fix comparison operator priority

[calc.git] / parser.c

#include <malloc.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#include "debug.h"

#include "parser.h"

/* global variables */

double answer = 0;

#define STORAGE_SIZE 10
double storage[STORAGE_SIZE] = {0};

/* compare codes */

int codecmp (char *ref, char *str)
{
    int sig;

    while (*ref != '\0') {
        if (*ref == '\t') {
             sig = (*str == '.') ? -1 : ((*str >= '0') && (*str <= '9'));
        } else {
            sig = *str - *ref;
        }
        if (sig != 0) {
            return (sig > 0) ? 1 : -1;
        }
        str++;
        ref++;
    }

    return 0;
}

/* allocate new element */

element_t *newelement (func_t function, int nbops, int prio)
{
    element_t *new = (element_t *) calloc (1, sizeof (element_t));
    if (new == NULL) {
        VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
        return NULL;
    }
    new->func = function;
    new->nbops = nbops;
    new->prio = prio;

    return new;
}

/* desallocate element */

void delelement (element_t *root)
{
    int i;
    if ((root != NULL) && (root != ERROR_OP)) {
        for (i = 0; i < root->nbops; i++) {
            if ((root->ops[i] != NULL) && (root->ops[i] != ERROR_OP)) {
                delelement (root->ops[i]);
            }
        }
        free (root);
    }
}

/* functions */

#define NB_OPERATORS 12

keyword_t operators[NB_OPERATORS] = {
    { "+\t", Add, 2, 1, 1},
    { "-\t", Sub, 2, 1, 1},
    { "*",   Mul, 2, 1, 2},
    { "/",   Div, 2, 1, 2},
    { "%",   Mod, 2, 1, 3},
    { "^",   Pow, 2, 1, 4},
    { "==",  Equal, 2, 2, 0},
    { "!=",  Diff, 2, 2, 0},
    { ">=",  Ge, 2, 2, 0},
    { "<=",  Le, 2, 2, 0},
    { ">",   Gt, 2, 1, 0},
    { "<",   Lt, 2, 1, 0}
};

#define NB_FUNCTIONS 12
keyword_t functions[NB_FUNCTIONS] = {
    { "sqrt", Sqr, 1, 4, 5},
    { "pow",  Pow, 2, 3, 5},
    { "cos",  Cos, 1, 3, 5},
    { "sin",  Sin, 1, 3, 5},
    { "atan", Atan, 1, 4, 5},
    { "exp",  Exp, 1, 3, 5},
    { "log",  Log, 1, 3, 5},
    { "sto",  Store, 2, 3, 5},
    { "rcl",  Recall, 1, 3, 5},
    { "disp", Disp, 0, 4, 5},
    { "quit", Quit, 0, 4, 5},
    { "help", Help, 0, 4, 5}
};

#define NB_CONSTANTS 3
keyword_t constants[NB_CONSTANTS] = {
    { "ans", Ans, 0, 3, 5},
    { "e",   E, 0, 1, 5},
    { "pi",  Pi, 0, 2, 5}
};

/* subparser function */

element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
{
    element_t *new = newelement (func, nbops, prio);
    if (new == NULL) {
        return ERROR_OP;
    }
    new->ops[0] = *proot;
    new->ops[1] = parser (*pstr, pstr, new->prio);
    if (new->ops[1] == ERROR_OP) {
        delelement (new);
        *proot = NULL;
        return ERROR_OP;
    }
    *proot = newelement (Val, 1, 5);
    if (*proot == NULL) {
        delelement (new);
        return ERROR_OP;
    }
    (*proot)->ops[0] = new;

    return *proot;
}

/* parser function */

element_t *parser (char *str, char **next, int prio)
{
    element_t *root = NULL;
    int i;

    VERBOSE (DEBUG, fprintf (stdout, "Starting parsing\n"));

    /* main loop */
    while (*str != '\0') {
        int found = 0;
        element_t *new = NULL;
        VERBOSE (INFO, fprintf (stdout, "Processing: %s\n", str));

        /* skip spaces and tabs */

        if ((*str == ' ') || (*str == '\t')) {
            str++;
            continue;
        }

        /* check for open bracket */

        if (*str == '(') {
            VERBOSE (DEBUG, fprintf (stdout, "start processing bracket\n"));
            if (root) {
                do {
                    found = 0;
                    new = parser (str + 1, &str, 0);
                    if (new == ERROR_OP) {
                        delelement (root);
                        return ERROR_OP;
                    }
                    for (i = 0; i < root->nbops; i++) {
                        if (root->ops[i] == NULL) {
                            root->ops[i] = new;
                            found = 1;
                            break;
                        }
                    }
                    if (!found) {
                        delelement (new);
                        delelement (root);
                        return ERROR_OP;
                    }
                } while (*str == ',');
            } else {
                root = newelement (Val, 1, 5);
                if (root == NULL) {
                    return ERROR_OP;
                }
                new = parser (str + 1, &str, 0);
                if ((new == ERROR_OP) || (*str == ',')) {
                    delelement (new);
                    delelement (root);
                    return ERROR_OP;
                }
                root->ops[0] = new;
            }
            str++;
            VERBOSE (DEBUG, fprintf (stdout, "stop processing bracket\n"));
            continue;
        }

        /* check for closing bracket or koma */

        if ((*str == ')') || (*str == ',')) {
            if (next != NULL) {
                *next = str;
            }
            return root;
        }

        /* look for operators */

        for (i = 0; i < NB_OPERATORS; i++) {
            keyword_t *operator = operators + i;
            if (codecmp (operator->keyword, str) == 0) {
                VERBOSE (DEBUG, fprintf (stdout, "start processing operator\n"));
                if (root) {
                    if ((prio) && (prio > operator->prio)) {
                        VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
                        *next = str;
                        return root;
                    }
                    str += operator->offset;
                    VERBOSE (INFO, fprintf (stdout, "Oper: %d\n", operator->func));
                    if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
                        delelement (root);
                        return ERROR_OP;
                    }
                } else if (*str == '-') {
                    new = newelement (Sig, 1, 9);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    root = new;
                } else {
                    return ERROR_OP;
                }
                found = 1;
                VERBOSE (DEBUG, fprintf (stdout, "stop processing operator\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for functions */

        for (i = 0; i < NB_FUNCTIONS; i++) {
            keyword_t *function = functions + i;
            if (codecmp (function->keyword, str) == 0) {
                VERBOSE (DEBUG, fprintf (stdout, "start processing function\n"));
                if (root == NULL) {
                    VERBOSE (INFO, fprintf (stdout, "Func: %d\n", function->func));
                    new = newelement (function->func, function->nbops, function->prio);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    root = new;
                } else {
                    delelement (root);
                    return ERROR_OP;
                }
                str += function->offset;
                found = 1;
                VERBOSE (DEBUG, fprintf (stdout, "stop processing function\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for constant */

        for (i = 0; i < NB_CONSTANTS; i++) {
            keyword_t *constant = constants + i;
            if (codecmp (constant->keyword, str) == 0) {
                VERBOSE (DEBUG, fprintf (stdout, "start processing constant\n"));
                if (root == NULL) {
                    VERBOSE (INFO, fprintf (stdout, "Const: %d\n", constant->func));
                    new = newelement (constant->func, constant->nbops, constant->prio);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    root = new;
                } else {
                    delelement (root);
                    return ERROR_OP;
                }
                str += constant->offset;
                found = 1;
                VERBOSE (DEBUG, fprintf (stdout, "stop processing constant\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for number */

        if (((*str >= '0') && (*str <= '9')) ||
            (*str == '.') || (*str == '+') || (*str == '-')) {
            VERBOSE (DEBUG, fprintf (stdout, "start processing value\n"));
            char *pt;
            double value = strtod (str, &pt);
            VERBOSE (INFO, fprintf (stdout, "Value: %f\n", value));
            if (str != pt) {
                if (root == NULL) {
                    new = newelement (Val, 1, 5);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    new->value = value;
                    root = new;
                    str = pt;
                } else if ((*str == '+') || (*str == '-')) {
                    if ((prio) && (prio > 1)) {
                        VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
                        *next = str;
                        return root;
                    }
                    if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
                        delelement (root);
                        return ERROR_OP;
                    }
                } else {
                    delelement (root);
                    return ERROR_OP;
                }
                found = 1;
            }
            VERBOSE (DEBUG, fprintf (stdout, "stop processing value\n"));
        }

        /* error */

        if (!found) {
            delelement (root);
            return ERROR_OP;
        }

    }

    if (next != NULL) {
        *next = str;
    }

    return root;
}

/* print element tree */

void print_element (element_t *root, int level)
{
    char *func = NULL;
    int i;

    if ((root == NULL) || (root == ERROR_OP)) {
        return;
    }

    for (i = 0; i < level; i++) {
        fprintf (stdout, " ");
    }

    switch (root->func) {
    case Val: func = "Value"; break;
    case Sig: func = "Sign"; break;
    case Add: func = "Addition"; break;
    case Sub: func = "Subtraction"; break;
    case Mul: func = "Multiplication"; break;
    case Div: func = "Division"; break;
    case Mod: func = "Modulo"; break;
    case Pow: func = "Power"; break;
    case Sqr: func = "Square Root"; break;
    case Cos: func = "Cosine"; break;
    case Sin: func = "Sine"; break;
    case Atan: func = "Arc Tangent"; break;
    case Log: func = "Logarithm"; break;
    case Exp: func = "Exponantial"; break;
    case Store: func = "Store"; break;
    case Recall: func = "Recall"; break;
    case Disp: func = "Display"; break;
    case Quit: func = "Quit"; break;
    case Help: func = "Help"; break;
    case Ans: func = "Ans"; break;
    case Pi: func = "Pi"; break;
    case E: func = "E"; break;
    case Equal: func = "Equal"; break;
    case Diff: func = "Different"; break;
    case Ge: func = "Greater or equal"; break;
    case Le: func = "Lesser or equal"; break;
    case Gt: func = "Greater"; break;
    case Lt: func = "Lesser"; break;
    }

    fprintf (stdout, "Function: %s\n", func);

    if ((root->func == Val) && (root->ops[0] == NULL)) {
        for (i = 0; i < level; i++) {
            fprintf (stdout, " ");
        }
        fprintf (stdout, "value: %f\n", root->value);
    } else {
        for (i = 0; i < root->nbops; i++) {
            print_element (root->ops[i], level + 1);
        }
    }
}

/* storage functions */

double store (int index, double value)
{
    if ((index > 0) && (index <= STORAGE_SIZE)) {
        storage[index - 1] = value;
    } else {
        VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [1, %d]\n", index, STORAGE_SIZE));
    }
    return value;
}

double recall (int index)
{
    if ((index > 0) && (index <= STORAGE_SIZE)) {
        return storage[index - 1];
    } else {
        VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [1, %d]\n", index, STORAGE_SIZE));
    }
    return 0;
}

void display (void)
{
    int i;
    fprintf (stdout, "storage:");
    for (i = 0; i < STORAGE_SIZE; i++) {
        fprintf (stdout, " %g", storage[i]);
    }
    fprintf (stdout, "\n");
}

/* quit function */

void quit (void)
{
    fprintf (stdout, "bye\n");
    exit (0);
}

/* help message */

void help (void)
{
    fprintf (stdout, "calc is a simple calculator\n\n");
    fprintf (stdout, "supported operators:\n");
    fprintf (stdout, " + - * / %% ^\n\n");
    fprintf (stdout, "camparison operators:\n");
    fprintf (stdout, " == != >= <= > <\n\n");
    fprintf (stdout, "supported functions:\n");
    fprintf (stdout, " pow sqrt cos sin atan log exp\n\n");
    fprintf (stdout, "storage functions:\n");
    fprintf (stdout, " sto rcl\n\n");
    fprintf (stdout, "miscellaneous functions:\n");
    fprintf (stdout, " quit help\n\n");
    fprintf (stdout, "supported constants:\n");
    fprintf (stdout, " e pi\n");
}

/* evaluate element tree */

#define MASK_SUB 0x1
#define MASK_DIV 0x2

double evaluate_element (element_t *root, char mask)
{
    double op0 = 0, op1 = 0;
    char nextmask = mask;

    if ((root == NULL) || (root == ERROR_OP)) {
        VERBOSE (WARNING, fprintf (stdout, "error while evaluating\n"));
        return 0;
    }

    /* mask to manage sub operator sub and div */
    switch (root->func) {
    case Add:
        nextmask &= ~MASK_SUB;
        nextmask &= ~MASK_DIV;
        break;
    case Sub:
        nextmask |= MASK_SUB;
        nextmask &= ~MASK_DIV;
        break;
    case Mul:
        nextmask &= ~MASK_DIV;
        break;
    case Div:
        nextmask |= MASK_DIV;
        break;
    default:
        nextmask = mask;
    }

    switch (root->func) {
    case Val:
    case Sig:
        op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
        break;
    case Add:
    case Sub:
    case Mul:
    case Div:
    case Mod:
    case Pow:
    case Store:
    case Equal:
    case Diff:
    case Ge:
    case Le:
    case Gt:
    case Lt:
        if (root->ops[1]) {
            op1 = evaluate_element (root->ops[1], nextmask);
        } else if (root->func != Store) {
            VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[1])\n"));
            return 0;
        }
        /* fallthrough */
    case Sqr:
    case Cos:
    case Sin:
    case Atan:
    case Log:
    case Exp:
    case Recall:
        if (root->ops[0]) {
            op0 = evaluate_element (root->ops[0], 0);
        } else {
            VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
            return 0;
        }
        break;
    case Disp:
    case Quit:
    case Help:
    case Ans:
    case Pi:
    case E:
        break;
    }

    switch (root->func) {
    case Val: return op0;
    case Sig: return -op0;
    case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
    case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
    case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
    case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
    case Mod: return fmod (op0, op1);
    case Pow: return pow (op0, op1);
    case Sqr: return sqrt (op0);
    case Cos: return cos (op0);
    case Sin: return sin (op0);
    case Atan: return atan (op0);
    case Log: return log (op0);
    case Exp: return exp (op0);
    case Store: return store ((int)op0, (op1) ? op1 : answer);
    case Recall: return recall ((int)op0);
    case Disp: display (); break;
    case Quit: quit (); break;
    case Help: help (); break;
    case Ans: return answer;
    case Pi: return M_PI;
    case E: return M_E;
    case Equal: return op0 == op1;
    case Diff: return op0 != op1;
    case Ge: return op0 >= op1;
    case Le: return op0 <= op1;
    case Gt: return op0 > op1;
    case Lt: return op0 < op1;
    }

    return 0;
}

/* vim: set ts=4 sw=4 et: */