Incremental linking in source-code development system

Abstract

A computer-aided software development system includes programs to implement edit, compile, link and run sequences, all from memory, at very high speed. The complier and linker operate on an incremental basis, line-by-line or increment-by-increment, so if only one line is changed in an edit session, then only that line and lines related to it need be recompiled if no other code is affected; linking is also done in a manner to save and re-use parts of link tables and link lists which are not changed from one edit session to another. Scanning is also done incrementally, and the resulting token lists and token tables, and lexical increment tables, are saved in memory to be used again where no changes are made. All of the linking tables are saved in memory so there is no need to generate link tables for increments of code where no changes in links are needed. The compiler is able to skip lines or blocks of lines of source code which haven't been changed. All of the source code text modules, the token lists, symbol tables, code tables, link lists and related data, etc., saved from one compile to another are maintained in virtual memory rather than in files so that speed of operation is enhanced. Also, the object code created is maintained in memory rather than in a file, and executed from this memory image, to reduce delays. A virtual memory management arrangement for the system assures that all of the needed data modules and code is present in real memory in the phase being implemented, with a minimum of page faults and page swapping during the phase, again to enhance operating speed.