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refactor(frontends/lean/parser): cleanup tactic support in the default lean parser

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-12-07 12:15:03 -08:00
parent 195ea24d71
commit bc3a6a3185
1 changed files with 106 additions and 73 deletions
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179
src/frontends/lean/parser.cpp
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@ -269,6 +269,10 @@ class parser::imp {
bool curr_is_in() const { return curr() == scanner::token::In; } bool curr_is_in() const { return curr() == scanner::token::In; }
/** \brief Return true iff the current token is '.' */ /** \brief Return true iff the current token is '.' */
bool curr_is_period() const { return curr() == scanner::token::Period; } bool curr_is_period() const { return curr() == scanner::token::Period; }
/** \brief Return true iff the current token is a tactic command */
bool curr_is_tactic_cmd() const {
return curr_is_identifier() && std::find(g_tactic_cmds.begin(), g_tactic_cmds.end(), curr_name()) != g_tactic_cmds.end();
}
/** \brief Throws a parser error if the current token is not an identifier. */ /** \brief Throws a parser error if the current token is not an identifier. */
void check_identifier(char const * msg) { if (!curr_is_identifier()) throw parser_error(msg, pos()); } void check_identifier(char const * msg) { if (!curr_is_identifier()) throw parser_error(msg, pos()); }
@ -1147,12 +1151,12 @@ class parser::imp {
expr pr = parse_expr(); expr pr = parse_expr();
check_rparen_next("invalid apply command, ')' expected"); check_rparen_next("invalid apply command, ')' expected");
expr pr_type = m_type_inferer(pr); expr pr_type = m_type_inferer(pr);
t = apply_tactic(pr, pr_type); t = ::lean::apply_tactic(pr, pr_type);
} else { } else {
name n = check_identifier_next("invalid apply command, identifier, '(' expr ')', or 'script-block' expected"); name n = check_identifier_next("invalid apply command, identifier, '(' expr ')', or 'script-block' expected");
object const & o = m_frontend.find_object(n); object const & o = m_frontend.find_object(n);
if (o && (o.is_theorem() || o.is_axiom())) { if (o && (o.is_theorem() || o.is_axiom())) {
t = apply_tactic(n); t = ::lean::apply_tactic(n);
} else { } else {
using_script([&](lua_State * L) { using_script([&](lua_State * L) {
lua_getglobal(L, n.to_string().c_str()); lua_getglobal(L, n.to_string().c_str());
@ -1310,7 +1314,50 @@ class parser::imp {
typedef std::vector<proof_state_seq> proof_state_seq_stack; typedef std::vector<proof_state_seq> proof_state_seq_stack;
void tactic_backtrack(proof_state_seq_stack & stack, proof_state & s) { /**
\brief Apply tactic \c t to state \c s.
When \c t succeeds, it returns the head and tail of the output state sequence.
Throws an exception if the tactic fails, and use \c p to sign the error position.
*/
std::pair<proof_state, proof_state_seq> apply_tactic(proof_state const & s, tactic const & t, pos_info const & p) {
proof_state_seq::maybe_pair r;
code_with_callbacks([&]() {
// t may have call-backs we should set ios in the script_state
proof_state_seq seq = t(m_frontend, m_frontend.get_state(), s);
r = seq.pull();
});
if (r) {
return mk_pair(r->first, r->second);
} else {
throw tactic_cmd_error("tactic failed", p, s);
}
}
/**
\brief Try to create a proof for the input state \c s.
It basically applies the proof_builder if \c s does not contain
any goals left. The position information is used to throw an exception
if \c s is not a final state.
*/
expr mk_proof_for(proof_state const & s, pos_info const & p) {
if (s.is_proof_final_state()) {
assignment a(s.get_menv());
proof_map m;
expr pr = s.get_proof_builder()(m, a);
return pr;
} else {
throw tactic_cmd_error("invalid 'done' command, proof cannot be produced from this state", p, s);
}
}
/**
\brief Execute the \c back (backtrack) tactic command. It
succeeds if the stack \c stack contains proof states. When it
succeeds, \c s is updated with the next state in the state
sequence on the top of \c stack. The new state is also removed
from the stack.
*/
void back_cmd(/* inout */ proof_state_seq_stack & stack, /* inout */ proof_state & s) {
auto p = pos(); auto p = pos();
next(); next();
while (!stack.empty()) { while (!stack.empty()) {
@ -1330,79 +1377,49 @@ class parser::imp {
throw tactic_cmd_error("failed to backtrack", p, s); throw tactic_cmd_error("failed to backtrack", p, s);
} }
void tactic_apply(proof_state_seq_stack & stack, proof_state & s, tactic const & t, pos_info const & p) { /**
proof_state_seq::maybe_pair r; \brief Execute the <tt>apply [tactic]</tt> tactic command.
code_with_callbacks([&]() { This command just applies the tactic to the input state \c s.
// t may have call-backs we should set ios in the script_state If it succeeds, \c s is assigned to the head of the output
proof_state_seq seq = t(m_frontend, m_frontend.get_state(), s); state sequence produced by the tactic. The rest/tail of the
r = seq.pull(); output state sequence is stored on the top of the stack \c
}); stack.
if (r) { */
s = r->first; void apply_cmd(/* inout */ proof_state_seq_stack & stack, /* inout */ proof_state & s) {
stack.push_back(r->second);
} else {
throw tactic_cmd_error("tactic failed", p, s);
}
}
proof_state tactic_apply(proof_state s, tactic const & t, pos_info const & p) {
proof_state_seq_stack stack;
tactic_apply(stack, s, t, p);
return s;
}
void tactic_apply(proof_state_seq_stack & stack, proof_state & s) {
auto tac_pos = pos(); auto tac_pos = pos();
next(); next();
tactic t = parse_tactic_expr(); tactic t = parse_tactic_expr();
tactic_apply(stack, s, t, tac_pos); auto r = apply_tactic(s, t, tac_pos);
s = r.first;
stack.push_back(r.second);
} }
void tactic_assumption(proof_state_seq_stack & stack, proof_state & s) { /**
\brief Execute the \c assumption tactic command. This command
is just syntax sugar for <tt>apply assumption_tac</tt>.
*/
void assumption_cmd(/* inout */ proof_state_seq_stack & stack, /* inout */ proof_state & s) {
auto tac_pos = pos(); auto tac_pos = pos();
next(); next();
tactic_apply(stack, s, assumption_tactic(), tac_pos); auto r = apply_tactic(s, assumption_tactic(), tac_pos);
s = r.first;
stack.push_back(r.second);
} }
expr mk_proof_for(proof_state const & s, pos_info const & p) { /**
if (s.is_proof_final_state()) { \brief Execute the \c done tactic command. It succeeds if
assignment a(s.get_menv()); a proof for \c s can be built.
proof_map m; */
expr pr = s.get_proof_builder()(m, a); expr done_cmd(proof_state const & s) {
if (has_metavar(pr)) {
throw exception("synthesized proof object has unsolved metavars");
}
return pr;
} else {
throw tactic_cmd_error("invalid 'done' command, proof cannot be produced from this state", p, s);
}
}
expr tactic_done(proof_state const & s) {
auto p = pos(); auto p = pos();
next(); next();
return mk_proof_for(s, p); return mk_proof_for(s, p);
} }
bool curr_is_tactic_cmd() { /**
if (curr_is_identifier()) { \brief Parse tactic command sequence for solving input state \c s.
name const & id = curr_name(); */
for (auto c : g_tactic_cmds) expr parse_tactic_cmds(proof_state s) {
if (id == c)
return true;
}
return false;
}
void show_tactic_prompt() {
if (m_interactive) {
regular(m_frontend) << "## ";
regular(m_frontend).flush();
}
}
expr parse_tactic(proof_state s) {
proof_state ini = s;
proof_state_seq_stack stack; proof_state_seq_stack stack;
expr pr; expr pr;
enum class status { Continue, Done, Eof, Abort }; enum class status { Continue, Done, Eof, Abort };
@ -1425,18 +1442,18 @@ class parser::imp {
case scanner::token::Id: case scanner::token::Id:
id = curr_name(); id = curr_name();
if (id == g_apply) { if (id == g_apply) {
tactic_apply(stack, s); apply_cmd(stack, s);
} else if (id == g_back) { } else if (id == g_back) {
tactic_backtrack(stack, s); back_cmd(stack, s);
} else if (id == g_done) { } else if (id == g_done) {
pr = tactic_done(s); pr = done_cmd(s);
if (pr) if (pr)
st = status::Done; st = status::Done;
} else if (id == g_abort) { } else if (id == g_abort) {
next(); next();
st = status::Abort; st = status::Abort;
} else if (id == g_assumption) { } else if (id == g_assumption) {
tactic_assumption(stack, s); assumption_cmd(stack, s);
} else { } else {
next(); next();
throw tactic_cmd_error(sstream() << "invalid tactic command '" << id << "'", p, s); throw tactic_cmd_error(sstream() << "invalid tactic command '" << id << "'", p, s);
@ -1483,22 +1500,31 @@ class parser::imp {
} }
} }
expr apply_tactics(expr const & type, expr const & val, metavar_env & menv) { /**
\brief Try to fill the 'holes' in \c val using tactics.
The expression \c expected_type is the type of \c val.
The metavar_env \c menv contains the definition of the metavariables occurring in \c val.
If a 'hole' is associated with a "hint tactic" ('show-by' and 'by' constructs),
then this will be the tactic used to "fill" the hole. Otherwise,
a tactic command sequence is expected in the input stream being parsed.
*/
expr apply_tactics(expr const & expected_type, expr const & val, metavar_env & menv) {
if (is_metavar(val)) { if (is_metavar(val)) {
// simple case // simple case
if (!m_type_inferer.is_proposition(type)) if (!m_type_inferer.is_proposition(expected_type))
throw exception("failed to synthesize metavar, its type is not a proposition"); throw exception("failed to synthesize metavar, its type is not a proposition");
proof_state s = to_proof_state(m_frontend, context(), type); proof_state s = to_proof_state(m_frontend, context(), expected_type);
std::pair<tactic, pos_info> hint_and_pos = get_tactic_tactic_for(val); std::pair<tactic, pos_info> hint_and_pos = get_tactic_tactic_for(val);
if (hint_and_pos.first) { if (hint_and_pos.first) {
// metavariable has an associated tactic hint // metavariable has an associated tactic hint
s = tactic_apply(s, hint_and_pos.first, hint_and_pos.second); s = apply_tactic(s, hint_and_pos.first, hint_and_pos.second).first;
return mk_proof_for(s, hint_and_pos.second); return mk_proof_for(s, hint_and_pos.second);
} else { } else {
display_proof_state_if_interactive(s); display_proof_state_if_interactive(s);
show_tactic_prompt(); show_tactic_prompt();
check_period_next("invalid theorem, '.' expected before tactical proof"); check_period_next("invalid theorem, '.' expected before tactical proof");
return parse_tactic(s); return parse_tactic_cmds(s);
} }
} else { } else {
buffer<expr> mvars; buffer<expr> mvars;
@ -1526,7 +1552,7 @@ class parser::imp {
std::pair<tactic, pos_info> hint_and_pos = get_tactic_tactic_for(mvar); std::pair<tactic, pos_info> hint_and_pos = get_tactic_tactic_for(mvar);
if (hint_and_pos.first) { if (hint_and_pos.first) {
// metavariable has an associated tactic hint // metavariable has an associated tactic hint
s = tactic_apply(s, hint_and_pos.first, hint_and_pos.second); s = apply_tactic(s, hint_and_pos.first, hint_and_pos.second).first;
menv.assign(mvar, mk_proof_for(s, hint_and_pos.second)); menv.assign(mvar, mk_proof_for(s, hint_and_pos.second));
} else { } else {
if (curr_is_period()) { if (curr_is_period()) {
@ -1534,7 +1560,7 @@ class parser::imp {
show_tactic_prompt(); show_tactic_prompt();
next(); next();
} }
expr mvar_val = parse_tactic(s); expr mvar_val = parse_tactic_cmds(s);
if (mvar_val) if (mvar_val)
menv.assign(mvar, mvar_val); menv.assign(mvar, mvar_val);
} }
@ -2092,6 +2118,13 @@ public:
show_prompt(m_interactive, m_frontend); show_prompt(m_interactive, m_frontend);
} }
void show_tactic_prompt() {
if (m_interactive) {
regular(m_frontend) << "## ";
regular(m_frontend).flush();
}
}
/** \brief Parse a sequence of commands. This method also perform error management. */ /** \brief Parse a sequence of commands. This method also perform error management. */
bool parse_commands() { bool parse_commands() {
bool done = false; bool done = false;