/* -*- C -*-
// -------------------------------------------------------------------
// MiniExp - Library for handling lisp expressions
// Copyright (c) 2005 Leon Bottou
//
// This software is subject to, and may be distributed under, the
// GNU General Public License, either Version 2 of the license,
// or (at your option) any later version. The license should have
// accompanied the software or you may obtain a copy of the license
// from the Free Software Foundation at http://www.fsf.org .
//
// This program 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 General Public License for more details.
// -------------------------------------------------------------------
*/
#ifndef MINIEXP_H
#define MINIEXP_H
#ifdef __cplusplus
extern "C" {
# ifndef __cplusplus
}
# endif
#endif
#ifndef MINILISPAPI
# ifdef _WIN32
# ifdef MINILISPAPI_EXPORT
# define MINILISPAPI __declspec(dllexport)
# else
# define MINILISPAPI __declspec(dllimport)
# endif
# endif
#endif
#ifndef MINILISPAPI
# define MINILISPAPI /**/
#endif
#ifndef __cplusplus
# ifndef inline
# if defined(__GNUC__)
# define inline __inline__
# elif defined(_MSC_VER)
# define inline __inline
# else
# define inline /**/
# endif
# endif
#endif
#include <stddef.h>
/* -------------------------------------------------- */
/* LISP EXPRESSIONS */
/* -------------------------------------------------- */
/* miniexp_t --
Opaque pointer type representing a lisp expression,
also known as s-expression.
S-expressions can be viewed as a simple and powerful
alternative to XML. DjVu uses s-expressions to handle
annotations. Both the decoding api <ddjvuapi.h> and
program <djvused> use s-expressions to describe the
hidden text information and the navigation
information */
typedef struct miniexp_s* miniexp_t;
/* There are four basic types of lisp expressions,
numbers, symbols, pairs, and objects.
The latter category can represent any c++ object
that inherits class <miniobj_t> defined later in this file.
Strings and floating point numbers are implemented this way.*/
/* -------- NUMBERS -------- */
/* Minilisp numbers represent integers
covering at least range [-2^29...2^29-1] */
/* miniexp_numberp --
Tests if an expression is a number. */
static inline int miniexp_numberp(miniexp_t p) {
return (((size_t)(p)&3)==3);
}
/* miniexp_to_int --
Returns the integer corresponding to a lisp expression.
Assume that the expression is indeed a number. */
static inline int miniexp_to_int(miniexp_t p) {
return (((int)(size_t)(p))>>2);
}
/* miniexp_number --
Constructs the expression corresponding to an integer. */
static inline miniexp_t miniexp_number(int x) {
return (miniexp_t) (size_t) ((x<<2)|3);
}
/* -------- SYMBOLS -------- */
/* The textual representation of a minilisp symbol is a
sequence of printable characters forming an identifier.
Each symbol has a unique representation and remain
permanently allocated. To compare two symbols,
simply compare the <miniexp_t> pointers. */
/* miniexp_symbolp --
Tests if an expression is a symbol. */
static inline int miniexp_symbolp(miniexp_t p) {
return ((((size_t)p)&3)==2);
}
/* miniexp_to_name --
Returns the symbol name as a string.
Returns NULL if the expression is not a symbol. */
MINILISPAPI const char* miniexp_to_name(miniexp_t p);
/* miniexp_symbol --
Returns the unique symbol expression with the specified name. */
MINILISPAPI miniexp_t miniexp_symbol(const char *name);
/* -------- PAIRS -------- */
/* Pairs (also named "cons") are the basic building blocks for
minilisp lists. Each pair contains two expression:
- the <car> represents the first element of a list.
- the <cdr> usually is a pair representing the rest of the list.
The empty list is represented by a null pointer. */
/* miniexp_nil --
The empty list. */
#define miniexp_nil ((miniexp_t)(size_t)0)
/* miniexp_dummy --
An invalid expression used to represent
various exceptional conditions. */
#define miniexp_dummy ((miniexp_t)(size_t)2)
/* miniexp_listp --
Tests if an expression is either a pair or the empty list. */
static inline int miniexp_listp(miniexp_t p) {
return ((((size_t)p)&3)==0);
}
/* miniexp_consp --
Tests if an expression is a pair. */
static inline int miniexp_consp(miniexp_t p) {
return p && miniexp_listp(p);
}
/* miniexp_length --
Returns the length of a list.
Returns 0 for non lists, -1 for circular lists. */
MINILISPAPI int miniexp_length(miniexp_t p);
/* miniexp_car --
miniexp_cdr --
Returns the car or cdr of a pair. */
static inline miniexp_t miniexp_car(miniexp_t p) {
if (miniexp_consp(p))
return ((miniexp_t*)p)[0];
return miniexp_nil;
}
static inline miniexp_t miniexp_cdr(miniexp_t p) {
if (miniexp_consp(p))
return ((miniexp_t*)p)[1];
return miniexp_nil;
}
/* miniexp_cXXr --
Represent common combinations of car and cdr. */
MINILISPAPI miniexp_t miniexp_caar (miniexp_t p);
MINILISPAPI miniexp_t miniexp_cadr (miniexp_t p);
MINILISPAPI miniexp_t miniexp_cdar (miniexp_t p);
MINILISPAPI miniexp_t miniexp_cddr (miniexp_t p);
MINILISPAPI miniexp_t miniexp_caddr(miniexp_t p);
MINILISPAPI miniexp_t miniexp_cdddr(miniexp_t p);
/* miniexp_nth --
Returns the n-th element of a list. */
MINILISPAPI miniexp_t miniexp_nth(int n, miniexp_t l);
/* miniexp_cons --
Constructs a pair. */
MINILISPAPI miniexp_t miniexp_cons(miniexp_t car, miniexp_t cdr);
/* miniexp_rplaca --
miniexp_rplacd --
Changes the car or the cdr of a pair. */
MINILISPAPI miniexp_t miniexp_rplaca(miniexp_t pair, miniexp_t newcar);
MINILISPAPI miniexp_t miniexp_rplacd(miniexp_t pair, miniexp_t newcdr);
/* miniexp_reverse --
Reverses a list in place. */
MINILISPAPI miniexp_t miniexp_reverse(miniexp_t p);
/* -------- OBJECTS (GENERIC) -------- */
/* Object expressions represent a c++ object
that inherits class <miniobj_t> defined later.
Each object expression has a symbolic class name
and a pointer to the c++ object. */
/* miniexp_objectp --
Tests if an expression is an object. */
static inline int miniexp_objectp(miniexp_t p) {
return ((((size_t)p)&3)==1);
}
/* miniexp_classof --
Returns the symbolic class of an expression.
Returns nil if the expression is not an object. */
MINILISPAPI miniexp_t miniexp_classof(miniexp_t p);
/* miniexp_isa --
If <p> is an instance of class named <c> or one of
its subclasses, returns the actual class name.
Otherwise returns miniexp_nil. */
MINILISPAPI miniexp_t miniexp_isa(miniexp_t p, miniexp_t c);
/* -------- OBJECTS (STRINGS) -------- */
/* miniexp_stringp --
Tests if an expression is a string. */
MINILISPAPI int miniexp_stringp(miniexp_t p);
/* miniexp_to_str --
Returns the c string represented by the expression.
Returns NULL if the expression is not a string.
The c string remains valid as long as the
corresponding lisp object exists. */
MINILISPAPI const char *miniexp_to_str(miniexp_t p);
/* miniexp_string --
Constructs a string expression by copying string s. */
MINILISPAPI miniexp_t miniexp_string(const char *s);
/* miniexp_substring --
Constructs a string expression by copying
at most n character from string s. */
MINILISPAPI miniexp_t miniexp_substring(const char *s, int n);
/* miniexp_concat --
Concat all the string expressions in list <l>. */
MINILISPAPI miniexp_t miniexp_concat(miniexp_t l);
/* -------- OBJECTS (FLOATNUM) -------- */
/* miniexp_floatnump --
Tests if an expression is an object
representing a floating point number. */
MINILISPAPI int miniexp_floatnump(miniexp_t p);
/* miniexp_floatnum --
Returns a new floating point number object. */
MINILISPAPI miniexp_t miniexp_floatnum(double x);
/* miniexp_doublep --
Tests if an expression can be converted
to a double precision number. */
static inline int miniexp_doublep(miniexp_t p) {
return miniexp_numberp(p) || miniexp_floatnump(p);
}
/* miniexp_to_double --
Returns a double precision number corresponding to
a lisp expression (a number or a floatnum.) */
MINILISPAPI double miniexp_to_double(miniexp_t p);
/* miniexp_double --
Returns a lisp expression representing a double
precision number. This will be a number if it fits
and a floatnum otherwise.
*/
MINILISPAPI miniexp_t miniexp_double(double x);
/* -------------------------------------------------- */
/* GARBAGE COLLECTION */
/* -------------------------------------------------- */
/* The garbage collector reclaims the memory allocated for
lisp expressions no longer in use. It is automatically
invoked by the pair and object allocation functions when
the available memory runs low. It is however possible to
temporarily disable it.
The trick is to determine which lisp expressions are in
use at a given moment. This package takes a simplistic
approach. All objects of type <minivar_t> are chained and
can reference an arbitrary lisp expression. Garbage
collection preserves all lisp expressions referenced by a
minivar, as well as all lisp expressions that can be
accessed from these. When called automatically,
garbage collection also preserves the sixteen most recently
created miniexps in order to make sure that temporaries do
not vanish in the middle of complicated C expressions.
The minivar class is designed such that C++ program can
directly use instances of <minivar_t> as normal
<miniexp_t> variables. There is almost no overhead
accessing or changing the lisp expression referenced by a
minivar. However, the minivar chain must be updated
whenever the minivar object is constructed or destructed.
Example (in C++ only):
miniexp_t copy_in_reverse(miniexp_t p) {
minivar_t l = miniexp_nil;
while (miniexp_consp(p)) {
l = miniexp_cons(miniexp_car(p), l);
p = miniexp_cdr(p);
}
return l;
}
When to use minivar_t instead of miniexp_t?
* A function that only navigates properly secured
s-expressions without modifying them does not need to
bother about minivars.
* Only the following miniexp functions can cause a
garbage collection: miniexp_cons(), miniexp_object(),
miniexp_string(), miniexp_substring(), miniexp_pname(),
miniexp_concat(), miniexp_pprin(), miniexp_pprint(),
miniexp_gc(), and minilisp_release_gc_lock(). A
function that does not cause calls to these functions
does not need to bother about minivars.
* Other functions should make sure that all useful
s-expression are directly or indirectly secured by a
minivar_t object. In case of doubt, use minivars
everywhere.
* Function arguments should remain <miniexp_t> in order
to allow interoperability with the C language.
It is assumed that these arguments have been properly
secured by the caller and cannot disappear if a
garbage collection occurs.
C programs cannot use minivars as easily as C++ programs.
Wrappers are provided to allocate minivars and to access
their value. This is somehow inconvenient. It might be
more practical to control the garbage collector
invocations with <minilisp_acquire_gc_lock()> and
<minilisp_release_gc_lock()>... */
/* minilisp_gc --
Invokes the garbage collector now. */
MINILISPAPI void minilisp_gc(void);
/* minilisp_info --
Prints garbage collector statistics. */
MINILISPAPI void minilisp_info(void);
/* minilisp_acquire_gc_lock --
minilisp_release_gc_lock --
Temporarily disables automatic garbage collection.
Acquire/release pairs may be nested.
Both functions return their argument unmodified.
This is practical because <minilisp_release_gc_lock>
can invoke the garbage collector. Before doing
so it stores its argument in a minivar to
preserve it.
Example (in C):
miniexp_t copy_in_reverse(miniexp_t p) {
miniexp_t l = 0;
minilisp_acquire_gc_lock(0);
while (miniexp_consp(p)) {
l = miniexp_cons(miniexp_car(p), l);
p = miniexp_cdr(p);
}
return minilisp_release_gc_lock(l);
}
Disabling garbage collection for a long time
increases the memory consumption. */
MINILISPAPI miniexp_t minilisp_acquire_gc_lock(miniexp_t);
MINILISPAPI miniexp_t minilisp_release_gc_lock(miniexp_t);
/* minivar_t --
The minivar type. */
#ifdef __cplusplus
class minivar_t;
#else
typedef struct minivar_s minivar_t;
#endif
/* minivar_alloc --
minivar_free --
Wrappers for creating and destroying minivars in C. */
MINILISPAPI minivar_t *minivar_alloc(void);
MINILISPAPI void minivar_free(minivar_t *v);
/* minivar_pointer --
Wrappers to access the lisp expression referenced
by a minivar. This function returns a pointer
to the actual miniexp_t variable. */
MINILISPAPI miniexp_t *minivar_pointer(minivar_t *v);
/* minilisp_debug --
Setting the debug flag runs the garbage collector
very often. This is extremely slow, but can be
useful to debug memory allocation problems. */
MINILISPAPI void minilisp_debug(int debugflag);
/* minilisp_finish --
Deallocates everything. This is only useful when using
development tools designed to check for memory leaks.
No miniexp function can be used after calling this. */
MINILISPAPI void minilisp_finish(void);
/* -------------------------------------------------- */
/* INPUT/OUTPUT */
/* -------------------------------------------------- */
/* Notes about the textual representation of miniexps.
- Special characters are:
* the parenthesis <(> and <)>,
* the double quote <">,
* the vertical bar <|>,
* any other ascii character with a non zero entry
in the macro character array.
* the dieze character <#>, when followed by another
dieze or by an ascii character with a non zero entry
in the dieze character array.
- Symbols are represented by their name.
Symbols whose name contains blanks, special characters,
non printable characters, non ascii characters,
or can be confused for a number are delimited
by vertical bars <|> and can contain two consecutive
vertical bars to represent a single vertical bar character.
- Numbers follow the syntax specified by the C
function strtol() with base=0, but are required
to start with a digit or with a sign character
followed by another character.
- Floating point follow the syntax specified by the C
function strtod() with base=0, but are required
to start with a digit or with a sign character
followed by another character.
- Strings are delimited by double quotes.
All non printable ASCII characters must be escaped.
Besides all the usual C string escape sequences,
UTF8-encoded Unicode characters in range 0..0x10ffff
can be represented by escape sequence <\u> followed
by four hexadecimal digits or escape sequence <\U>
followed by six hexadecimal digits. Surrogate pairs
are always recognized as a single Unicode character.
The effect of invalid escape sequences is unspecified.
- List are represented by an open parenthesis <(>
followed by the space separated list elements,
followed by a closing parenthesis <)>.
When the cdr of the last pair is non zero,
the closed parenthesis is preceded by
a space, a dot <.>, a space, and the textual
representation of the cdr.
- When the parser encounters an ascii character corresponding
to a non zero function pointer in the macro character array,
the function is invoked and must return a possibly empty
list of miniexps to be returned by subsequent
invocations of the parser. The same process happens when
the parser encounters a dieze character followed by an
ascii character corresponding to a non zero function pointer
int the dieze character array. */
/* miniexp_pname --
Returns a string containing the textual representation
of a minilisp expression. Set argument <width> to zero
to output a single line, or to a positive value to
perform pretty line breaks for this intended number of columns.
This function can cause a garbage collection to occur. */
MINILISPAPI miniexp_t miniexp_pname(miniexp_t p, int width);
/* miniexp_io_t --
This structure is used to describe how to perform input/output
operations. Input/output operations are performed through function
pointers <fputs>, <fgetc>, and <ungetc>, which are similar to their
stdio counterparts. Variable <data> defines four pointers that can
be used as a closure by the I/O functions.
Variable <p_flags> optionally points to a flag word that customize the
printing operation. All ASCII control characters present in strings are
displayed using C escapes sequences. Flag <miniexp_io_print7bits> causes
all other non ASCII characters to be escaped. Flag <miniexp_io_u6escape>
and <miniexp_io_u4escape> respectively authorize using the long and
short utf8 escape sequences "\U" and "\u". Their absence may force
using surrogate short escape sequences or only octal sequences.
Flag <miniexp_io_quotemoresyms> causes the output code to also quote
all symbols that start with a digit or with a sign character followed
by another character.
When both <p_macrochar> and <p_macroqueue> are non zero, a non zero
entry in <p_macrochar[c]> defines a special parsing function that is called
when <miniexp_read_r> encounters the character <c> (in range 0 to 127.)
When both <p_diezechar> and <p_macroqueue> are non zero, a non zero entry
in <p_diezechar[c]> defines a special parsing function that is called when
<miniexp_read_r> encounters the character '#' followed by character <c> (in
range 0 to 127.) These parsing functions return a list of <miniexp_t> that
function <miniexp_read_r> returns one-by-one before processing more
input. This list is stored in the variable pointed by <io.p_macroqueue>.
*/
typedef struct miniexp_io_s miniexp_io_t;
typedef miniexp_t (*miniexp_macrochar_t)(miniexp_io_t*);
struct miniexp_io_s
{
int (*fputs)(miniexp_io_t*, const char*);
int (*fgetc)(miniexp_io_t*);
int (*ungetc)(miniexp_io_t*, int);
void *data[4];
int *p_flags; /* previously named p_print7bits */
miniexp_macrochar_t *p_macrochar;
miniexp_macrochar_t *p_diezechar;
minivar_t *p_macroqueue;
minivar_t *p_reserved;
};
#define miniexp_io_print7bits 0x1
#define miniexp_io_u4escape 0x2
#define miniexp_io_u6escape 0x4
#define miniexp_io_quotemoresymbols 0x20
/* miniexp_io_init --
Initialize a default <miniexp_io_t> structure
that reads from stdin and prints to stdout.
Field <data[0]> is used to hold the stdin file pointer.
Field <data[1]> is used to hold the stdout file pointer.
Fields <p_flags>, <p_macrochar>, <p_diezechar>
and <p_macroqueue> are set to point to zero-initialized
shared variables. */
MINILISPAPI void miniexp_io_init(miniexp_io_t *io);
/* miniexp_io_set_{input,output} --
Override the file descriptor used for input or output.
You must call <miniexp_io_init> before. */
#if defined(stdin)
MINILISPAPI void miniexp_io_set_output(miniexp_io_t *io, FILE *f);
MINILISPAPI void miniexp_io_set_input(miniexp_io_t *io, FILE *f);
#endif
/* miniexp_read_r --
Reads an expression by repeatedly
invoking <minilisp_getc> and <minilisp_ungetc>.
Returns <miniexp_dummy> when an error occurs. */
MINILISPAPI miniexp_t miniexp_read_r(miniexp_io_t *io);
/* miniexp_prin_r, miniexp_print_r --
Prints a minilisp expression by repeatedly invoking <minilisp_puts>.
Only <minilisp_print> outputs a final newline character.
These functions are safe to call anytime. */
MINILISPAPI miniexp_t miniexp_prin_r(miniexp_io_t *io, miniexp_t p);
MINILISPAPI miniexp_t miniexp_print_r(miniexp_io_t *io, miniexp_t p);
/* miniexp_pprin_r, miniexp_pprint_r --
Prints a minilisp expression with reasonably pretty line breaks.
Argument <width> is the intended number of columns.
Only <minilisp_pprint> outputs a final newline character.
These functions can cause a garbage collection to occur. */
MINILISPAPI miniexp_t miniexp_pprin_r(miniexp_io_t *io, miniexp_t p, int w);
MINILISPAPI miniexp_t miniexp_pprint_r(miniexp_io_t *io, miniexp_t p, int w);
/* miniexp_io, miniexp_read, miniexp_{,p}prin{,t} --
Variable <miniexp_io> contains the pre-initialized input/output data
structure that is used by the non-reentrant input/output functions. */
extern MINILISPAPI miniexp_io_t miniexp_io;
MINILISPAPI miniexp_t miniexp_read(void);
MINILISPAPI miniexp_t miniexp_prin(miniexp_t p);
MINILISPAPI miniexp_t miniexp_print(miniexp_t p);
MINILISPAPI miniexp_t miniexp_pprin(miniexp_t p, int width);
MINILISPAPI miniexp_t miniexp_pprint(miniexp_t p, int width);
/* Backward compatibility (will eventually disappear) */
extern MINILISPAPI int (*minilisp_puts)(const char *);
extern MINILISPAPI int (*minilisp_getc)(void);
extern MINILISPAPI int (*minilisp_ungetc)(int);
extern MINILISPAPI miniexp_t (*minilisp_macrochar_parser[128])(void);
extern MINILISPAPI miniexp_t (*minilisp_diezechar_parser[128])(void);
extern MINILISPAPI miniexp_macrochar_t miniexp_macrochar[128];
extern MINILISPAPI minivar_t miniexp_macroqueue;
extern MINILISPAPI int minilisp_print_7bits;
#if defined(stdin)
MINILISPAPI void minilisp_set_output(FILE *f);
MINILISPAPI void minilisp_set_input(FILE *f);
#endif
/* -------------------------------------------------- */
/* STUFF FOR C++ ONLY */
/* -------------------------------------------------- */
#ifdef __cplusplus
# ifndef __cplusplus
{
# endif
} // extern "C"
typedef void minilisp_mark_t(miniexp_t *pp);
/* -------- MINIVARS -------- */
/* minivar_t --
A class for protected garbage collector variables. */
class MINILISPAPI
minivar_t
{
miniexp_t data;
minivar_t *next;
minivar_t **pprev;
public:
minivar_t();
minivar_t(miniexp_t p);
minivar_t(const minivar_t &v);
operator miniexp_t&() { return data; }
miniexp_t* operator&() { return &data; }
minivar_t& operator=(miniexp_t p) { data = p; return *this; }
minivar_t& operator=(const minivar_t &v) { data = v.data; return *this; }
~minivar_t();
#ifdef MINIEXP_IMPLEMENTATION
static minivar_t *vars;
static void mark(minilisp_mark_t*);
#endif
};
/* -------- MINIOBJ -------- */
/* miniobj_t --
The base class for c++ objects
represented by object expressions. */
class MINILISPAPI
miniobj_t {
public:
virtual ~miniobj_t();
/* --- stuff defined by MINIOBJ_DECLARE --- */
/* classname: a symbol characterizing this class. */
static const miniexp_t classname;
/* classof: class name symbol for this object. */
virtual miniexp_t classof() const = 0;
/* isa -- tests if this is an instance of <classname>. */
virtual bool isa(miniexp_t classname) const;
/* --- optional stuff --- */
/* pname: returns a printable name for this object.
The caller must deallocate the result with delete[]. */
virtual char *pname() const;
/* mark: calls action() on all member miniexps of the object,
for garbage collecting purposes. */
virtual void mark(minilisp_mark_t *action);
/* destroy: called by the garbage collector to
deallocate the object. Defaults to 'delete this'. */
virtual void destroy();
};
/* MINIOBJ_DECLARE --
MINIOBJ_IMPLEMENT --
Useful code fragments for implementing
the mandatory part of miniobj subclasses. */
#define MINIOBJ_DECLARE(cls, supercls, name) \
public: static const miniexp_t classname; \
virtual miniexp_t classof() const; \
virtual bool isa(miniexp_t) const;
#define MINIOBJ_IMPLEMENT(cls, supercls, name)\
const miniexp_t cls::classname = miniexp_symbol(name);\
miniexp_t cls::classof() const {\
return cls::classname; }\
bool cls::isa(miniexp_t n) const {\
return (cls::classname==n) || (supercls::isa(n)); }
/* miniexp_to_obj --
Returns a pointer to the object represented by an lisp
expression. Returns NULL if the expression is not an
object expression.
*/
static inline miniobj_t *miniexp_to_obj(miniexp_t p) {
if (miniexp_objectp(p))
return ((miniobj_t**)(((size_t)p)&~((size_t)3)))[0];
return 0;
}
/* miniexp_object --
Create an object expression for a given object. */
MINILISPAPI miniexp_t miniexp_object(miniobj_t *obj);
/* miniexp_mutate --
Atomically modifies a member of a garbage collected object.
The object implementation must call this function to change
the contents of a member variable <v> of object <obj>.
Returns <p>*/
MINILISPAPI miniexp_t miniexp_mutate(miniexp_t obj, miniexp_t *v, miniexp_t p);
#endif /* __cplusplus */
/* -------------------------------------------------- */
/* THE END */
/* -------------------------------------------------- */
#endif /* MINIEXP_H */