[PATCH] guile: Add 'history-push!' procedure

[PATCH] guile: Add 'history-push!' procedure

[Ludovic Courtès]

Hello,

This patch adds the ‘history-push!’ procedure to add a value in the
history.

I think it’s useful to procedures that display a lot of values that the
user may then want to inspect individually.  One example is the Guile VM
stack walker: it displays each VM frame local variables, and having them
in the history makes it easier to recall them later on (similar the what
Guile’s “,locals” meta-command does.)

WDYT?

Thanks,
Ludo’.

gdb/
2014-02-19  Ludovic Courtès  <ludo@gnu.org>

	* guile/scm-value.c (gdbscm_history_push_x): New function.
	(value_functions): Add it.

gdb/testsuite/
2014-02-19  Ludovic Courtès  <ludo@gnu.org>

	* gdb.guile/scm-value.exp (test_value_in_inferior): Add
	test for 'history-push!'.

gdb/doc/
2014-02-19  Ludovic Courtès  <ludo@gnu.org>

	* gdb/doc/guile.texi (Basic Guile): Document 'history-push!'.
---
 gdb/doc/guile.texi                    |  9 +++++++++
 gdb/guile/scm-value.c                 | 26 ++++++++++++++++++++++++++
 gdb/testsuite/gdb.guile/scm-value.exp |  8 ++++++++
 3 files changed, 43 insertions(+)

diff --git a/gdb/doc/guile.texi b/gdb/doc/guile.texi
index ceb98dc..b916dd8 100644
--- a/gdb/doc/guile.texi
+++ b/gdb/doc/guile.texi
@@ -278,6 +278,15 @@ history contains the result of evaluating an expression from Guile's
 command line.
 @end deffn
 
+@deffn {Scheme Procedure} history-push! value
+Push @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
+value history.  Return its index in the history, or @code{#f} if it is
+not saved.
+
+This function is useful to make it easier to access individual values
+from a set of values displayed by a user function.
+@end deffn
+
 @deffn {Scheme Procedure} parse-and-eval expression
 Parse @var{expression} as an expression in the current language,
 evaluate it, and return the result as a @code{<gdb:value>}.
diff --git a/gdb/guile/scm-value.c b/gdb/guile/scm-value.c
index f7f27ce..8198d8b 100644
--- a/gdb/guile/scm-value.c
+++ b/gdb/guile/scm-value.c
@@ -1297,6 +1297,28 @@ gdbscm_history_ref (SCM index)
 
   return vlscm_scm_from_value (res_val);
 }
+
+/* (history-push! <gdb:value>) -> index
+   Push VALUE to GDB's value history.  Return its index in the history,
+   or #f if it is not saved.  */
+
+static SCM
+gdbscm_history_push_x (SCM value)
+{
+  int res_index = -1;
+  struct value *v;
+  volatile struct gdb_exception except;
+
+  v = vlscm_scm_to_value (value);
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      res_index = record_latest_value (v);
+    }
+  GDBSCM_HANDLE_GDB_EXCEPTION (except);
+
+  return res_index < 0 ? SCM_BOOL_F : scm_from_int (res_index);
+}
 \f
 /* Initialize the Scheme value code.  */
 
@@ -1459,6 +1481,10 @@ Evaluates string in gdb and returns the result as a <gdb:value> object." },
     "\
 Return the specified value from GDB's value history." },
 
+  { "history-push!", 1, 0, 0, gdbscm_history_push_x,
+    "\
+Push the specified value onto GDB's value history." },
+
   END_FUNCTIONS
 };
 
diff --git a/gdb/testsuite/gdb.guile/scm-value.exp b/gdb/testsuite/gdb.guile/scm-value.exp
index 3ebdd58..d6e63fb 100644
--- a/gdb/testsuite/gdb.guile/scm-value.exp
+++ b/gdb/testsuite/gdb.guile/scm-value.exp
@@ -59,6 +59,14 @@ proc test_value_in_inferior {} {
     gdb_test "gu (print (value-field s \"a\"))" \
 	"= 3" "access element inside struct using string name"
 
+    # Push value in the value history.
+    gdb_scm_test_silent_cmd "gu (define i (history-push! (make-value 42)))" \
+	"push 42"
+
+    gdb_test "gu i" "\[0-9\]+"
+    gdb_test "gu (history-ref i)" "#<gdb:value 42>"
+    gdb_test "p \$" "= 42"
+
     # Test dereferencing the argv pointer.
 
     # Just get inferior variable argv the value history, available to guile.
-- 
1.8.4

Re: [PATCH] guile: Add 'history-push!' procedure

[Eli Zaretskii]

> From: ludo@gnu.org (Ludovic Courtès)
> Date: Tue, 18 Feb 2014 23:40:14 +0100
> 
> This patch adds the ‘history-push!’ procedure to add a value in the
> history.

Thanks.

> +@deffn {Scheme Procedure} history-push! value
> +Push @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
> +value history.

I think we should explain what "push" means in this context.  It is
not self-evident.

>                 Return its index in the history, or @code{#f} if it is
> +not saved.

Why would it not be saved?

> +This function is useful to make it easier to access individual values
> +from a set of values displayed by a user function.

Not sure what this sentence is about.  "Easier" how, and what do you
mean by "user function"?

Re: [PATCH] guile: Add 'history-push!' procedure

[Ludovic Courtès]

Eli Zaretskii <eliz@gnu.org> skribis:

>> From: ludo@gnu.org (Ludovic Courtès)
>> Date: Tue, 18 Feb 2014 23:40:14 +0100
>> 
>> This patch adds the ‘history-push!’ procedure to add a value in the
>> history.
>
> Thanks.
>
>> +@deffn {Scheme Procedure} history-push! value
>> +Push @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
>> +value history.
>
> I think we should explain what "push" means in this context.  It is
> not self-evident.

Right.  How about s/push/append/?  (In the procedure name as well.)

>>                 Return its index in the history, or @code{#f} if it is
>> +not saved.
>
> Why would it not be saved?

Good question.  The doc above ‘record_latest_value’ mentions that it can
return -1, but I see no path leading to that.  Can I assume that -1 is
never returned?

>> +This function is useful to make it easier to access individual values
>> +from a set of values displayed by a user function.
>
> Not sure what this sentence is about.  "Easier" how, and what do you
> mean by "user function"?

By “user function”, I mean a Scheme procedure written by the user to
extend GDB functionality.  Such a procedure might display several
values–one example is the Guile VM stack walker, which displays local
variables.  Instead of simply displaying something like this:

--8<---------------cut here---------------start------------->8---
(gdb) gu (display-vm-frames)
#0 #<program 7ffff5d0e420>
  slot 0 -> "scheme@(guile-user)> "
  slot 1 -> #<port file 6f70a0>
  slot 2 -> #<port file 6f7070>
  slot 3 -> #<program bc8100>
[...]
--8<---------------cut here---------------end--------------->8---

it could instead display something like this:

--8<---------------cut here---------------start------------->8---
(gdb) gu (display-vm-frames)
#0 #<program 7ffff5d0e420>
  $12 -> "scheme@(guile-user)> "
  $13 -> #<port file 6f70a0>
  $14 -> #<port file 6f7070>
  $15 -> #<program bc8100>
[...]
--8<---------------cut here---------------end--------------->8---

... thus allowing users to directly refer to $12 etc.

How about simply this:

  Using this function is useful to provide convenient access to values
  manipulated by a Guile extension of GDB.

Thanks,
Ludo’.

Re: [PATCH] guile: Add 'history-push!' procedure

[Eli Zaretskii]

> From: ludo@gnu.org (Ludovic Courtès)
> Cc: gdb-patches@sourceware.org,  xdje42@gmail.com
> Date: Wed, 19 Feb 2014 22:43:43 +0100
> 
> >> +@deffn {Scheme Procedure} history-push! value
> >> +Push @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
> >> +value history.
> >
> > I think we should explain what "push" means in this context.  It is
> > not self-evident.
> 
> Right.  How about s/push/append/?  (In the procedure name as well.)

Fine with me.

> >>                 Return its index in the history, or @code{#f} if it is
> >> +not saved.
> >
> > Why would it not be saved?
> 
> Good question.  The doc above ‘record_latest_value’ mentions that it can
> return -1, but I see no path leading to that.  Can I assume that -1 is
> never returned?

I don't know, but if that is your reading, I see no reason not to.

> How about simply this:
> 
>   Using this function is useful to provide convenient access to values
>   manipulated by a Guile extension of GDB.

I suggest

  Putting into history values returned by Guile extensions will allow
  the user convenient access to those values via CLI history
  facilities.

Thanks.

Re: [PATCH] guile: Add 'history-push!' procedure

[Ludovic Courtès]

Eli Zaretskii <eliz@gnu.org> skribis:

>> From: ludo@gnu.org (Ludovic Courtès)
>> Cc: gdb-patches@sourceware.org,  xdje42@gmail.com
>> Date: Wed, 19 Feb 2014 22:43:43 +0100
>> 
>> >> +@deffn {Scheme Procedure} history-push! value
>> >> +Push @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
>> >> +value history.
>> >
>> > I think we should explain what "push" means in this context.  It is
>> > not self-evident.
>> 
>> Right.  How about s/push/append/?  (In the procedure name as well.)
>
> Fine with me.

Done.

>> >>                 Return its index in the history, or @code{#f} if it is
>> >> +not saved.
>> >
>> > Why would it not be saved?
>> 
>> Good question.  The doc above ‘record_latest_value’ mentions that it can
>> return -1, but I see no path leading to that.  Can I assume that -1 is
>> never returned?
>
> I don't know, but if that is your reading, I see no reason not to.

OK, I changed it to assume it always returns a positive value.

>> How about simply this:
>> 
>>   Using this function is useful to provide convenient access to values
>>   manipulated by a Guile extension of GDB.
>
> I suggest
>
>   Putting into history values returned by Guile extensions will allow
>   the user convenient access to those values via CLI history
>   facilities.

Perfect.

The version below incorporates those changes.

Thanks,
Ludo’.

gdb/
2014-02-21  Ludovic Courtès  <ludo@gnu.org>

	* guile/scm-value.c (gdbscm_history_append_x): New function.
	(value_functions): Add it.

gdb/testsuite/
2014-02-21  Ludovic Courtès  <ludo@gnu.org>

	* gdb.guile/scm-value.exp (test_value_in_inferior): Add
	test for 'history-append!'.

gdb/doc/
2014-02-21  Ludovic Courtès  <ludo@gnu.org>

	* gdb/doc/guile.texi (Basic Guile): Document 'history-append!'.
---
 gdb/doc/guile.texi                    |  9 +++++++++
 gdb/guile/scm-value.c                 | 25 +++++++++++++++++++++++++
 gdb/testsuite/gdb.guile/scm-value.exp |  8 ++++++++
 3 files changed, 42 insertions(+)

diff --git a/gdb/doc/guile.texi b/gdb/doc/guile.texi
index ceb98dc..56d817e 100644
--- a/gdb/doc/guile.texi
+++ b/gdb/doc/guile.texi
@@ -278,6 +278,15 @@ history contains the result of evaluating an expression from Guile's
 command line.
 @end deffn
 
+@deffn {Scheme Procedure} history-append! value
+Append @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
+value history.  Return its index in the history.
+
+Putting into history values returned by Guile extensions will allow
+the user convenient access to those values via CLI history
+facilities.
+@end deffn
+
 @deffn {Scheme Procedure} parse-and-eval expression
 Parse @var{expression} as an expression in the current language,
 evaluate it, and return the result as a @code{<gdb:value>}.
diff --git a/gdb/guile/scm-value.c b/gdb/guile/scm-value.c
index f7f27ce..8ca0762 100644
--- a/gdb/guile/scm-value.c
+++ b/gdb/guile/scm-value.c
@@ -1297,6 +1297,27 @@ gdbscm_history_ref (SCM index)
 
   return vlscm_scm_from_value (res_val);
 }
+
+/* (history-append! <gdb:value>) -> index
+   Append VALUE to GDB's value history.  Return its index in the history.  */
+
+static SCM
+gdbscm_history_append_x (SCM value)
+{
+  int res_index = -1;
+  struct value *v;
+  volatile struct gdb_exception except;
+
+  v = vlscm_scm_to_value (value);
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      res_index = record_latest_value (v);
+    }
+  GDBSCM_HANDLE_GDB_EXCEPTION (except);
+
+  return scm_from_int (res_index);
+}
 \f
 /* Initialize the Scheme value code.  */
 
@@ -1459,6 +1480,10 @@ Evaluates string in gdb and returns the result as a <gdb:value> object." },
     "\
 Return the specified value from GDB's value history." },
 
+  { "history-append!", 1, 0, 0, gdbscm_history_append_x,
+    "\
+Append the specified value onto GDB's value history." },
+
   END_FUNCTIONS
 };
 
diff --git a/gdb/testsuite/gdb.guile/scm-value.exp b/gdb/testsuite/gdb.guile/scm-value.exp
index 3ebdd58..89f0ff1 100644
--- a/gdb/testsuite/gdb.guile/scm-value.exp
+++ b/gdb/testsuite/gdb.guile/scm-value.exp
@@ -59,6 +59,14 @@ proc test_value_in_inferior {} {
     gdb_test "gu (print (value-field s \"a\"))" \
 	"= 3" "access element inside struct using string name"
 
+    # Append value in the value history.
+    gdb_scm_test_silent_cmd "gu (define i (history-append! (make-value 42)))" \
+	"append 42"
+
+    gdb_test "gu i" "\[0-9\]+"
+    gdb_test "gu (history-ref i)" "#<gdb:value 42>"
+    gdb_test "p \$" "= 42"
+
     # Test dereferencing the argv pointer.
 
     # Just get inferior variable argv the value history, available to guile.
-- 
1.8.4

Re: [PATCH] guile: Add 'history-push!' procedure

[Doug Evans]

On Thu, Feb 20, 2014 at 2:29 PM, Ludovic Courtès <ludo@gnu.org> wrote:
> Eli Zaretskii <eliz@gnu.org> skribis:
>
>>> From: ludo@gnu.org (Ludovic Courtès)
>>> Cc: gdb-patches@sourceware.org,  xdje42@gmail.com
>>> Date: Wed, 19 Feb 2014 22:43:43 +0100
>>>
>>> >> +@deffn {Scheme Procedure} history-push! value
>>> >> +Push @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
>>> >> +value history.
>>> >
>>> > I think we should explain what "push" means in this context.  It is
>>> > not self-evident.
>>>
>>> Right.  How about s/push/append/?  (In the procedure name as well.)
>>
>> Fine with me.
>
> Done.
>
>>> >>                 Return its index in the history, or @code{#f} if it is
>>> >> +not saved.
>>> >
>>> > Why would it not be saved?
>>>
>>> Good question.  The doc above ‘record_latest_value’ mentions that it can
>>> return -1, but I see no path leading to that.  Can I assume that -1 is
>>> never returned?
>>
>> I don't know, but if that is your reading, I see no reason not to.
>
> OK, I changed it to assume it always returns a positive value.
>
>>> How about simply this:
>>>
>>>   Using this function is useful to provide convenient access to values
>>>   manipulated by a Guile extension of GDB.
>>
>> I suggest
>>
>>   Putting into history values returned by Guile extensions will allow
>>   the user convenient access to those values via CLI history
>>   facilities.
>
> Perfect.
>
> The version below incorporates those changes.
>
> Thanks,
> Ludo’.
>
> gdb/
> 2014-02-21  Ludovic Courtès  <ludo@gnu.org>
>
>         * guile/scm-value.c (gdbscm_history_append_x): New function.
>         (value_functions): Add it.
>
> gdb/testsuite/
> 2014-02-21  Ludovic Courtès  <ludo@gnu.org>
>
>         * gdb.guile/scm-value.exp (test_value_in_inferior): Add
>         test for 'history-append!'.
>
> gdb/doc/
> 2014-02-21  Ludovic Courtès  <ludo@gnu.org>
>
>         * gdb/doc/guile.texi (Basic Guile): Document 'history-append!'.

LGTM.

Thanks!

Re: [PATCH] guile: Add 'history-push!' procedure

[Ludovic Courtès]

Doug Evans <dje@google.com> skribis:

> On Thu, Feb 20, 2014 at 2:29 PM, Ludovic Courtès <ludo@gnu.org> wrote:

[...]

>> gdb/
>> 2014-02-21  Ludovic Courtès  <ludo@gnu.org>
>>
>>         * guile/scm-value.c (gdbscm_history_append_x): New function.
>>         (value_functions): Add it.
>>
>> gdb/testsuite/
>> 2014-02-21  Ludovic Courtès  <ludo@gnu.org>
>>
>>         * gdb.guile/scm-value.exp (test_value_in_inferior): Add
>>         test for 'history-append!'.
>>
>> gdb/doc/
>> 2014-02-21  Ludovic Courtès  <ludo@gnu.org>
>>
>>         * gdb/doc/guile.texi (Basic Guile): Document 'history-append!'.
>
> LGTM.

Pushed, thanks.

Ludo’.