--- /dev/null
+/* Copyright (C) 1999,2000,2001, 2003, 2006, 2008 Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+\f
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libguile/_scm.h"
+#include "libguile/alist.h"
+#include "libguile/eval.h"
+#include "libguile/gh.h"
+#include "libguile/hash.h"
+#include "libguile/list.h"
+#include "libguile/ports.h"
+#include "libguile/smob.h"
+#include "libguile/symbols.h"
+#include "libguile/vectors.h"
+#include "libguile/weaks.h"
+
+#include "libguile/environments.h"
+
+\f
+
+scm_t_bits scm_tc16_environment;
+scm_t_bits scm_tc16_observer;
+#define DEFAULT_OBARRAY_SIZE 31
+
+SCM scm_system_environment;
+
+\f
+
+/* error conditions */
+
+/*
+ * Throw an error if symbol is not bound in environment func
+ */
+void
+scm_error_environment_unbound (const char *func, SCM env, SCM symbol)
+{
+ /* Dirk:FIXME:: Should throw an environment:unbound type error */
+ char error[] = "Symbol `~A' not bound in environment `~A'.";
+ SCM arguments = scm_cons2 (symbol, env, SCM_EOL);
+ scm_misc_error (func, error, arguments);
+}
+
+
+/*
+ * Throw an error if func tried to create (define) or remove
+ * (undefine) a new binding for symbol in env
+ */
+void
+scm_error_environment_immutable_binding (const char *func, SCM env, SCM symbol)
+{
+ /* Dirk:FIXME:: Should throw an environment:immutable-binding type error */
+ char error[] = "Immutable binding in environment ~A (symbol: `~A').";
+ SCM arguments = scm_cons2 (env, symbol, SCM_EOL);
+ scm_misc_error (func, error, arguments);
+}
+
+
+/*
+ * Throw an error if func tried to change an immutable location.
+ */
+void
+scm_error_environment_immutable_location (const char *func, SCM env, SCM symbol)
+{
+ /* Dirk:FIXME:: Should throw an environment:immutable-location type error */
+ char error[] = "Immutable location in environment `~A' (symbol: `~A').";
+ SCM arguments = scm_cons2 (env, symbol, SCM_EOL);
+ scm_misc_error (func, error, arguments);
+}
+
+\f
+
+/* generic environments */
+
+
+/* Create an environment for the given type. Dereferencing type twice must
+ * deliver the initialized set of environment functions. Thus, type will
+ * also determine the signature of the underlying environment implementation.
+ * Dereferencing type once will typically deliver the data fields used by the
+ * underlying environment implementation.
+ */
+SCM
+scm_make_environment (void *type)
+{
+ return scm_cell (scm_tc16_environment, (scm_t_bits) type);
+}
+
+
+SCM_DEFINE (scm_environment_p, "environment?", 1, 0, 0,
+ (SCM obj),
+ "Return @code{#t} if @var{obj} is an environment, or @code{#f}\n"
+ "otherwise.")
+#define FUNC_NAME s_scm_environment_p
+{
+ return scm_from_bool (SCM_ENVIRONMENT_P (obj));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_bound_p, "environment-bound?", 2, 0, 0,
+ (SCM env, SCM sym),
+ "Return @code{#t} if @var{sym} is bound in @var{env}, or\n"
+ "@code{#f} otherwise.")
+#define FUNC_NAME s_scm_environment_bound_p
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, FUNC_NAME);
+
+ return scm_from_bool (SCM_ENVIRONMENT_BOUND_P (env, sym));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_ref, "environment-ref", 2, 0, 0,
+ (SCM env, SCM sym),
+ "Return the value of the location bound to @var{sym} in\n"
+ "@var{env}. If @var{sym} is unbound in @var{env}, signal an\n"
+ "@code{environment:unbound} error.")
+#define FUNC_NAME s_scm_environment_ref
+{
+ SCM val;
+
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, FUNC_NAME);
+
+ val = SCM_ENVIRONMENT_REF (env, sym);
+
+ if (!SCM_UNBNDP (val))
+ return val;
+ else
+ scm_error_environment_unbound (FUNC_NAME, env, sym);
+}
+#undef FUNC_NAME
+
+
+/* This C function is identical to environment-ref, except that if symbol is
+ * unbound in env, it returns the value SCM_UNDEFINED, instead of signalling
+ * an error.
+ */
+SCM
+scm_c_environment_ref (SCM env, SCM sym)
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, "scm_c_environment_ref");
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, "scm_c_environment_ref");
+ return SCM_ENVIRONMENT_REF (env, sym);
+}
+
+
+static SCM
+environment_default_folder (SCM proc, SCM symbol, SCM value, SCM tail)
+{
+ return scm_call_3 (proc, symbol, value, tail);
+}
+
+
+SCM_DEFINE (scm_environment_fold, "environment-fold", 3, 0, 0,
+ (SCM env, SCM proc, SCM init),
+ "Iterate over all the bindings in @var{env}, accumulating some\n"
+ "value.\n"
+ "For each binding in @var{env}, apply @var{proc} to the symbol\n"
+ "bound, its value, and the result from the previous application\n"
+ "of @var{proc}.\n"
+ "Use @var{init} as @var{proc}'s third argument the first time\n"
+ "@var{proc} is applied.\n"
+ "If @var{env} contains no bindings, this function simply returns\n"
+ "@var{init}.\n"
+ "If @var{env} binds the symbol sym1 to the value val1, sym2 to\n"
+ "val2, and so on, then this procedure computes:\n"
+ "@lisp\n"
+ " (proc sym1 val1\n"
+ " (proc sym2 val2\n"
+ " ...\n"
+ " (proc symn valn\n"
+ " init)))\n"
+ "@end lisp\n"
+ "Each binding in @var{env} will be processed exactly once.\n"
+ "@code{environment-fold} makes no guarantees about the order in\n"
+ "which the bindings are processed.\n"
+ "Here is a function which, given an environment, constructs an\n"
+ "association list representing that environment's bindings,\n"
+ "using environment-fold:\n"
+ "@lisp\n"
+ " (define (environment->alist env)\n"
+ " (environment-fold env\n"
+ " (lambda (sym val tail)\n"
+ " (cons (cons sym val) tail))\n"
+ " '()))\n"
+ "@end lisp")
+#define FUNC_NAME s_scm_environment_fold
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (scm_is_true (scm_procedure_p (proc)),
+ proc, SCM_ARG2, FUNC_NAME);
+
+ return SCM_ENVIRONMENT_FOLD (env, environment_default_folder, proc, init);
+}
+#undef FUNC_NAME
+
+
+/* This is the C-level analog of environment-fold. For each binding in ENV,
+ * make the call:
+ * (*proc) (data, symbol, value, previous)
+ * where previous is the value returned from the last call to *PROC, or INIT
+ * for the first call. If ENV contains no bindings, return INIT.
+ */
+SCM
+scm_c_environment_fold (SCM env, scm_environment_folder proc, SCM data, SCM init)
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, "scm_c_environment_fold");
+
+ return SCM_ENVIRONMENT_FOLD (env, proc, data, init);
+}
+
+
+SCM_DEFINE (scm_environment_define, "environment-define", 3, 0, 0,
+ (SCM env, SCM sym, SCM val),
+ "Bind @var{sym} to a new location containing @var{val} in\n"
+ "@var{env}. If @var{sym} is already bound to another location\n"
+ "in @var{env} and the binding is mutable, that binding is\n"
+ "replaced. The new binding and location are both mutable. The\n"
+ "return value is unspecified.\n"
+ "If @var{sym} is already bound in @var{env}, and the binding is\n"
+ "immutable, signal an @code{environment:immutable-binding} error.")
+#define FUNC_NAME s_scm_environment_define
+{
+ SCM status;
+
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, FUNC_NAME);
+
+ status = SCM_ENVIRONMENT_DEFINE (env, sym, val);
+
+ if (scm_is_eq (status, SCM_ENVIRONMENT_SUCCESS))
+ return SCM_UNSPECIFIED;
+ else if (scm_is_eq (status, SCM_ENVIRONMENT_BINDING_IMMUTABLE))
+ scm_error_environment_immutable_binding (FUNC_NAME, env, sym);
+ else
+ abort();
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_undefine, "environment-undefine", 2, 0, 0,
+ (SCM env, SCM sym),
+ "Remove any binding for @var{sym} from @var{env}. If @var{sym}\n"
+ "is unbound in @var{env}, do nothing. The return value is\n"
+ "unspecified.\n"
+ "If @var{sym} is already bound in @var{env}, and the binding is\n"
+ "immutable, signal an @code{environment:immutable-binding} error.")
+#define FUNC_NAME s_scm_environment_undefine
+{
+ SCM status;
+
+ SCM_ASSERT(SCM_ENVIRONMENT_P(env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT(scm_is_symbol(sym), sym, SCM_ARG2, FUNC_NAME);
+
+ status = SCM_ENVIRONMENT_UNDEFINE (env, sym);
+
+ if (scm_is_eq (status, SCM_ENVIRONMENT_SUCCESS))
+ return SCM_UNSPECIFIED;
+ else if (scm_is_eq (status, SCM_ENVIRONMENT_BINDING_IMMUTABLE))
+ scm_error_environment_immutable_binding (FUNC_NAME, env, sym);
+ else
+ abort();
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_set_x, "environment-set!", 3, 0, 0,
+ (SCM env, SCM sym, SCM val),
+ "If @var{env} binds @var{sym} to some location, change that\n"
+ "location's value to @var{val}. The return value is\n"
+ "unspecified.\n"
+ "If @var{sym} is not bound in @var{env}, signal an\n"
+ "@code{environment:unbound} error. If @var{env} binds @var{sym}\n"
+ "to an immutable location, signal an\n"
+ "@code{environment:immutable-location} error.")
+#define FUNC_NAME s_scm_environment_set_x
+{
+ SCM status;
+
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, FUNC_NAME);
+
+ status = SCM_ENVIRONMENT_SET (env, sym, val);
+
+ if (scm_is_eq (status, SCM_ENVIRONMENT_SUCCESS))
+ return SCM_UNSPECIFIED;
+ else if (SCM_UNBNDP (status))
+ scm_error_environment_unbound (FUNC_NAME, env, sym);
+ else if (scm_is_eq (status, SCM_ENVIRONMENT_LOCATION_IMMUTABLE))
+ scm_error_environment_immutable_binding (FUNC_NAME, env, sym);
+ else
+ abort();
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_cell, "environment-cell", 3, 0, 0,
+ (SCM env, SCM sym, SCM for_write),
+ "Return the value cell which @var{env} binds to @var{sym}, or\n"
+ "@code{#f} if the binding does not live in a value cell.\n"
+ "The argument @var{for-write} indicates whether the caller\n"
+ "intends to modify the variable's value by mutating the value\n"
+ "cell. If the variable is immutable, then\n"
+ "@code{environment-cell} signals an\n"
+ "@code{environment:immutable-location} error.\n"
+ "If @var{sym} is unbound in @var{env}, signal an\n"
+ "@code{environment:unbound} error.\n"
+ "If you use this function, you should consider using\n"
+ "@code{environment-observe}, to be notified when @var{sym} gets\n"
+ "re-bound to a new value cell, or becomes undefined.")
+#define FUNC_NAME s_scm_environment_cell
+{
+ SCM location;
+
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, FUNC_NAME);
+ SCM_ASSERT (scm_is_bool (for_write), for_write, SCM_ARG3, FUNC_NAME);
+
+ location = SCM_ENVIRONMENT_CELL (env, sym, scm_is_true (for_write));
+ if (!SCM_IMP (location))
+ return location;
+ else if (SCM_UNBNDP (location))
+ scm_error_environment_unbound (FUNC_NAME, env, sym);
+ else if (scm_is_eq (location, SCM_ENVIRONMENT_LOCATION_IMMUTABLE))
+ scm_error_environment_immutable_location (FUNC_NAME, env, sym);
+ else /* no cell */
+ return location;
+}
+#undef FUNC_NAME
+
+
+/* This C function is identical to environment-cell, with the following
+ * exceptions: If symbol is unbound in env, it returns the value
+ * SCM_UNDEFINED, instead of signalling an error. If symbol is bound to an
+ * immutable location but the cell is requested for write, the value
+ * SCM_ENVIRONMENT_LOCATION_IMMUTABLE is returned.
+ */
+SCM
+scm_c_environment_cell(SCM env, SCM sym, int for_write)
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, "scm_c_environment_cell");
+ SCM_ASSERT (scm_is_symbol (sym), sym, SCM_ARG2, "scm_c_environment_cell");
+
+ return SCM_ENVIRONMENT_CELL (env, sym, for_write);
+}
+
+
+static void
+environment_default_observer (SCM env, SCM proc)
+{
+ scm_call_1 (proc, env);
+}
+
+
+SCM_DEFINE (scm_environment_observe, "environment-observe", 2, 0, 0,
+ (SCM env, SCM proc),
+ "Whenever @var{env}'s bindings change, apply @var{proc} to\n"
+ "@var{env}.\n"
+ "This function returns an object, token, which you can pass to\n"
+ "@code{environment-unobserve} to remove @var{proc} from the set\n"
+ "of procedures observing @var{env}. The type and value of\n"
+ "token is unspecified.")
+#define FUNC_NAME s_scm_environment_observe
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return SCM_ENVIRONMENT_OBSERVE (env, environment_default_observer, proc, 0);
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_observe_weak, "environment-observe-weak", 2, 0, 0,
+ (SCM env, SCM proc),
+ "This function is the same as environment-observe, except that\n"
+ "the reference @var{env} retains to @var{proc} is a weak\n"
+ "reference. This means that, if there are no other live,\n"
+ "non-weak references to @var{proc}, it will be\n"
+ "garbage-collected, and dropped from @var{env}'s\n"
+ "list of observing procedures.")
+#define FUNC_NAME s_scm_environment_observe_weak
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return SCM_ENVIRONMENT_OBSERVE (env, environment_default_observer, proc, 1);
+}
+#undef FUNC_NAME
+
+
+/* This is the C-level analog of the Scheme functions environment-observe and
+ * environment-observe-weak. Whenever env's bindings change, call the
+ * function proc, passing it env and data. If weak_p is non-zero, env will
+ * retain only a weak reference to data, and if data is garbage collected, the
+ * entire observation will be dropped. This function returns a token, with
+ * the same meaning as those returned by environment-observe and
+ * environment-observe-weak.
+ */
+SCM
+scm_c_environment_observe (SCM env, scm_environment_observer proc, SCM data, int weak_p)
+#define FUNC_NAME "scm_c_environment_observe"
+{
+ SCM_ASSERT (SCM_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return SCM_ENVIRONMENT_OBSERVE (env, proc, data, weak_p);
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_environment_unobserve, "environment-unobserve", 1, 0, 0,
+ (SCM token),
+ "Cancel the observation request which returned the value\n"
+ "@var{token}. The return value is unspecified.\n"
+ "If a call @code{(environment-observe env proc)} returns\n"
+ "@var{token}, then the call @code{(environment-unobserve token)}\n"
+ "will cause @var{proc} to no longer be called when @var{env}'s\n"
+ "bindings change.")
+#define FUNC_NAME s_scm_environment_unobserve
+{
+ SCM env;
+
+ SCM_ASSERT (SCM_OBSERVER_P (token), token, SCM_ARG1, FUNC_NAME);
+
+ env = SCM_OBSERVER_ENVIRONMENT (token);
+ SCM_ENVIRONMENT_UNOBSERVE (env, token);
+
+ return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+
+static SCM
+environment_mark (SCM env)
+{
+ return (*(SCM_ENVIRONMENT_FUNCS (env)->mark)) (env);
+}
+
+
+static size_t
+environment_free (SCM env)
+{
+ (*(SCM_ENVIRONMENT_FUNCS (env)->free)) (env);
+ return 0;
+}
+
+
+static int
+environment_print (SCM env, SCM port, scm_print_state *pstate)
+{
+ return (*(SCM_ENVIRONMENT_FUNCS (env)->print)) (env, port, pstate);
+}
+
+\f
+
+/* observers */
+
+static SCM
+observer_mark (SCM observer)
+{
+ scm_gc_mark (SCM_OBSERVER_ENVIRONMENT (observer));
+ scm_gc_mark (SCM_OBSERVER_DATA (observer));
+ return SCM_BOOL_F;
+}
+
+
+static int
+observer_print (SCM type, SCM port, scm_print_state *pstate SCM_UNUSED)
+{
+ SCM address = scm_from_size_t (SCM_UNPACK (type));
+ SCM base16 = scm_number_to_string (address, scm_from_int (16));
+
+ scm_puts ("#<observer ", port);
+ scm_display (base16, port);
+ scm_puts (">", port);
+
+ return 1;
+}
+
+\f
+
+/* obarrays
+ *
+ * Obarrays form the basic lookup tables used to implement most of guile's
+ * built-in environment types. An obarray is implemented as a hash table with
+ * symbols as keys. The content of the data depends on the environment type.
+ */
+
+
+/*
+ * Enter symbol into obarray. The symbol must not already exist in obarray.
+ * The freshly generated (symbol . data) cell is returned.
+ */
+static SCM
+obarray_enter (SCM obarray, SCM symbol, SCM data)
+{
+ size_t hash = scm_i_symbol_hash (symbol) % SCM_HASHTABLE_N_BUCKETS (obarray);
+ SCM entry = scm_cons (symbol, data);
+ SCM slot = scm_cons (entry, SCM_HASHTABLE_BUCKET (obarray, hash));
+ SCM_SET_HASHTABLE_BUCKET (obarray, hash, slot);
+ SCM_HASHTABLE_INCREMENT (obarray);
+ if (SCM_HASHTABLE_N_ITEMS (obarray) > SCM_HASHTABLE_UPPER (obarray))
+ scm_i_rehash (obarray, scm_i_hash_symbol, 0, "obarray_enter");
+
+ return entry;
+}
+
+
+/*
+ * Enter symbol into obarray. An existing entry for symbol is replaced. If
+ * an entry existed, the old (symbol . data) cell is returned, #f otherwise.
+ */
+static SCM
+obarray_replace (SCM obarray, SCM symbol, SCM data)
+{
+ size_t hash = scm_i_symbol_hash (symbol) % SCM_HASHTABLE_N_BUCKETS (obarray);
+ SCM new_entry = scm_cons (symbol, data);
+ SCM lsym;
+ SCM slot;
+
+ for (lsym = SCM_HASHTABLE_BUCKET (obarray, hash);
+ !scm_is_null (lsym);
+ lsym = SCM_CDR (lsym))
+ {
+ SCM old_entry = SCM_CAR (lsym);
+ if (scm_is_eq (SCM_CAR (old_entry), symbol))
+ {
+ SCM_SETCAR (lsym, new_entry);
+ return old_entry;
+ }
+ }
+
+ slot = scm_cons (new_entry, SCM_HASHTABLE_BUCKET (obarray, hash));
+ SCM_SET_HASHTABLE_BUCKET (obarray, hash, slot);
+ SCM_HASHTABLE_INCREMENT (obarray);
+ if (SCM_HASHTABLE_N_ITEMS (obarray) > SCM_HASHTABLE_UPPER (obarray))
+ scm_i_rehash (obarray, scm_i_hash_symbol, 0, "obarray_replace");
+
+ return SCM_BOOL_F;
+}
+
+
+/*
+ * Look up symbol in obarray
+ */
+static SCM
+obarray_retrieve (SCM obarray, SCM sym)
+{
+ size_t hash = scm_i_symbol_hash (sym) % SCM_HASHTABLE_N_BUCKETS (obarray);
+ SCM lsym;
+
+ for (lsym = SCM_HASHTABLE_BUCKET (obarray, hash);
+ !scm_is_null (lsym);
+ lsym = SCM_CDR (lsym))
+ {
+ SCM entry = SCM_CAR (lsym);
+ if (scm_is_eq (SCM_CAR (entry), sym))
+ return entry;
+ }
+
+ return SCM_UNDEFINED;
+}
+
+
+/*
+ * Remove entry from obarray. If the symbol was found and removed, the old
+ * (symbol . data) cell is returned, #f otherwise.
+ */
+static SCM
+obarray_remove (SCM obarray, SCM sym)
+{
+ size_t hash = scm_i_symbol_hash (sym) % SCM_HASHTABLE_N_BUCKETS (obarray);
+ SCM table_entry = SCM_HASHTABLE_BUCKET (obarray, hash);
+ SCM handle = scm_sloppy_assq (sym, table_entry);
+
+ if (scm_is_pair (handle))
+ {
+ SCM new_table_entry = scm_delq1_x (handle, table_entry);
+ SCM_SET_HASHTABLE_BUCKET (obarray, hash, new_table_entry);
+ SCM_HASHTABLE_DECREMENT (obarray);
+ }
+
+ return handle;
+}
+
+
+static void
+obarray_remove_all (SCM obarray)
+{
+ size_t size = SCM_HASHTABLE_N_BUCKETS (obarray);
+ size_t i;
+
+ for (i = 0; i < size; i++)
+ {
+ SCM_SET_HASHTABLE_BUCKET (obarray, i, SCM_EOL);
+ }
+ SCM_SET_HASHTABLE_N_ITEMS (obarray, 0);
+}
+
+\f
+
+/* core environments base
+ *
+ * This struct and the corresponding functions form a base class for guile's
+ * built-in environment types.
+ */
+
+
+struct core_environments_base {
+ struct scm_environment_funcs *funcs;
+
+ SCM observers;
+ SCM weak_observers;
+};
+
+
+#define CORE_ENVIRONMENTS_BASE(env) \
+ ((struct core_environments_base *) SCM_CELL_WORD_1 (env))
+#define CORE_ENVIRONMENT_OBSERVERS(env) \
+ (CORE_ENVIRONMENTS_BASE (env)->observers)
+#define SCM_SET_CORE_ENVIRONMENT_OBSERVERS(env, v) \
+ (CORE_ENVIRONMENT_OBSERVERS (env) = (v))
+#define CORE_ENVIRONMENT_WEAK_OBSERVER_VECTOR(env) \
+ (CORE_ENVIRONMENTS_BASE (env)->weak_observers)
+#define CORE_ENVIRONMENT_WEAK_OBSERVERS(env) \
+ (scm_c_vector_ref (CORE_ENVIRONMENT_WEAK_OBSERVER_VECTOR (env), 0))
+#define SCM_SET_CORE_ENVIRONMENT_WEAK_OBSERVERS(env, v) \
+ (scm_c_vector_set_x (CORE_ENVIRONMENT_WEAK_OBSERVER_VECTOR (env), 0, (v)))
+
+\f
+
+static SCM
+core_environments_observe (SCM env, scm_environment_observer proc, SCM data, int weak_p)
+{
+ SCM observer = scm_double_cell (scm_tc16_observer,
+ SCM_UNPACK (env),
+ SCM_UNPACK (data),
+ (scm_t_bits) proc);
+
+ if (!weak_p)
+ {
+ SCM observers = CORE_ENVIRONMENT_OBSERVERS (env);
+ SCM new_observers = scm_cons (observer, observers);
+ SCM_SET_CORE_ENVIRONMENT_OBSERVERS (env, new_observers);
+ }
+ else
+ {
+ SCM observers = CORE_ENVIRONMENT_WEAK_OBSERVERS (env);
+ SCM new_observers = scm_acons (SCM_BOOL_F, observer, observers);
+ SCM_SET_CORE_ENVIRONMENT_WEAK_OBSERVERS (env, new_observers);
+ }
+
+ return observer;
+}
+
+
+static void
+core_environments_unobserve (SCM env, SCM observer)
+{
+ unsigned int handling_weaks;
+ for (handling_weaks = 0; handling_weaks <= 1; ++handling_weaks)
+ {
+ SCM l = handling_weaks
+ ? CORE_ENVIRONMENT_WEAK_OBSERVERS (env)
+ : CORE_ENVIRONMENT_OBSERVERS (env);
+
+ if (!scm_is_null (l))
+ {
+ SCM rest = SCM_CDR (l);
+ SCM first = handling_weaks
+ ? SCM_CDAR (l)
+ : SCM_CAR (l);
+
+ if (scm_is_eq (first, observer))
+ {
+ /* Remove the first observer */
+ if (handling_weaks)
+ SCM_SET_CORE_ENVIRONMENT_WEAK_OBSERVERS (env, rest);
+ else
+ SCM_SET_CORE_ENVIRONMENT_OBSERVERS (env, rest);
+ return;
+ }
+
+ do {
+ SCM rest = SCM_CDR (l);
+
+ if (!scm_is_null (rest))
+ {
+ SCM next = handling_weaks
+ ? SCM_CDAR (l)
+ : SCM_CAR (l);
+
+ if (scm_is_eq (next, observer))
+ {
+ SCM_SETCDR (l, SCM_CDR (rest));
+ return;
+ }
+ }
+
+ l = rest;
+ } while (!scm_is_null (l));
+ }
+ }
+
+ /* Dirk:FIXME:: What to do now, since the observer is not found? */
+}
+
+
+static SCM
+core_environments_mark (SCM env)
+{
+ scm_gc_mark (CORE_ENVIRONMENT_OBSERVERS (env));
+ return CORE_ENVIRONMENT_WEAK_OBSERVER_VECTOR (env);
+}
+
+
+static void
+core_environments_finalize (SCM env SCM_UNUSED)
+{
+}
+
+
+static void
+core_environments_preinit (struct core_environments_base *body)
+{
+ body->funcs = NULL;
+ body->observers = SCM_BOOL_F;
+ body->weak_observers = SCM_BOOL_F;
+}
+
+
+static void
+core_environments_init (struct core_environments_base *body,
+ struct scm_environment_funcs *funcs)
+{
+ body->funcs = funcs;
+ body->observers = SCM_EOL;
+ body->weak_observers = scm_make_weak_value_alist_vector (scm_from_int (1));
+}
+
+
+/* Tell all observers to clear their caches.
+ *
+ * Environments have to be informed about changes in the following cases:
+ * - The observed env has a new binding. This must be always reported.
+ * - The observed env has dropped a binding. This must be always reported.
+ * - A binding in the observed environment has changed. This must only be
+ * reported, if there is a chance that the binding is being cached outside.
+ * However, this potential optimization is not performed currently.
+ *
+ * Errors that occur while the observers are called are accumulated and
+ * signalled as one single error message to the caller.
+ */
+
+struct update_data
+{
+ SCM observer;
+ SCM environment;
+};
+
+
+static SCM
+update_catch_body (void *ptr)
+{
+ struct update_data *data = (struct update_data *) ptr;
+ SCM observer = data->observer;
+
+ (*SCM_OBSERVER_PROC (observer))
+ (data->environment, SCM_OBSERVER_DATA (observer));
+
+ return SCM_UNDEFINED;
+}
+
+
+static SCM
+update_catch_handler (void *ptr, SCM tag, SCM args)
+{
+ struct update_data *data = (struct update_data *) ptr;
+ SCM observer = data->observer;
+ SCM message =
+ scm_from_locale_string ("Observer `~A' signals `~A' error: ~S");
+
+ return scm_cons (message, scm_list_3 (observer, tag, args));
+}
+
+
+static void
+core_environments_broadcast (SCM env)
+#define FUNC_NAME "core_environments_broadcast"
+{
+ unsigned int handling_weaks;
+ SCM errors = SCM_EOL;
+
+ for (handling_weaks = 0; handling_weaks <= 1; ++handling_weaks)
+ {
+ SCM observers = handling_weaks
+ ? CORE_ENVIRONMENT_WEAK_OBSERVERS (env)
+ : CORE_ENVIRONMENT_OBSERVERS (env);
+
+ for (; !scm_is_null (observers); observers = SCM_CDR (observers))
+ {
+ struct update_data data;
+ SCM observer = handling_weaks
+ ? SCM_CDAR (observers)
+ : SCM_CAR (observers);
+ SCM error;
+
+ data.observer = observer;
+ data.environment = env;
+
+ error = scm_internal_catch (SCM_BOOL_T,
+ update_catch_body, &data,
+ update_catch_handler, &data);
+
+ if (!SCM_UNBNDP (error))
+ errors = scm_cons (error, errors);
+ }
+ }
+
+ if (!scm_is_null (errors))
+ {
+ /* Dirk:FIXME:: As soon as scm_misc_error is fixed to handle the name
+ * parameter correctly it should not be necessary any more to also pass
+ * namestr in order to get the desired information from the error
+ * message.
+ */
+ SCM ordered_errors = scm_reverse (errors);
+ scm_misc_error
+ (FUNC_NAME,
+ "Observers of `~A' have signalled the following errors: ~S",
+ scm_cons2 (env, ordered_errors, SCM_EOL));
+ }
+}
+#undef FUNC_NAME
+
+\f
+
+/* leaf environments
+ *
+ * A leaf environment is simply a mutable set of definitions. A leaf
+ * environment supports no operations beyond the common set.
+ *
+ * Implementation: The obarray of the leaf environment holds (symbol . value)
+ * pairs. No further information is necessary, since all bindings and
+ * locations in a leaf environment are mutable.
+ */
+
+
+struct leaf_environment {
+ struct core_environments_base base;
+
+ SCM obarray;
+};
+
+
+#define LEAF_ENVIRONMENT(env) \
+ ((struct leaf_environment *) SCM_CELL_WORD_1 (env))
+
+\f
+
+static SCM
+leaf_environment_ref (SCM env, SCM sym)
+{
+ SCM obarray = LEAF_ENVIRONMENT (env)->obarray;
+ SCM binding = obarray_retrieve (obarray, sym);
+ return SCM_UNBNDP (binding) ? binding : SCM_CDR (binding);
+}
+
+
+static SCM
+leaf_environment_fold (SCM env, scm_environment_folder proc, SCM data, SCM init)
+{
+ size_t i;
+ SCM result = init;
+ SCM obarray = LEAF_ENVIRONMENT (env)->obarray;
+
+ for (i = 0; i < SCM_HASHTABLE_N_BUCKETS (obarray); i++)
+ {
+ SCM l;
+ for (l = SCM_HASHTABLE_BUCKET (obarray, i);
+ !scm_is_null (l);
+ l = SCM_CDR (l))
+ {
+ SCM binding = SCM_CAR (l);
+ SCM symbol = SCM_CAR (binding);
+ SCM value = SCM_CDR (binding);
+ result = (*proc) (data, symbol, value, result);
+ }
+ }
+ return result;
+}
+
+
+static SCM
+leaf_environment_define (SCM env, SCM sym, SCM val)
+#define FUNC_NAME "leaf_environment_define"
+{
+ SCM obarray = LEAF_ENVIRONMENT (env)->obarray;
+
+ obarray_replace (obarray, sym, val);
+ core_environments_broadcast (env);
+
+ return SCM_ENVIRONMENT_SUCCESS;
+}
+#undef FUNC_NAME
+
+
+static SCM
+leaf_environment_undefine (SCM env, SCM sym)
+#define FUNC_NAME "leaf_environment_undefine"
+{
+ SCM obarray = LEAF_ENVIRONMENT (env)->obarray;
+ SCM removed = obarray_remove (obarray, sym);
+
+ if (scm_is_true (removed))
+ core_environments_broadcast (env);
+
+ return SCM_ENVIRONMENT_SUCCESS;
+}
+#undef FUNC_NAME
+
+
+static SCM
+leaf_environment_set_x (SCM env, SCM sym, SCM val)
+#define FUNC_NAME "leaf_environment_set_x"
+{
+ SCM obarray = LEAF_ENVIRONMENT (env)->obarray;
+ SCM binding = obarray_retrieve (obarray, sym);
+
+ if (!SCM_UNBNDP (binding))
+ {
+ SCM_SETCDR (binding, val);
+ return SCM_ENVIRONMENT_SUCCESS;
+ }
+ else
+ {
+ return SCM_UNDEFINED;
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+leaf_environment_cell (SCM env, SCM sym, int for_write SCM_UNUSED)
+{
+ SCM obarray = LEAF_ENVIRONMENT (env)->obarray;
+ SCM binding = obarray_retrieve (obarray, sym);
+ return binding;
+}
+
+
+static SCM
+leaf_environment_mark (SCM env)
+{
+ scm_gc_mark (LEAF_ENVIRONMENT (env)->obarray);
+ return core_environments_mark (env);
+}
+
+
+static void
+leaf_environment_free (SCM env)
+{
+ core_environments_finalize (env);
+ scm_gc_free (LEAF_ENVIRONMENT (env), sizeof (struct leaf_environment),
+ "leaf environment");
+}
+
+
+static int
+leaf_environment_print (SCM type, SCM port, scm_print_state *pstate SCM_UNUSED)
+{
+ SCM address = scm_from_size_t (SCM_UNPACK (type));
+ SCM base16 = scm_number_to_string (address, scm_from_int (16));
+
+ scm_puts ("#<leaf environment ", port);
+ scm_display (base16, port);
+ scm_puts (">", port);
+
+ return 1;
+}
+
+
+static struct scm_environment_funcs leaf_environment_funcs = {
+ leaf_environment_ref,
+ leaf_environment_fold,
+ leaf_environment_define,
+ leaf_environment_undefine,
+ leaf_environment_set_x,
+ leaf_environment_cell,
+ core_environments_observe,
+ core_environments_unobserve,
+ leaf_environment_mark,
+ leaf_environment_free,
+ leaf_environment_print
+};
+
+
+void *scm_type_leaf_environment = &leaf_environment_funcs;
+
+
+SCM_DEFINE (scm_make_leaf_environment, "make-leaf-environment", 0, 0, 0,
+ (),
+ "Create a new leaf environment, containing no bindings.\n"
+ "All bindings and locations created in the new environment\n"
+ "will be mutable.")
+#define FUNC_NAME s_scm_make_leaf_environment
+{
+ size_t size = sizeof (struct leaf_environment);
+ struct leaf_environment *body = scm_gc_malloc (size, "leaf environment");
+ SCM env;
+
+ core_environments_preinit (&body->base);
+ body->obarray = SCM_BOOL_F;
+
+ env = scm_make_environment (body);
+
+ core_environments_init (&body->base, &leaf_environment_funcs);
+ body->obarray = scm_c_make_hash_table (DEFAULT_OBARRAY_SIZE);
+
+ return env;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_leaf_environment_p, "leaf-environment?", 1, 0, 0,
+ (SCM object),
+ "Return @code{#t} if object is a leaf environment, or @code{#f}\n"
+ "otherwise.")
+#define FUNC_NAME s_scm_leaf_environment_p
+{
+ return scm_from_bool (SCM_LEAF_ENVIRONMENT_P (object));
+}
+#undef FUNC_NAME
+
+\f
+
+/* eval environments
+ *
+ * A module's source code refers to definitions imported from other modules,
+ * and definitions made within itself. An eval environment combines two
+ * environments -- a local environment and an imported environment -- to
+ * produce a new environment in which both sorts of references can be
+ * resolved.
+ *
+ * Implementation: The obarray of the eval environment is used to cache
+ * entries from the local and imported environments such that in most of the
+ * cases only a single lookup is necessary. Since for neither the local nor
+ * the imported environment it is known, what kind of environment they form,
+ * the most general case is assumed. Therefore, entries in the obarray take
+ * one of the following forms:
+ *
+ * 1) (<symbol> location mutability . source-env), where mutability indicates
+ * one of the following states: IMMUTABLE if the location is known to be
+ * immutable, MUTABLE if the location is known to be mutable, UNKNOWN if
+ * the location has only been requested for non modifying accesses.
+ *
+ * 2) (symbol . source-env) if the symbol has a binding in the source-env, but
+ * if the source-env can't provide a cell for the binding. Thus, for every
+ * access, the source-env has to be contacted directly.
+ */
+
+
+struct eval_environment {
+ struct core_environments_base base;
+
+ SCM obarray;
+
+ SCM imported;
+ SCM imported_observer;
+ SCM local;
+ SCM local_observer;
+};
+
+
+#define EVAL_ENVIRONMENT(env) \
+ ((struct eval_environment *) SCM_CELL_WORD_1 (env))
+
+#define IMMUTABLE SCM_I_MAKINUM (0)
+#define MUTABLE SCM_I_MAKINUM (1)
+#define UNKNOWN SCM_I_MAKINUM (2)
+
+#define CACHED_LOCATION(x) SCM_CAR (x)
+#define CACHED_MUTABILITY(x) SCM_CADR (x)
+#define SET_CACHED_MUTABILITY(x, v) SCM_SETCAR (SCM_CDR (x), (v))
+#define CACHED_SOURCE_ENVIRONMENT(x) SCM_CDDR (x)
+
+\f
+
+/* eval_environment_lookup will report one of the following distinct results:
+ * a) (<object> . value) if a cell could be obtained.
+ * b) <environment> if the environment has to be contacted directly.
+ * c) IMMUTABLE if an immutable cell was requested for write.
+ * d) SCM_UNDEFINED if there is no binding for the symbol.
+ */
+static SCM
+eval_environment_lookup (SCM env, SCM sym, int for_write)
+{
+ SCM obarray = EVAL_ENVIRONMENT (env)->obarray;
+ SCM binding = obarray_retrieve (obarray, sym);
+
+ if (!SCM_UNBNDP (binding))
+ {
+ /* The obarray holds an entry for the symbol. */
+
+ SCM entry = SCM_CDR (binding);
+
+ if (scm_is_pair (entry))
+ {
+ /* The entry in the obarray is a cached location. */
+
+ SCM location = CACHED_LOCATION (entry);
+ SCM mutability;
+
+ if (!for_write)
+ return location;
+
+ mutability = CACHED_MUTABILITY (entry);
+ if (scm_is_eq (mutability, MUTABLE))
+ return location;
+
+ if (scm_is_eq (mutability, UNKNOWN))
+ {
+ SCM source_env = CACHED_SOURCE_ENVIRONMENT (entry);
+ SCM location = SCM_ENVIRONMENT_CELL (source_env, sym, 1);
+
+ if (scm_is_pair (location))
+ {
+ SET_CACHED_MUTABILITY (entry, MUTABLE);
+ return location;
+ }
+ else /* IMMUTABLE */
+ {
+ SET_CACHED_MUTABILITY (entry, IMMUTABLE);
+ return IMMUTABLE;
+ }
+ }
+
+ return IMMUTABLE;
+ }
+ else
+ {
+ /* The obarray entry is an environment */
+
+ return entry;
+ }
+ }
+ else
+ {
+ /* There is no entry for the symbol in the obarray. This can either
+ * mean that there has not been a request for the symbol yet, or that
+ * the symbol is really undefined. We are looking for the symbol in
+ * both the local and the imported environment. If we find a binding, a
+ * cached entry is created.
+ */
+
+ struct eval_environment *body = EVAL_ENVIRONMENT (env);
+ unsigned int handling_import;
+
+ for (handling_import = 0; handling_import <= 1; ++handling_import)
+ {
+ SCM source_env = handling_import ? body->imported : body->local;
+ SCM location = SCM_ENVIRONMENT_CELL (source_env, sym, for_write);
+
+ if (!SCM_UNBNDP (location))
+ {
+ if (scm_is_pair (location))
+ {
+ SCM mutability = for_write ? MUTABLE : UNKNOWN;
+ SCM entry = scm_cons2 (location, mutability, source_env);
+ obarray_enter (obarray, sym, entry);
+ return location;
+ }
+ else if (scm_is_eq (location, SCM_ENVIRONMENT_LOCATION_NO_CELL))
+ {
+ obarray_enter (obarray, sym, source_env);
+ return source_env;
+ }
+ else
+ {
+ return IMMUTABLE;
+ }
+ }
+ }
+
+ return SCM_UNDEFINED;
+ }
+}
+
+
+static SCM
+eval_environment_ref (SCM env, SCM sym)
+#define FUNC_NAME "eval_environment_ref"
+{
+ SCM location = eval_environment_lookup (env, sym, 0);
+
+ if (scm_is_pair (location))
+ return SCM_CDR (location);
+ else if (!SCM_UNBNDP (location))
+ return SCM_ENVIRONMENT_REF (location, sym);
+ else
+ return SCM_UNDEFINED;
+}
+#undef FUNC_NAME
+
+
+static SCM
+eval_environment_folder (SCM extended_data, SCM symbol, SCM value, SCM tail)
+{
+ SCM local = SCM_CAR (extended_data);
+
+ if (!SCM_ENVIRONMENT_BOUND_P (local, symbol))
+ {
+ SCM proc_as_nr = SCM_CADR (extended_data);
+ unsigned long int proc_as_ul = scm_to_ulong (proc_as_nr);
+ scm_environment_folder proc = (scm_environment_folder) proc_as_ul;
+ SCM data = SCM_CDDR (extended_data);
+
+ return (*proc) (data, symbol, value, tail);
+ }
+ else
+ {
+ return tail;
+ }
+}
+
+
+static SCM
+eval_environment_fold (SCM env, scm_environment_folder proc, SCM data, SCM init)
+{
+ SCM local = EVAL_ENVIRONMENT (env)->local;
+ SCM imported = EVAL_ENVIRONMENT (env)->imported;
+ SCM proc_as_nr = scm_from_ulong ((unsigned long) proc);
+ SCM extended_data = scm_cons2 (local, proc_as_nr, data);
+ SCM tmp_result = scm_c_environment_fold (imported, eval_environment_folder, extended_data, init);
+
+ return scm_c_environment_fold (local, proc, data, tmp_result);
+}
+
+
+static SCM
+eval_environment_define (SCM env, SCM sym, SCM val)
+#define FUNC_NAME "eval_environment_define"
+{
+ SCM local = EVAL_ENVIRONMENT (env)->local;
+ return SCM_ENVIRONMENT_DEFINE (local, sym, val);
+}
+#undef FUNC_NAME
+
+
+static SCM
+eval_environment_undefine (SCM env, SCM sym)
+#define FUNC_NAME "eval_environment_undefine"
+{
+ SCM local = EVAL_ENVIRONMENT (env)->local;
+ return SCM_ENVIRONMENT_UNDEFINE (local, sym);
+}
+#undef FUNC_NAME
+
+
+static SCM
+eval_environment_set_x (SCM env, SCM sym, SCM val)
+#define FUNC_NAME "eval_environment_set_x"
+{
+ SCM location = eval_environment_lookup (env, sym, 1);
+
+ if (scm_is_pair (location))
+ {
+ SCM_SETCDR (location, val);
+ return SCM_ENVIRONMENT_SUCCESS;
+ }
+ else if (SCM_ENVIRONMENT_P (location))
+ {
+ return SCM_ENVIRONMENT_SET (location, sym, val);
+ }
+ else if (scm_is_eq (location, IMMUTABLE))
+ {
+ return SCM_ENVIRONMENT_LOCATION_IMMUTABLE;
+ }
+ else
+ {
+ return SCM_UNDEFINED;
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+eval_environment_cell (SCM env, SCM sym, int for_write)
+#define FUNC_NAME "eval_environment_cell"
+{
+ SCM location = eval_environment_lookup (env, sym, for_write);
+
+ if (scm_is_pair (location))
+ return location;
+ else if (SCM_ENVIRONMENT_P (location))
+ return SCM_ENVIRONMENT_LOCATION_NO_CELL;
+ else if (scm_is_eq (location, IMMUTABLE))
+ return SCM_ENVIRONMENT_LOCATION_IMMUTABLE;
+ else
+ return SCM_UNDEFINED;
+}
+#undef FUNC_NAME
+
+
+static SCM
+eval_environment_mark (SCM env)
+{
+ struct eval_environment *body = EVAL_ENVIRONMENT (env);
+
+ scm_gc_mark (body->obarray);
+ scm_gc_mark (body->imported);
+ scm_gc_mark (body->imported_observer);
+ scm_gc_mark (body->local);
+ scm_gc_mark (body->local_observer);
+
+ return core_environments_mark (env);
+}
+
+
+static void
+eval_environment_free (SCM env)
+{
+ core_environments_finalize (env);
+ scm_gc_free (EVAL_ENVIRONMENT (env), sizeof (struct eval_environment),
+ "eval environment");
+}
+
+
+static int
+eval_environment_print (SCM type, SCM port, scm_print_state *pstate SCM_UNUSED)
+{
+ SCM address = scm_from_size_t (SCM_UNPACK (type));
+ SCM base16 = scm_number_to_string (address, scm_from_int (16));
+
+ scm_puts ("#<eval environment ", port);
+ scm_display (base16, port);
+ scm_puts (">", port);
+
+ return 1;
+}
+
+
+static struct scm_environment_funcs eval_environment_funcs = {
+ eval_environment_ref,
+ eval_environment_fold,
+ eval_environment_define,
+ eval_environment_undefine,
+ eval_environment_set_x,
+ eval_environment_cell,
+ core_environments_observe,
+ core_environments_unobserve,
+ eval_environment_mark,
+ eval_environment_free,
+ eval_environment_print
+};
+
+
+void *scm_type_eval_environment = &eval_environment_funcs;
+
+
+static void
+eval_environment_observer (SCM caller SCM_UNUSED, SCM eval_env)
+{
+ SCM obarray = EVAL_ENVIRONMENT (eval_env)->obarray;
+
+ obarray_remove_all (obarray);
+ core_environments_broadcast (eval_env);
+}
+
+
+SCM_DEFINE (scm_make_eval_environment, "make-eval-environment", 2, 0, 0,
+ (SCM local, SCM imported),
+ "Return a new environment object eval whose bindings are the\n"
+ "union of the bindings in the environments @var{local} and\n"
+ "@var{imported}, with bindings from @var{local} taking\n"
+ "precedence. Definitions made in eval are placed in @var{local}.\n"
+ "Applying @code{environment-define} or\n"
+ "@code{environment-undefine} to eval has the same effect as\n"
+ "applying the procedure to @var{local}.\n"
+ "Note that eval incorporates @var{local} and @var{imported} by\n"
+ "reference:\n"
+ "If, after creating eval, the program changes the bindings of\n"
+ "@var{local} or @var{imported}, those changes will be visible\n"
+ "in eval.\n"
+ "Since most Scheme evaluation takes place in eval environments,\n"
+ "they transparently cache the bindings received from @var{local}\n"
+ "and @var{imported}. Thus, the first time the program looks up\n"
+ "a symbol in eval, eval may make calls to @var{local} or\n"
+ "@var{imported} to find their bindings, but subsequent\n"
+ "references to that symbol will be as fast as references to\n"
+ "bindings in finite environments.\n"
+ "In typical use, @var{local} will be a finite environment, and\n"
+ "@var{imported} will be an import environment")
+#define FUNC_NAME s_scm_make_eval_environment
+{
+ SCM env;
+ struct eval_environment *body;
+
+ SCM_ASSERT (SCM_ENVIRONMENT_P (local), local, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (SCM_ENVIRONMENT_P (imported), imported, SCM_ARG2, FUNC_NAME);
+
+ body = scm_gc_malloc (sizeof (struct eval_environment), "eval environment");
+
+ core_environments_preinit (&body->base);
+ body->obarray = SCM_BOOL_F;
+ body->imported = SCM_BOOL_F;
+ body->imported_observer = SCM_BOOL_F;
+ body->local = SCM_BOOL_F;
+ body->local_observer = SCM_BOOL_F;
+
+ env = scm_make_environment (body);
+
+ core_environments_init (&body->base, &eval_environment_funcs);
+ body->obarray = scm_c_make_hash_table (DEFAULT_OBARRAY_SIZE);
+ body->imported = imported;
+ body->imported_observer
+ = SCM_ENVIRONMENT_OBSERVE (imported, eval_environment_observer, env, 1);
+ body->local = local;
+ body->local_observer
+ = SCM_ENVIRONMENT_OBSERVE (local, eval_environment_observer, env, 1);
+
+ return env;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_eval_environment_p, "eval-environment?", 1, 0, 0,
+ (SCM object),
+ "Return @code{#t} if object is an eval environment, or @code{#f}\n"
+ "otherwise.")
+#define FUNC_NAME s_scm_eval_environment_p
+{
+ return scm_from_bool (SCM_EVAL_ENVIRONMENT_P (object));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_eval_environment_local, "eval-environment-local", 1, 0, 0,
+ (SCM env),
+ "Return the local environment of eval environment @var{env}.")
+#define FUNC_NAME s_scm_eval_environment_local
+{
+ SCM_ASSERT (SCM_EVAL_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return EVAL_ENVIRONMENT (env)->local;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_eval_environment_set_local_x, "eval-environment-set-local!", 2, 0, 0,
+ (SCM env, SCM local),
+ "Change @var{env}'s local environment to @var{local}.")
+#define FUNC_NAME s_scm_eval_environment_set_local_x
+{
+ struct eval_environment *body;
+
+ SCM_ASSERT (SCM_EVAL_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (SCM_ENVIRONMENT_P (local), local, SCM_ARG2, FUNC_NAME);
+
+ body = EVAL_ENVIRONMENT (env);
+
+ obarray_remove_all (body->obarray);
+ SCM_ENVIRONMENT_UNOBSERVE (body->local, body->local_observer);
+
+ body->local = local;
+ body->local_observer
+ = SCM_ENVIRONMENT_OBSERVE (local, eval_environment_observer, env, 1);
+
+ core_environments_broadcast (env);
+
+ return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_eval_environment_imported, "eval-environment-imported", 1, 0, 0,
+ (SCM env),
+ "Return the imported environment of eval environment @var{env}.")
+#define FUNC_NAME s_scm_eval_environment_imported
+{
+ SCM_ASSERT (SCM_EVAL_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return EVAL_ENVIRONMENT (env)->imported;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_eval_environment_set_imported_x, "eval-environment-set-imported!", 2, 0, 0,
+ (SCM env, SCM imported),
+ "Change @var{env}'s imported environment to @var{imported}.")
+#define FUNC_NAME s_scm_eval_environment_set_imported_x
+{
+ struct eval_environment *body;
+
+ SCM_ASSERT (SCM_EVAL_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (SCM_ENVIRONMENT_P (imported), imported, SCM_ARG2, FUNC_NAME);
+
+ body = EVAL_ENVIRONMENT (env);
+
+ obarray_remove_all (body->obarray);
+ SCM_ENVIRONMENT_UNOBSERVE (body->imported, body->imported_observer);
+
+ body->imported = imported;
+ body->imported_observer
+ = SCM_ENVIRONMENT_OBSERVE (imported, eval_environment_observer, env, 1);
+
+ core_environments_broadcast (env);
+
+ return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+\f
+
+/* import environments
+ *
+ * An import environment combines the bindings of a set of argument
+ * environments, and checks for naming clashes.
+ *
+ * Implementation: The import environment does no caching at all. For every
+ * access, the list of imported environments is scanned.
+ */
+
+
+struct import_environment {
+ struct core_environments_base base;
+
+ SCM imports;
+ SCM import_observers;
+
+ SCM conflict_proc;
+};
+
+
+#define IMPORT_ENVIRONMENT(env) \
+ ((struct import_environment *) SCM_CELL_WORD_1 (env))
+
+\f
+
+/* Lookup will report one of the following distinct results:
+ * a) <environment> if only environment binds the symbol.
+ * b) (env-1 env-2 ...) for conflicting bindings in env-1, ...
+ * c) SCM_UNDEFINED if there is no binding for the symbol.
+ */
+static SCM
+import_environment_lookup (SCM env, SCM sym)
+{
+ SCM imports = IMPORT_ENVIRONMENT (env)->imports;
+ SCM result = SCM_UNDEFINED;
+ SCM l;
+
+ for (l = imports; !scm_is_null (l); l = SCM_CDR (l))
+ {
+ SCM imported = SCM_CAR (l);
+
+ if (SCM_ENVIRONMENT_BOUND_P (imported, sym))
+ {
+ if (SCM_UNBNDP (result))
+ result = imported;
+ else if (scm_is_pair (result))
+ result = scm_cons (imported, result);
+ else
+ result = scm_cons2 (imported, result, SCM_EOL);
+ }
+ }
+
+ if (scm_is_pair (result))
+ return scm_reverse (result);
+ else
+ return result;
+}
+
+
+static SCM
+import_environment_conflict (SCM env, SCM sym, SCM imports)
+{
+ SCM conflict_proc = IMPORT_ENVIRONMENT (env)->conflict_proc;
+ SCM args = scm_cons2 (env, sym, scm_cons (imports, SCM_EOL));
+
+ return scm_apply_0 (conflict_proc, args);
+}
+
+
+static SCM
+import_environment_ref (SCM env, SCM sym)
+#define FUNC_NAME "import_environment_ref"
+{
+ SCM owner = import_environment_lookup (env, sym);
+
+ if (SCM_UNBNDP (owner))
+ {
+ return SCM_UNDEFINED;
+ }
+ else if (scm_is_pair (owner))
+ {
+ SCM resolve = import_environment_conflict (env, sym, owner);
+
+ if (SCM_ENVIRONMENT_P (resolve))
+ return SCM_ENVIRONMENT_REF (resolve, sym);
+ else
+ return SCM_UNSPECIFIED;
+ }
+ else
+ {
+ return SCM_ENVIRONMENT_REF (owner, sym);
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+import_environment_folder (SCM extended_data, SCM symbol, SCM value, SCM tail)
+#define FUNC_NAME "import_environment_fold"
+{
+ SCM import_env = SCM_CAR (extended_data);
+ SCM imported_env = SCM_CADR (extended_data);
+ SCM owner = import_environment_lookup (import_env, symbol);
+ SCM proc_as_nr = SCM_CADDR (extended_data);
+ unsigned long int proc_as_ul = scm_to_ulong (proc_as_nr);
+ scm_environment_folder proc = (scm_environment_folder) proc_as_ul;
+ SCM data = SCM_CDDDR (extended_data);
+
+ if (scm_is_pair (owner) && scm_is_eq (SCM_CAR (owner), imported_env))
+ owner = import_environment_conflict (import_env, symbol, owner);
+
+ if (SCM_ENVIRONMENT_P (owner))
+ return (*proc) (data, symbol, value, tail);
+ else /* unresolved conflict */
+ return (*proc) (data, symbol, SCM_UNSPECIFIED, tail);
+}
+#undef FUNC_NAME
+
+
+static SCM
+import_environment_fold (SCM env, scm_environment_folder proc, SCM data, SCM init)
+{
+ SCM proc_as_nr = scm_from_ulong ((unsigned long) proc);
+ SCM result = init;
+ SCM l;
+
+ for (l = IMPORT_ENVIRONMENT (env)->imports; !scm_is_null (l); l = SCM_CDR (l))
+ {
+ SCM imported_env = SCM_CAR (l);
+ SCM extended_data = scm_cons (env, scm_cons2 (imported_env, proc_as_nr, data));
+
+ result = scm_c_environment_fold (imported_env, import_environment_folder, extended_data, result);
+ }
+
+ return result;
+}
+
+
+static SCM
+import_environment_define (SCM env SCM_UNUSED,
+ SCM sym SCM_UNUSED,
+ SCM val SCM_UNUSED)
+#define FUNC_NAME "import_environment_define"
+{
+ return SCM_ENVIRONMENT_BINDING_IMMUTABLE;
+}
+#undef FUNC_NAME
+
+
+static SCM
+import_environment_undefine (SCM env SCM_UNUSED,
+ SCM sym SCM_UNUSED)
+#define FUNC_NAME "import_environment_undefine"
+{
+ return SCM_ENVIRONMENT_BINDING_IMMUTABLE;
+}
+#undef FUNC_NAME
+
+
+static SCM
+import_environment_set_x (SCM env, SCM sym, SCM val)
+#define FUNC_NAME "import_environment_set_x"
+{
+ SCM owner = import_environment_lookup (env, sym);
+
+ if (SCM_UNBNDP (owner))
+ {
+ return SCM_UNDEFINED;
+ }
+ else if (scm_is_pair (owner))
+ {
+ SCM resolve = import_environment_conflict (env, sym, owner);
+
+ if (SCM_ENVIRONMENT_P (resolve))
+ return SCM_ENVIRONMENT_SET (resolve, sym, val);
+ else
+ return SCM_ENVIRONMENT_LOCATION_IMMUTABLE;
+ }
+ else
+ {
+ return SCM_ENVIRONMENT_SET (owner, sym, val);
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+import_environment_cell (SCM env, SCM sym, int for_write)
+#define FUNC_NAME "import_environment_cell"
+{
+ SCM owner = import_environment_lookup (env, sym);
+
+ if (SCM_UNBNDP (owner))
+ {
+ return SCM_UNDEFINED;
+ }
+ else if (scm_is_pair (owner))
+ {
+ SCM resolve = import_environment_conflict (env, sym, owner);
+
+ if (SCM_ENVIRONMENT_P (resolve))
+ return SCM_ENVIRONMENT_CELL (resolve, sym, for_write);
+ else
+ return SCM_ENVIRONMENT_LOCATION_NO_CELL;
+ }
+ else
+ {
+ return SCM_ENVIRONMENT_CELL (owner, sym, for_write);
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+import_environment_mark (SCM env)
+{
+ scm_gc_mark (IMPORT_ENVIRONMENT (env)->imports);
+ scm_gc_mark (IMPORT_ENVIRONMENT (env)->import_observers);
+ scm_gc_mark (IMPORT_ENVIRONMENT (env)->conflict_proc);
+ return core_environments_mark (env);
+}
+
+
+static void
+import_environment_free (SCM env)
+{
+ core_environments_finalize (env);
+ scm_gc_free (IMPORT_ENVIRONMENT (env), sizeof (struct import_environment),
+ "import environment");
+}
+
+
+static int
+import_environment_print (SCM type, SCM port,
+ scm_print_state *pstate SCM_UNUSED)
+{
+ SCM address = scm_from_size_t (SCM_UNPACK (type));
+ SCM base16 = scm_number_to_string (address, scm_from_int (16));
+
+ scm_puts ("#<import environment ", port);
+ scm_display (base16, port);
+ scm_puts (">", port);
+
+ return 1;
+}
+
+
+static struct scm_environment_funcs import_environment_funcs = {
+ import_environment_ref,
+ import_environment_fold,
+ import_environment_define,
+ import_environment_undefine,
+ import_environment_set_x,
+ import_environment_cell,
+ core_environments_observe,
+ core_environments_unobserve,
+ import_environment_mark,
+ import_environment_free,
+ import_environment_print
+};
+
+
+void *scm_type_import_environment = &import_environment_funcs;
+
+
+static void
+import_environment_observer (SCM caller SCM_UNUSED, SCM import_env)
+{
+ core_environments_broadcast (import_env);
+}
+
+
+SCM_DEFINE (scm_make_import_environment, "make-import-environment", 2, 0, 0,
+ (SCM imports, SCM conflict_proc),
+ "Return a new environment @var{imp} whose bindings are the union\n"
+ "of the bindings from the environments in @var{imports};\n"
+ "@var{imports} must be a list of environments. That is,\n"
+ "@var{imp} binds a symbol to a location when some element of\n"
+ "@var{imports} does.\n"
+ "If two different elements of @var{imports} have a binding for\n"
+ "the same symbol, the @var{conflict-proc} is called with the\n"
+ "following parameters: the import environment, the symbol and\n"
+ "the list of the imported environments that bind the symbol.\n"
+ "If the @var{conflict-proc} returns an environment @var{env},\n"
+ "the conflict is considered as resolved and the binding from\n"
+ "@var{env} is used. If the @var{conflict-proc} returns some\n"
+ "non-environment object, the conflict is considered unresolved\n"
+ "and the symbol is treated as unspecified in the import\n"
+ "environment.\n"
+ "The checking for conflicts may be performed lazily, i. e. at\n"
+ "the moment when a value or binding for a certain symbol is\n"
+ "requested instead of the moment when the environment is\n"
+ "created or the bindings of the imports change.\n"
+ "All bindings in @var{imp} are immutable. If you apply\n"
+ "@code{environment-define} or @code{environment-undefine} to\n"
+ "@var{imp}, Guile will signal an\n"
+ " @code{environment:immutable-binding} error. However,\n"
+ "notice that the set of bindings in @var{imp} may still change,\n"
+ "if one of its imported environments changes.")
+#define FUNC_NAME s_scm_make_import_environment
+{
+ size_t size = sizeof (struct import_environment);
+ struct import_environment *body = scm_gc_malloc (size, "import environment");
+ SCM env;
+
+ core_environments_preinit (&body->base);
+ body->imports = SCM_BOOL_F;
+ body->import_observers = SCM_BOOL_F;
+ body->conflict_proc = SCM_BOOL_F;
+
+ env = scm_make_environment (body);
+
+ core_environments_init (&body->base, &import_environment_funcs);
+ body->imports = SCM_EOL;
+ body->import_observers = SCM_EOL;
+ body->conflict_proc = conflict_proc;
+
+ scm_import_environment_set_imports_x (env, imports);
+
+ return env;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_import_environment_p, "import-environment?", 1, 0, 0,
+ (SCM object),
+ "Return @code{#t} if object is an import environment, or\n"
+ "@code{#f} otherwise.")
+#define FUNC_NAME s_scm_import_environment_p
+{
+ return scm_from_bool (SCM_IMPORT_ENVIRONMENT_P (object));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_import_environment_imports, "import-environment-imports", 1, 0, 0,
+ (SCM env),
+ "Return the list of environments imported by the import\n"
+ "environment @var{env}.")
+#define FUNC_NAME s_scm_import_environment_imports
+{
+ SCM_ASSERT (SCM_IMPORT_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return IMPORT_ENVIRONMENT (env)->imports;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_import_environment_set_imports_x, "import-environment-set-imports!", 2, 0, 0,
+ (SCM env, SCM imports),
+ "Change @var{env}'s list of imported environments to\n"
+ "@var{imports}, and check for conflicts.")
+#define FUNC_NAME s_scm_import_environment_set_imports_x
+{
+ struct import_environment *body = IMPORT_ENVIRONMENT (env);
+ SCM import_observers = SCM_EOL;
+ SCM l;
+
+ SCM_ASSERT (SCM_IMPORT_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ for (l = imports; scm_is_pair (l); l = SCM_CDR (l))
+ {
+ SCM obj = SCM_CAR (l);
+ SCM_ASSERT (SCM_ENVIRONMENT_P (obj), imports, SCM_ARG2, FUNC_NAME);
+ }
+ SCM_ASSERT (scm_is_null (l), imports, SCM_ARG2, FUNC_NAME);
+
+ for (l = body->import_observers; !scm_is_null (l); l = SCM_CDR (l))
+ {
+ SCM obs = SCM_CAR (l);
+ SCM_ENVIRONMENT_UNOBSERVE (env, obs);
+ }
+
+ for (l = imports; !scm_is_null (l); l = SCM_CDR (l))
+ {
+ SCM imp = SCM_CAR (l);
+ SCM obs = SCM_ENVIRONMENT_OBSERVE (imp, import_environment_observer, env, 1);
+ import_observers = scm_cons (obs, import_observers);
+ }
+
+ body->imports = imports;
+ body->import_observers = import_observers;
+
+ return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+\f
+
+/* export environments
+ *
+ * An export environment restricts an environment to a specified set of
+ * bindings.
+ *
+ * Implementation: The export environment does no caching at all. For every
+ * access, the signature is scanned. The signature that is stored internally
+ * is an alist of pairs (symbol . (mutability)).
+ */
+
+
+struct export_environment {
+ struct core_environments_base base;
+
+ SCM private;
+ SCM private_observer;
+
+ SCM signature;
+};
+
+
+#define EXPORT_ENVIRONMENT(env) \
+ ((struct export_environment *) SCM_CELL_WORD_1 (env))
+
+
+SCM_SYMBOL (symbol_immutable_location, "immutable-location");
+SCM_SYMBOL (symbol_mutable_location, "mutable-location");
+
+\f
+
+static SCM
+export_environment_ref (SCM env, SCM sym)
+#define FUNC_NAME "export_environment_ref"
+{
+ struct export_environment *body = EXPORT_ENVIRONMENT (env);
+ SCM entry = scm_assq (sym, body->signature);
+
+ if (scm_is_false (entry))
+ return SCM_UNDEFINED;
+ else
+ return SCM_ENVIRONMENT_REF (body->private, sym);
+}
+#undef FUNC_NAME
+
+
+static SCM
+export_environment_fold (SCM env, scm_environment_folder proc, SCM data, SCM init)
+{
+ struct export_environment *body = EXPORT_ENVIRONMENT (env);
+ SCM result = init;
+ SCM l;
+
+ for (l = body->signature; !scm_is_null (l); l = SCM_CDR (l))
+ {
+ SCM symbol = SCM_CAR (l);
+ SCM value = SCM_ENVIRONMENT_REF (body->private, symbol);
+ if (!SCM_UNBNDP (value))
+ result = (*proc) (data, symbol, value, result);
+ }
+ return result;
+}
+
+
+static SCM
+export_environment_define (SCM env SCM_UNUSED,
+ SCM sym SCM_UNUSED,
+ SCM val SCM_UNUSED)
+#define FUNC_NAME "export_environment_define"
+{
+ return SCM_ENVIRONMENT_BINDING_IMMUTABLE;
+}
+#undef FUNC_NAME
+
+
+static SCM
+export_environment_undefine (SCM env SCM_UNUSED, SCM sym SCM_UNUSED)
+#define FUNC_NAME "export_environment_undefine"
+{
+ return SCM_ENVIRONMENT_BINDING_IMMUTABLE;
+}
+#undef FUNC_NAME
+
+
+static SCM
+export_environment_set_x (SCM env, SCM sym, SCM val)
+#define FUNC_NAME "export_environment_set_x"
+{
+ struct export_environment *body = EXPORT_ENVIRONMENT (env);
+ SCM entry = scm_assq (sym, body->signature);
+
+ if (scm_is_false (entry))
+ {
+ return SCM_UNDEFINED;
+ }
+ else
+ {
+ if (scm_is_eq (SCM_CADR (entry), symbol_mutable_location))
+ return SCM_ENVIRONMENT_SET (body->private, sym, val);
+ else
+ return SCM_ENVIRONMENT_LOCATION_IMMUTABLE;
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+export_environment_cell (SCM env, SCM sym, int for_write)
+#define FUNC_NAME "export_environment_cell"
+{
+ struct export_environment *body = EXPORT_ENVIRONMENT (env);
+ SCM entry = scm_assq (sym, body->signature);
+
+ if (scm_is_false (entry))
+ {
+ return SCM_UNDEFINED;
+ }
+ else
+ {
+ if (!for_write || scm_is_eq (SCM_CADR (entry), symbol_mutable_location))
+ return SCM_ENVIRONMENT_CELL (body->private, sym, for_write);
+ else
+ return SCM_ENVIRONMENT_LOCATION_IMMUTABLE;
+ }
+}
+#undef FUNC_NAME
+
+
+static SCM
+export_environment_mark (SCM env)
+{
+ struct export_environment *body = EXPORT_ENVIRONMENT (env);
+
+ scm_gc_mark (body->private);
+ scm_gc_mark (body->private_observer);
+ scm_gc_mark (body->signature);
+
+ return core_environments_mark (env);
+}
+
+
+static void
+export_environment_free (SCM env)
+{
+ core_environments_finalize (env);
+ scm_gc_free (EXPORT_ENVIRONMENT (env), sizeof (struct export_environment),
+ "export environment");
+}
+
+
+static int
+export_environment_print (SCM type, SCM port,
+ scm_print_state *pstate SCM_UNUSED)
+{
+ SCM address = scm_from_size_t (SCM_UNPACK (type));
+ SCM base16 = scm_number_to_string (address, scm_from_int (16));
+
+ scm_puts ("#<export environment ", port);
+ scm_display (base16, port);
+ scm_puts (">", port);
+
+ return 1;
+}
+
+
+static struct scm_environment_funcs export_environment_funcs = {
+ export_environment_ref,
+ export_environment_fold,
+ export_environment_define,
+ export_environment_undefine,
+ export_environment_set_x,
+ export_environment_cell,
+ core_environments_observe,
+ core_environments_unobserve,
+ export_environment_mark,
+ export_environment_free,
+ export_environment_print
+};
+
+
+void *scm_type_export_environment = &export_environment_funcs;
+
+
+static void
+export_environment_observer (SCM caller SCM_UNUSED, SCM export_env)
+{
+ core_environments_broadcast (export_env);
+}
+
+
+SCM_DEFINE (scm_make_export_environment, "make-export-environment", 2, 0, 0,
+ (SCM private, SCM signature),
+ "Return a new environment @var{exp} containing only those\n"
+ "bindings in private whose symbols are present in\n"
+ "@var{signature}. The @var{private} argument must be an\n"
+ "environment.\n\n"
+ "The environment @var{exp} binds symbol to location when\n"
+ "@var{env} does, and symbol is exported by @var{signature}.\n\n"
+ "@var{signature} is a list specifying which of the bindings in\n"
+ "@var{private} should be visible in @var{exp}. Each element of\n"
+ "@var{signature} should be a list of the form:\n"
+ " (symbol attribute ...)\n"
+ "where each attribute is one of the following:\n"
+ "@table @asis\n"
+ "@item the symbol @code{mutable-location}\n"
+ " @var{exp} should treat the\n"
+ " location bound to symbol as mutable. That is, @var{exp}\n"
+ " will pass calls to @code{environment-set!} or\n"
+ " @code{environment-cell} directly through to private.\n"
+ "@item the symbol @code{immutable-location}\n"
+ " @var{exp} should treat\n"
+ " the location bound to symbol as immutable. If the program\n"
+ " applies @code{environment-set!} to @var{exp} and symbol, or\n"
+ " calls @code{environment-cell} to obtain a writable value\n"
+ " cell, @code{environment-set!} will signal an\n"
+ " @code{environment:immutable-location} error. Note that, even\n"
+ " if an export environment treats a location as immutable, the\n"
+ " underlying environment may treat it as mutable, so its\n"
+ " value may change.\n"
+ "@end table\n"
+ "It is an error for an element of signature to specify both\n"
+ "@code{mutable-location} and @code{immutable-location}. If\n"
+ "neither is specified, @code{immutable-location} is assumed.\n\n"
+ "As a special case, if an element of signature is a lone\n"
+ "symbol @var{sym}, it is equivalent to an element of the form\n"
+ "@code{(sym)}.\n\n"
+ "All bindings in @var{exp} are immutable. If you apply\n"
+ "@code{environment-define} or @code{environment-undefine} to\n"
+ "@var{exp}, Guile will signal an\n"
+ "@code{environment:immutable-binding} error. However,\n"
+ "notice that the set of bindings in @var{exp} may still change,\n"
+ "if the bindings in private change.")
+#define FUNC_NAME s_scm_make_export_environment
+{
+ size_t size;
+ struct export_environment *body;
+ SCM env;
+
+ SCM_ASSERT (SCM_ENVIRONMENT_P (private), private, SCM_ARG1, FUNC_NAME);
+
+ size = sizeof (struct export_environment);
+ body = scm_gc_malloc (size, "export environment");
+
+ core_environments_preinit (&body->base);
+ body->private = SCM_BOOL_F;
+ body->private_observer = SCM_BOOL_F;
+ body->signature = SCM_BOOL_F;
+
+ env = scm_make_environment (body);
+
+ core_environments_init (&body->base, &export_environment_funcs);
+ body->private = private;
+ body->private_observer
+ = SCM_ENVIRONMENT_OBSERVE (private, export_environment_observer, env, 1);
+ body->signature = SCM_EOL;
+
+ scm_export_environment_set_signature_x (env, signature);
+
+ return env;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_export_environment_p, "export-environment?", 1, 0, 0,
+ (SCM object),
+ "Return @code{#t} if object is an export environment, or\n"
+ "@code{#f} otherwise.")
+#define FUNC_NAME s_scm_export_environment_p
+{
+ return scm_from_bool (SCM_EXPORT_ENVIRONMENT_P (object));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_export_environment_private, "export-environment-private", 1, 0, 0,
+ (SCM env),
+ "Return the private environment of export environment @var{env}.")
+#define FUNC_NAME s_scm_export_environment_private
+{
+ SCM_ASSERT (SCM_EXPORT_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return EXPORT_ENVIRONMENT (env)->private;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_export_environment_set_private_x, "export-environment-set-private!", 2, 0, 0,
+ (SCM env, SCM private),
+ "Change the private environment of export environment @var{env}.")
+#define FUNC_NAME s_scm_export_environment_set_private_x
+{
+ struct export_environment *body;
+
+ SCM_ASSERT (SCM_EXPORT_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ SCM_ASSERT (SCM_ENVIRONMENT_P (private), private, SCM_ARG2, FUNC_NAME);
+
+ body = EXPORT_ENVIRONMENT (env);
+ SCM_ENVIRONMENT_UNOBSERVE (private, body->private_observer);
+
+ body->private = private;
+ body->private_observer
+ = SCM_ENVIRONMENT_OBSERVE (private, export_environment_observer, env, 1);
+
+ return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_export_environment_signature, "export-environment-signature", 1, 0, 0,
+ (SCM env),
+ "Return the signature of export environment @var{env}.")
+#define FUNC_NAME s_scm_export_environment_signature
+{
+ SCM_ASSERT (SCM_EXPORT_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+
+ return EXPORT_ENVIRONMENT (env)->signature;
+}
+#undef FUNC_NAME
+
+
+static SCM
+export_environment_parse_signature (SCM signature, const char* caller)
+{
+ SCM result = SCM_EOL;
+ SCM l;
+
+ for (l = signature; scm_is_pair (l); l = SCM_CDR (l))
+ {
+ SCM entry = SCM_CAR (l);
+
+ if (scm_is_symbol (entry))
+ {
+ SCM new_entry = scm_cons2 (entry, symbol_immutable_location, SCM_EOL);
+ result = scm_cons (new_entry, result);
+ }
+ else
+ {
+ SCM sym;
+ SCM new_entry;
+ int immutable = 0;
+ int mutable = 0;
+ SCM mutability;
+ SCM l2;
+
+ SCM_ASSERT (scm_is_pair (entry), entry, SCM_ARGn, caller);
+ SCM_ASSERT (scm_is_symbol (SCM_CAR (entry)), entry, SCM_ARGn, caller);
+
+ sym = SCM_CAR (entry);
+
+ for (l2 = SCM_CDR (entry); scm_is_pair (l2); l2 = SCM_CDR (l2))
+ {
+ SCM attribute = SCM_CAR (l2);
+ if (scm_is_eq (attribute, symbol_immutable_location))
+ immutable = 1;
+ else if (scm_is_eq (attribute, symbol_mutable_location))
+ mutable = 1;
+ else
+ SCM_ASSERT (0, entry, SCM_ARGn, caller);
+ }
+ SCM_ASSERT (scm_is_null (l2), entry, SCM_ARGn, caller);
+ SCM_ASSERT (!mutable || !immutable, entry, SCM_ARGn, caller);
+
+ if (!mutable && !immutable)
+ immutable = 1;
+
+ mutability = mutable ? symbol_mutable_location : symbol_immutable_location;
+ new_entry = scm_cons2 (sym, mutability, SCM_EOL);
+ result = scm_cons (new_entry, result);
+ }
+ }
+ SCM_ASSERT (scm_is_null (l), signature, SCM_ARGn, caller);
+
+ /* Dirk:FIXME:: Now we know that signature is syntactically correct. There
+ * are, however, no checks for symbols entered twice with contradicting
+ * mutabilities. It would be nice, to implement this test, to be able to
+ * call the sort functions conveniently from C.
+ */
+
+ return scm_reverse (result);
+}
+
+
+SCM_DEFINE (scm_export_environment_set_signature_x, "export-environment-set-signature!", 2, 0, 0,
+ (SCM env, SCM signature),
+ "Change the signature of export environment @var{env}.")
+#define FUNC_NAME s_scm_export_environment_set_signature_x
+{
+ SCM parsed_sig;
+
+ SCM_ASSERT (SCM_EXPORT_ENVIRONMENT_P (env), env, SCM_ARG1, FUNC_NAME);
+ parsed_sig = export_environment_parse_signature (signature, FUNC_NAME);
+
+ EXPORT_ENVIRONMENT (env)->signature = parsed_sig;
+
+ return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+\f
+
+void
+scm_environments_prehistory ()
+{
+ /* create environment smob */
+ scm_tc16_environment = scm_make_smob_type ("environment", 0);
+ scm_set_smob_mark (scm_tc16_environment, environment_mark);
+ scm_set_smob_free (scm_tc16_environment, environment_free);
+ scm_set_smob_print (scm_tc16_environment, environment_print);
+
+ /* create observer smob */
+ scm_tc16_observer = scm_make_smob_type ("observer", 0);
+ scm_set_smob_mark (scm_tc16_observer, observer_mark);
+ scm_set_smob_print (scm_tc16_observer, observer_print);
+
+ /* create system environment */
+ scm_system_environment = scm_make_leaf_environment ();
+ scm_permanent_object (scm_system_environment);
+}
+
+
+void
+scm_init_environments ()
+{
+#include "libguile/environments.x"
+}
+
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/
projects / lilypond.git / blobdiff