lh-l4v/lib/Apply_Debug_Test.thy

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(*
*
* Copyright 2017, Data61, CSIRO
*
* This software may be distributed and modified according to the terms of
* the BSD 2-Clause license. Note that NO WARRANTY is provided.
* See "LICENSE_BSD2.txt" for details.
*
* @TAG(DATA61_BSD)
*)
theory Apply_Debug_Test
imports
Lib.Apply_Debug
Lib.Apply_Trace_Cmd
begin
chapter \<open>Apply_Debug\<close>
text \<open>
Apply_debug can be invoked as a backwards refinement step (wherever "apply" works). It invokes
the given proof method (expression) in a managed thread and blocks when it encounters a special
"#break" method. Either this is written as part of the definition in an inner method written in Eisbach,
or appears directly in the invoked method.
Once a break point is hit, the proof thread blocks and the command returns with whatever the proof
state was at the breakpoint.
The provided "continue" command allows for execution to resume. Note that regular proof commands
can be written between continue commands and method execution will continue as if that were
the proof state at the break point. This can allow for debugging methods without necessarily rewriting
their implementation.
Some interactive markup is given in jEdit: clicking on
an apply_debug or continue command will show the subsequent breakpoint that was hit (and
the method in the original expression that hit it),
clicking on a breakpoint will highlight all "continue" commands which stopped at that breakpoint.
Note that breakpoints inside of Eisbach definitions are highlighted as well.
Finally the "finish" command will resume execution and ignore all further breakpoints.
Outside of an apply_debug invocation the #break method is ignored and any "continue" or "finish"
commands will throw a runtime error. The debug command that finally terminates the method
(either finish or continue) will exit the debugger and print "Final Result".
\<close>
method some_break = #break
lemma assumes B: B
shows "A \<Longrightarrow> A \<and> B \<and> A \<and> A"
apply (rule conjI, #break, assumption) (* #break is ignored here *)
apply_debug (rule conjI, #break, some_break, #break, assumption?)+
continue
continue
apply (rule B) (* this effect is saved *)
continue
continue
apply assumption
finish
done
section \<open>Tags\<close>
text \<open>
Tags can be used to filter the kind of breakpoints that are hit by any given breakpoint
invocation. By default apply_debug will only hit untagged breakpoints, if any tags are given
then both untagged breakpoints and those matching the given tags will trigger a break.
Each breakpoint can be given 0 or 1 tags.
\<close>
method my_conjI = (#break "conjI", rule conjI)
method my_assumption = (#break "assumption", assumption)
lemma "A \<Longrightarrow> A \<and> A \<and> A \<and> A \<and> A"
apply_debug (my_conjI, my_assumption) (* no breakpoints hit *)
apply_debug (tags "assumption")
(#break, my_conjI, my_assumption) (* inline breakpoint *)
continue (* assumption breakpoint *)
finish (* goal finished *)
apply_debug (tags "conjI")
(my_conjI, my_assumption) (* conjI is hit *)
continue (* assumption breakpoint is skipped *)
apply_debug (tags "assumption", "conjI")
(my_conjI, my_assumption) (* conjI is hit *)
continue (* assumption is hit *)
finish
by assumption
section \<open>Arguments to Continue Command\<close>
text \<open>Continue can be given a single positive number that will skip over that many breakpoints.
NB: continue 1 is the same as a bare continue.\<close>
lemma
assumes AB: "A \<Longrightarrow> B"
assumes BA: "B \<Longrightarrow> A"
assumes BC: "B \<Longrightarrow> C"
assumes CB: "C \<Longrightarrow> B"
assumes CD: "C \<Longrightarrow> D"
assumes DC: "D \<Longrightarrow> C"
assumes DE: "D \<Longrightarrow> E"
assumes ED: "E \<Longrightarrow> D"
assumes FE: "F \<Longrightarrow> E"
assumes EF: "E \<Longrightarrow> F"
assumes E: "E"
shows
"A"
apply_debug ((((#break, rule assms, #break, rule assms,#break, rule assms, #break, rule assms, #break,
rule assms, #break, rule assms, #break, rule assms)));fail)
continue 3
continue 11
continue
done
text \<open>
Continue may also be given a method, which is understood as a filter on each breakpoint.
If the method successfully applies, then the breakpoint is hit and the result of executing the
method is left as the proof state. If it fails at a given breakpoint, it is ignored and execution
continues, either until the next breakpoint or until the method terminates.
NB: "finish" is equivalent to "continue fail".
Note that a breakpoint alone cannot fail or affect backtracking directly.
\<close>
lemma
assumes B: B and C: C
shows "A \<or> D \<or> (B \<and> C)"
apply_debug ((rule disjI1 disjI2, #break)+, rule conjI, #break)
continue (rule B) (* skip until conjI reveals B *)
apply (rule C)
finish
done
section \<open>Element binding\<close>
text \<open>
Inside of a "continue" block we can refer to Eisbach variables that are in the
lexographical scope of the associated breakpoint.
This includes arguments passed to Eisbach methods and variables that are bound inside of a
"match" body.
\<close>
named_theorems rule3
method bazz for C :: int uses rule1 rule2 declares rule3 =
(match premises in H[OF rule2]:"PROP G" for G \<Rightarrow> \<open>#break\<close>)
schematic_goal Z:
assumes AC: "A \<Longrightarrow> C"
assumes BA: "B \<Longrightarrow> A"
assumes AB: "A \<Longrightarrow> B"
assumes A: "A"
assumes rule1: "ZZZ"
assumes A: "A"
assumes C
shows "(A \<Longrightarrow> ?C) \<Longrightarrow> D \<Longrightarrow> A \<and> B \<and> C"
apply (intro conjI)
prefer 2
apply_debug (match premises in H:"PROP C" for C \<Rightarrow>
\<open>#break, bazz 4 rule1: AB rule2: A\<close>)
term ?C (* C from match is bound *)
thm H (* H is bound as the (focused) fact proving C *)
continue (* inside bazz method now *)
term ?C (* C is now argument to bazz *)
term ?G (* G is bound from inner match from bazz *)
thm rule1 (* bound to AB from call site *)
thm rule2 (* bound to A from call site *)
thm H (* bound to match result from bazz (shadows original H) *)
finish
oops
section \<open>Tracing used rules\<close>
text \<open>
We can observe any used rules between breakpoints by passing apply_debug the "trace" flag. This
implicitly invokes apply_trace after each continue, showing the rules that have been used since
the last breakpoint. Note that this is subject to backtracking, so any rules that were used
as part of a backtracking branch that has since been discarded will not appear.
\<close>
lemma assumes A: A and B: B
shows "A \<and> B"
apply_debug (trace) ((rule conjI | rule A B), #break)+
continue
continue
finish
done
text \<open>
The trace flag can be passed an argument string (in a cartouche) which accepts the same syntax
as find_theorems. This will filter the list of all used theorems shown.
\<close>
lemma assumes A: A and B: B
shows "A \<and> B"
apply_debug (trace \<open>"_ \<and> _"\<close>) ((rule conjI | rule A B), #break)+
continue
finish
done
section \<open>Show currently-executing method\<close>
text \<open>
Internally, apply_debug manages a proof thread that is restarted periodically depending on
how far along it is in its execution when "continue" is invoked. This allows us to seamlessly
interact with it in jEdit where we might want to rewind time by editing a previous continue
statement.
We can observe this internal state by passing the flag "show_running" to apply_debug, which
will give jEdit markup to show which method is currently being executed by the internal thread.
Note that this is not necessarily the "continue" that is currently in focus in jEdit.
This can be particularly useful to discover which method is causing the whole execution to fail
or time out (even in the absence of any breakpoints).
In the following example, try making whitespace edits to the continues to see how the proof thread
is affected.
\<close>
lemma "A \<Longrightarrow> A \<and> A \<and> A \<and> A"
apply_debug (show_running)
(rule conjI,
sleep 0.1, #break, sleep 0.1, assumption, sleep 0.1, #break, sleep 0.1, rule conjI,
sleep 0.1, #break,
assumption, sleep 0.1, #break, sleep 0.1, rule conjI, sleep 0.1, #break, sleep 0.1,
assumption)
continue
continue
continue
continue
continue
apply assumption
done
section \<open>Final Notes\<close>
text \<open>
Breakpoints are subject to the real execution path of the method, which includes all backtracking
branches. This can result in potentially confusing traces when, for example, we see the same proof
state revisited multiple times.
\<close>
text \<open>
Only the "raw" proof state is lifted when continuing from a breakpoint: any additional context
information (e.g. from supply or other Isar commands) is discarded.
\<close>
text \<open>
The jEdit markup is limited in its ability to descend into higher-order method syntax (e.g. in match).
The highlighted breakpoint/currently executing method will therefore simply show an entire match
execution being executed, rather than any particular sub-method. This is not a fundamental
limitation, but requires more cooperation from the Method module to make the method stack trace
known as context data.
\<close>
end