symbol.c

/*
 * symbol - global and local symbol routines
 *
 * Copyright (C) 1999-2007,2021-2023  David I. Bell and Ernest Bowen
 *
 * Primary author:  David I. Bell
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc 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.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:   1990/02/15 01:48:23
 * File existed as early as:    before 1990
 *
 * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
 */


#include <stdio.h>
#include "calc.h"
#include "token.h"
#include "symbol.h"
#include "str.h"
#include "opcodes.h"
#include "func.h"


#include "errtbl.h"
#include "banned.h"     /* include after system header <> includes */


#define HASHSIZE        37      /* size of hash table */

E_FUNC FILE *f_open(char *name, char *mode);

STATIC int filescope;           /* file scope level for static variables */
STATIC int funcscope;           /* function scope level for static variables */
STATIC STRINGHEAD localnames;   /* list of local variable names */
STATIC STRINGHEAD globalnames;  /* list of global variable names */
STATIC STRINGHEAD paramnames;   /* list of parameter variable names */
STATIC GLOBAL *globalhash[HASHSIZE];    /* hash table for globals */

S_FUNC void printtype(VALUE *);
S_FUNC void unscope(void);
S_FUNC void addstatic(GLOBAL *);
STATIC long staticcount = 0;
STATIC long staticavail = 0;
STATIC GLOBAL **statictable;


/*
 * Hash a symbol name so we can find it in the hash table.
 * Args are the symbol name and the symbol name size.
 */
#define HASHSYM(n, s) ((unsigned)((n)[0]*123 + (n)[s-1]*135 + (s)*157) % \
                       HASHSIZE)


/*
 * Initialize the global symbol table.
 */
void
initglobals(void)
{
        int i;          /* index counter */

        for (i = 0; i < HASHSIZE; i++)
                globalhash[i] = NULL;
        initstr(&globalnames);
        filescope = SCOPE_STATIC;
        funcscope = 0;
}


/*
 * Define a possibly new global variable which may or may not be static.
 * If it did not already exist, it is created with a value of zero.
 * The address of the global symbol structure is returned.
 *
 * given:
 *      name            name of global variable
 *      isstatic        true if symbol is static
 */
GLOBAL *
addglobal(char *name, bool isstatic)
{
        GLOBAL *sp;             /* current symbol pointer */
        GLOBAL **hp;            /* hash table head address */
        size_t len;             /* length of string */
        int newfilescope;       /* file scope being looked for */
        int newfuncscope;       /* function scope being looked for */

        newfilescope = SCOPE_GLOBAL;
        newfuncscope = 0;
        if (isstatic) {
                newfilescope = filescope;
                newfuncscope = funcscope;
        }
        len = strlen(name);
        if (len <= 0)
                return NULL;
        hp = &globalhash[HASHSYM(name, len)];
        for (sp = *hp; sp; sp = sp->g_next) {
                if ((sp->g_len == len) &&
                    (strncmp(sp->g_name, name, len+1) == 0)
                        && (sp->g_filescope == newfilescope)
                        && (sp->g_funcscope == newfuncscope))
                                return sp;
        }
        sp = (GLOBAL *) malloc(sizeof(GLOBAL));
        if (sp == NULL)
                return sp;
        sp->g_name = addstr(&globalnames, name);
        sp->g_len = len;
        sp->g_filescope = newfilescope;
        sp->g_funcscope = newfuncscope;
        sp->g_value.v_num = qlink(&_qzero_);
        sp->g_value.v_type = V_NUM;
        sp->g_value.v_subtype = V_NOSUBTYPE;
        sp->g_next = *hp;
        *hp = sp;
        return sp;
}


/*
 * Look for the highest-scope global variable with a specified name.
 * Returns the address of the variable or NULL according as the search
 * succeeds or fails.
 */
GLOBAL *
findglobal(char *name)
{
        GLOBAL *sp;             /* current symbol pointer */
        GLOBAL *bestsp;         /* found symbol with highest scope */
        size_t len;             /* length of string */

        bestsp = NULL;
        len = strlen(name);
        for (sp = globalhash[HASHSYM(name, len)]; sp != NULL; sp = sp->g_next) {
                if ((sp->g_len == len) &&
                   (strncmp(sp->g_name, name, len+1) == 0)) {
                        if ((bestsp == NULL) ||
                                (sp->g_filescope > bestsp->g_filescope) ||
                                 (sp->g_funcscope > bestsp->g_funcscope))
                                bestsp = sp;
                }
        }
        return bestsp;
}


/*
 * Return the name of a global variable given its address.
 *
 * given:
 *      sp              address of global pointer
 */
char *
globalname(GLOBAL *sp)
{
        if (sp)
                return sp->g_name;
        return "";
}


/*
 * Show the value of all real-number valued global variables, displaying
 * only the head and tail of very large numerators and denominators.
 * Static variables are not included.
 */
void
showglobals(void)
{
        GLOBAL **hp;                    /* hash table head address */
        register GLOBAL *sp;            /* current global symbol pointer */
        long count;                     /* number of global variables shown */

        count = 0;
        for (hp = &globalhash[HASHSIZE-1]; hp >= globalhash; hp--) {
                for (sp = *hp; sp; sp = sp->g_next) {
                        if (sp->g_value.v_type != V_NUM)
                                continue;
                        if (count++ == 0) {
                                printf("\nName    Digits           Value\n");
                                printf(  "----    ------           -----\n");
                        }
                        printf("%-8s", sp->g_name);
                        if (sp->g_filescope != SCOPE_GLOBAL)
                                printf(" (s)");
                        fitprint(sp->g_value.v_num, 50);
                        printf("\n");
                }
        }
        if (count == 0) {
                printf("No real-valued global variables\n");
        }
        putchar('\n');
}


void
showallglobals(void)
{
        GLOBAL **hp;                    /* hash table head address */
        register GLOBAL *sp;            /* current global symbol pointer */
        long count;                     /* number of global variables shown */

        count = 0;
        for (hp = &globalhash[HASHSIZE-1]; hp >= globalhash; hp--) {
                for (sp = *hp; sp; sp = sp->g_next) {
                        if (count++ == 0) {
                                printf("\nName    Level    Type\n");
                                printf(  "----    -----    -----\n");
                        }
                        printf("%-8s%4d     ", sp->g_name, sp->g_filescope);
                        printtype(&sp->g_value);
                        printf("\n");
                }
        }
        if (count > 0)
                printf("\nNumber: %ld\n", count);
        else
                printf("No global variables\n");
}


S_FUNC void
printtype(VALUE *vp)
{
        int     type;
        char    *s;
        char *errsym;
        bool alloced;

        type = vp->v_type;
        if (type < 0) {
                errsym = errnum_2_errsym(-type, &alloced);
                if (errsym == NULL) {
                        printf("Error %d", -type);
                } else {
                        printf("Error %s", errsym);
                        if (alloced == true) {
                                free(errsym);
                        }
                }
                return;
        }
        switch (type) {
        case V_NUM:
                printf("real = ");
                fitprint(vp->v_num, 32);
                return;
        case V_COM:
                printf("complex = ");
                fitprint(vp->v_com->real, 8);
                if (!vp->v_com->imag->num.sign)
                        printf("+");
                fitprint(vp->v_com->imag, 8);
                printf("i");
                return;
        case V_STR:
                printf("string = \"");
                fitstring(vp->v_str->s_str, vp->v_str->s_len, 50);
                printf("\"");
                return;
        case V_NULL:
                s = "null";
                break;
        case V_MAT:
                s = "matrix";
                break;
        case V_LIST:
                s = "list";
                break;
        case V_ASSOC:
                s = "association";
                break;
        case V_OBJ:
                printf("%s ", objtypename(
                        vp->v_obj->o_actions->oa_index));
                s = "object";
                break;
        case V_FILE:
                s = "file id";
                break;
        case V_RAND:
                s = "subtractive 100 random state";
                break;
        case V_RANDOM:
                s = "Blum random state";
                break;
        case V_CONFIG:
                s = "config state";
                break;
        case V_HASH:
                s = "hash state";
                break;
        case V_BLOCK:
                s = "unnamed block";
                break;
        case V_NBLOCK:
                s = "named block";
                break;
        case V_VPTR:
                s = "value pointer";
                break;
        case V_OPTR:
                s = "octet pointer";
                break;
        case V_SPTR:
                s = "string pointer";
                break;
        case V_NPTR:
                s = "number pointer";
                break;
        default:
                s = "???";
                break;
        }
        printf("%s", s);
}


/*
 * Write all normal global variables to an output file.
 * Note: Currently only simple types are saved.
 * Returns nonzero on error.
 */
int
writeglobals(char *name)
{
        FILE *fp;
        GLOBAL **hp;                    /* hash table head address */
        register GLOBAL *sp;            /* current global symbol pointer */
        int savemode;                   /* saved output mode */
        E_FUNC void math_setfp(FILE *fp);

        fp = f_open(name, "w");
        if (fp == NULL)
                return 1;
        math_setfp(fp);
        for (hp = &globalhash[HASHSIZE-1]; hp >= globalhash; hp--) {
                for (sp = *hp; sp; sp = sp->g_next) {
                        switch (sp->g_value.v_type) {
                        case V_NUM:
                        case V_COM:
                        case V_STR:
                                break;
                        default:
                                continue;
                        }
                        math_fmt("%s = ", sp->g_name);
                        savemode = math_setmode(MODE_HEX);
                        printvalue(&sp->g_value, PRINT_UNAMBIG);
                        math_setmode(savemode);
                        math_str(";\n");
                }
        }
        math_setfp(stdout);
        if (fclose(fp))
                return 1;
        return 0;
}


/*
 * Free all non-null global and visible static variables
 */
void
freeglobals(void)
{
        GLOBAL **hp;            /* hash table head address */
        GLOBAL *sp;             /* current global symbol pointer */

        /*
         * We prevent the hp pointer from walking behind globalhash
         * by stopping one short of the end and running the loop one
         * more time.
         *
         * We could stop the loop with just hp >= globalhash, but stopping
         * short and running the loop one last time manually helps make
         * code checkers such as insure happy.
         */
        for (hp = &globalhash[HASHSIZE-1]; hp > globalhash; hp--) {
                for (sp = *hp; sp; sp = sp->g_next) {
                        if (sp->g_value.v_type != V_NULL) {
                                freevalue(&sp->g_value);
                        }
                }
        }
        /* run the loop manually one last time */
        for (sp = *hp; sp; sp = sp->g_next) {
                if (sp->g_value.v_type != V_NULL) {
                        freevalue(&sp->g_value);
                }
        }
}

/*
 * Free all invisible static variables
 */
void
freestatics(void)
{
        GLOBAL **stp;
        GLOBAL *sp;
        long count;

        stp = statictable;
        count = staticcount;
        while (count-- > 0) {
                sp = *stp++;
                freevalue(&sp->g_value);
        }
}


/*
 * Reset the file and function scope levels back to the original values.
 * This is called on errors to forget any static variables which were being
 * defined.
 */
void
resetscopes(void)
{
        filescope = SCOPE_STATIC;
        funcscope = 0;
        unscope();
}


/*
 * Enter a new file scope level so that newly defined static variables
 * will have the appropriate scope, and so that previously defined static
 * variables will temporarily be unaccessible.  This should only be called
 * when the function scope level is zero.
 */
void
enterfilescope(void)
{
        filescope++;
        funcscope = 0;
}


/*
 * Exit from a file scope level.  This deletes from the global symbol table
 * all of the static variables that were defined within this file scope level.
 * The function scope level is also reset to zero.
 */
void
exitfilescope(void)
{
        if (filescope > SCOPE_STATIC)
                filescope--;
        funcscope = 0;
        unscope();
}


/*
 * Enter a new function scope level within the current file scope level.
 * This allows newly defined static variables to override previously defined
 * static variables in the same file scope level.
 */
void
enterfuncscope(void)
{
        funcscope++;
}


/*
 * Exit from a function scope level.  This deletes static symbols which were
 * defined within the current function scope level, and makes previously
 * defined symbols with the same name within the same file scope level
 * accessible again.
 */
void
exitfuncscope(void)
{
        if (funcscope > 0)
                funcscope--;
        unscope();
}


/*
 * To end the scope of any static variable with identifier id when
 * id is being declared as global, or when id is declared as static and the
 * variable is at the same file and function level.
 */
void
endscope(char *name, bool isglobal)
{
        GLOBAL *sp;
        GLOBAL *prevsp;
        GLOBAL **hp;
        size_t len;

        len = strlen(name);
        prevsp = NULL;
        hp = &globalhash[HASHSYM(name, len)];
        for (sp = *hp; sp; sp = sp->g_next) {
                if (sp->g_len == len && !strcmp(sp->g_name, name) &&
                                sp->g_filescope > SCOPE_GLOBAL) {
                        if (isglobal || (sp->g_filescope == filescope &&
                                        sp->g_funcscope == funcscope)) {
                                addstatic(sp);
                                if (prevsp)
                                        prevsp->g_next = sp->g_next;
                                else
                                        *hp = sp->g_next;
                                continue;
                        }
                }
                prevsp = sp;
        }
}

/*
 * To store in a table a static variable whose scope is being ended
 */
void
addstatic(GLOBAL *sp)
{
        GLOBAL **stp;

        if (staticavail <= 0) {
                if (staticcount <= 0)
                        stp = (GLOBAL **) malloc(20 * sizeof(GLOBAL *));
                else
                        stp = (GLOBAL **) realloc(statictable,
                                 (20 + staticcount) * sizeof(GLOBAL *));
                if (stp == NULL) {
                        math_error("Cannot allocate static-variable table");
                        not_reached();
                }
                statictable = stp;
                staticavail = 20;
        }
        statictable[staticcount++] = sp;
        staticavail--;
}

/*
 * To display all static variables whose scope has been ended
 */
void
showstatics(void)
{
        long count;
        GLOBAL **stp;
        GLOBAL *sp;

        for (count = 0, stp = statictable; count < staticcount; count++) {
                sp = *stp++;
                if (count == 0) {
                        printf("\nName    Scopes    Type\n");
                        printf(  "----    ------    -----\n");
                }
                printf("%-8s", sp->g_name);
                printf("%3d", sp->g_filescope);
                printf("%3d    ", sp->g_funcscope);
                printtype(&sp->g_value);
                printf("\n");
        }
        if (count > 0)
                printf("\nNumber: %ld\n", count);
        else
                printf("No un-scoped static variables\n");
}

/*
 * Remove all the symbols from the global symbol table which have file or
 * function scopes larger than the current scope levels.  Their memory
 * remains allocated since their values still actually exist.
 */
S_FUNC void
unscope(void)
{
        GLOBAL **hp;                    /* hash table head address */
        register GLOBAL *sp;            /* current global symbol pointer */
        GLOBAL *prevsp;                 /* previous kept symbol pointer */

        /*
         * We prevent the hp pointer from walking behind globalhash
         * by stopping one short of the end and running the loop one
         * more time.
         *
         * We could stop the loop with just hp >= globalhash, but stopping
         * short and running the loop one last time manually helps make
         * code checkers such as insure happy.
         */
        for (hp = &globalhash[HASHSIZE-1]; hp > globalhash; hp--) {
                prevsp = NULL;
                for (sp = *hp; sp; sp = sp->g_next) {
                        if ((sp->g_filescope == SCOPE_GLOBAL) ||
                                (sp->g_filescope < filescope) ||
                                ((sp->g_filescope == filescope) &&
                                        (sp->g_funcscope <= funcscope))) {
                                prevsp = sp;
                                continue;
                        }

                        /*
                         * This symbol needs removing.
                         */
                        addstatic(sp);
                        if (prevsp)
                                prevsp->g_next = sp->g_next;
                        else
                                *hp = sp->g_next;
                }
        }
        /* run the loop manually one last time */
        prevsp = NULL;
        for (sp = *hp; sp; sp = sp->g_next) {
                if ((sp->g_filescope == SCOPE_GLOBAL) ||
                        (sp->g_filescope < filescope) ||
                        ((sp->g_filescope == filescope) &&
                                (sp->g_funcscope <= funcscope))) {
                        prevsp = sp;
                        continue;
                }

                /*
                 * This symbol needs removing.
                 */
                addstatic(sp);
                if (prevsp)
                        prevsp->g_next = sp->g_next;
                else
                        *hp = sp->g_next;
        }
}


/*
 * Initialize the local and parameter symbol table information.
 */
void
initlocals(void)
{
        initstr(&localnames);
        initstr(&paramnames);
        curfunc->f_localcount = 0;
        curfunc->f_paramcount = 0;
}


/*
 * Add a possibly new local variable definition.
 * Returns the index of the variable into the local symbol table.
 * Minus one indicates the symbol could not be added.
 *
 * given:
 *      name            name of local variable
 */
long
addlocal(char *name)
{
        long index;             /* current symbol index */

        index = findstr(&localnames, name);
        if (index >= 0)
                return index;
        index = localnames.h_count;
        (void) addstr(&localnames, name);
        curfunc->f_localcount++;
        return index;
}


/*
 * Find a local variable name and return its index.
 * Returns minus one if the variable name is not defined.
 *
 * given:
 *      name            name of local variable
 */
long
findlocal(char *name)
{
        return findstr(&localnames, name);
}


/*
 * Return the name of a local variable.
 */
char *
localname(long n)
{
        return namestr(&localnames, n);
}


/*
 * Add a possibly new parameter variable definition.
 * Returns the index of the variable into the parameter symbol table.
 * Minus one indicates the symbol could not be added.
 *
 * given:
 *      name            name of parameter variable
 */
long
addparam(char *name)
{
        long index;             /* current symbol index */

        index = findstr(&paramnames, name);
        if (index >= 0)
                return index;
        index = paramnames.h_count;
        (void) addstr(&paramnames, name);
        curfunc->f_paramcount++;
        return index;
}


/*
 * Find a parameter variable name and return its index.
 * Returns minus one if the variable name is not defined.
 *
 * given:
 *      name            name of parameter variable
 */
long
findparam(char *name)
{
        return findstr(&paramnames, name);
}


/*
 * Return the name of a parameter variable.
 */
char *
paramname(long n)
{
        return namestr(&paramnames, n);
}


/*
 * Return the type of a variable name.
 * This is either local, parameter, global, static, or undefined.
 *
 * given:
 *      name            variable name to find
 */
int
symboltype(char *name)
{
        GLOBAL *sp;

        if (findparam(name) >= 0)
                return SYM_PARAM;
        if (findlocal(name) >= 0)
                return SYM_LOCAL;
        sp = findglobal(name);
        if (sp) {
                if (sp->g_filescope == SCOPE_GLOBAL)
                        return SYM_GLOBAL;
                return SYM_STATIC;
        }
        return SYM_UNDEFINED;
}

/* END CODE */