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* symbols.c (scm_intern_obarray_soft, scm_sysintern): Doc fixes.
* symbols.h, tags.h: Doc fixes.
This commit is contained in:
Jim Blandy
parent
35457f1e68
commit
8ce9450492
3 changed files with 96 additions and 29 deletions
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@ -220,6 +220,28 @@ scm_sym2ovcell (sym, obarray)
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return SCM_UNSPECIFIED; /* not reached */
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}
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/* Intern a symbol whose name is the LEN characters at NAME in OBARRAY.
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OBARRAY should be a vector of lists, indexed by the name's hash
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value, modulo OBARRAY's length. Each list has the form
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((SYMBOL . VALUE) ...), where SYMBOL is a symbol, and VALUE is the
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value associated with that symbol (in the current module? in the
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system module?)
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To "intern" a symbol means: if OBARRAY already contains a symbol by
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that name, return its (SYMBOL . VALUE) pair; otherwise, create a
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new symbol, add the pair (SYMBOL . SCM_UNDEFINED) to the
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appropriate list of the OBARRAY, and return the pair.
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If softness is non-zero, don't create a symbol if it isn't already
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in OBARRAY; instead, just return #f.
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If OBARRAY is SCM_BOOL_F, create a symbol listed in no obarray and
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return (SYMBOL . SCM_UNDEFINED).
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If OBARRAY is scm_symhash, and that doesn't contain the symbol,
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check scm_weak_symhash instead. */
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#ifdef __STDC__
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SCM
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scm_intern_obarray_soft (char *name, scm_sizet len, SCM obarray, int softness)
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@ -251,8 +273,12 @@ scm_intern_obarray_soft (name, len, obarray, softness)
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scm_hash = scm_strhash (tmp, i, SCM_LENGTH(obarray));
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/* softness == -1 used to mean that it was known that the symbol
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wasn't already in the obarray. I don't think there are any
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callers that use that case any more, but just in case...
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-- JimB, Oct 1996 */
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if (softness == -1)
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goto mustintern_symbol;
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abort ();
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retry_new_obarray:
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for (lsym = SCM_VELTS (obarray)[scm_hash]; SCM_NIMP (lsym); lsym = SCM_CDR (lsym))
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@ -287,7 +313,6 @@ scm_intern_obarray_soft (name, len, obarray, softness)
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return SCM_BOOL_F;
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}
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mustintern_symbol:
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lsym = scm_makfromstr (name, len, SCM_SYMBOL_SLOTS);
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SCM_SETLENGTH (lsym, (long) len, scm_tc7_msymbol);
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@ -363,6 +388,8 @@ scm_intern0 (name)
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}
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/* Intern the symbol named NAME in scm_symhash, and give it the value VAL.
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NAME is null-terminated. */
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#ifdef __STDC__
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SCM
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scm_sysintern (char *name, SCM val)
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@ -49,6 +49,31 @@
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extern int scm_symhash_dim;
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/* SCM_LENGTH(SYM) is the length of SYM's name in characters, and
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SCM_CHARS(SYM) is the address of the first character of SYM's name.
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Beyond that, there are two kinds of symbols: ssymbols and msymbols,
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distinguished by the 'S' bit in the type.
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Ssymbols are just uniquified strings. They have a length, chars,
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and that's it. They use the scm_tc7_ssymbol tag (S bit clear).
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Msymbols are symbols with extra slots. These slots hold a property
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list and a function value (for Emacs Lisp compatibility), a hash
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code, and a flag to indicate whether their name contains multibyte
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characters. They use the scm_tc7_msymbol tag.
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We'd like SCM_CHARS to work on msymbols just as it does on
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ssymbols, so we'll have it point to the symbol's name as usual, and
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store a pointer to the slots just before the name in memory. Thus,
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you have to do some casting and pointer arithmetic to find the
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slots; see the SCM_SLOTS macro.
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In practice, the slots always live just before the pointer to them.
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So why not ditch the pointer, and use negative indices to refer to
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the slots? That's a good question; ask the author. I think it was
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the cognac. */
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#define SCM_SYMBOLP(x) (SCM_TYP7S(x)==scm_tc7_ssymbol)
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#define SCM_LENGTH(x) (((unsigned long)SCM_CAR(x))>>8)
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#define SCM_LENGTH_MAX (0xffffffL)
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@ -3,17 +3,17 @@
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#ifndef TAGSH
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#define TAGSH
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/* Copyright (C) 1995,1996 Free Software Foundation, Inc.
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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@ -40,11 +40,11 @@
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*
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* If you write modifications of your own for GUILE, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice.
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* If you do not wish that, delete this exception notice.
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*/
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/** This file defines the format of SCM values and cons pairs.
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/** This file defines the format of SCM values and cons pairs.
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** It is here that tag bits are assigned for various purposes.
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**/
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@ -106,11 +106,11 @@ typedef long SCM;
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#define SCM_NIMP(x) (!SCM_IMP(x))
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/* Here is a summary of tagging in SCM values as they might occur in
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* SCM variables or in the heap.
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* SCM variables or in the heap.
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*
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* low bits meaning
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*
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*
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*
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* 0 Most objects except...
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* 1 ...glocs and structs (this tag valid only in a SCM_CAR or
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* in the header of a struct's data).
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@ -134,7 +134,7 @@ typedef long SCM;
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* 100 --- IMMEDIATES
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*
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* Looking at the seven final bits of an immediate:
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*
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*
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* 0000-100 short instruction
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* 0001-100 short instruction
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* 0010-100 short instruction
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@ -152,7 +152,7 @@ typedef long SCM;
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* 1110-100 immediate characters
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* 1111-100 ilocs
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*
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* Some of the 0110100 immediates are long instructions (they dispatch
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* Some of the 0110100 immediates are long instructions (they dispatch
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* in two steps compared to one step for a short instruction).
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* The two steps are, (1) dispatch on 7 bits to the long instruction
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* handler, (2) dispatch on 7 additional bits.
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@ -196,8 +196,13 @@ typedef long SCM;
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*
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* 101 & 111 --- tc7_ types
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*
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* tc7_tags are 7 bit tags ending in 1x1. These tags occur
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* only in the CAR of heap cells.
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* tc7_tags are 7 bit tags ending in 1x1. These tags
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* occur only in the CAR of heap cells, and have the
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* handy property that all bits of the CAR above the
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* bottom eight can be used to store a length, thus
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* saving a word in the body itself. Thus, we use them
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* for strings, symbols, and vectors (among other
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* things).
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*
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* SCM_LENGTH returns the bits in "length" (see the diagram).
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* SCM_CHARS returns the data cast to "char *"
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@ -208,25 +213,36 @@ typedef long SCM;
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* that applies to a particular type, see the header file
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* for that type.
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*
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* Sometimes we choose the bottom seven bits carefully,
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* so that the 4- and 1-valued bits (called the D and S
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* bits) can be masked off to reveal a common type.
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*
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* TYP7S(X) returns TYP7, but masking out the option bit S.
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* TYP7D(X) returns TYP7, but masking out the option bit D.
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* TYP7SD(X) masks out both option bits.
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*
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* For example, all strings have 001 in the 'xxx' bits in
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* the diagram above, the D bit says whether it's a
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* substring, and the S bit says whether it's a multibyte
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* character string.
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*
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* for example:
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* D S
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* scm_tc7_string = Gxxx0101
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* scm_tc7_mb_string = Gxxx0111
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* scm_tc7_substring = Gxxx1101
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* scm_tc7_mb_substring = Gxxx1111
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* scm_tc7_string = G0010101
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* scm_tc7_mb_string = G0010111
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* scm_tc7_substring = G0011101
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* scm_tc7_mb_substring = G0011111
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*
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* TYP7S turns tc7_mb_string into tc7_string and
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* TYP7DS turns all string tags into tc7_string; thus,
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* testing TYP7DS against tc7_string is a quick way to
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* test for any kind of string.
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*
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* TYP7S turns tc7_mb_string into tc7_string and
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* tc7_mb_substring into tc7_substring.
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*
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* TYP7D turns tc7_mb_substring into tc7_mb_string and
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* TYP7D turns tc7_mb_substring into tc7_mb_string and
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* tc7_substring into tc7_string.
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*
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* TYP7DS turns all string tags into tc7_string.
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*
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* Some TC7 types are subdivided into 256 subtypes giving
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* rise to the macros:
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*
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@ -237,8 +253,7 @@ typedef long SCM;
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* TYP16S functions similarly wrt to TYP16 as TYP7S to TYP7,
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* but a different option bit is used (bit 2 for TYP7S,
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* bit 8 for TYP16S).
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*
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*/
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* */
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@ -249,7 +264,7 @@ typedef long SCM;
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* figure out Xs type. X may be a cons pair, in which case the
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* value SCM_CAR (x) will be either an immediate or non-immediate value.
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* X may be something other than a cons pair, in which case the value SCM_CAR (x)
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* will be a non-object value.
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* will be a non-object value.
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*
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* All immediates and non-immediates have a 0 in bit 0. We additionally preserve
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* the invariant that all non-object values stored in the SCM_CAR of a non-immediate
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@ -272,7 +287,7 @@ typedef long SCM;
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#define SCM_CELLP(x) (!SCM_NCELLP(x))
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#define SCM_NCELLP(x) ((sizeof(scm_cell)-1) & (int)(x))
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/* See numbers.h for macros relating to immediate integers.
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/* See numbers.h for macros relating to immediate integers.
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*/
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#define SCM_ITAG3(x) (7 & (int)x)
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@ -400,14 +415,14 @@ typedef long SCM;
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#define scm_tc_dblc (scm_tc16_flo|SCM_REAL_PART|SCM_IMAG_PART)
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/* Smob types 2 and 3:
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/* Smob types 2 and 3:
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*/
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#define scm_tc16_bigpos 0x027f
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#define scm_tc16_bigneg 0x037f
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/* {Immediate Values}
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/* {Immediate Values}
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*/
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enum scm_tags
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@ -436,7 +451,7 @@ enum scm_tags
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#define SCM_MAKISYM(n) (((n)<<9)+0x74L)
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#define SCM_MAKIFLAG(n) (((n)<<9)+0x174L)
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/* This table must agree with the declarations
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/* This table must agree with the declarations
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* in repl.c: {Names of immediate symbols}.
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*
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* These are used only in eval but their values
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@ -476,7 +491,7 @@ enum scm_tags
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*/
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/* For cons pairs with immediate values in the CAR
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/* For cons pairs with immediate values in the CAR
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*/
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#define scm_tcs_cons_imcar 2:case 4:case 6:case 10:\
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