gnu.regexp
Class RE

java.lang.Object
  |
  +--gnu.regexp.REToken
        |
        +--gnu.regexp.RE

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

RegExFilter

public class RE

extends gnu.regexp.REToken

RE provides the user interface for compiling and matching regular expressions.

A regular expression object (class RE) is compiled by constructing it from a String, StringBuffer or character array, with optional compilation flags (below) and an optional syntax specification (see RESyntax; if not specified, RESyntax.RE_SYNTAX_PERL5 is used).

Various methods attempt to match input text against a compiled regular expression. These methods are:

isMatch: returns true if the input text in its entirety matches the regular expression pattern.

getMatch: returns the first match found in the input text, or null if no match is found.

getAllMatches: returns an array of all non-overlapping matches found in the input text. If no matches are found, the array is zero-length.

substitute: substitute the first occurence of the pattern in the input text with a replacement string (which may include metacharacters $0-$9, see REMatch.substituteInto).

substituteAll: same as above, but repeat for each match before returning.

getMatchEnumeration: returns an REMatchEnumeration object that allows iteration over the matches (see REMatchEnumeration for some reasons why you may want to do this instead of using getAllMatches.

These methods all have similar argument lists. The input can be a String, a character array, a StringBuffer, a Reader or an InputStream of some sort. Note that when using a Reader or InputStream, the stream read position cannot be guaranteed after attempting a match (this is not a bug, but a consequence of the way regular expressions work). Using an REMatchEnumeration can eliminate most positioning problems.

The optional index argument specifies the offset from the beginning of the text at which the search should start (see the descriptions of some of the execution flags for how this can affect positional pattern operators). For a Reader or InputStream, this means an offset from the current read position, so subsequent calls with the same index argument on a Reader or an InputStream will not necessarily be accessing the same position on the stream, whereas repeated searches at a given index in a fixed string will return consistent results.

You can optionally affect the execution environment by using a combination of execution flags (constants listed below).

See Also:

Serialized Form

Field Summary

protected gnu.regexp.REToken	m_next
protected int	m_subIndex
protected gnu.regexp.REToken	m_uncle
static int	REG_ANCHORINDEX Execution flag.
static int	REG_DOT_NEWLINE Compilation flag.
static int	REG_ICASE Compilation flag.
static int	REG_MULTILINE Compilation flag.
static int	REG_NO_INTERPOLATE Execution flag.
static int	REG_NOTBOL Execution flag.
static int	REG_NOTEOL Execution flag.

Constructor Summary

RE(java.lang.Object pattern)
Constructs a regular expression pattern buffer without any compilation flags set, and using the default syntax (RESyntax.RE_SYNTAX_PERL5).

RE(java.lang.Object pattern, int cflags)
Constructs a regular expression pattern buffer using the specified compilation flags and the default syntax (RESyntax.RE_SYNTAX_PERL5).

RE(java.lang.Object pattern, int cflags, RESyntax syntax)
Constructs a regular expression pattern buffer using the specified compilation flags and regular expression syntax.

Method Summary

REMatch[]	getAllMatches(java.lang.Object input) Returns an array of all matches found in the input.
REMatch[]	getAllMatches(java.lang.Object input, int index) Returns an array of all matches found in the input, beginning at the specified index position.
REMatch[]	getAllMatches(java.lang.Object input, int index, int eflags) Returns an array of all matches found in the input string, beginning at the specified index position and using the specified execution flags.
REMatch	getMatch(java.lang.Object input) Returns the first match found in the input.
REMatch	getMatch(java.lang.Object input, int index) Returns the first match found in the input, beginning the search at the specified index.
REMatch	getMatch(java.lang.Object input, int index, int eflags) Returns the first match found in the input, beginning the search at the specified index, and using the specified execution flags.
REMatch	getMatch(java.lang.Object input, int index, int eflags, java.lang.StringBuffer buffer) Returns the first match found in the input, beginning the search at the specified index, and using the specified execution flags.
REMatchEnumeration	getMatchEnumeration(java.lang.Object input) Returns an REMatchEnumeration that can be used to iterate over the matches found in the input text.
REMatchEnumeration	getMatchEnumeration(java.lang.Object input, int index) Returns an REMatchEnumeration that can be used to iterate over the matches found in the input text.
REMatchEnumeration	getMatchEnumeration(java.lang.Object input, int index, int eflags) Returns an REMatchEnumeration that can be used to iterate over the matches found in the input text.
int	getMinimumLength() Returns the minimum number of characters that could possibly constitute a match of this regular expression.
int	getNumSubs() Returns the maximum number of subexpressions in this regular expression.
boolean	isMatch(java.lang.Object input) Checks if the input in its entirety is an exact match of this regular expression.
boolean	isMatch(java.lang.Object input, int index) Checks if the input string, starting from index, is an exact match of this regular expression.
boolean	isMatch(java.lang.Object input, int index, int eflags) Checks if the input, starting from index and using the specified execution flags, is an exact match of this regular expression.
protected boolean	next(CharIndexed input, REMatch mymatch) Returns true if the rest of the tokens match, false if they fail.
java.lang.String	substitute(java.lang.Object input, java.lang.String replace) Substitutes the replacement text for the first match found in the input.
java.lang.String	substitute(java.lang.Object input, java.lang.String replace, int index) Substitutes the replacement text for the first match found in the input beginning at the specified index position.
java.lang.String	substitute(java.lang.Object input, java.lang.String replace, int index, int eflags) Substitutes the replacement text for the first match found in the input string, beginning at the specified index position and using the specified execution flags.
java.lang.String	substituteAll(java.lang.Object input, java.lang.String replace) Substitutes the replacement text for each non-overlapping match found in the input text.
java.lang.String	substituteAll(java.lang.Object input, java.lang.String replace, int index) Substitutes the replacement text for each non-overlapping match found in the input text, starting at the specified index.
java.lang.String	substituteAll(java.lang.Object input, java.lang.String replace, int index, int eflags) Substitutes the replacement text for each non-overlapping match found in the input text, starting at the specified index and using the specified execution flags.
java.lang.String	toString() Return a human readable form of the compiled regular expression, useful for debugging.
static java.lang.String	version() Returns a string representing the version of the gnu.regexp package.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

REG_ICASE

public static final int REG_ICASE

Compilation flag. Do not differentiate case. Subsequent searches using this RE will be case insensitive.

REG_DOT_NEWLINE

public static final int REG_DOT_NEWLINE

Compilation flag. The match-any-character operator (dot) will match a newline character. When set this overrides the syntax bit RE_DOT_NEWLINE (see RESyntax for details). This is equivalent to the "/s" operator in Perl.

REG_MULTILINE

public static final int REG_MULTILINE

Compilation flag. Use multiline mode. In this mode, the ^ and $ anchors will match based on newlines within the input. This is equivalent to the "/m" operator in Perl.

REG_NOTBOL

public static final int REG_NOTBOL

Execution flag. The match-beginning operator (^) will not match at the beginning of the input string. Useful for matching on a substring when you know the context of the input is such that position zero of the input to the match test is not actually position zero of the text.

This example demonstrates the results of various ways of matching on a substring.

String s = "food bar fool";
RE exp = new RE("^foo.");
REMatch m0 = exp.getMatch(s);
REMatch m1 = exp.getMatch(s.substring(8));
REMatch m2 = exp.getMatch(s.substring(8),0,RE.REG_NOTBOL);
REMatch m3 = exp.getMatch(s,8);
REMatch m4 = exp.getMatch(s,8,RE.REG_ANCHORINDEX);


// Results:
// m0 = "food"
// m1 = "fool"
// m2 = null
// m3 = null
// m4 = "fool"


REG_NOTEOL

public static final int REG_NOTEOL

Execution flag. The match-end operator ($) does not match at the end of the input string. Useful for matching on substrings.

REG_ANCHORINDEX

public static final int REG_ANCHORINDEX

Execution flag. The match-beginning operator (^) matches not at position 0 in the input string, but at the position the search started at (based on the index input given to the getMatch function). See the example under REG_NOTBOL.

REG_NO_INTERPOLATE

public static final int REG_NO_INTERPOLATE

Execution flag. The substitute and substituteAll methods will not attempt to interpolate occurrences of $1-$9 in the replacement text with the corresponding subexpressions. For example, you may want to replace all matches of "one dollar" with "$1".

m_next

protected gnu.regexp.REToken m_next

m_uncle

protected gnu.regexp.REToken m_uncle

m_subIndex

protected int m_subIndex

Constructor Detail

RE

public RE(java.lang.Object pattern)
   throws REException

Constructs a regular expression pattern buffer without any compilation flags set, and using the default syntax (RESyntax.RE_SYNTAX_PERL5).

Parameters:

pattern - A regular expression pattern, in the form of a String, StringBuffer or char[]. Other input types will be converted to strings using the toString() method.

Throws:

REException - The input pattern could not be parsed.

NullPointerException - The pattern was null.

RE

public RE(java.lang.Object pattern,
          int cflags)
   throws REException

Constructs a regular expression pattern buffer using the specified compilation flags and the default syntax (RESyntax.RE_SYNTAX_PERL5).

Parameters:

pattern - A regular expression pattern, in the form of a String, StringBuffer, or char[]. Other input types will be converted to strings using the toString() method.

cflags - The logical OR of any combination of the compilation flags listed above.

Throws:

REException - The input pattern could not be parsed.

NullPointerException - The pattern was null.

RE

public RE(java.lang.Object pattern,
          int cflags,
          RESyntax syntax)
   throws REException

Constructs a regular expression pattern buffer using the specified compilation flags and regular expression syntax.

Parameters:

pattern - A regular expression pattern, in the form of a String, StringBuffer, or char[]. Other input types will be converted to strings using the toString() method.

cflags - The logical OR of any combination of the compilation flags listed above.

syntax - The type of regular expression syntax to use.

Throws:

REException - The input pattern could not be parsed.

NullPointerException - The pattern was null.

Method Detail

version

public static final java.lang.String version()

Returns a string representing the version of the gnu.regexp package.

isMatch

public boolean isMatch(java.lang.Object input)

Checks if the input in its entirety is an exact match of this regular expression.

Parameters:

input - The input text.

isMatch

public boolean isMatch(java.lang.Object input,
                       int index)

Checks if the input string, starting from index, is an exact match of this regular expression.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

isMatch

public boolean isMatch(java.lang.Object input,
                       int index,
                       int eflags)

Checks if the input, starting from index and using the specified execution flags, is an exact match of this regular expression.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

getNumSubs

public int getNumSubs()

Returns the maximum number of subexpressions in this regular expression. If the expression contains branches, the value returned will be the maximum subexpressions in any of the branches.

getMinimumLength

public int getMinimumLength()

Returns the minimum number of characters that could possibly constitute a match of this regular expression.

getAllMatches

public REMatch[] getAllMatches(java.lang.Object input)

Returns an array of all matches found in the input. If the regular expression allows the empty string to match, it will substitute matches at all positions except the end of the input.

Parameters:

input - The input text.

Returns:

a non-null (but possibly zero-length) array of matches

getAllMatches

public REMatch[] getAllMatches(java.lang.Object input,
                               int index)

Returns an array of all matches found in the input, beginning at the specified index position. If the regular expression allows the empty string to match, it will substitute matches at all positions except the end of the input.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

Returns:

a non-null (but possibly zero-length) array of matches

getAllMatches

public REMatch[] getAllMatches(java.lang.Object input,
                               int index,
                               int eflags)

Returns an array of all matches found in the input string, beginning at the specified index position and using the specified execution flags. If the regular expression allows the empty string to match, it will substitute matches at all positions except the end of the input.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

Returns:

a non-null (but possibly zero-length) array of matches

getMatch

public REMatch getMatch(java.lang.Object input)

Returns the first match found in the input. If no match is found, null is returned.

Parameters:

input - The input text.

getMatch

public REMatch getMatch(java.lang.Object input,
                        int index)

Returns the first match found in the input, beginning the search at the specified index. If no match is found, returns null.

Parameters:

input - The input text.

index - The offset within the text to begin looking for a match.

getMatch

public REMatch getMatch(java.lang.Object input,
                        int index,
                        int eflags)

Returns the first match found in the input, beginning the search at the specified index, and using the specified execution flags. If no match is found, returns null.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

getMatch

public REMatch getMatch(java.lang.Object input,
                        int index,
                        int eflags,
                        java.lang.StringBuffer buffer)

Returns the first match found in the input, beginning the search at the specified index, and using the specified execution flags. If no match is found, returns null. If a StringBuffer is provided and is non-null, the contents of the input text from the index to the beginning of the match (or to the end of the input, if there is no match) are appended to the StringBuffer.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

buffer - The StringBuffer to save pre-match text in.

getMatchEnumeration

public REMatchEnumeration getMatchEnumeration(java.lang.Object input)

Returns an REMatchEnumeration that can be used to iterate over the matches found in the input text.

Parameters:

input - The input text.

getMatchEnumeration

public REMatchEnumeration getMatchEnumeration(java.lang.Object input,
                                              int index)

Returns an REMatchEnumeration that can be used to iterate over the matches found in the input text.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

getMatchEnumeration

public REMatchEnumeration getMatchEnumeration(java.lang.Object input,
                                              int index,
                                              int eflags)

Returns an REMatchEnumeration that can be used to iterate over the matches found in the input text.

Parameters:

input - The input text.

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

substitute

public java.lang.String substitute(java.lang.Object input,
                                   java.lang.String replace)

Substitutes the replacement text for the first match found in the input.

Parameters:

input - The input text.

replace - The replacement text, which may contain $x metacharacters (see REMatch.substituteInto).

See Also:

REMatch.substituteInto(java.lang.String)

substitute

public java.lang.String substitute(java.lang.Object input,
                                   java.lang.String replace,
                                   int index)

Substitutes the replacement text for the first match found in the input beginning at the specified index position.

Parameters:

input - The input text.

replace - The replacement text, which may contain $x metacharacters (see REMatch.substituteInto).

index - The offset index at which the search should be begin.

See Also:

REMatch.substituteInto(java.lang.String)

substitute

public java.lang.String substitute(java.lang.Object input,
                                   java.lang.String replace,
                                   int index,
                                   int eflags)

Substitutes the replacement text for the first match found in the input string, beginning at the specified index position and using the specified execution flags.

Parameters:

input - The input text.

replace - The replacement text, which may contain $x metacharacters (see REMatch.substituteInto).

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

See Also:

REMatch.substituteInto(java.lang.String)

substituteAll

public java.lang.String substituteAll(java.lang.Object input,
                                      java.lang.String replace)

Substitutes the replacement text for each non-overlapping match found in the input text.

Parameters:

input - The input text.

replace - The replacement text, which may contain $x metacharacters (see REMatch.substituteInto).

See Also:

REMatch.substituteInto(java.lang.String)

substituteAll

public java.lang.String substituteAll(java.lang.Object input,
                                      java.lang.String replace,
                                      int index)

Substitutes the replacement text for each non-overlapping match found in the input text, starting at the specified index. If the regular expression allows the empty string to match, it will substitute matches at all positions except the end of the input.

Parameters:

input - The input text.

replace - The replacement text, which may contain $x metacharacters (see REMatch.substituteInto).

index - The offset index at which the search should be begin.

See Also:

REMatch.substituteInto(java.lang.String)

substituteAll

public java.lang.String substituteAll(java.lang.Object input,
                                      java.lang.String replace,
                                      int index,
                                      int eflags)

Substitutes the replacement text for each non-overlapping match found in the input text, starting at the specified index and using the specified execution flags.

Parameters:

input - The input text.

replace - The replacement text, which may contain $x metacharacters (see REMatch.substituteInto).

index - The offset index at which the search should be begin.

eflags - The logical OR of any execution flags above.

See Also:

REMatch.substituteInto(java.lang.String)

toString

public java.lang.String toString()

Return a human readable form of the compiled regular expression, useful for debugging.

Overrides:

toString in class java.lang.Object

next

protected boolean next(CharIndexed input,
                       REMatch mymatch)

Returns true if the rest of the tokens match, false if they fail.