org.gnome.glib.MatchInfo

All Implemented Interfaces:: Proxy

@Generated("org.javagi.JavaGI") public class MatchInfo extends ProxyInstance

A GMatchInfo is an opaque struct used to return information about matches.

Constructor Summary

Constructors

Constructor

Description

MatchInfo(MemorySegment address)

Create a MatchInfo proxy instance for the provided memory address.
Method Summary

Modifier and Type

Method

Description

@Nullable String

expandReferences(String stringToExpand)

Returns a new string containing the text in stringToExpand with references and escape sequences expanded.

@Nullable String

fetch(int matchNum)

Retrieves the text matching the matchNum'th capturing parentheses.

String[]

fetchAll()

Bundles up pointers to each of the matching substrings from a match and stores them in an array of gchar pointers.

@Nullable String

fetchNamed(String name)

Retrieves the text matching the capturing parentheses named name.

boolean

fetchNamedPos(String name, @Nullable Out<Integer> startPos, @Nullable Out<Integer> endPos)

Retrieves the position in bytes of the capturing parentheses named name.

boolean

fetchPos(int matchNum, @Nullable Out<Integer> startPos, @Nullable Out<Integer> endPos)

Returns the start and end positions (in bytes) of a successfully matching capture parenthesis.

void

free()

If this MatchInfo is not null, calls g_match_info_unref(); otherwise does nothing.

int

getMatchCount()

Retrieves the number of matched substrings (including substring 0, that is the whole matched text), so 1 is returned if the pattern has no substrings in it and 0 is returned if the match failed.

static MemoryLayout

getMemoryLayout()

The memory layout of the native struct.

Regex

getRegex()

Returns GRegex object used in matchInfo. It belongs to Glib and must not be freed.

String

getString()

Returns the string searched with matchInfo. This is the string passed to g_regex_match() or g_regex_replace() so you may not free it before calling this function.

static @Nullable Type

getType()

Get the GType of the MatchInfo class.

boolean

isPartialMatch()

Usually if the string passed to g_regex_match*() matches as far as it goes, but is too short to match the entire pattern, false is returned.

boolean

matches()

Returns whether the previous match operation succeeded.

boolean

next()

Scans for the next match using the same parameters of the previous call to g_regex_match_full() or g_regex_match() that returned matchInfo.

MatchInfo

ref()

Increases reference count of this MatchInfo by 1.

void

unref()

Decreases reference count of this MatchInfo by 1.

Methods inherited from class ProxyInstance
equals, handle, hashCode

Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details
- MatchInfo
  
  public MatchInfo(MemorySegment address)
  
  Create a MatchInfo proxy instance for the provided memory address.
  
  Parameters:
  
  address - the memory address of the native object

Method Details

getType

public static @Nullable Type getType()

Get the GType of the MatchInfo class.

Returns:

the GType
getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout
expandReferences

public @Nullable String expandReferences(String stringToExpand) throws GErrorException

Returns a new string containing the text in stringToExpand with references and escape sequences expanded. References refer to the last match done with string against regex and have the same syntax used by g_regex_replace().

The stringToExpand must be UTF-8 encoded even if RegexCompileFlags.RAW was passed to g_regex_new().

The backreferences are extracted from the string passed to the match function, so you cannot call this function after freeing the string.

this MatchInfo may be null in which case stringToExpand must not contain references. For instance "foo\n" does not refer to an actual pattern and '\n' merely will be replaced with \n character, while to expand "\0" (whole match) one needs the result of a match. Use g_regex_check_replacement() to find out whether stringToExpand contains references.

Parameters:

stringToExpand - the string to expand

Returns:

the expanded string, or null if an error occurred

Throws:

GErrorException - see GError

Since:

2.14
fetch

public @Nullable String fetch(int matchNum)

Retrieves the text matching the matchNum'th capturing parentheses. 0 is the full text of the match, 1 is the first paren set, 2 the second, and so on.

If matchNum is a valid sub pattern but it didn't match anything (e.g. sub pattern 1, matching "b" against "(a)?b") then an empty string is returned.

If the match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved string is not that of a set of parentheses but that of a matched substring. Substrings are matched in reverse order of length, so 0 is the longest match.

The string is fetched from the string passed to the match function, so you cannot call this function after freeing the string.

Parameters:

matchNum - number of the sub expression

Returns:

The matched substring, or null if an error occurred. You have to free the string yourself

Since:

2.14
fetchAll

public String[] fetchAll()

Bundles up pointers to each of the matching substrings from a match and stores them in an array of gchar pointers. The first element in the returned array is the match number 0, i.e. the entire matched text.

If a sub pattern didn't match anything (e.g. sub pattern 1, matching "b" against "(a)?b") then an empty string is inserted.

If the last match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved strings are not that matched by sets of parentheses but that of the matched substring. Substrings are matched in reverse order of length, so the first one is the longest match.

The strings are fetched from the string passed to the match function, so you cannot call this function after freeing the string.

Returns:

a null-terminated array of gchar * pointers. It must be freed using g_strfreev(). If the previous match failed null is returned

Since:

2.14
fetchNamed

public @Nullable String fetchNamed(String name)

Retrieves the text matching the capturing parentheses named name.

If name is a valid sub pattern name but it didn't match anything (e.g. sub pattern "X", matching "b" against "(?P<X>a)?b") then an empty string is returned.

The string is fetched from the string passed to the match function, so you cannot call this function after freeing the string.

Parameters:

name - name of the subexpression

Returns:

The matched substring, or null if an error occurred. You have to free the string yourself

Since:

2.14
fetchNamedPos

public boolean fetchNamedPos(String name, @Nullable Out<Integer> startPos, @Nullable Out<Integer> endPos)

Retrieves the position in bytes of the capturing parentheses named name.

If name is a valid sub pattern name but it didn't match anything (e.g. sub pattern "X", matching "b" against "(?P<X>a)?b") then startPos and endPos are set to -1 and true is returned.

As endPos is set to the byte after the final byte of the match (on success), the length of the match can be calculated as end_pos - start_pos.

Parameters:

name - name of the subexpression

startPos - pointer to location where to store the start position, or null

endPos - pointer to location where to store the end position (the byte after the final byte of the match), or null

Returns:

true if the position was fetched, false otherwise. If the position cannot be fetched, startPos and endPos are left unchanged.

Since:

2.14

fetchPos

public boolean fetchPos(int matchNum, @Nullable Out<Integer> startPos, @Nullable Out<Integer> endPos)

Returns the start and end positions (in bytes) of a successfully matching capture parenthesis.

Valid values for matchNum are 0 for the full text of the match, 1 for the first paren set, 2 for the second, and so on.

As endPos is set to the byte after the final byte of the match (on success), the length of the match can be calculated as end_pos - start_pos.

As a best practice, initialize startPos and endPos to identifiable values, such as G_MAXINT, so that you can test if g_match_info_fetch_pos() actually changed the value for a given capture parenthesis.

The parameter matchNum corresponds to a matched capture parenthesis. The actual value you use for matchNum depends on the method used to generate matchInfo. The following sections describe those methods.

Methods Using Non-deterministic Finite Automata Matching

The methods Regex.match(String, Set, Out) and Regex.matchFull(String[], int, Set, Out) return a GLib.MatchInfo using traditional (greedy) pattern matching, also known as Non-deterministic Finite Automaton (NFA) matching. You pass the returned GMatchInfo from these methods to g_match_info_fetch_pos() to determine the start and end positions of capture parentheses. The values for matchNum correspond to the capture parentheses in order, with 0 corresponding to the entire matched string.

matchNum can refer to a capture parenthesis with no match. For example, the string b matches against the pattern (a)?b, but the capture parenthesis (a) has no match. In this case, g_match_info_fetch_pos() returns true and sets startPos and endPos to -1 when called with match_num as 1 (for (a)).

For an expanded example, a regex pattern is (a)?(.*?)the (.*), and a candidate string is glib regexes are the best. In this scenario there are four capture parentheses numbered 0–3: an implicit one for the entire string, and three explicitly declared in the regex pattern.

Given this example, the following table describes the return values from g_match_info_fetch_pos() for various values of matchNum.

`match_num`	Contents	Return value	Returned `start_pos`	Returned `end_pos`
0	Matches entire string	True	0	25
1	Does not match first character	True	-1	-1
2	All text before `the`	True	0	17
3	All text after `the`	True	21	25
4	Capture paren out of range	False	Unchanged	Unchanged

The following code sample and output implements this example.

#include <glib.h>

int
main (int argc, char *argv[])
{
  g_autoptr(GError) local_error = NULL;
  const char *regex_pattern = "(a)?(.*?)the (.*)";
  const char *test_string = "glib regexes are the best";
  g_autoptr(GRegex) regex = NULL;

  regex = g_regex_new (regex_pattern,
                       G_REGEX_DEFAULT,
                       G_REGEX_MATCH_DEFAULT,
                       &local_error);
  if (regex == NULL)
    {
      g_printerr ("Error creating regex: %s\\n", local_error->message);
      return 1;
    }

  g_autoptr(GMatchInfo) match_info = NULL;
  g_regex_match (regex, test_string, G_REGEX_MATCH_DEFAULT, &match_info);

  int n_matched_strings = g_match_info_get_match_count (match_info);

  // Print header line
  g_print ("match_num Contents                  Return value returned start_pos returned end_pos\\n");

  // Iterate over each capture paren, including one that is out of range as a demonstration.
  for (int match_num = 0; match_num <= n_matched_strings; match_num++)
    {
      gboolean found_match;
      g_autofree char *paren_string = NULL;
      int start_pos = G_MAXINT;
      int end_pos = G_MAXINT;

      found_match = g_match_info_fetch_pos (match_info,
                                            match_num,
                                            &start_pos,
                                            &end_pos);

      // If no match, display N/A as the found string.
      if (start_pos == G_MAXINT || start_pos == -1)
        paren_string = g_strdup ("N/A");
      else
        paren_string = g_strndup (test_string + start_pos, end_pos - start_pos);

      g_print ("%-9d %-25s %-12d %-18d %d\\n", match_num, paren_string, found_match, start_pos, end_pos);
    }

  return 0;
}

match_num Contents                  Return value returned start_pos returned end_pos
0         glib regexes are the best 1            0                  25
1         N/A                       1            -1                 -1
2         glib regexes are          1            0                  17
3         best                      1            21                 25
4         N/A                       0            2147483647         2147483647

Methods Using Deterministic Finite Automata Matching

The methods Regex.matchAll(String, Set, Out) and Regex.matchAllFull(String[], int, Set, Out) return a GMatchInfo using Deterministic Finite Automaton (DFA) pattern matching. This algorithm detects overlapping matches. You pass the returned GMatchInfo from these methods to g_match_info_fetch_pos() to determine the start and end positions of each overlapping match. Use the method getMatchCount() to determine the number of overlapping matches.

For example, a regex pattern is <.*>, and a candidate string is <a> <b> <c>. In this scenario there are three implicit capture parentheses: one for the entire string, one for <a> <b>, and one for <a>.

Given this example, the following table describes the return values from g_match_info_fetch_pos() for various values of matchNum.

`match_num`	Contents	Return value	Returned `start_pos`	Returned `end_pos`
0	Matches entire string	True	0	11
1	Matches `<a> <b>`	True	0	7
2	Matches `<a>`	True	0	3
3	Capture paren out of range	False	Unchanged	Unchanged

The following code sample and output implements this example.

#include <glib.h>

int
main (int argc, char *argv[])
{
  g_autoptr(GError) local_error = NULL;
  const char *regex_pattern = "<.*>";
  const char *test_string = "<a> <b> <c>";
  g_autoptr(GRegex) regex = NULL;

  regex = g_regex_new (regex_pattern,
                       G_REGEX_DEFAULT,
                       G_REGEX_MATCH_DEFAULT,
                       &local_error);
  if (regex == NULL)
    {
      g_printerr ("Error creating regex: %s\\n", local_error->message);
      return -1;
    }

  g_autoptr(GMatchInfo) match_info = NULL;
  g_regex_match_all (regex, test_string, G_REGEX_MATCH_DEFAULT, &match_info);

  int n_matched_strings = g_match_info_get_match_count (match_info);

  // Print header line
  g_print ("match_num Contents                  Return value returned start_pos returned end_pos\\n");

  // Iterate over each capture paren, including one that is out of range as a demonstration.
  for (int match_num = 0; match_num <= n_matched_strings; match_num++)
    {
      gboolean found_match;
      g_autofree char *paren_string = NULL;
      int start_pos = G_MAXINT;
      int end_pos = G_MAXINT;

      found_match = g_match_info_fetch_pos (match_info, match_num, &start_pos, &end_pos);

      // If no match, display N/A as the found string.
      if (start_pos == G_MAXINT || start_pos == -1)
        paren_string = g_strdup ("N/A");
      else
        paren_string = g_strndup (test_string + start_pos, end_pos - start_pos);

      g_print ("%-9d %-25s %-12d %-18d %d\\n", match_num, paren_string, found_match, start_pos, end_pos);
    }

  return 0;
}

match_num Contents                  Return value returned start_pos returned end_pos
0         <a> <b> <c>               1            0                  11
1         <a> <b>                   1            0                  7
2         <a>                       1            0                  3
3         N/A                       0            2147483647         2147483647

Parameters:: matchNum - number of the capture parenthesis; startPos - pointer to location where to store the start position, or null; endPos - pointer to location where to store the end position (the byte after the final byte of the match), or null
Returns:: True if matchNum is within range, false otherwise. If the capture paren has a match, startPos and endPos contain the start and end positions (in bytes) of the matching substring. If the capture paren has no match, startPos and endPos are -1. If matchNum is out of range, startPos and endPos are left unchanged.
Since:: 2.14

free

public void free()

If this MatchInfo is not null, calls g_match_info_unref(); otherwise does nothing.

Since:

2.14
getMatchCount

public int getMatchCount()

Retrieves the number of matched substrings (including substring 0, that is the whole matched text), so 1 is returned if the pattern has no substrings in it and 0 is returned if the match failed.

If the last match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved count is not that of the number of capturing parentheses but that of the number of matched substrings.

Returns:

Number of matched substrings, or -1 if an error occurred

Since:

2.14
getRegex

public Regex getRegex()

Returns GRegex object used in matchInfo. It belongs to Glib and must not be freed. Use g_regex_ref() if you need to keep it after you free this MatchInfo object.

Returns:

GRegex object used in this MatchInfo

Since:

2.14
getString

public String getString()

Returns the string searched with matchInfo. This is the string passed to g_regex_match() or g_regex_replace() so you may not free it before calling this function.

Returns:

the string searched with this MatchInfo

Since:

2.14
isPartialMatch

public boolean isPartialMatch()

Usually if the string passed to g_regex_match*() matches as far as it goes, but is too short to match the entire pattern, false is returned. There are circumstances where it might be helpful to distinguish this case from other cases in which there is no match.

Consider, for example, an application where a human is required to type in data for a field with specific formatting requirements. An example might be a date in the form ddmmmyy, defined by the pattern "^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$". If the application sees the user’s keystrokes one by one, and can check that what has been typed so far is potentially valid, it is able to raise an error as soon as a mistake is made.

GRegex supports the concept of partial matching by means of the RegexMatchFlags.PARTIAL_SOFT and RegexMatchFlags.PARTIAL_HARD flags. When they are used, the return code for g_regex_match() or g_regex_match_full() is, as usual, true for a complete match, false otherwise. But, when these functions return false, you can check if the match was partial calling g_match_info_is_partial_match().

The difference between RegexMatchFlags.PARTIAL_SOFT and RegexMatchFlags.PARTIAL_HARD is that when a partial match is encountered with RegexMatchFlags.PARTIAL_SOFT, matching continues to search for a possible complete match, while with RegexMatchFlags.PARTIAL_HARD matching stops at the partial match. When both RegexMatchFlags.PARTIAL_SOFT and RegexMatchFlags.PARTIAL_HARD are set, the latter takes precedence.

There were formerly some restrictions on the pattern for partial matching. The restrictions no longer apply.

See pcrepartial(3) for more information on partial matching.

Returns:

true if the match was partial, false otherwise

Since:

2.14
matches

public boolean matches()

Returns whether the previous match operation succeeded.

Returns:

true if the previous match operation succeeded, false otherwise

Since:

2.14
next

public boolean next() throws GErrorException

Scans for the next match using the same parameters of the previous call to g_regex_match_full() or g_regex_match() that returned matchInfo.

The match is done on the string passed to the match function, so you cannot free it before calling this function.

Returns:

true is the string matched, false otherwise

Throws:

GErrorException - see GError

Since:

2.14
ref

public MatchInfo ref()

Increases reference count of this MatchInfo by 1.

Returns:

this MatchInfo

Since:

2.30
unref

public void unref()

Decreases reference count of this MatchInfo by 1. When reference count drops to zero, it frees all the memory associated with the match_info structure.

Since:

2.30

Class MatchInfo

Constructor Summary

Method Summary

Methods inherited from class ProxyInstance

Methods inherited from class Object

Constructor Details

MatchInfo

Method Details

getType

getMemoryLayout

expandReferences

fetch

fetchAll

fetchNamed

fetchNamedPos

fetchPos

Methods Using Non-deterministic Finite Automata Matching

Methods Using Deterministic Finite Automata Matching

free

getMatchCount

getRegex

getString

isPartialMatch

matches

next

ref

unref