README.cords

This is a string packages that uses a tree-based representation.
See cord.h for a description of the functions provided.  Ec.h describes
"extensible cords", which are essentially output streams that write
to a cord.  These allow for efficient construction of cords without
requiring a bound on the size of a cord.

The cord library is built by default in case of the GNU autoconf-based build
and the CMake-based one (unless "-Dbuild_cord=OFF" option is given to cmake).
If you wish to build the library with the stand-alone Makefile.direct, type
"make -f Makefile.direct cords".

More details on the data structure can be found in:

Boehm, Atkinson, and Plass, "Ropes: An Alternative to Strings",
Software Practice and Experience 25, 12, December 1995, pp. 1315-1330.

A fundamentally similar "rope" data structure is also part of SGI's standard
template library implementation, and its descendants, which include the
GNU C++ library.  That uses reference counting by default.
There is a short description of that data structure at
http://www.sgi.com/tech/stl/ropeimpl.html .

All of these are descendants of the "ropes" in Xerox Cedar.

cord/tests/de.c is a very dumb text editor that illustrates the use of cords.
It maintains a list of file versions.  Each version is simply a
cord representing the file contents.  Nonetheless, standard
editing operations are efficient, even on very large files.
(Its 3 line "user manual" can be obtained by invoking it without
arguments.  Note that ^R^N and ^R^P move the cursor by
almost a screen.  It does not understand tabs, which will show
up as highlighted "I"s.  Use the UNIX "expand" program first.)
To build the editor, type "make de" in the bdwgc root directory.

Note that CORD_printf and friends use C functions with variable numbers
of arguments in non-standard-conforming ways.  This code is known to
break on some platforms, notably PowerPC.  It should be possible to
build the remainder of the library (everything but cordprnt.c) on
any platform that supports the collector.