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Matching Pair of Tags

Tools for matching pair of tags.

Warning

Functions below assume the tags are well balanced. May work for certain unbalanced scenarios without guarantee.

When the open tag and the close tag are identical, there is no nested tag structure.

Info

Functions below use similar arguments.

• tag specifies the open tag, while closetag specifies the close tag. If closetag is unspecified, the open tag and the close tag are assumed to be identical.

• useregex specifies whether to use regular expression for tag and closetag, and defaults to False.

Finding Pair of Tags

Tools for finding pair of tags.

findtagpairspans

findtagpairspans(s, tag, closetag=None, useregex=False) finds the position span of each pair of tags in string s.

# ~~~~ denotes each span.

list(findtagpairspans("a$b$c$$d#ef#g", r"\$|#", useregex=True))
# [(1, 4),              ~~~
#  (5, 7),                  ~~
#  (8, 12)]                    ~~~~

list(findtagpairspans("a(b(c()d)ef)g", '(', ')'))
# [(5, 7),                  ~~
#  (3, 9),                ~~~~~~
#  (1, 12)]             ~~~~~~~~~~~

list(findtagpairspans("a<a>b<b>c<c></c>d</b>ef</a>g", r"<\w+>", r"</\w+>", useregex=True))
# [(9, 16),                     ~~~~~~~
#  (5, 21),                 ~~~~~~~~~~~~~~~~
#  (1, 27)]             ~~~~~~~~~~~~~~~~~~~~~~~~~~

findmatchingtag

findmatchingtag(s, pos, tag, closetag=None, useregex=False) finds the other matching tag of the current tag at the specified position pos in string s. Returns None if there is no covering pair of tags.

• If there is no tag at the specified position, returns the open tag.

Tip

The behavior of this function is designed to mimic Vim’s % operation.

# | denotes each specified position.
# ~~~~ denotes each span.
# == denotes the other matching tag.

#                      |
findmatchingtag("a$b$c$$d#ef#g", 6, r"\$|#", useregex=True)
#                     ~~
# (5, 6)              =

#                    |
findmatchingtag("a(b(c()d)ef)g", 4, '(', ')')
#                   ~~~~~~
# (3, 4)            =

#                      |
findmatchingtag("a<a>b<b>c<c></c>d</b>ef</a>g", 6, r"<\w+>", r"</\w+>", useregex=True)
#                     ~~~~~~~~~~~~~~~~
# (17, 21)                        ====

gettagpair

gettagpair(s, pos, tag, closetag=None, useregex=False) finds the pair of tags covering the specified position pos in string s. Returns None if there is no covering pair of tags.

# | denotes each specified position.

#               |
gettagpair("a$b$c$$d#ef#g", 4, r"\$|#", useregex=True)
# None

#                 |
gettagpair("a$b$c$$d#ef#g", 6, r"\$|#", useregex=True)
#               '$$'

#               |
gettagpair("a(b(c()d)ef)g", 4, '(', ')')
#             '(c()d)'

#                 |
gettagpair("a(b(c()d)ef)g", 6, '(', ')')
#               '()'

#                   |
gettagpair("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", useregex=True)
#               '<b>c<c></c>d</b>'

#                     |
gettagpair("a<a>b<b>c<c></c>d</b>ef</a>g", 10, r"<\w+>", r"</\w+>", useregex=True)
#                   '<c></c>'

gettagpaircontent

gettagpaircontent(s, pos, tag, closetag=None, useregex=False) finds the content of the pair of tags covering the specified position pos in string s. Returns None if there is no covering pair of tags.

# | denotes each specified position.

#                        |
gettagpaircontent("a$b$c$$d#ef#g", 6, r"\$|#", useregex=True)
#                       ''

#                      |
gettagpaircontent("a(b(c()d)ef)g", 4, '(', ')')
#                     'c()d'

#                          |
gettagpaircontent("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", useregex=True)
#                         'c<c></c>d'

Updating Pair of Tags

Tools for updating pair of tags.

addtagpair

addtagpair(s, pos, tag, closetag=None, newtag=None, newclosetag=None, useregex=False) adds a new pair of tags, specified by newtag and newclosetag, around the pair of tags covering the specified position pos in string s. Returns s if there is no covering pair of tags.

Info

If newtag is not specified, tag is used as the new open tag. Same for newclosetag. This only works properly when useregex = False.

# | denotes each specified position.
# == denotes each matched part.
# + denotes each added part.

#                 |
addtagpair("a$b$c$$d#ef#g", 6, r"\$|#", newtag='%', useregex=True)
#                ==
#          'a$b$c%$$%d#ef#g'
#                +==+

#               |
addtagpair("a(b(c()d)ef)g", 4, '(', ')')
#              ======
#          'a(b((c()d))ef)g'
#              +======+

#                 |
addtagpair("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", "<x>", "</x>", useregex=True)
#                ================
#          'a<a>b<x><b>c<c></c>d</b></x>ef</a>g'
#                +++================++++

settagpair

settagpair(s, pos, tag, closetag=None, newtag=None, newclosetag=None, useregex=False) changes the pair of tags, specified by newtag and newclosetag, covering the specified position pos in string s. Returns s if there is no covering pair of tags.

Info

If newtag is not specified, tag is used as the new open tag. Same for newclosetag. This only works properly when useregex = False.

# | denotes each specified position.
# == denotes each matched part.
# - denotes each removed part.
# + denotes each added part.

#                 |
settagpair("a$b$c$$d#ef#g", 6, r"\$|#", newtag='%', useregex=True)
#                --
#          'a$b$c%%d#ef#g'
#                ++

#               |
settagpair("a(b(c()d)ef)g", 4, '(', ')', '[', ']')
#              -====-
#          'a(b[c()d]ef)g'
#              +====+

#                 |
settagpair("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", "<x>", "</x>", useregex=True)
#                ---=========----
#          'a<a>b<x>c<c></c>d</x>ef</a>g'
#                +++=========++++

settagpaircontent

settagpaircontent(s, pos, tag, closetag=None, newcontent='', useregex=False) changes the content of the pair of tags, specified by newtag and newclosetag, covering the specified position pos in string s. Returns s if there is no covering pair of tags.

# | denotes each specified position.
# - denotes each removed part.
# + denotes each added part.

#                        |
settagpaircontent("a$b$c$$d#ef#g", 6, r"\$|#", newcontent='x', useregex=True)
#                 'a$b$c$x$d#ef#g'
#                        +

#                      |
settagpaircontent("a(b(c()d)ef)g", 4, '(', ')', newcontent="xyz")
#                      ----
#                 'a(b(xyz)ef)g'
#                      +++

#                        |
settagpaircontent("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", newcontent="xyz", useregex=True)
#                          ---------
#                 'a<a>b<b>xyz</b>ef</a>g'
#                          +++

removetagpair

removetagpair(s, pos, tag, closetag=None, useregex=False, removecontent=False) removes the pair of tags covering the specified position pos in string s. Returns s if there is no covering pair of tags.

• Option removecontent controls whether to remove the respective content as well.

# | denotes each specified position.
# == denotes each matched part.
# - denotes each removed part.

#                    |
removetagpair("a$b$c$$d#ef#g", 6, r"\$|#", useregex=True)
#                   --
#             'a$b$cd#ef#g'

#                    |
removetagpair("a$b$c$$d#ef#g", 6, r"\$|#", useregex=True, removecontent=True)
#                   --
#             'a$b$cd#ef#g'

#                  |
removetagpair("a(b(c()d)ef)g", 4, '(', ')')
#                 -====-
#             'a(bc()def)g'
#                 ====

#                  |
removetagpair("a(b(c()d)ef)g", 4, '(', ')', removecontent=True)
#                 ------
#             'a(bef)g'

#                    |
removetagpair("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", useregex=True)
#                   ---=========----
#             'a<a>bc<c></c>def</a>g'
#                   =========

#                    |
removetagpair("a<a>b<b>c<c></c>d</b>ef</a>g", 8, r"<\w+>", r"</\w+>", useregex=True, removecontent=True)
#                   ----------------
#             'a<a>bef</a>g'