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bt_input(3)			    btparse			   bt_input(3)

NAME
       bt_input - input/parsing functions in btparse library

SYNOPSIS
	  void	bt_set_stringopts (bt_metatype_t metatype, ushort options);
	  AST * bt_parse_entry_s (char *    entry_text,
				  char *    filename,
				  int	    line,
				  ushort    options,
				  boolean * status);
	  AST * bt_parse_entry	 (FILE *    infile,
				  char *    filename,
				  ushort    options,
				  boolean * status);
	  AST * bt_parse_file	 (char *    filename,
				  ushort    options,
				  boolean * overall_status);

DESCRIPTION
       The functions described here are used to read and parse BibTeX data,
       converting it from raw text to abstract-syntax trees (ASTs).

       bt_set_stringopts ()
	      void bt_set_stringopts (bt_metatype_t metatype, ushort options);

	   Set the string-processing options for a particular entry metatype.
	   This affects the entry post-processing done by
	   "bt_parse_entry_s()", "bt_parse_entry()", and "bt_parse_file()".
	   If "bt_set_stringopts()" is never called, the four metatypes
	   default to the following sets of string options:

	      BTE_REGULAR    BTO_CONVERT ⎪ BTO_EXPAND ⎪ BTO_PASTE ⎪ BTO_COLLAPSE
	      BTE_COMMENT    0
	      BTE_PREAMBLE   0
	      BTE_MACRODEF   BTO_CONVERT ⎪ BTO_EXPAND ⎪ BTO_PASTE

	   For example,

	      bt_set_stringopts (BTE_COMMENT, BTO_COLLAPSE);

	   will cause the library to collapse whitespace in the value from all
	   comment entries; the AST returned by one of the "bt_parse_*" func‐
	   tions will reflect this change.

       bt_parse_entry ()
	      AST * bt_parse_entry (FILE *    infile,
				    char *    filename,
				    ushort    options,
				    boolean * status);

	   Scans and parses the next BibTeX entry in "infile".	You should
	   supply "filename" to help btparse generate accurate error messages;
	   the library keeps track of "infile"'s current line number inter‐
	   nally, so you don't need to pass that in.  "options" should be a
	   bitmap of non-string-processing options (currently, "BTO_NOSTORE"
	   to disable storing macro expansions is the only such option).
	   *status will be set to "TRUE" if the entry parsed successfully or
	   with only minor warnings, and "FALSE" if there were any serious
	   lexical or syntactic errors.	 If "status" is "NULL", then the parse
	   status will be unavailable to you.  Both minor warnings and serious
	   errors are reported on "stderr".

	   Returns a pointer to the abstract-syntax tree (AST) describing the
	   entry just parsed, or "NULL" if no more entries were found in
	   "infile" (this will leave "infile" at end-of-file).	Do not attempt
	   to second guess "bt_parse_entry()" by detecting end-of-file your‐
	   self; it must be allowed to determine this on its own so it can
	   clean up some static data that is preserved between calls on the
	   same file.

	   "bt_parse_entry()" has two important restrictions that you should
	   know about.	First, you should let btparse manage all the input on
	   the file; this is for reasons both superficial (so the library
	   knows the current line number in order to generate accurate error
	   messages) and fundamental (the library must be allowed to detect
	   end-of-file in order to cleanup certain static variables and allow
	   you to parse another file).	Second, you cannot interleave the
	   parsing of two different files; attempting to do so will result in
	   a fatal error that will crash your program.	This is a direct
	   result of the static state maintained between calls of
	   "bt_parse_entry()".

	   Because of two distinct "failures" possible for "bt_parse_entry()"
	   (end-of-file, which is expected but means to stop processing the
	   current file; and error-in-input, which is not expected but allows
	   you to continue processing the same file), you should usually call
	   it like this:

	      while (entry = bt_parse_entry (file, filename, options, &ok))
	      {
		 if (ok)
		 {
		    /* ... process entry ... */
		 }
	      }

	   At the end of this loop, "feof (file)" will be true.

       bt_parse_entry_s ()
	      AST * bt_parse_entry_s (char *	entry_text,
				      char *	filename,
				      int	line,
				      ushort	options,
				      boolean * status)

	   Scans and parses a single complete BibTeX entry contained in a
	   string, "entry_text".  If you read this string from a file, you
	   should help btparse generate accurate error messages by supplying
	   the name of the file as "filename" and the line number of the
	   beginning of the entry as "line"; otherwise, set "filename" to
	   "NULL" and "line" to 1.  "options" and "status" are the same as for
	   "bt_parse_entry()".

	   Returns a pointer to the abstract-syntax tree (AST) describing the
	   entry just parsed, and "NULL" if no entries were found in
	   "entry_text" or if "entry_text" was "NULL".

	   You should call "bt_parse_entry_s()" once more than the total num‐
	   ber of entries you wish to parse; on the final call, set
	   "entry_text" to "NULL" so the function knows there's no more text
	   to parse.  This final call allows it to clean up some structures
	   allocated on the first call.	 Thus, "bt_parse_entry_s()" is usually
	   used like this:

	      char *  entry_text;
	      ushort  options = 0;
	      boolean ok;
	      AST *   entry_ast;

	      while (entry_text = get_more_text ())
	      {
		 entry_ast = bt_parse_entry_s (entry_text, NULL, 1, options, &ok);
		 if (ok)
		 {
		    /* ... process entry ... */
		 }
	      }

	      bt_parse_entry_s (NULL, NULL, 1, options, NULL);	  /* cleanup */

	   assuming that "get_more_text()" returns a pointer to the text of an
	   entry to parse, or "NULL" if there's no more text available.

       bt_parse_file ()
	      AST * bt_parse_file (char *    filename,
				   ushort    options,
				   boolean * status)

	   Scans and parses an entire BibTeX file.  If "filename" is "NULL" or
	   "-", then "stdin" will be read; otherwise, attempts to open the
	   named file.	If this attempt fails, prints an error message to
	   "stderr" and returns "NULL".	 "options" and "status" are the same
	   as for "bt_parse_entry()"---note that *status will be "FALSE" if
	   there were any errors in the entire file; for finer granularity of
	   error-checking, you should use "bt_parse_entry()".

	   Returns a pointer to a linked list of ASTs representing the entries
	   in the file, or "NULL" if no entries were found in the file.	 This
	   list can be traversed with "bt_next_entry()", and the individual
	   entries then traversed as usual (see bt_traversal).

SEE ALSO
       btparse, bt_postprocess, bt_traversal

AUTHOR
       Greg Ward <gward@python.net>

btparse, version 0.34		  2003-10-25			   bt_input(3)
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