII, Assigned), but also bidirectional types, blocks, etc. - (see L</"Unicode Character Properties">) - [4] \d \D \s \S \w \W \X [:prop:] [:^prop:] - [5] can use regular expression look-ahead [a] or - user-defined character properties [b] to emulate set operations - [6] \b \B - [7] note that Perl does Full case-folding in matching, not Simple: - for example U+1F88 is equivalent with U+1F00 U+03B9, - not with 1F80. This difference matters for certain Greek - capital letters with certain modifiers: the Full case-folding - decomposes the letter, while the Simple case-folding would map - it to a single character. - [8] should do ^ and $ also on U+000B (\v in C), FF (\f), CR (\r), - CRLF (\r\n), NEL (U+0085), LS (U+2028), and PS (U+2029); - should also affect <>, $., and script line numbers; - should not split lines within CRLF [c] (i.e. there is no empty - line between \r and \n) - [9] UTF-8/UTF-EBDDIC used in perl allows not only U+10000 to U+10FFFF - but also beyond U+10FFFF [d] - -[a] You can mimic class subtraction using lookahead. -For example, what UTS#18 might write as - - [{Greek}-[{UNASSIGNED}]] - -in Perl can be written as: - - (?!\p{Unassigned})\p{InGreekAndCoptic} - (?=\p{Assigned})\p{InGreekAndCoptic} - -But in this particular example, you probably really want - - \p{GreekAndCoptic} - -which will match assigned characters known to be part of the Greek script. - -Also see the Unicode::Regex::Set module, it does implement the full -UTS#18 grouping, intersection, union, and removal (subtraction) syntax. - -[b] '+' for union, '-' for removal (set-difference), '&' for intersection -(see L</"User-Defined Character Properties">) - -[c] Try the C<:crlf> layer (see L<PerlIO>). - -[d] Avoid C<use warning 'utf8';> (or say C<no warning 'utf8';>) to allow -U+FFFF (C<\x{FFFF}>). - -=item * - -Level 2 - Extended Unicode Support - - RL2.1 Canonical Equivalents - MISSING [10][11] - RL2.2 Default Grapheme Clusters - MISSING [12][13] - RL2.3 Default Word Boundaries - MISSING [14] - RL2.4 Default Loose Matches - MISSING [15] - RL2.5 Name Properties - MISSING [16] - RL2.6 Wildcard Properties - MISSING - - [10] see UAX#15 "Unicode Normalization Forms" - [11] have Unicode::Normalize but not integrated to regexes - [12] have \X but at this level . should equal that - [13] UAX#29 "Text Boundaries" considers CRLF and Hangul syllable - clusters as a single grapheme cluster. - [14] see UAX#29, Word Boundaries - [15] see UAX#21 "Case Mappings" - [16] have \N{...} but neither compute names of CJK Ideographs - and Hangul Syllables nor use a loose match [e] - -[e] C<\N{...}> allows namespaces (see L<charnames>). - -=item * - -Level 3 - Tailored Support - - RL3.1 Tailored Punctuation - MISSING - RL3.2 Tailored Grapheme Clusters - MISSING [17][18] - RL3.3 Tailored Word Boundaries - MISSING - RL3.4 Tailored Loose Matches - MISSING - RL3.5 Tailored Ranges - MISSING - RL3.6 Context Matching - MISSING [19] - RL3.7 Incremental Matches - MISSING - ( RL3.8 Unicode Set Sharing ) - RL3.9 Possible Match Sets - MISSING - RL3.10 Folded Matching - MISSING [20] - RL3.11 Submatchers - MISSING - - [17] see UAX#10 "Unicode Collation Algorithms" - [18] have Unicode::Collate but not integrated to regexes - [19] have (?<=x) and (?=x), but look-aheads or look-behinds should see - outside of the target substring - [20] need insensitive matching for linguistic features other than case; - for example, hiragana to katakana, wide and narrow, simplified Han - to traditional Han (see UTR#30 "Character Foldings") - -=back - -=head2 Unicode Encodings - -Unicode characters are assigned to I<code points>, which are abstract -numbers. To use these numbers, various encodings are needed. - -=over 4 - -=item * - -UTF-8 - -UTF-8 is a variable-length (1 to 6 bytes, current character allocations -require 4 bytes), byte-order independent encoding. For ASCII (and we -really do mean 7-bit ASCII, not another 8-bit encoding), UTF-8 is -transparent. - -The following table is from Unicode 3.2. - - Code Points 1st Byte 2nd Byte 3rd Byte 4th Byte - - U+0000..U+007F 00..7F - U+0080..U+07FF C2..DF 80..BF - U+0800..U+0FFF E0 A0..BF 80..BF - U+1000..U+CFFF E1..EC 80..BF 80..BF - U+D000..U+D7FF ED 80..9F 80..BF - U+D800..U+DFFF ******* ill-formed ******* - U+E000..U+FFFF EE..EF 80..BF 80..BF - U+10000..U+3FFFF F0 90..BF 80..BF 80..BF - U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF - U+100000..U+10FFFF F4 80..8F 80..BF 80..BF - -Note the C<A0..BF> in C<U+0800..U+0FFF>, the C<80..9F> in -C<U+D000...U+D7FF>, the C<90..B>F in C<U+10000..U+3FFFF>, and the -C<80...8F> in C<U+100000..U+10FFFF>. The "gaps" are caused by legal -UTF-8 avoiding non-shortest encodings: it is technically possible to -UTF-8-encode a single code point in different ways, but that is -explicitly forbidden, and the shortest possible encoding should always -be used. So that's what Perl does. - -Another way to look at it is via bits: - - Code Points 1st Byte 2nd Byte 3rd Byte 4th Byte - - 0aaaaaaa 0aaaaaaa - 00000bbbbbaaaaaa 110bbbbb 10aaaaaa - ccccbbbbbbaaaaaa 1110cccc 10bbbbbb 10aaaaaa - 00000dddccccccbbbbbbaaaaaa 11110ddd 10cccccc 10bbbbbb 10aaaaaa - -As you can see, the continuation bytes all begin with C<10>, and the -leading bits of the start byte tell how many bytes the are in the -encoded character. - -=item * - -UTF-EBCDIC - -Like UTF-8 but EBCDIC-safe, in the way that UTF-8 is ASCII-safe. - -=item * - -UTF-16, UTF-16BE, UTF-16LE, Surrogates, and BOMs (Byte Order Marks) - -The followings items are mostly for reference and general Unicode -knowledge, Perl doesn't use these constructs internally. - -UTF-16 is a 2 or 4 byte encoding. The Unicode code points -C<U+0000..U+FFFF> are stored in a single 16-bit unit, and the code -points C<U+10000..U+10FFFF> in two 16-bit units. The latter case is -using I<surrogates>, the first 16-bit unit being the I<high -surrogate>, and the second being the I<low surrogate>. - -Surrogates are code points set aside to encode the C<U+10000..U+10FFFF> -range of Unicode code points in pairs of 16-bit units. The I<high -surrogates> are the range C<U+D800..U+DBFF>, and the I<low surrogates> -are the range C<U+DC00..U+DFFF>. The surrogate encoding is - - $hi = ($uni - 0x10000) / 0x400 + 0xD800; - $lo = ($uni - 0x10000) % 0x400 + 0xDC00; - -and the decoding is - - $uni = 0x10000 + ($hi - 0xD800) * 0x400 + ($lo - 0xDC00); - -If you try to generate surrogates (for example by using chr()), you -will get a warning if warnings are turned on, because those code -points are not valid for a Unicode character. - -Because of the 16-bitness, UTF-16 is byte-order dependent. UTF-16 -itself can be used for in-memory computations, but if storage or -transfer is required either UTF-16BE (big-endian) or UTF-16LE -(little-endian) encodings must be chosen. - -This introduces another problem: what if you just know that your data -is UTF-16, but you don't know which endianness? Byte Order Marks, or -BOMs, are a solution to this. A special character has been reserved -in Unicode to function as a byte order marker: the character with the -code point C<U+FEFF> is the BOM. - -The trick is that if you read a BOM, you will know the byte order, -since if it was written on a big-endian platform, you will read the -bytes C<0xFE 0xFF>, but if it was written on a little-endian platform, -you will read the bytes C<0xFF 0xFE>. (And if the originating platform -was writing in UTF-8, you will read the bytes C<0xEF 0xBB 0xBF>.) - -The way this trick works is that the character with the code point -C<U+FFFE> is guaranteed not to be a valid Unicode character, so the -sequence of bytes C<0xFF 0xFE> is unambiguously "BOM, represented in -little-endian format" and cannot be C<U+FFFE>, represented in big-endian -format". - -=item * - -UTF-32, UTF-32BE, UTF-32LE - -The UTF-32 family is pretty much like the UTF-16 family, expect that -the units are 32-bit, and therefore the surrogate scheme is not -needed. The BOM signatures will be C<0x00 0x00 0xFE 0xFF> for BE and -C<0xFF 0xFE 0x00 0x00> for LE. - -=item * - -UCS-2, UCS-4 - -Encodings defined by the ISO 10646 standard. UCS-2 is a 16-bit -encoding. Unlike UTF-16, UCS-2 is not extensible beyond C<U+FFFF>, -because it does not use surrogates. UCS-4 is a 32-bit encoding, -functionally identical to UTF-32. - -=item * - -UTF-7 - -A seven-bit safe (non-eight-bit) encoding, which is useful if the -transport or storage is not eight-bit safe. Defined by RFC 2152. - -=back - -=head2 Security Implications of Unicode - -=over 4 - -=item * - -Malformed UTF-8 - -Unfortunately, the specification of UTF-8 leaves some room for -interpretation of how many bytes of encoded output one should generate -from one input Unicode character. Strictly speaking, the shortest -possible sequence of UTF-8 bytes should be generated, -because otherwise there is potential for an input buffer overflow at -the receiving end of a UTF-8 connection. Perl always generates the -shortest length UTF-8, and with warnings on Perl will warn about -non-shortest length UTF-8 along with other malformations, such as the -surrogates, which are not real Unicode code points. - -=item * - -Regular expressions behave slightly differently between byte data and -character (Unicode) data. For example, the "word character" character -class C<\w> will work differently depending on if data is eight-bit bytes -or Unicode. - -In the first case, the set of C<\w> characters is either small--the -default set of alphabetic characters, digits, and the "_"--or, if you -are using a locale (see L<perllocale>), the C<\w> might contain a few -more letters according to your language and country. - -In the second case, the C<\w> set of characters is much, much larger. -Most importantly, even in the set of the first 256 characters, it will -probably match different characters: unlike most locales, which are -specific to a language and country pair, Unicode classifies all the -characters that are letters I<somewhere> as C<\w>. For example, your -locale might not think that LATIN SMALL LETTER ETH is a letter (unless -you happen to speak Icelandic), but Unicode does. - -As discussed elsewhere, Perl has one foot (two hooves?) planted in -each of two worlds: the old world of bytes and the new world of -characters, upgrading from bytes to characters when necessary. -If your legacy code does not explicitly use Unicode, no automatic -switch-over to characters should happen. Characters shouldn't get -downgraded to bytes, either. It is possible to accidentally mix bytes -and characters, however (see L<perluniintro>), in which case C<\w> in -regular expressions might start behaving differently. Review your -code. Use warnings and the C<strict> pragma. - -=back - -=head2 Unicode in Perl on EBCDIC - -The way Unicode is handled on EBCDIC platforms is still -experimental. On such platforms, references to UTF-8 encoding in this -document and elsewhere should be read as meaning the UTF-EBCDIC -specified in Unicode Technical Report 16, unless ASCII vs. EBCDIC issues -are specifically discussed. There is no C<utfebcdic> pragma or -":utfebcdic" layer; rather, "utf8" and ":utf8" are reused to mean -the platform's "natural" 8-bit encoding of Unicode. See L<perlebcdic> -for more discussion of the issues. - -=head2 Locales - -Usually locale settings and Unicode do not affect each other, but -there are a couple of exceptions: - -=over 4 - -=item * - -You can enable automatic UTF-8-ification of your standard file -handles, default C<open()> layer, and C<@ARGV> by using either -the C<-C> command line switch or the C<PERL_UNICODE> environment -variable, see L<perlrun> for the documentation of the C<-C> switch. - -=item * - -Perl tries really hard to work both with Unicode and the old -byte-oriented world. Most often this is nice, but sometimes Perl's -straddling of the proverbial fence causes problems. - -=back - -=head2 When Unicode Does Not Happen - -While Perl does have extensive ways to input and output in Unicode, -and few other 'entry points' like the @ARGV which can be interpreted -as Unicode (UTF-8), there still are many places where Unicode (in some -encoding or another) could be given as arguments or received as -results, or both, but it is not. - -The following are such interfaces. For all of these interfaces Perl -currently (as of 5.8.3) simply assumes byte strings both as arguments -and results, or UTF-8 strings if the C<encoding> pragma has been used. - -One reason why Perl does not attempt to resolve the role of Unicode in -this cases is that the answers are highly dependent on the operating -system and the file system(s). For example, whether filenames can be -in Unicode, and in exactly what kind of encoding, is not exactly a -portable concept. Similarly for the qx and system: how well will the -'command line interface' (and which of them?) handle Unicode? - -=over 4 - -=item * - -chdir, chmod, chown, chroot, exec, link, lstat, mkdir, -rename, rmdir, stat, symlink, truncate, unlink, utime, -X - -=item * - -%ENV - -=item * - -glob (aka the <*>) - -=item * - -open, opendir, sysopen - -=item * - -qx (aka the backtick operator), system - -=item * - -readdir, readlink - -=back - -=head2 Forcing Unicode in Perl (Or Unforcing Unicode in Perl) - -Sometimes (see L</"When Unicode Does Not Happen">) there are -situations where you simply need to force Perl to believe that a byte -string is UTF-8, or vice versa. The low-level calls -utf8::upgrade($bytestring) and utf8::downgrade($utf8string) are -the answers. - -Do not use them without careful thought, though: Perl may easily get -very confused, angry, or even crash, if you suddenly change the 'nature' -of scalar like that. Especially careful you have to be if you use the -utf8::upgrade(): any random byte string is not valid UTF-8. - -=head2 Using Unicode in XS - -If you want to handle Perl Unicode in XS extensions, you may find the -following C APIs useful. See also L<perlguts/"Unicode Support"> for an -explanation about Unicode at the XS level, and L<perlapi> for the API -details. - -=over 4 - -=item * - -C<DO_UTF8(sv)> returns true if the C<UTF8> flag is on and the bytes -pragma is not in effect. C<SvUTF8(sv)> returns true is the C<UTF8> -flag is on; the bytes pragma is ignored. The C<UTF8> flag being on -does B<not> mean that there are any characters of code points greater -than 255 (or 127) in the scalar or that there are even any characters -in the scalar. What the C<UTF8> flag means is that the sequence of -octets in the representation of the scalar is the sequence of UTF-8 -encoded code points of the characters of a string. The C<UTF8> flag -being off means that each octet in this representation encodes a -single character with code point 0..255 within the string. Perl's -Unicode model is not to use UTF-8 until it is absolutely necessary. - -=item * - -C<uvuni_to_utf8(buf, chr)> writes a Unicode character code point into -a buffer encoding the code point as UTF-8, and returns a pointer -pointing after the UTF-8 bytes. - -=item * - -C<utf8_to_uvuni(buf, lenp)> reads UTF-8 encoded bytes from a buffer and -returns the Unicode character code point and, optionally, the length of -the UTF-8 byte sequence. - -=item * - -C<utf8_length(start, end)> returns the length of the UTF-8 encoded buffer -in characters. C<sv_len_utf8(sv)> returns the length of the UTF-8 encoded -scalar. - -=item * - -C<sv_utf8_upgrade(sv)> converts the string of the scalar to its UTF-8 -encoded form. C<sv_utf8_downgrade(sv)> does the opposite, if -possible. C<sv_utf8_encode(sv)> is like sv_utf8_upgrade except that -it does not set the C<UTF8> flag. C<sv_utf8_decode()> does the -opposite of C<sv_utf8_encode()>. Note that none of these are to be -used as general-purpose encoding or decoding interfaces: C<use Encode> -for that. C<sv_utf8_upgrade()> is affected by the encoding pragma -but C<sv_utf8_downgrade()> is not (since the encoding pragma is -designed to be a one-way street). - -=item * - -C<is_utf8_char(s)> returns true if the pointer points to a valid UTF-8 -character. - -=item * - -C<is_utf8_string(buf, len)> returns true if C<len> bytes of the buffer -are valid UTF-8. - -=item * - -C<UTF8SKIP(buf)> will return the number of bytes in the UTF-8 encoded -character in the buffer. C<UNISKIP(chr)> will return the number of bytes -required to UTF-8-encode the Unicode character code point. C<UTF8SKIP()> -is useful for example for iterating over the characters of a UTF-8 -encoded buffer; C<UNISKIP()> is useful, for example, in computing -the size required for a UTF-8 encoded buffer. - -=item * - -C<utf8_distance(a, b)> will tell the distance in characters between the -two pointers pointing to the same UTF-8 encoded buffer. - -=item * - -C<utf8_hop(s, off)> will return a pointer to an UTF-8 encoded buffer -that is C<off> (positive or negative) Unicode characters displaced -from the UTF-8 buffer C<s>. Be careful not to overstep the buffer: -C<utf8_hop()> will merrily run off the end or the beginning of the -buffer if told to do so. - -=item * - -C<pv_uni_display(dsv, spv, len, pvlim, flags)> and -C<sv_uni_display(dsv, ssv, pvlim, flags)> are useful for debugging the -output of Unicode strings and scalars. By default they are useful -only for debugging--they display B<all> characters as hexadecimal code -points--but with the flags C<UNI_DISPLAY_ISPRINT>, -C<UNI_DISPLAY_BACKSLASH>, and C<UNI_DISPLAY_QQ> you can make the -output more readable. - -=item * - -C<ibcmp_utf8(s1, pe1, u1, l1, u1, s2, pe2, l2, u2)> can be used to -compare two strings case-insensitively in Unicode. For case-sensitive -comparisons you can just use C<memEQ()> and C<memNE()> as usual. - -=back - -For more information, see L<perlapi>, and F<utf8.c> and F<utf8.h> -in the Perl source code distribution. - -=head1 BUGS - -=head2 Interaction with Locales - -Use of locales with Unicode data may lead to odd results. Currently, -Perl attempts to attach 8-bit locale info to characters in the range -0..255, but this technique is demonstrably incorrect for locales that -use characters above that range when mapped into Unicode. Perl's -Unicode support will also tend to run slower. Use of locales with -Unicode is discouraged. - -=head2 Interaction with Extensions - -When Perl exchanges data with an extension, the extension should be -able to understand the UTF8 flag and act accordingly. If the -extension doesn't know about the flag, it's likely that the extension -will return incorrectly-flagged data. - -So if you're working with Unicode data, consult the documentation of -every module you're using if there are any issues with Unicode data -exchange. If the documentation does not talk about Unicode at all, -suspect the worst and probably look at the source to learn how the -module is implemented. Modules written completely in Perl shouldn't -cause problems. Modules that directly or indirectly access code written -in other programming languages are at risk. - -For affected functions, the simple strategy to avoid data corruption is -to always make the encoding of the exchanged data explicit. Choose an -encoding that you know the extension can handle. Convert arguments passed -to the extensions to that encoding and convert results back from that -encoding. Write wrapper functions that do the conversions for you, so -you can later change the functions when the extension catches up. - -To provide an example, let's say the popular Foo::Bar::escape_html -function doesn't deal with Unicode data yet. The wrapper function -would convert the argument to raw UTF-8 and convert the result back to -Perl's internal representation like so: - - sub my_escape_html ($) { - my($what) = shift; - return unless defined $what; - Encode::decode_utf8(Foo::Bar::escape_html(Encode::encode_utf8($what))); - } - -Sometimes, when the extension does not convert data but just stores -and retrieves them, you will be in a position to use the otherwise -dangerous Encode::_utf8_on() function. Let's say the popular -C<Foo::Bar> extension, written in C, provides a C<param> method that -lets you store and retrieve data according to these prototypes: - - $self->param($name, $value); # set a scalar - $value = $self->param($name); # retrieve a scalar - -If it does not yet provide support for any encoding, one could write a -derived class with such a C<param> method: - - sub param { - my($self,$name,$value) = @_; - utf8::upgrade($name); # make sure it is UTF-8 encoded - if (defined $value) { - utf8::upgrade($value); # make sure it is UTF-8 encoded - return $self->SUPER::param($name,$value); - } else { - my $ret = $self->SUPER::param($name); - Encode::_utf8_on($ret); # we know, it is UTF-8 encoded - return $ret; - } - } - -Some extensions provide filters on data entry/exit points, such as -DB_File::filter_store_key and family. Look out for such filters in -the documentation of your extensions, they can make the transition to -Unicode data much easier. - -=head2 Speed - -Some functions are slower when working on UTF-8 encoded strings than -on byte encoded strings. All functions that need to hop over -characters such as length(), substr() or index(), or matching regular -expressions can work B<much> faster when the underlying data are -byte-encoded. - -In Perl 5.8.0 the slowness was often quite spectacular; in Perl 5.8.1 -a caching scheme was introduced which will hopefully make the slowness -somewhat less spectacular, at least for some operations. In general, -operations with UTF-8 encoded strings are still slower. As an example, -the Unicode properties (character classes) like C<\p{Nd}> are known to -be quite a bit slower (5-20 times) than their simpler counterparts -like C<\d> (then again, there 268 Unicode characters matching C<Nd> -compared with the 10 ASCII characters matching C<d>). - -=head2 Porting code from perl-5.6.X - -Perl 5.8 has a different Unicode model from 5.6. In 5.6 the programmer -was required to use the C<utf8> pragma to declare that a given scope -expected to deal with Unicode data and had to make sure that only -Unicode data were reaching that scope. If you have code that is -working with 5.6, you will need some of the following adjustments to -your code. The examples are written such that the code will continue -to work under 5.6, so you should be safe to try them out. - -=over 4 - -=item * - -A filehandle that should read or write UTF-8 - - if ($] > 5.007) { - binmode $fh, ":encoding(utf8)"; - } - -=item * - -A scalar that is going to be passed to some extension - -Be it Compress::Zlib, Apache::Request or any extension that has no -mention of Unicode in the manpage, you need to make sure that the -UTF8 flag is stripped off. Note that at the time of this writing -(October 2002) the mentioned modules are not UTF-8-aware. Please -check the documentation to verify if this is still true. - - if ($] > 5.007) { - require Encode; - $val = Encode::encode_utf8($val); # make octets - } - -=item * - -A scalar we got back from an extension - -If you believe the scalar comes back as UTF-8, you will most likely -want the UTF8 flag restored: - - if ($] > 5.007) { - require Encode; - $val = Encode::decode_utf8($val); - } - -=item * - -Same thing, if you are really sure it is UTF-8 - - if ($] > 5.007) { - require Encode; - Encode::_utf8_on($val); - } - -=item * - -A wrapper for fetchrow_array and fetchrow_hashref - -When the database contains only UTF-8, a wrapper function or method is -a convenient way to replace all your fetchrow_array and -fetchrow_hashref calls. A wrapper function will also make it easier to -adapt to future enhancements in your database driver. Note that at the -time of this writing (October 2002), the DBI has no standardized way -to deal with UTF-8 data. Please check the documentation to verify if -that is still true. - - sub fetchrow { - my($self, $sth, $what) = @_; # $what is one of fetchrow_{array,hashref} - if ($] < 5.007) { - return $sth->$what; - } else { - require Encode; - if (wantarray) { - my @arr = $sth->$what; - for (@arr) { - defined && /[^\000-\177]/ && Encode::_utf8_on($_); - } - return @arr; - } else { - my $ret = $sth->$what; - if (ref $ret) { - for my $k (keys %$ret) { - defined && /[^\000-\177]/ && Encode::_utf8_on($_) for $ret->{$k}; - } - return $ret; - } else { - defined && /[^\000-\177]/ && Encode::_utf8_on($_) for $ret; - return $ret; - } - } - } - } - - -=item * - -A large scalar that you know can only contain ASCII - -Scalars that contain only ASCII and are marked as UTF-8 are sometimes -a drag to your program. If you recognize such a situation, just remove -the UTF8 flag: - - utf8::downgrade($val) if $] > 5.007; - -=back - -=head1 SEE ALSO - -L<perlunitut>, L<perluniintro>, L<Encode>, L<open>, L<utf8>, L<bytes>, -L<perlretut>, L<perlvar/"${^UNICODE}"> - -=cut |