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The symbol table is an ephemeron table
* libguile/symbols.c: Rework the symbol table to be an ephemeron table instead of a weak set. It is no longer resizeable; getting that to work will involve some GC cooperation.
This commit is contained in:
Andy Wingo
parent
dbc384a6ba
commit
4138d3c646
1 changed files with 120 additions and 136 deletions
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@ -1,4 +1,4 @@
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/* Copyright 1995-1998,2000-2001,2003-2004,2006,2009,2011,2013,2015,2018,2022,2023
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/* Copyright 1995-1998,2000-2001,2003-2004,2006,2009,2011,2013,2015,2018,2022,2023,2025
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Free Software Foundation, Inc.
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This file is part of Guile.
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@ -29,6 +29,7 @@
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#include "alist.h"
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#include "boolean.h"
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#include "chars.h"
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#include "ephemerons.h"
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#include "eval.h"
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#include "fluids.h"
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#include "gsubr.h"
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@ -46,14 +47,13 @@
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#include "threads.h"
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#include "variable.h"
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#include "vectors.h"
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#include "weak-set.h"
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#include "symbols.h"
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static SCM symbols;
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static struct scm_ephemeron_table *symbols;
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#ifdef GUILE_DEBUG
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SCM_DEFINE (scm_sys_symbols, "%symbols", 0, 0, 0,
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@ -61,7 +61,7 @@ SCM_DEFINE (scm_sys_symbols, "%symbols", 0, 0, 0,
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"Return the system symbol obarray.")
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#define FUNC_NAME s_scm_sys_symbols
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{
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return symbols;
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return scm_from_ephemeron_table (symbols);
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}
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#undef FUNC_NAME
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#endif
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@ -77,187 +77,171 @@ scm_i_hash_symbol (SCM obj, unsigned long n, void *closure)
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return scm_i_symbol_hash (obj) % n;
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}
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struct string_lookup_data
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{
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SCM string;
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unsigned long string_hash;
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};
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static int
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string_lookup_predicate_fn (SCM sym, void *closure)
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symbol_equals_string (SCM sym, SCM str, size_t len, unsigned long hash)
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{
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struct string_lookup_data *data = closure;
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if (scm_i_symbol_hash (sym) == data->string_hash
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&& scm_i_symbol_length (sym) == scm_i_string_length (data->string))
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{
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size_t n = scm_i_symbol_length (sym);
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while (n--)
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if (scm_i_symbol_ref (sym, n) != scm_i_string_ref (data->string, n))
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return 0;
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return 1;
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}
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else
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if (scm_i_symbol_hash (sym) != hash)
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return 0;
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if (scm_i_symbol_length (sym) != len)
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return 0;
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}
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static SCM
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lookup_interned_symbol (SCM name, unsigned long raw_hash)
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{
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struct string_lookup_data data;
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data.string = name;
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data.string_hash = raw_hash;
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return scm_c_weak_set_lookup (symbols, raw_hash,
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string_lookup_predicate_fn,
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&data, SCM_BOOL_F);
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}
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for (size_t i = 0; i < len; i++)
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if (scm_i_symbol_ref (sym, i) != scm_i_string_ref (str, i))
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return 0;
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struct latin1_lookup_data
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{
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const char *str;
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size_t len;
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unsigned long string_hash;
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};
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return 1;
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}
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static int
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latin1_lookup_predicate_fn (SCM sym, void *closure)
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symbol_equals_latin1_string (SCM sym, const char *str, size_t len,
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unsigned long hash)
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{
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struct latin1_lookup_data *data = closure;
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return scm_i_symbol_hash (sym) == data->string_hash
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&& scm_i_is_narrow_symbol (sym)
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&& scm_i_symbol_length (sym) == data->len
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&& strncmp (scm_i_symbol_chars (sym), data->str, data->len) == 0;
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if (scm_i_symbol_hash (sym) != hash)
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return 0;
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if (scm_i_symbol_length (sym) != len)
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return 0;
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if (!scm_i_is_narrow_symbol (sym))
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return 0;
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return strncmp (scm_i_symbol_chars (sym), str, len) == 0;
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}
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static SCM
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lookup_interned_latin1_symbol (const char *str, size_t len,
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unsigned long raw_hash)
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{
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struct latin1_lookup_data data;
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data.str = str;
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data.len = len;
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data.string_hash = raw_hash;
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return scm_c_weak_set_lookup (symbols, raw_hash,
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latin1_lookup_predicate_fn,
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&data, SCM_BOOL_F);
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size_t bucket = raw_hash % scm_c_ephemeron_table_length (symbols);
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for (struct gc_ephemeron *e = scm_c_ephemeron_table_ref (symbols, bucket);
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e;
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e = scm_c_ephemeron_next (e))
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{
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SCM sym = scm_c_ephemeron_key (e);
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if (scm_is_true (sym)
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&& symbol_equals_latin1_string (sym, str, len, raw_hash))
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return sym;
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}
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return SCM_BOOL_F;
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}
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struct utf8_lookup_data
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{
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const char *str;
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size_t len;
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unsigned long string_hash;
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};
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static int
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utf8_string_equals_wide_string (const uint8_t *narrow, size_t nlen,
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const scm_t_wchar *wide, size_t wlen)
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utf8_string_equals_narrow_string (const uint8_t *utf8, size_t ulen,
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const char *narrow)
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{
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size_t byte_idx = 0, char_idx = 0;
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/* Precondition: utf8,ulen is valid UTF-8. */
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size_t byte_idx = 0;
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while (byte_idx < nlen && char_idx < wlen)
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while (byte_idx < ulen)
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{
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ucs4_t c;
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int nbytes;
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nbytes = u8_mbtoucr (&c, narrow + byte_idx, nlen - byte_idx);
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if (nbytes == 0)
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break;
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else if (nbytes < 0)
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/* Bad UTF-8. */
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ucs4_t c = -1;
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byte_idx += u8_mbtoucr (&c, utf8 + byte_idx, ulen - byte_idx);
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if (c != *narrow)
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return 0;
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else if (c != wide[char_idx])
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return 0;
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byte_idx += nbytes;
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char_idx++;
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narrow++;
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}
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return byte_idx == nlen && char_idx == wlen;
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return 1;
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}
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static int
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utf8_lookup_predicate_fn (SCM sym, void *closure)
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utf8_string_equals_wide_string (const uint8_t *utf8, size_t ulen,
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const scm_t_wchar *wide)
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{
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struct utf8_lookup_data *data = closure;
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/* Precondition: utf8,ulen is valid UTF-8. */
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size_t byte_idx = 0;
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while (byte_idx < ulen)
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{
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ucs4_t c = -1;
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byte_idx += u8_mbtoucr (&c, utf8 + byte_idx, ulen - byte_idx);
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if (c != *wide)
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return 0;
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wide++;
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}
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if (scm_i_symbol_hash (sym) != data->string_hash)
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return 1;
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}
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static int
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symbol_equals_utf8_string (SCM sym, const uint8_t *str, size_t len,
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unsigned long hash, int codepoint_count)
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{
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if (scm_i_symbol_hash (sym) != hash)
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return 0;
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if (scm_i_symbol_length (sym) != codepoint_count)
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return 0;
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if (scm_i_is_narrow_symbol (sym))
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return (scm_i_symbol_length (sym) == data->len
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&& strncmp (scm_i_symbol_chars (sym), data->str, data->len) == 0);
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return utf8_string_equals_narrow_string (str, len,
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scm_i_symbol_chars (sym));
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else
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return utf8_string_equals_wide_string ((const uint8_t *) data->str,
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data->len,
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scm_i_symbol_wide_chars (sym),
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scm_i_symbol_length (sym));
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return utf8_string_equals_wide_string (str, len,
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scm_i_symbol_wide_chars (sym));
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}
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static SCM
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lookup_interned_utf8_symbol (const char *str, size_t len,
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lookup_interned_utf8_symbol (const uint8_t *str, size_t len,
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unsigned long raw_hash)
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{
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struct utf8_lookup_data data;
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int codepoint_count = u8_mbsnlen (str, len);
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if (codepoint_count == -1)
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/* Bad UTF-8. */
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return SCM_BOOL_F;
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data.str = str;
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data.len = len;
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data.string_hash = raw_hash;
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return scm_c_weak_set_lookup (symbols, raw_hash,
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utf8_lookup_predicate_fn,
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&data, SCM_BOOL_F);
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}
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if (codepoint_count == len)
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return lookup_interned_latin1_symbol ((const char *) str, len, raw_hash);
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static int
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symbol_lookup_predicate_fn (SCM sym, void *closure)
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{
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SCM other = SCM_PACK_POINTER (closure);
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if (scm_i_symbol_hash (sym) == scm_i_symbol_hash (other)
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&& scm_i_symbol_length (sym) == scm_i_symbol_length (other))
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size_t bucket = raw_hash % scm_c_ephemeron_table_length (symbols);
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for (struct gc_ephemeron *e = scm_c_ephemeron_table_ref (symbols, bucket);
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e;
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e = scm_c_ephemeron_next (e))
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{
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if (scm_i_is_narrow_symbol (sym))
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return scm_i_is_narrow_symbol (other)
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&& (strncmp (scm_i_symbol_chars (sym),
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scm_i_symbol_chars (other),
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scm_i_symbol_length (other)) == 0);
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else
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return scm_is_true
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(scm_string_equal_p (scm_symbol_to_string (sym),
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scm_symbol_to_string (other)));
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SCM sym = scm_c_ephemeron_key (e);
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if (scm_is_true (sym)
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&& symbol_equals_utf8_string (sym, str, len, raw_hash,
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codepoint_count))
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return sym;
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}
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return 0;
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return SCM_BOOL_F;
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}
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static SCM
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scm_i_str2symbol (SCM str)
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{
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SCM symbol;
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unsigned long raw_hash = scm_i_string_hash (str);
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size_t bucket = raw_hash % scm_c_ephemeron_table_length (symbols);
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size_t len = scm_i_string_length (str);
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symbol = lookup_interned_symbol (str, raw_hash);
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if (scm_is_true (symbol))
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return symbol;
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else
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struct gc_ephemeron *chain = scm_c_ephemeron_table_ref (symbols, bucket);
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/* First see if a symbol with this name is already interned. */
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for (struct gc_ephemeron *e = chain; e; e = scm_c_ephemeron_next (e))
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{
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/* The symbol was not found, create it. */
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symbol = scm_i_make_symbol (str, 0, raw_hash);
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/* Might return a different symbol, if another one was interned at
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the same time. */
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return scm_c_weak_set_add_x (symbols, raw_hash,
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symbol_lookup_predicate_fn,
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SCM_UNPACK_POINTER (symbol), symbol);
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SCM sym = scm_c_ephemeron_key (e);
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if (scm_is_true (sym) && symbol_equals_string (sym, str, len, raw_hash))
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return sym;
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}
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/* The symbol was not found, create it. */
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SCM sym = scm_i_make_symbol (str, 0, raw_hash);
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struct gc_ephemeron *link = scm_c_make_ephemeron (sym, SCM_BOOL_T);
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while (1)
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{
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struct gc_ephemeron *prev =
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scm_c_ephemeron_table_try_push_x (symbols, bucket, link, chain);
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if (prev == chain)
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return sym;
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/* Lost a race, someone else added a symbol in this bucket. Check
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the chain and try again. */
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chain = prev;
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for (struct gc_ephemeron *e = chain; e; e = scm_c_ephemeron_next (e))
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{
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SCM sym = scm_c_ephemeron_key (e);
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if (scm_is_true (sym)
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&& symbol_equals_string (sym, str, len, raw_hash))
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return sym;
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}
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}
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}
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static SCM
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scm_i_str2uninterned_symbol (SCM str)
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{
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@ -449,7 +433,7 @@ scm_from_utf8_symboln (const char *sym, size_t len)
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len = strlen (sym);
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hash = scm_i_utf8_string_hash (sym, len);
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ret = lookup_interned_utf8_symbol (sym, len, hash);
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ret = lookup_interned_utf8_symbol ((const uint8_t *)sym, len, hash);
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if (scm_is_false (ret))
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{
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SCM str = scm_from_utf8_stringn (sym, len);
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@ -462,7 +446,7 @@ scm_from_utf8_symboln (const char *sym, size_t len)
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void
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scm_symbols_prehistory ()
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{
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symbols = scm_c_make_weak_set (5000);
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symbols = scm_c_make_ephemeron_table (5000);
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}
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