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lispreader.cxx

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/* $Id: lispreader.cxx,v 1.2 2003/01/08 23:30:43 grumbel Exp $ */
/*
 * lispreader.c
 *
 * Copyright (C) 1998-2000 Mark Probst
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <assert.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>

#include "construo_error.hxx"
#include <lispreader.hxx>

#define TOKEN_ERROR                   -1
#define TOKEN_EOF                     0
#define TOKEN_OPEN_PAREN              1
#define TOKEN_CLOSE_PAREN             2
#define TOKEN_SYMBOL                  3
#define TOKEN_STRING                  4
#define TOKEN_INTEGER                 5
#define TOKEN_REAL                    6
#define TOKEN_PATTERN_OPEN_PAREN      7
#define TOKEN_DOT                     8
#define TOKEN_TRUE                    9
#define TOKEN_FALSE                   10


#define MAX_TOKEN_LENGTH           1024

static char token_string[MAX_TOKEN_LENGTH + 1] = "";
static int token_length = 0;

static lisp_object_t end_marker = { LISP_TYPE_EOF };
static lisp_object_t error_object = { LISP_TYPE_PARSE_ERROR };
static lisp_object_t close_paren_marker = { LISP_TYPE_PARSE_ERROR };
static lisp_object_t dot_marker = { LISP_TYPE_PARSE_ERROR };

static void
_token_clear (void)
{
    token_string[0] = '\0';
    token_length = 0;
}

static void
_token_append (char c)
{
    assert(token_length < MAX_TOKEN_LENGTH);

    token_string[token_length++] = c;
    token_string[token_length] = '\0';
}

static int
_next_char (lisp_stream_t *stream)
{
    switch (stream->type)
    {
        case LISP_STREAM_FILE :
            return getc(stream->v.file);

        case LISP_STREAM_STRING :
            {
                char c = stream->v.string.buf[stream->v.string.pos];

                if (c == 0)
                    return EOF;

                ++stream->v.string.pos;

                return c;
            }

        case LISP_STREAM_ANY:
            return stream->v.any.next_char(stream->v.any.data);
    }
    assert(0);
    return EOF;
}

static void
_unget_char (char c, lisp_stream_t *stream)
{
    switch (stream->type)
    {
        case LISP_STREAM_FILE :
            ungetc(c, stream->v.file);
            break;

        case LISP_STREAM_STRING :
            --stream->v.string.pos;
            break;

       case LISP_STREAM_ANY:
            stream->v.any.unget_char(c, stream->v.any.data);
            break;
         
        default :
            assert(0);
    }
}

static int
_scan (lisp_stream_t *stream)
{
    static char *delims = "\"();";

    int c;

    _token_clear();

    do
    {
        c = _next_char(stream);
        if (c == EOF)
            return TOKEN_EOF;
        else if (c == ';')       /* comment start */
            while (1)
            {   
                c = _next_char(stream);
                if (c == EOF)           
                    return TOKEN_EOF;   
                else if (c == '\n')     
                    break;
            }
    } while (isspace(c));

    switch (c)
    {
        case '(' :
            return TOKEN_OPEN_PAREN;

        case ')' :
            return TOKEN_CLOSE_PAREN;

        case '"' :
            while (1)
            {
                c = _next_char(stream);
                if (c == EOF)
                    return TOKEN_ERROR;
                if (c == '"')
                    break;
                if (c == '\\')
                {
                    c = _next_char(stream);

                    switch (c)
                    {
                        case EOF :
                            return TOKEN_ERROR;
                        
                        case 'n' :
                            c = '\n';
                            break;

                        case 't' :
                            c = '\t';
                            break;
                    }
                }

                _token_append(c);
            }
            return TOKEN_STRING;

        case '#' :
            c = _next_char(stream);
            if (c == EOF)
                return TOKEN_ERROR;

            switch (c)
            {
                case 't' :
                    return TOKEN_TRUE;

                case 'f' :
                    return TOKEN_FALSE;

                case '?' :
                    c = _next_char(stream);
                    if (c == EOF)
                        return TOKEN_ERROR;

                    if (c == '(')
                        return TOKEN_PATTERN_OPEN_PAREN;
                    else
                        return TOKEN_ERROR;
            }
            return TOKEN_ERROR;

        default :
            if (isdigit(c) || c == '-')
            {
                int have_nondigits = 0;
                int have_digits = 0;
                int have_floating_point = 0;

                do
                {
                    if (isdigit(c))
                        have_digits = 1;
                    else if (c == '.')
                        have_floating_point++;
                    _token_append(c);

                    c = _next_char(stream);

                    if (c != EOF && !isdigit(c) && !isspace(c) && c != '.' && !strchr(delims, c))
                        have_nondigits = 1;
                } while (c != EOF && !isspace(c) && !strchr(delims, c));

                if (c != EOF)
                    _unget_char(c, stream);

                if (have_nondigits || !have_digits || have_floating_point > 1)
                  return TOKEN_SYMBOL;
                else if (have_floating_point == 1)
                  return TOKEN_REAL;
                else
                  return TOKEN_INTEGER;
            }
            else
            {
                if (c == '.')
                {
                    c = _next_char(stream);
                    if (c != EOF && !isspace(c) && !strchr(delims, c))
                        _token_append('.');
                    else
                    {
                        _unget_char(c, stream);
                        return TOKEN_DOT;
                    }
                }
                do
                {
                    _token_append(c);
                    c = _next_char(stream);
                } while (c != EOF && !isspace(c) && !strchr(delims, c));
                if (c != EOF)
                    _unget_char(c, stream);

                return TOKEN_SYMBOL;
            }
    }

    assert(0);
    return TOKEN_ERROR;
}

static lisp_object_t*
lisp_object_alloc (int type)
{
    lisp_object_t *obj = (lisp_object_t*)malloc(sizeof(lisp_object_t));

    obj->type = type;

    return obj;
}

lisp_stream_t*
lisp_stream_init_file (lisp_stream_t *stream, FILE *file)
{
    stream->type = LISP_STREAM_FILE;
    stream->v.file = file;

    return stream;
}

lisp_stream_t*
lisp_stream_init_string (lisp_stream_t *stream, char *buf)
{
    stream->type = LISP_STREAM_STRING;
    stream->v.string.buf = buf;
    stream->v.string.pos = 0;

    return stream;
}

lisp_stream_t* 
lisp_stream_init_any (lisp_stream_t *stream, void *data, 
                      int (*next_char) (void *data),
                      void (*unget_char) (char c, void *data))
{
    assert(next_char != 0 && unget_char != 0);
    
    stream->type = LISP_STREAM_ANY;
    stream->v.any.data = data;
    stream->v.any.next_char= next_char;
    stream->v.any.unget_char = unget_char;

    return stream;
}

lisp_object_t*
lisp_make_integer (int value)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_INTEGER);

    obj->v.integer = value;

    return obj;
}

lisp_object_t*
lisp_make_real (float value)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_REAL);

    obj->v.real = value;

    return obj;
}

lisp_object_t*
lisp_make_symbol (const char *value)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_SYMBOL);

    obj->v.string = strdup(value);

    return obj;
}

lisp_object_t*
lisp_make_string (const char *value)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_STRING);

    obj->v.string = strdup(value);

    return obj;
}

lisp_object_t*
lisp_make_cons (lisp_object_t *car, lisp_object_t *cdr)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_CONS);

    obj->v.cons.car = car;
    obj->v.cons.cdr = cdr;

    return obj;
}

lisp_object_t*
lisp_make_boolean (int value)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_BOOLEAN);

    obj->v.integer = value ? 1 : 0;

    return obj;
}

static lisp_object_t*
lisp_make_pattern_cons (lisp_object_t *car, lisp_object_t *cdr)
{
    lisp_object_t *obj = lisp_object_alloc(LISP_TYPE_PATTERN_CONS);

    obj->v.cons.car = car;
    obj->v.cons.cdr = cdr;

    return obj;
}

lisp_object_t*
lisp_read (lisp_stream_t *in)
{
    int token = _scan(in);
    lisp_object_t *obj = lisp_nil();

    if (token == TOKEN_EOF)
        return &end_marker;

    switch (token)
    {
        case TOKEN_ERROR :
            return &error_object;

        case TOKEN_EOF :
            return &end_marker;

        case TOKEN_OPEN_PAREN :
        case TOKEN_PATTERN_OPEN_PAREN :
            {
                lisp_object_t *last = lisp_nil(), *car;

                do
                {
                    car = lisp_read(in);
                    if (car == &error_object || car == &end_marker)
                    {
                        lisp_free(obj);
                        return &error_object;
                    }
                    else if (car == &dot_marker)
                    {
                        if (lisp_nil_p(last))
                        {
                            lisp_free(obj);
                            return &error_object;
                        }

                        car = lisp_read(in);
                        if (car == &error_object || car == &end_marker)
                        {
                            lisp_free(obj);
                            return car;
                        }
                        else
                        {
                            last->v.cons.cdr = car;

                            if (_scan(in) != TOKEN_CLOSE_PAREN)
                            {
                                lisp_free(obj);
                                return &error_object;
                            }

                            car = &close_paren_marker;
                        }
                    }
                    else if (car != &close_paren_marker)
                    {
                        if (lisp_nil_p(last))
                            obj = last = (token == TOKEN_OPEN_PAREN ? lisp_make_cons(car, lisp_nil()) : lisp_make_pattern_cons(car, lisp_nil()));
                        else
                            last = last->v.cons.cdr = lisp_make_cons(car, lisp_nil());
                    }
                } while (car != &close_paren_marker);
            }
            return obj;

        case TOKEN_CLOSE_PAREN :
            return &close_paren_marker;

        case TOKEN_SYMBOL :
            return lisp_make_symbol(token_string);

        case TOKEN_STRING :
            return lisp_make_string(token_string);

        case TOKEN_INTEGER :
            return lisp_make_integer(atoi(token_string));
        
        case TOKEN_REAL :
            return lisp_make_real((float)atof(token_string));

        case TOKEN_DOT :
            return &dot_marker;

        case TOKEN_TRUE :
            return lisp_make_boolean(1);

        case TOKEN_FALSE :
            return lisp_make_boolean(0);
    }

    assert(0);
    return &error_object;
}

void
lisp_free (lisp_object_t *obj)
{
    if (obj == 0)
        return;

    switch (obj->type)
    {
        case LISP_TYPE_INTERNAL :
        case LISP_TYPE_PARSE_ERROR :
        case LISP_TYPE_EOF :
            return;

        case LISP_TYPE_SYMBOL :
        case LISP_TYPE_STRING :
            free(obj->v.string);
            break;

        case LISP_TYPE_CONS :
        case LISP_TYPE_PATTERN_CONS :
            lisp_free(obj->v.cons.car);
            lisp_free(obj->v.cons.cdr);
            break;

        case LISP_TYPE_PATTERN_VAR :
            lisp_free(obj->v.pattern.sub);
            break;
    }

    free(obj);
}

lisp_object_t*
lisp_read_from_string (const char *buf)
{
    lisp_stream_t stream;

    lisp_stream_init_string(&stream, (char*)buf);
    return lisp_read(&stream);
}

int
lisp_type (lisp_object_t *obj)
{
    if (obj == 0)
        return LISP_TYPE_NIL;
    return obj->type;
}

int
lisp_integer (lisp_object_t *obj)
{
    assert(obj->type == LISP_TYPE_INTEGER);

    return obj->v.integer;
}

char*
lisp_symbol (lisp_object_t *obj)
{
    assert(obj->type == LISP_TYPE_SYMBOL);

    return obj->v.string;
}

char*
lisp_string (lisp_object_t *obj)
{
  if (obj->type != LISP_TYPE_STRING)
    ConstruoError::raise("lispreader Error: obj->type != LISP_TYPE_STRING");

    return obj->v.string;
}

int
lisp_boolean (lisp_object_t *obj)
{
    assert(obj->type == LISP_TYPE_BOOLEAN);

    return obj->v.integer;
}

float
lisp_real (lisp_object_t *obj)
{
    assert(obj->type == LISP_TYPE_REAL || obj->type == LISP_TYPE_INTEGER);

    if (obj->type == LISP_TYPE_INTEGER)
        return obj->v.integer;
    return obj->v.real;
}
           
lisp_object_t*
lisp_car (lisp_object_t *obj)
{
  if (!(obj->type == LISP_TYPE_CONS || obj->type == LISP_TYPE_PATTERN_CONS))
    ConstruoError::raise("lispreader Error: !(obj->type == LISP_TYPE_CONS || obj->type == LISP_TYPE_PATTERN_CONS)");
    
    return obj->v.cons.car;
}

lisp_object_t*
lisp_cdr (lisp_object_t *obj)
{
    assert(obj->type == LISP_TYPE_CONS || obj->type == LISP_TYPE_PATTERN_CONS);

    return obj->v.cons.cdr;
}

lisp_object_t*
lisp_cxr (lisp_object_t *obj, const char *x)
{
    int i;

    for (i = strlen(x) - 1; i >= 0; --i)
        if (x[i] == 'a')
            obj = lisp_car(obj);
        else if (x[i] == 'd')
            obj = lisp_cdr(obj);
        else
            assert(0);

    return obj;
}

int
lisp_list_length (lisp_object_t *obj)
{
    int length = 0;

    while (obj != 0)
    {
        assert(obj->type == LISP_TYPE_CONS || obj->type == LISP_TYPE_PATTERN_CONS);

        ++length;
        obj = obj->v.cons.cdr;
    }

    return length;
}

lisp_object_t*
lisp_list_nth_cdr (lisp_object_t *obj, int index)
{
    while (index > 0)
    {
        assert(obj != 0);
        assert(obj->type == LISP_TYPE_CONS || obj->type == LISP_TYPE_PATTERN_CONS);

        --index;
        obj = obj->v.cons.cdr;
    }

    return obj;
}

lisp_object_t*
lisp_list_nth (lisp_object_t *obj, int index)
{
    obj = lisp_list_nth_cdr(obj, index);

    assert(obj != 0);

    return obj->v.cons.car;
}

void
lisp_dump (lisp_object_t *obj, FILE *out)
{
    if (obj == 0)
    {
        fprintf(out, "()");
        return;
    }

    switch (lisp_type(obj))
    {
        case LISP_TYPE_EOF :
            fputs("#<eof>", out);
            break;

        case LISP_TYPE_PARSE_ERROR :
            fputs("#<error>", out);
            break;

        case LISP_TYPE_INTEGER :
            fprintf(out, "%d", lisp_integer(obj));
            break;

        case LISP_TYPE_REAL :
            fprintf(out, "%f", lisp_real(obj));
            break;

        case LISP_TYPE_SYMBOL :
            fputs(lisp_symbol(obj), out);
            break;

        case LISP_TYPE_STRING :
            {
                char *p;

                fputc('"', out);
                for (p = lisp_string(obj); *p != 0; ++p)
                {
                    if (*p == '"' || *p == '\\')
                        fputc('\\', out);
                    fputc(*p, out);
                }
                fputc('"', out);
            }
            break;

        case LISP_TYPE_CONS :
        case LISP_TYPE_PATTERN_CONS :
            fputs(lisp_type(obj) == LISP_TYPE_CONS ? "(" : "#?(", out);
            while (obj != 0)
            {
                lisp_dump(lisp_car(obj), out);
                obj = lisp_cdr(obj);
                if (obj != 0)
                {
                    if (lisp_type(obj) != LISP_TYPE_CONS
                        && lisp_type(obj) != LISP_TYPE_PATTERN_CONS)
                    {
                        fputs(" . ", out);
                        lisp_dump(obj, out);
                        break;
                    }
                    else
                        fputc(' ', out);
                }
            }
            fputc(')', out);
            break;

        case LISP_TYPE_BOOLEAN :
            if (lisp_boolean(obj))
                fputs("#t", out);
            else
                fputs("#f", out);
            break;

        default :
            assert(0);
    }
}

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