116 lines
5 KiB
C++
116 lines
5 KiB
C++
/*
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Copyright (c) 2013-2014 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#pragma once
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#include <functional>
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#include "util/lua.h"
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#include "util/optional.h"
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#include "util/lbool.h"
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#include "util/buffer.h"
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#include "util/name_map.h"
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#include "kernel/expr.h"
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#include "kernel/environment.h"
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#include "library/idx_metavar.h"
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namespace lean {
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/** \brief Context for match_plugins. */
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class match_context {
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public:
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/** \brief Create a fresh name. */
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virtual name mk_name() = 0;
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/** \brief Given a variable \c x, return its assignment (if available) */
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virtual optional<expr> get_subst(expr const & x) const = 0;
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/** \brief Given a universe level meta-variable \c x (created using #mk_idx_metauniv),
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return its assignment (if available) */
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virtual optional<level> get_subst(level const & x) const = 0;
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/** \brief Assign the variable \c x to \c e
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\pre \c x is not assigned
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*/
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virtual void assign(expr const & x, expr const & e) = 0;
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/** \brief Assign the variable \c x to \c l
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\pre \c x is not assigned, \c x was created using #mk_idx_metauniv.
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*/
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virtual void assign(level const & x, level const & l) = 0;
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virtual bool match(expr const & p, expr const & t) = 0;
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};
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/** \brief Callback for extending the higher-order pattern matching procedure.
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It is invoked before the matcher fails.
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plugin(p, t, s) must return true iff for updated substitution s', s'(p) is definitionally equal to t.
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*/
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class match_plugin {
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public:
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virtual ~match_plugin() {}
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/** \brief The following method is invoked before the matcher tries to process
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\c p and \c t. The method is only invoked when \c p and \c t have the same kind,
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\c p is not a special metavariable created using \c mk_idx_metavar, and
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\c p and \c t are not structurally identical.
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The result should be:
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- l_false : did not match
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- l_true : matched
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- l_undef : did not handled (i.e., default matcher should be used)
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*/
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virtual lbool pre(expr const & /*p*/, expr const & /*t*/, match_context & /*ctx*/) const { return l_undef; }
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/** \brief The following method is invoked when matcher doesn't have anything else to do.
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This method is usually used to invoke expensive procedures such as the normalizer.
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It should return true it the plugin did manage to match p and t.
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*/
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virtual bool on_failure(expr const & p, expr const & t, match_context & ctx) const = 0;
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};
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/** \brief Simple plugin that just puts terms in whnf and tries again */
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class whnf_match_plugin : public match_plugin {
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type_checker & m_tc;
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public:
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whnf_match_plugin(type_checker & tc):m_tc(tc) {}
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virtual bool on_failure(expr const & p, expr const & t, match_context & ctx) const;
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};
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/**
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\brief Matching for higher-order patterns. Return true iff \c t matches the higher-order pattern \c p.
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The substitution is stored in \c subst. Note that, this procedure treats "special" meta-variables
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(created using #mk_idx_metauniv and #mk_idx_metavar) as placeholders. The substitution of these
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metavariable can be quickly accessed using an index stored in them. The parameters
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\c esubst and \c lsubst store the substitutions for them. There are just buffers.
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\pre \p and \c t must not contain free variables. Thus, free-variables must be replaced with local constants
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before invoking this function.
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Other (non special) meta-variables are treated as opaque constants.
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\c p is a higher-order pattern when in all applications in \c p
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1- A special meta-variable is not the function OR
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2- A special meta-variable is the function, but all other arguments are distinct local constants.
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\pre \c esubst and \c lsubst must be big enough to store the substitution.
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That is, their size should be > than the index of any special metavariable occuring in p.
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If prefix is provided, then it is used for creating unique names.
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If name_subst is different from nullptr, then the procedure stores in name_subst
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a mapping for binder names. It maps the binder names used in the pattern \c p into
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the binder names used in \c t.
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If the plugin is provided, then it is invoked before a failure.
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If \c assigned is provided, then it is set to true if \c esubst or \c lsubst is updated.
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*/
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bool match(expr const & p, expr const & t, buffer<optional<level>> & lsubst, buffer<optional<expr>> & esubst,
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name const * prefix = nullptr, name_map<name> * name_subst = nullptr, match_plugin const * plugin = nullptr,
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bool * assigned = nullptr);
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bool match(expr const & p, expr const & t,
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unsigned lsubst_sz, optional<level> * lsubst,
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unsigned esubst_sz, optional<expr> * esubst,
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name const * prefix = nullptr, name_map<name> * name_subst = nullptr,
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match_plugin const * plugin = nullptr, bool * assigned = nullptr);
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void open_match(lua_State * L);
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void initialize_match();
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void finalize_match();
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}
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