code review 77140045: ogle: allow multi-valued expressions such as regular ex...

ogle: allow multi-valued expressions such as regular expressions
Allows us to set a group of breakpoints in a single call.
Clean up expression evaluation a bit (it's still rudimentary).
Fix a bug in breakpoint: need to back up the PC after the trap.
Also fix a silly bug in formatting the startup error in ogleproxy.

Can now trace a simple program using breakpoints.

[r, 2014-03-25 04:02:39]

Hello nigeltao,

I'd like you to review this change to
https://code.google.com/p/ogle

[r, 2014-03-26 02:50:11]

Hello nigeltao@golang.org,

Please take another look.

[nigeltao, 2014-03-26 03:41:02]

LGTM.

https://codereview.appspot.com/77140045/diff/90001/program/program.go
File program/program.go (right):

https://codereview.appspot.com/77140045/diff/90001/program/program.go#newcode65
program/program.go:65: //	"/regexp/" Set of addresses whose symbolic names match
"re:regexp" or say it's the same mini-language that Eval accepts.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go
File program/server/server.go (right):

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:258: // If we're stopped on a breakpoint, restore the
original code,
Move the "Back up PC" comment from 10-ish lines down to up here?

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:355: sym := s.symbols.LookupFunc(expr)
expr[4:]

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:356: if sym != nil {
Check == instead of !=, on the general principle of returning early for errors
and following straight-line code for the expected inputs?? You do that for the
next case.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:359: return nil, fmt.Errorf("symbol %q not found",
expr)
expr[4:] ??

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:381: return strings.Contains("0123456789", s[0:1])
Isn't this
return len(s) != 0 && '0' <= s[0] && s[0] <= '9'
You could possibly then manually inline it above.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:396: return 0, err
How about
return 0, fmt.Errorf("evalAddress: %q is neither a symbol or a number", expr)

[r, 2014-03-26 03:54:07]

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go
File program/server/server.go (right):

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:258: // If we're stopped on a breakpoint, restore the
original code,
On 2014/03/26 03:41:02, nigeltao wrote:
> Move the "Back up PC" comment from 10-ish lines down to up here?

Done.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:355: sym := s.symbols.LookupFunc(expr)
On 2014/03/26 03:41:02, nigeltao wrote:
> expr[4:]

Done.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:356: if sym != nil {
On 2014/03/26 03:41:02, nigeltao wrote:
> Check == instead of !=, on the general principle of returning early for errors
> and following straight-line code for the expected inputs?? You do that for the
> next case.

Done.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:359: return nil, fmt.Errorf("symbol %q not found",
expr)
On 2014/03/26 03:41:02, nigeltao wrote:
> expr[4:] ??

Done.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:381: return strings.Contains("0123456789", s[0:1])
On 2014/03/26 03:41:02, nigeltao wrote:
> Isn't this
> return len(s) != 0 && '0' <= s[0] && s[0] <= '9'
> You could possibly then manually inline it above.

Done.

https://codereview.appspot.com/77140045/diff/90001/program/server/server.go#n...
program/server/server.go:396: return 0, err
On 2014/03/26 03:41:02, nigeltao wrote:
> How about
> return 0, fmt.Errorf("evalAddress: %q is neither a symbol or a number", expr)

Done.

[r, 2014-03-26 03:54:23]

*** Submitted as https://code.google.com/p/ogle/source/detail?r=b032139f0204 ***

ogle: allow multi-valued expressions such as regular expressions
Allows us to set a group of breakpoints in a single call.
Clean up expression evaluation a bit (it's still rudimentary).
Fix a bug in breakpoint: need to back up the PC after the trap.
Also fix a silly bug in formatting the startup error in ogleproxy.

Can now trace a simple program using breakpoints.

LGTM=nigeltao
R=nigeltao
https://codereview.appspot.com/77140045