cirno/plan9port
1
0
Fork 0
mirror of https://github.com/9fans/plan9port.git synced 2025-01-12 11:10:07 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

plumb/basic: avoid wrap around in file:1:2 (#158)

Browse source 
Fixes #122, #140.

As reported in #122, `file:1:1` moves to the end of the file,
and `file:1:2` fails with “address out of range”.

I’ll use file:2:3 as an example so we can tell the line and column number apart.

What’s happening is this:
plumb/basic matches `2:3` using twocolonaddr (from plumb/fileaddr),
then sets addr to `2-#1+#3`
(the 1 is constant and was introduced because column numbers are 1-based).
Acme interprets this in three steps:

1. find the range (q0, q1) that contains line 2
2. create the range (q2, q2) where q2 = q0 - 1
3. create the range (q3, q3) where q3 = q2 + 3

The second step has a branch where if q0 == 0 and 1 > 0
(remember that 1 is constant and comes form plumb/basic),
q0 is set to the end of the file.
This makes addressing things at the end of the file easier.

The problem then is that if we select line 1,
which starts at the beginning of the file,
q0 is always 0 and the branch in step 2) will always be used.
`1:1` is interpreted as `1-#1+#1` which starts at 0, wraps around to the end of the file, then moves 1 character backwards and then forwards again, ending at the end of the file.
`1:2` is interpretes as `1-#1+#2` which starts at 0, wraps around to the end od the file, then moves 1 character backwards and tries moving 2 characters forwards beyond the end of the file, resulting in the out of range error.

In #140 @rsc proposed transforming `:X:Y` into `:X-#0+#Y-#1` instead since that
avoids wrapping around by not moving backwards at first.
This change modifies `plumb/basic` to do that.
This commit is contained in:
Martin Kühl 2018-11-14 05:59:04 +01:00 committed by Russ Cox
parent a9e66ffa4e
commit 73ea36569e
1 changed files with 2 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
plumb/basic
View file

@ -64,7 +64,7 @@ type is text
data matches '([.a-zA-Z¡-￿0-9_/\-@]*[a-zA-Z¡-￿0-9_/\-])':$twocolonaddr,$twocolonaddr data matches '([.a-zA-Z¡-￿0-9_/\-@]*[a-zA-Z¡-￿0-9_/\-])':$twocolonaddr,$twocolonaddr
arg isfile $1 arg isfile $1
data set $file data set $file
attr add addr=$2-#1+#$3,$4-#1+#$5 attr add addr=$2-#0+#$3-#1,$4-#0+#$5-#1
plumb to edit plumb to edit
plumb client $editor plumb client $editor
@ -73,7 +73,7 @@ type is text
data matches '([.a-zA-Z¡-￿0-9_/\-@]*[a-zA-Z¡-￿0-9_/\-])':$twocolonaddr data matches '([.a-zA-Z¡-￿0-9_/\-@]*[a-zA-Z¡-￿0-9_/\-])':$twocolonaddr
arg isfile $1 arg isfile $1
data set $file data set $file
attr add addr=$2-#1+#$3 attr add addr=$2-#0+#$3-#1
plumb to edit plumb to edit
plumb client $editor plumb client $editor