parser 2

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h> /* isspace() */

/* initial defines - pre-set limits. Subject to future changes.*/
#define MAX_KEY_STRING_LEN 51 /* a 'key' can only be 50 chars long, not
                               * including '[]'. This was chosen arbitrarily
                               * to simplify programming and waste fewer CPU
                               * cycles. '51' includes the null termination
                               * byte.*/

#define DEBUG 1


/* global vars */
FILE *fp;    /* file pointer should be accessible anywhere in the parser */

int  pos = -1; /* position in file */

char chr;    /* value of current char in file, as grabbed by fgetc(). */

char key[MAX_KEY_STRING_LEN]; /* char array containing key name being operated
                               * on*/

char *value; /* pointer to a string containing the value of a key in string
              * form */

/*
 * current offset (position) in file. becomes zero the first time nextChar()
 * is called, and is added to on each subsequent call. This is here in case I
 * need to use fseek() at some point.
 */

/* end of global vars */

int nextChar() /* set chr to char and return 0 unless EOF reached, skip white
                 * space */
{
  chr = fgetc(fp);
  pos = pos + 1;

  /* keep going until we find non-whitespace. characters. */
  while ( isspace(chr) != 0 ) { /* isspace() returns non-zero for whitespace. */
    chr = fgetc(fp);
    pos = pos + 1;
  }

  if ( chr == EOF ) {
    return (4); /* End-Of-Transmission character */
  }

  return (0);
}


int nextCharInclSpace() {/* basically a wrapper to fgetc(), but it also
                         * increments where we are in the file. */

                        /* also it does not return a char, but rather sets
                         * 'chr'. Sorry if you hate it, it made more sense to
                         * me because I'm an insane assembly programmer at
                         * heart. Feel free to fix it, or I might later if
                         * the urge strikes me.
                         */

  chr = fgetc(fp);
  pos = pos + 1;

  if ( chr == EOF ) {
    return (4); /* End-Of-Transmission character */
  }

  return (0);
}



int openFile(char *filename) {
  /* open file (first arg) in read-only mode */
  fp=fopen(filename,"r");

  /* make sure file was readable */
  if(fp == NULL) {
    printf("Error reading file. Check permissions!\n");
    return (-1);
  }
  return (0);
}


int getValString() {
  int i = 0;
  long int oldpos=ftell(fp); /* starting point to return to once we've
                                * checked how long our string is.*/
  int len;
  /* first, find out how long the string is */

  /* skip opening quote mark */
  nextCharInclSpace();
  i = 1;

  while( (chr != '"') && (chr != EOF) ) {
    nextCharInclSpace();
    i = i + 1;
  }
  if(chr == '"') {
    len = i; /* not `i - 1` since the end quote will become a null terminator. */
    printf("length %d\n",len);
  }

  /* now, set a value length to match */
  char val[len];

  /* seek back to where we were before doing this and this time read the value
   * into the buffer we've allocated */

  fseek(fp,oldpos,SEEK_SET);
  /* could also probably make it SEEK_CUR and move negative `i` places. */

  /* skip opening quote mark, again */
  nextCharInclSpace();


  pos = pos - i + 1;
  /* TODO - might need to move one further back sine 'i' starts at 0? */
  /* if there are bugs, this is one of the likely spots. */

  i=0;
  while (i<len) {
    val[i]=chr;
    nextCharInclSpace();
    i = i + 1;
  }

  val[len - 1] = '\0';

  #ifdef DEBUG
    printf("value name is %s\n",val);
  #endif



  /* now catch things that go wrong */

  if ( chr == EOF ) {
    printf("Malformed save data! Reached end-of-file while looking for ']'\n");
    exit(EXIT_FAILURE);
  }

  if ( i == (MAX_KEY_STRING_LEN) ) {
    key[MAX_KEY_STRING_LEN - 1] = '\0'; /* force null termination */

    printf("Malformed save data!\n"
            "key name starting with '%s'\n"
            "is too long!\n"
            "(maximum length: %d characters)\n",key,MAX_KEY_STRING_LEN);
    exit(EXIT_FAILURE);
  }

  if (chr == ']') {
    key[i] = '\0'; /* replace ']' with null terminator. */
    return (0);
  }

  /* Error if we reached this point. Should be unreachable. */
  return (-1);

} /* int getValString() */




int getKeyName() {
  int i = 0;

  /*
   * called to get a key name, when the next byte to be read from the file is
   * immediately proceeding a '['.
   */
  while ( (chr != ']') && (chr != EOF) && ( i < ( MAX_KEY_STRING_LEN ) ) ) {
    /* start grabbing chars */
    nextChar(fp);
/*    pos = pos + 1; */ /* nextChar() handles incrementing. Only needed if
                         * using fgetc() directly. */


    key[i] = chr;
    i = i + 1;
  }

  if (chr == ']') {
    key[i - 1] = '\0'; /* replace ']' with null terminator. */
    return (0);
  }

  /* now catch things that go wrong */

  if ( chr == EOF ) {
    printf("Malformed save data! Reached end-of-file while looking for ']'\n");
    exit(EXIT_FAILURE);
  }

  if ( i == (MAX_KEY_STRING_LEN) ) {
    key[MAX_KEY_STRING_LEN - 1] = '\0'; /* force null termination */

    printf("Malformed save data!\n"
            "key name starting with '%s'\n"
            "is too long!\n"
            "(maximum length: %d characters)\n",key,MAX_KEY_STRING_LEN);
    exit(EXIT_FAILURE);
  }

  /* Error if we reached this point. Should be unreachable. */
  return (-1);

} /* int getKeyName() */


int parse(){
  /* first, check if item is an array. This is determined by if a curly brace
   * appears in text prior to a semicolon (if a semicolon is first, it is not
   * an array; just a value).
   */

  while ( (nextChar() == 0) ) { /* as long as we are able to read data */

/* first we need a 'key,' which is enclosed in square brackets ([]), then we
 * need a 'value,' which is enclosed in double quote marks ("").
 */

    if (chr == '[') { /* get a new key name. */
      getKeyName(); /* this function sets 'key' to a string containing the key
                     * value */

      #ifdef DEBUG
        printf("key name is %s\n",key);
      #endif

    /* done getting key name */
    } /* if(chr == '[') */


    if (chr == '=') { /* set key to value(s) within the next quote or '{' */
      /* first, seek for the special chars ( '{' and '"' ). */
      while( ( chr != '{' ) && ( chr != '"' ) && ( chr != EOF )) {
        nextChar();
      }


      /* now, we've found the value presumably.
       * the next byte we read will be the 1st char after the quote or '{'.
       * if it's a quote, we know the next value is part of the stored data
       * string. Otherwise, we have to do the same thing we just did to find
       * another key-value pair, separate from the first one.
       */


      if ( chr == '"' ) {

      /* once we have found quote marks, start getting the value within.
       * IT IS IMPORTANT TO NOT USE NEXTCHAR() FOR THIS PART, AS WITHIN THE
       * QUOTE MARKS, SPACES ARE IMPORTANT. */
        getValString();


      } /* if ( chr == '"' ) */

    } /* if (chr == '=') */


  } /*  while ( (nextChar() == 0) ) */


/* TODO */
/* if nothing else is true, print a warning message,
 * and try again. If EOF is reached, error. */

return 0;
} /* int parse() */





int main(int argc, char *argv[]) {

  /* make sure file name was given */
  if(argc <=1) { /* no arguments passed */
    printf("Error: No file argument was given.\n");
    exit(EXIT_FAILURE);
  }

  /* open file, exit if it goes wrong */
  if(openFile(argv[1]) != 0) {
    /* something went wrong opening the file; check in openFile() function */
    exit(EXIT_FAILURE);
  }

  else {
    /* we're golden. start parsing HERE. */
    return parse();

  }
}




/* internal memory structure:
 * the first item in any object struct is a string identifying it.
 *
 * the player can hold up to ten items, so the inventory array contains
 * ten item structs, and each item struct contains an item name and an item
 * quantity (a char array and an int).
 */

/* this code just checks for hardcoded keys to start work on.
 * arrays/objects cannot be embedded in other arrays/objects to
 * simplify things for me. so for player->inventory, we do a separate
 * key called 'player.inventory'.*/