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Class com.oroinc.text.awk.AwkCompiler

java.lang.Object
   |
   +----com.oroinc.text.awk.AwkCompiler

public final class AwkCompiler
extends Object
implements PatternCompiler

The AwkCompiler class is used to create compiled regular expressions conforming to the Awk regular expression syntax. It generates AwkPattern instances upon compilation to be used in conjunction with an AwkMatcher instance. AwkMatcher finds true leftmost-longest matches, so you must take care with how you formulate your regular expression to avoid matching more than you really want.

The supported regular expression syntax is a superset of traditional AWK, but NOT to be confused with GNU AWK or other AWK variants. Additionally, this AWK implementation is DFA-based and only supports 8-bit ASCII. Consequently, these classes can perform very fast pattern matches in most cases.

This is the traditional Awk syntax that is supported:

Alternatives separated by |
Quantified atoms

*
Match 0 or more times.
+
Match 1 or more times.
?
Match 0 or 1 times.
Atoms
- regular expression within parentheses
- a . matches everything including newline
- a ^ is a null token matching the beginning of a string but has no relation to newlines (and is only valid at the beginning of a regex; this differs from traditional awk for the sake of efficiency in Java).
- a $ is a null token matching the end of a string but has no relation to newlines (and is only valid at the end of a regex; this differs from traditional awk for the sake of efficiency in Java).
- Character classes (e.g., [abcd]) and ranges (e.g. [a-z])
  - Special backslashed characters work within a character class
- Special backslashed characters
  
  \b
  backspace
  \n
  newline
  \r
  carriage return
  \t
  tab
  \f
  formfeed
  \xnn
  hexadecimal representation of character
  \nn or \nnn
  octal representation of character
  Any other backslashed character matches itself

This is the extended syntax that is supported:

Quantified atoms

{n,m}
Match at least n but not more than m times.
{n,}
Match at least n times.
{n}
Match exactly n times.
Atoms
- Special backslashed characters
  
  \d
  digit [0-9]
  \D
  non-digit [^0-9]
  \w
  word character [0-9a-z_A-Z]
  \W
  a non-word character [^0-9a-z_A-Z]
  \s
  a whitespace character [ \t\n\r\f]
  \S
  a non-whitespace character [^ \t\n\r\f]
  \cD
  matches the corresponding control character
  \0
  matches null character

See Also:: PatternCompiler, MalformedPatternException, AwkPattern, AwkMatcher

CASE_INSENSITIVE_MASK
DEFAULT_MASK

AwkCompiler()

compile(char[]): Same as calling compile(pattern, AwkCompiler.DEFAULT_MASK);
compile(char[], int): Compiles an Awk regular expression into an AwkPattern instance that can be used by an AwkMatcher object to perform pattern matching.
compile(String): Same as calling compile(pattern, AwkCompiler.DEFAULT_MASK);
compile(String, int): Compiles an Awk regular expression into an AwkPattern instance that can be used by an AwkMatcher object to perform pattern matching.

DEFAULT_MASK

 public static final int DEFAULT_MASK

CASE_INSENSITIVE_MASK

 public static final int CASE_INSENSITIVE_MASK

AwkCompiler

 public AwkCompiler()

compile

 public Pattern compile(char pattern[],
                        int options) throws MalformedPatternException

Compiles an Awk regular expression into an AwkPattern instance that can be used by an AwkMatcher object to perform pattern matching.

Parameters:: pattern - An Awkregular expression to compile.; options - A set of flags giving the compiler instructions on how to treat the regular expression. Currently the only meaningful flag is AwkCompiler.CASE_INSENSITIVE_MASK.
Returns:: A Pattern instance constituting the compiled regular expression. This instance will always be an AwkPattern and can be reliably be casted to an AwkPattern.
Throws: MalformedPatternException: If the compiled expression is not a valid Awk regular expression.

compile

 public Pattern compile(String pattern,
                        int options) throws MalformedPatternException

Compiles an Awk regular expression into an AwkPattern instance that can be used by an AwkMatcher object to perform pattern matching.

Parameters:: pattern - An Awkregular expression to compile.; options - A set of flags giving the compiler instructions on how to treat the regular expression. Currently the only meaningful flag is AwkCompiler.CASE_INSENSITIVE_MASK.
Returns:: A Pattern instance constituting the compiled regular expression. This instance will always be an AwkPattern and can be reliably be casted to an AwkPattern.
Throws: MalformedPatternException: If the compiled expression is not a valid Awk regular expression.

compile

 public Pattern compile(char pattern[]) throws MalformedPatternException

Same as calling compile(pattern, AwkCompiler.DEFAULT_MASK);

Parameters:: pattern - A regular expression to compile.
Returns:: A Pattern instance constituting the compiled regular expression. This instance will always be an AwkPattern and can be reliably be casted to an AwkPattern.
Throws: MalformedPatternException: If the compiled expression is not a valid Awk regular expression.

compile

 public Pattern compile(String pattern) throws MalformedPatternException

Same as calling compile(pattern, AwkCompiler.DEFAULT_MASK);

Parameters:: pattern - A regular expression to compile.
Returns:: A Pattern instance constituting the compiled regular expression. This instance will always be an AwkPattern and can be reliably be casted to an AwkPattern.
Throws: MalformedPatternException: If the compiled expression is not a valid Awk regular expression.

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