NAME¶
bt_split_names - splitting up BibTeX names and lists of names
SYNOPSIS¶
bt_stringlist * bt_split_list (char * string,
char * delim,
char * filename,
int line,
char * description);
void bt_free_list (bt_stringlist *list);
bt_name * bt_split_name (char * name,
char * filename,
int line,
int name_num);
void bt_free_name (bt_name * name);
DESCRIPTION¶
When BibTeX files are used for their original purpose---bibliographic entries
describing scholarly publications---processing lists of names (authors and
editors mostly) becomes important. Although such name-processing is outside
the general-purpose database domain of most of the
btparse library,
these splitting functions are provided as a concession to reality: most BibTeX
data files use the BibTeX conventions for author names, and a library to
process that data ought to be capable of processing the names.
Name-processing comes in two stages: first, split up a list of names into
individual strings; second, split up each name into "parts" (first,
von, last, and jr). The first is actually quite general: you could pick a
delimiter (such as 'and', used for lists of names) and use it to divide any
string into substrings. "bt_split_list()" could then be called to
break up the original string and extract the substrings.
"bt_split_name()", however, is quite specific to four-part author
names written using BibTeX conventions. (These conventions are described
informally in any BibTeX documentation; the description you will find here is
more formal and algorithmic---and thus harder to understand.)
See bt_format_names for information on turning split-up names back into strings
in a variety of ways.
FUNCTIONS¶
- bt_split_list()
-
bt_stringlist * bt_split_list (char * string,
char * delim,
char * filename,
int line,
char * description)
Splits "string" into substrings delimited by "delim" (a
fixed string). The splitting is done according to the rules used by BibTeX
for splitting up a list of names, in particular:
- •
- delimiters at beginning or end of string are ignored
- •
- delimiters must be surrounded by whitespace
- •
- matching of delimiters is case insensitive
- •
- delimiters at non-zero brace depth are ignored
For instance, if the delimiter is "and", then the string
Candy and Apples AnD {Green Eggs and Ham}
splits into three substrings: "Candy", "Apples", and
"{Green Eggs and Ham}".
If there are extra delimiters at the extremities of the string---say, an
"and" at the beginning of the string---then they are included in the
first/last string; no warning is currently printed, but this may change.
Successive delimiters ("and and") result in a warning and a NULL
string being added to the list of substrings. For instance, the string
and Joe Q. Blow and and Smith, Jr., John
would split into three substrings: "and Joe Q. Blow",
"NULL", and "Smith, Jr., John".
(If these rules seem somewhat odd, don't blame me: I just implemented BibTeX's
observed behaviour and added warning messages for one of the more obvious and
easily-detected mistakes.)
The substrings are returned as a "bt_stringlist" structure:
typedef struct
{
char * string;
int num_items;
char ** items;
} bt_stringlist;
There is currently no elegant interface to this structure: you just have to poke
around in it yourself. The fields are:
- "string"
- a copy of the "string" parameter passed to
"bt_split_list()", but with NUL characters replacing the space
after each substring. (This is safe because delimiters must be surrounded
by whitespace, which means that each substring is followed by whitespace
which is not part of the substring.) You probably shouldn't fiddle with
"string"; it's just there so that "bt_free_list()" has
something to "free()".
- "num_items"
- the number of substrings found in the string passed to
"bt_split_list()".
- "items"
- an array of "num_items" pointers into
"string". For instance, "items[1]" points to the
second substring. Since "string" has been mangled with NUL
characters, it is safe to treat "items[i]" as a regular C
string.
"filename", "line", and "description" are all
used for generating warning messages. "filename" and
"line" simply describe where the string came from, and
"description" is a brief (one word) description of the
substrings. For instance, if you are splitting a list of names, supply
"name" for "description"---that way, warnings will
refer to "name X" rather than "substring x".
- bt_free_list()
-
void bt_free_list (bt_stringlist *list)
Frees a "bt_stringlist" structure as returned by
"bt_split_list()". That is, it frees the copy of the string you
passed to "bt_split_list()", and then frees the structure
itself.
- bt_split_name()
-
bt_name * bt_split_name (char * name,
char * filename,
int line,
int name_num)
Splits a single BibTeX-style author name into four parts: first, von, last,
and jr. This can handle almost all names in the style of the major Western
European languages, but not quite. (Alas!)
A name is split by first dividing into tokens; tokens are separated by
whitespace or commas at brace-level zero. Thus the name
van der Graaf, Horace Q.
has five tokens, whereas the name
{Foo, Bar, and Sons}
consists of a single token.
How tokens are divided into parts depends on the form of the name. If the
name has no commas at brace-level zero (as in the second example), then it
is assumed to be in either "first last" or "first von
last" form. If there are no tokens that start with a lower-case
letter, then "first last" form is assumed: the final token is
the last name, and all other tokens form the first name. Otherwise, the
earliest contiguous sequence of tokens with initial lower-case letters is
taken as the `von' part; if this sequence includes the final token, then a
warning is printed and the final token is forced to be the `last' part.
If a name has a single comma, then it is assumed to be in "von last,
first" form. A leading sequence of tokens with initial lower-case
letters, if any, forms the `von' part; tokens between the `von' and the
comma form the `last' part; tokens following the comma form the `first'
part. Again, if there are no token following a leading sequence of
lowercase tokens, a warning is printed and the token immediately preceding
the comma is taken to be the `last' part.
If a name has more than two commas, a warning is printed and the name is
treated as though only the first two commas were present.
Finally, if a name has two commas, it is assumed to be in "von last,
jr, first" form. (This is the only way to represent a name with a
`jr' part.) The parsing of the name is the same as for a one-comma name,
except that tokens between the two commas are taken to be the `jr' part.
The one case not properly handled by BibTeX name conventions is a name with
a 'jr' part not separated from the last name by a comma; for example:
Henry Ford Jr.
George Herbert Walker Bush III
Both of these would be incorrectly interpreted by both BibTeX and
bt_split_name(): the "Jr." or "III" token would
be taken as the last name, and the other tokekens as a two- or four-part
first name. The workaround is to shoehorn the 'jr' into the last name:
Henry {Ford Jr.}
George Herbert Walker {Bush III}
but this will make it impossible to extract the last name on its own, e.g.
to generate "author-year" style citations. This design flaw may
be fixed in a future version of btparse.
The split-up name is returned as a "bt_name" structure:
typedef struct
{
bt_stringlist * tokens;
char ** parts[BT_MAX_NAMEPARTS];
int part_len[BT_MAX_NAMEPARTS];
} bt_name;
Again, there's no nice interface to this structure; you'll just have to
access the fields individually. They are:
- "tokens"
- the name, broken down into a flat list of tokens. See above
for a description of the "bt_stringlist" structure.
- "parts"
- an array of arrays of pointers into the token list. The
major dimension of this beast is the "name part;" you should
index this dimension using the "bt_namepart" enum. For instance,
"parts[BTN_LAST]" is an array of pointers to the tokens
comprising the last name; "parts[BTN_LAST][1]" is a "char
*": the second token of the 'last' part; and
"parts[BTN_LAST][1][0]" is the first character of the second
token of the 'last' part.
- "part_len"
- the length, in tokens, of each part. For instance, you
might loop over all tokens in the 'first' part as follows (assuming
"name" is a "bt_name *" returned by
"bt_split_name()"):
for (i = 0; i < name->part_len[BTN_FIRST]; i++)
{
printf ("token %d of first name: %s\n",
i, name->parts[BTN_FIRST][i]);
}
- bt_free_name()
-
void bt_free_name (bt_name * name)
Frees the "bt_name" structure created by
"bt_split_name()" (including the "bt_stringlist"
structure inside the "bt_name").
SEE ALSO¶
btparse, bt_format_names
AUTHOR¶
Greg Ward <gward@python.net>