Paths and programs, which is the half that makes it worth having. The first word
of a line is a command or a PROGRAM, offered under the name somebody would type
- the extension taken off - and anything after it is a file, offered as it
really is. A separator anywhere in the word says which directory to look in.
A directory answers with a separator on the end instead of a space, which says
what it is and lets the next part be typed straight away. The answer ending in
one is also what stops a space being added, so that is one test rather than a
flag.
PROGRAMS ARE LOOKED FOR WHERE THE SHELL WOULD LOOK to run one: where you are,
/Apps on the disk you are on, and /Apps on drive 0. Offering something the shell
would not find would be finishing a word into a thing that then does not work.
Drive 0's is skipped when that is already the drive, or every program in it
would be offered twice and nothing would ever be the only match.
Walking somebody else's directory means standing in it, which is the only way to
walk one here, so where the person was and which drive they were on are put down
first and restored whatever happens.
Three bugs, all found by running it:
THE DIRECTORY TEST WAS INVERTED. dir asks the same question the same way round
four hundred lines further up, which is what made it obvious once looked at.
THE /Apps WALK OVERWROTE THE TYPED PATH. The whole search runs a second time to
list the matches, and by then TabDir said "/Apps" - so a word that had named
nowhere went looking in the wrong place and listed nothing at all. Two ways into
the walk now, and the typed path is never written over.
AND LISTING ONLY KNEW ABOUT COMMANDS, because it was a second copy of the walk.
It is the same walk with a flag now: finding the answer and showing the matches
are the same question asked twice.
Also cosmosMonitor, which had been RE-BLESSED INTO MEANINGLESSNESS by the wall
move. It disassembles a loaded program, at an address the input names - and that
address moved a page while the recording was simply re-recorded to whatever came
out, which was a page of zeroes. It is pointed at 5000 again.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
The first word of a line, against the shell's fifteen commands. One match goes in
with a space after it, because a word that can only be one thing is finished.
Several are folded into their longest common prefix and that goes in, which is
the most that can be said without guessing which was meant - and if that adds
nothing, the matches are listed and the line put back underneath.
THE LINE COMING BACK IS THE HALF I EXPECTED TO BE HARD and it was already
solved. The prompt has been reprinted somewhere else entirely, so the editor's
idea of where the line begins is wrong - but editAnchor works that out backwards
from where printing ended, precisely so it survives the screen moving. Listing is
a redraw it already knew how to do.
editInsert became editPut, a routine, because completing a word puts in several
characters and every one of them is that. Which cost a bug immediately: the old
inline code left the insertion point in A, and a RET puts A back to what the
caller had.
Two more bugs worth naming, both mine and both the same shape - a pointer that
had moved:
THE CANDIDATE'S START HAS TO BE KEPT. The comparison walks DP3 through the name
as it matches, so by the time a match is declared, DP3 points at the part AFTER
what was typed - and that is what got copied. "he" completed to "he" because the
answer taken was "lp".
AND THE INSERTION STOPS AT OR PAST, not exactly equal. With the wrong answer the
two counters passed each other and the loop ran off the end of the buffer,
filling the line with whatever was next in memory. They cannot pass each other
now, and the branch stays, because the cheaper failure is worth nothing.
MY OWN TEST HAD A HOLE and breaking the code found it. The later-word case
pressed Tab after a space, where there is nothing to finish anyway, so it passed
whether or not the shell checked which word it was on. It types "echo he" now,
which would become "echo help" if it did not.
The assembler's label table went past 1024 and is doubled. A ceiling reached
once will be reached again, and it is pointers into source already in memory.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
AnachronautandClaude Opus 5