Package com.ibm.icu.impl

Class UnicodeRegex

    • Constructor Detail

      • UnicodeRegex

        public UnicodeRegex()

    • Method Detail

      • getSymbolTable

        public SymbolTable getSymbolTable()
        Set the symbol table for internal processing

      • setSymbolTable

        public UnicodeRegex setSymbolTable​(SymbolTable symbolTable)
        Get the symbol table for internal processing

      • transform

        public String transform​(String regex)
        Adds full Unicode property support, with the latest version of Unicode, to Java Regex, bringing it up to Level 1 (see http://www.unicode.org/reports/tr18/). It does this by preprocessing the regex pattern string and interpreting the character classes (\p{...}, \P{...}, [...]) according to their syntax and meaning in UnicodeSet. With this utility, Java regex expressions can be updated to work with the latest version of Unicode, and with all Unicode properties. Note that the UnicodeSet syntax has not yet, however, been updated to be completely consistent with Java regex, so be careful of the differences.

        Not thread-safe; create a separate copy for different threads.

        In the future, we may extend this to support other regex packages.

        Specified by:
        transform in interface StringTransform
        Specified by:
        transform in interface Transform<String,​String>
        Parameters:
        regex - text to be transformed (eg lowercased)
        Returns:
        A processed Java regex pattern, suitable for input to Pattern.compile().

      • fix

        public static String fix​(String regex)
        Convenience static function, using standard parameters.
        Parameters:
        regex - as in process()
        Returns:
        processed regex pattern, as in process()

      • compile

        public static Pattern compile​(String regex)
        Compile a regex string, after processing by fix(...).
        Parameters:
        regex - Raw regex pattern, as in fix(...).
        Returns:
        Pattern

      • compile

        public static Pattern compile​(String regex,
                              int options)
        Compile a regex string, after processing by fix(...).
        Parameters:
        regex - Raw regex pattern, as in fix(...).
        Returns:
        Pattern

      • compileBnf

        public String compileBnf​(String bnfLines)
        Compile a composed string from a set of BNF lines; see the List version for more information.
        Parameters:
        bnfLines - Series of BNF lines.
        Returns:
        Pattern

      • compileBnf

        public String compileBnf​(List<String> lines)
        Compile a composed string from a set of BNF lines, such as for composing a regex expression. The lines can be in any order, but there must not be any cycles. The result can be used as input for fix().

        Example: 

         uri = (?: (scheme) \\:)? (host) (?: \\? (query))? (?: \\u0023 (fragment))?;
 scheme = reserved+;
 host = // reserved+;
 query = [\\=reserved]+;
 fragment = reserved+;
 reserved = [[:ascii:][:alphabetic:]];

        Caveats: at this point the parsing is simple; for example, # cannot be quoted (use \\u0023); you can set it to null to disable. The equality sign and a few others can be reset with setBnfX().

        Parameters:
        lines - Series of lines that represent a BNF expression. The lines contain a series of statements that of the form x=y;. A statement can take multiple lines, but there can't be multiple statements on a line. A hash quotes to the end of the line.
        Returns:
        Pattern

      • getBnfCommentString

        public String getBnfCommentString()

      • setBnfCommentString

        public void setBnfCommentString​(String bnfCommentString)

      • getBnfVariableInfix

        public String getBnfVariableInfix()

      • setBnfVariableInfix

        public void setBnfVariableInfix​(String bnfVariableInfix)

      • getBnfLineSeparator

        public String getBnfLineSeparator()

      • setBnfLineSeparator

        public void setBnfLineSeparator​(String bnfLineSeparator)

      • appendLines

        public static List<String> appendLines​(List<String> result,
                                       String file,
                                       String encoding)
                                throws IOException
        Utility for loading lines from a file.
        Parameters:
        result - The result of the appended lines.
        file - The file to have an input stream.
        encoding - if null, then UTF-8
        Returns:
        filled list
        Throws:
        IOException - If there were problems opening the file for input stream.

      • isFrozen

        public boolean isFrozen()
        Description copied from interface: Freezable
        Determines whether the object has been frozen or not.
        Specified by:
        isFrozen in interface Freezable<UnicodeRegex>