stable.c

/* Filename: stable.c
 * Compiler: msvc (Visual Studio 2015)
 * Store and provide functions for the symbol table database
 * CST8152, Assignment #3
 * Professor: S^R
 * Author: Victor Fernandes, 040772243
 * Version: 0.1
 * Date: 24 March 2017
 */
#include "stable.h"

#define PLSBD_SZ 128
#define PLSBD_INC 64

#define DEBUG
#undef DEBUG

 /* Forward function declarations */
static void st_setsize(void);
static void st_incoffset(void);
extern STD sym_table;

/* Create a symbol table
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: malloc, b_create, free
 * Parameters:
	int - size of the symbol table
 * Return value:
	STD - The symbol table
 * Algorithm:
 */
STD st_create(int st_size) {
	STD new_stable;

	new_stable.plsBD = NULL;
	new_stable.pstvr = (STVR*)malloc((size_t)st_size * sizeof(STVR));
	if (st_size <= 0 || (new_stable.pstvr == NULL)) {
		new_stable.st_size = 0;
	}
	new_stable.plsBD = b_create(PLSBD_SZ, PLSBD_INC, 'a');
	if (new_stable.plsBD == NULL) {
		free(new_stable.plsBD);
		new_stable.st_size = 0;
	}

	new_stable.st_size = st_size;
	new_stable.st_offset = 0;

	return new_stable;
}

/* Install a new entry in the symbol table
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: st_lookup, b_setmark, b_size, b_addc, b_rflag, st_incoffset
 * Parameters:
	STD  - The symbol table
	char - The lexeme to be stored
	char - the type of the lexeme
	int  - the line in the source file where the lexeme was found
 * Return value:
	int - the element offset of where the symbol table is pointing to
	-1 if an internal error occurs
 * Algorithm:
*/
int st_install(STD s_table, char *lexeme, char type, int line) {
	int offset = -1, i, j, lex_len, lex_offset = 0, flag = 0;

	/* Cannot add new entry, table full */
	if (s_table.st_offset >= s_table.st_size)
		return -1;

	/* Look for an existing entry in the symbol table */
	if (s_table.st_offset > 0)
		offset = st_lookup(s_table, lexeme);

	if (offset > -1)
		return offset;

	/* Add lexeme to the symbol table's lexeme buffer */
	lex_len = strlen(lexeme);
	for (i = 0; i <= lex_len; ++i) {
		if (!b_addc(s_table.plsBD, lexeme[i]))
			return -1;
		if (b_rflag(s_table.plsBD) == SET_R_FLAG) { /* Trigger reassignment loop once lexeme is stored */
			flag = 1;
		}
	}
	/* If reallocation happened...*/
	if (flag == 1) {
		for (j = 0; j < s_table.st_offset; ++j) {
			s_table.pstvr[j].plex = b_setmark(s_table.plsBD, (short) s_table.pstvr[j].i_value.str_offset);
		}
	}


	/* Set proper pointer values on symbol table */
	 /* Get buffer offset location of the lexeme stored */
	lex_offset = b_size(s_table.plsBD) - (strlen(lexeme) + 1);

	s_table.pstvr[s_table.st_offset].plex = b_setmark(s_table.plsBD, (short) lex_offset);
	s_table.pstvr[s_table.st_offset].o_line = line;
	s_table.pstvr[s_table.st_offset].i_value.str_offset = lex_offset;

	/* Set the default mask before setting the rest of the masks */
	s_table.pstvr[s_table.st_offset].status_field = DFT_MASK;

	switch (type) {
	case 'I': /* Integer type */
		s_table.pstvr[s_table.st_offset].status_field |= INT_MASK;
		s_table.pstvr[s_table.st_offset].i_value.int_val = 0;
		
		break;
	case 'F': /* Floating point type */
		s_table.pstvr[s_table.st_offset].status_field |= FLT_MASK;
		s_table.pstvr[s_table.st_offset].i_value.fpl_val = 0.0f;
		break;
	case 'S': /* String type */
		s_table.pstvr[s_table.st_offset].status_field |= STR_MASK;
		s_table.pstvr[s_table.st_offset].i_value.int_val = -1;
		s_table.pstvr[s_table.st_offset].i_value.fpl_val = -1.0f;
		break;
	default:
		return -1; /* Not supposed to fall into here */
	}

	/* Increment the symbol table offset */
	st_incoffset();
	return s_table.st_offset;

}

/* Look up the lexeme string in the symbol table's buffer
 * Author: Victor Fernandes
 * Version: 0.1
 * Called functions: b_setmark, strcmp, strlen
 * Parameters:
	STD - The symbol table
	char - The lexeme to be searched
 * Return value:
	int - the element offset index in the symbol table
	-1 if no element was found
*/
int st_lookup(STD s_table, char *lexeme) {
	int i; /* idx: index location for symbol table, i: increment counter*/
#ifdef DEBUG
	printf("Looking up %s...", lexeme);
#endif
	for (i = s_table.st_offset - 1; i >= 0; --i) {
		if (strcmp(lexeme, s_table.pstvr[i].plex) == 0) {
#ifdef DEBUG
			printf("YES\n");
#endif
			return i;
		}
	}
#ifdef DEBUG
	printf("NO\n");
#endif
	return -1; /* Found nothing */
}

/* Change the data type indicator of the variable entry located in vid_offset.
 * Author: Victor Fernandes
 * Version: 0.1
 * Called functions: N/A
 * Parameters:
	STD - The symbol table
	int - the offset location of the VID
	char - the new type of the VID
 * Return value:
	1 if change successful, -1 if no change was made or internal error
*/
int st_change_type(STD s_table, int vid_offset, char v_type) {

	/* Do nothing if update flag has already been set */
	if ((s_table.pstvr[vid_offset].status_field & U_MASK)) return -1;

	/* Reset to new type with default mask and update flag
	   Note: Can separate the statements to set the update flag at the
	   end, but this resets AND updates at once
	 */
	 /*sym_table.pstvr[vid_offset].status_field = sym_table.pstvr[vid_offset].status_field & DFT_U_MASK;*/
	s_table.pstvr[vid_offset].status_field &= DFT_U_MASK;

	switch (v_type) {
	case 'I': /* Integer type */
		s_table.pstvr[vid_offset].status_field |= INT_MASK;
		break;
	case 'F': /* Floating point type */
		s_table.pstvr[vid_offset].status_field |= FLT_MASK;
		break;
	case 'S': /* String type, do nothing as it cannot be changed */
		break;
	default:
		return -1; /* Not supposed to fall into here */
	}
	return 1;

}

/* Change the i_value of the variable located by vid_offset to new Value
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: N/A
 * Parameters:
	STD - The symbol table
	int - the offset location of the VID
	Value - the new value of the VID
 * Return value: the offset location of the VID
*/
int st_change_value(STD s_table, int vid_offset, Value value) {
	s_table.pstvr[vid_offset].i_value = value;
	return vid_offset;
}

/* Get the type of the variable specified by vid_offset
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: N/A
 * Parameters:
	STD - The symbol table
	int - the offset of the VID in the table
 * Return value:
	char - the type of the VID ('I','F', or 'S')
	-1 if there is an invalid value set
*/
char st_get_type(STD s_table, int vid_offset) {
	unsigned short mask;
	mask = s_table.pstvr[vid_offset].status_field & CHK_MASK;
	switch (mask) {
	case INT_MASK:
		return 'I';
	case FLT_MASK:
		return 'F';
	case STR_MASK:
		return 'S';
	default:
		return -1; /* Not supposed to fall into here */
	}
}

/* Return the i_value of the variable specified by vid_offset
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions:
 * Parameters:
	STD - The symbol table
	int - the offset of the VID in the table
 * Return value:
	Value - the value of the VID
	Incorrect parameters will cause undefined behaviour
*/
Value st_get_value(STD s_table, int vid_offset) {
	return s_table.pstvr[vid_offset].i_value;
}

/* Free memory used by the symbol table
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: free, b_free
 * Parameters:
	STD - The symbol table
*/
void st_destroy(STD s_table) {
	if (s_table.pstvr != NULL) {
		free(s_table.pstvr);
		s_table.pstvr = NULL;
	}
	b_free(s_table.plsBD);
}

/* Print the contents of the symbol table to standard output
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: printf
 * Parameters:
	STD - The symbol table
 * Return value:
	int - the number of items printed to stdout
*/
int st_print(STD s_table) {
	int i;

	if (s_table.st_size <= 0) return -1;

	printf("Symbol Table\n____________\nLine Number\tVariable Identifier\n");
	for (i = 0; i <= s_table.st_offset - 1 ; ++i)
		printf("%2d\t\t%s\n", s_table.pstvr[i].o_line, s_table.pstvr[i].plex);

	return i;
}

/* Store the symbol table to a file named $stable.ste.
 It overwrites any existing file named $stable.ste.
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: fopen, fprintf, st_get_type, fclose, printf
 * Parameters:
	STD - The symbol table
 * Return value:
	int - the number of items stored
	-1 if the file stream cannot be opened
*/
int st_store(STD s_table) {
	FILE *out; /* The target file*/
	int i;

	/* Windows does not like fopen, and fopen_s is Windows-only. This will ensure the
	 * use of the proper function call if PLATYPUS is being built on a non-windows system.
	 * Best approach is to add _CRT_SECURE_NO_WARNINGS to the preprocessor definitions, but
	 * this works, too.
	*/
#ifdef _WIN32
	if (fopen_s(&out, ST_FILE_NAME, "w+") != 0 || out == NULL)
#else
	if ((out = fopen(ST_FILE_NAME, "w+")) == NULL)
#endif
		return -1; /* Can't open file, stop. */

	fprintf(out, "%d", s_table.st_size);

	for (i = 0; i < s_table.st_offset; ++i) {
		fprintf(out, " %4X %d %s %d",
			s_table.pstvr[i].status_field,      /* Status flag */
			(int)strlen(s_table.pstvr[i].plex), /* Length of lexeme */
			s_table.pstvr[i].plex,              /* The lexeme itself */
			s_table.pstvr[i].o_line);           /* Line number */

		/* Initial value */
		char type = st_get_type(s_table, i);
		switch (type) {
		case 'I':
		case 'F':
		case 'S':
			fprintf(out, " %c", type);
		}
	}
	fclose(out);
	printf("Symbol Table stored\n");
	return i;
}


/* Internal function to set the table size to 0.
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: N/A
 * Parameters: N/A
 * Return value: N/A
*/
static void st_setsize(void) {
	sym_table.st_size = 0;
}

/* Internal function to increment st_offset by 1.
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions: N/A
 * Parameters: N/A
 * Return value: N/A
*/
static void st_incoffset(void) {
	++sym_table.st_offset;
}


/* Sorts the table by variable name in ascending/descending order
 * Author: Victor Fernandes, 040772243
 * Version: 0.0.1
 * Called functions:
 * Parameters:
 * Return value:
 * Algorithm:
*/
int st_sort(STD s_table, char s_order) {
	/* Compiler warning about unused parameters,
	 * this is fine for this dummy method
	*/
	return 0; /* SYKE! */
}