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platypus/scanner.c

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/* Filename: scanner.c
PURPOSE:
* SCANNER.C: Functions implementing a Lexical Analyzer (Scanner)
* as required for CST8152, Assignment #2
* scanner_init() must be called before using the scanner.
* The file is incomplete;
* Author: Victor Fernandes, 040772243
* Provided by: Svillen Ranev
* Version: 1.17.1
* Date: 30 January 2017
*/
/* The #define _CRT_SECURE_NO_WARNINGS should be used in MS Visual Studio projects
* to suppress the warnings about using "unsafe" functions like fopen()
* and standard sting library functions defined in string.h.
* The define does not have any effect in Borland compiler projects.
*/
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h> /* standard input / output */
#include <ctype.h> /* conversion functions */
#include <stdlib.h> /* standard library functions and constants */
#include <string.h> /* string functions */
#include <limits.h> /* integer types constants */
#include <float.h> /* floating-point types constants */
/*#define NDEBUG to suppress assert() call */
#include <assert.h> /* assert() prototype */
/* project header files */
#include "buffer.h"
#include "token.h"
#include "table.h"
#define DEBUG /* for conditional processing */
#undef DEBUG
/* Global objects - variables */
/* This buffer is used as a repository for string literals.
It is defined in platy_st.c */
extern Buffer * str_LTBL; /*String literal table */
int line; /* current line number of the source code */
extern int scerrnum; /* defined in platy_st.c - run-time error number */
/* Local(file) global objects - variables */
static Buffer *lex_buf;/*pointer to temporary lexeme buffer*/
/* No other global variable declarations/definitiond are allowed */
/* scanner.c static(local) function prototypes */
static int char_class(char c); /* character class function */
static int get_next_state(int, char, int *); /* state machine function */
static int iskeyword(char * kw_lexeme); /*keywords lookup functuion */
static long atool(char * lexeme); /* converts octal string to decimal value */
int scanner_init(Buffer * sc_buf) {
if (b_isempty(sc_buf)) return EXIT_FAILURE;/*1*/
/* in case the buffer has been read previously */
b_setmark(sc_buf, 0);
b_retract_to_mark(sc_buf);
b_reset(str_LTBL);
line = 1;
return EXIT_SUCCESS;/*0*/
/* scerrnum = 0; *//*no need - global ANSI C */
}
Token malar_next_token(Buffer * sc_buf)
{
Token t; /* token to return after recognition */
unsigned char c; /* input symbol */
int state = 0; /* initial state of the FSM */
short lexstart; /*start offset of a lexeme in the input buffer */
short lexend; /*end offset of a lexeme in the input buffer */
int accept = NOAS; /* type of state - initially not accepting */
/*
lexstart is the offset from the beginning of the char buffer of the
input buffer (sc_buf) to the first character of the current lexeme,
which is being processed by the scanner.
lexend is the offset from the beginning of the char buffer of the
input buffer (sc_buf) to the last character of the current lexeme,
which is being processed by the scanner.
*/
/*DECLARE YOUR VARIABLES HERE IF NEEDED */
/* Counter for loops in string error case */
int i;
/*String offset for the str_LTBL*/
static short str_offset = 0;
if (sc_buf == NULL) {
scerrnum = 1;
return aa_table[ES]("RUN TIME ERROR: "); /* WHOOPS */
}
while (1) { /* endless loop broken by token returns it will generate a warning */
/* GET THE NEXT SYMBOL FROM THE INPUT BUFFER */
c = b_getc(sc_buf);
switch (c) {
case 255: t.code = SEOF_T; return t; /* EOF */
case '\0': t.code = SEOF_T; return t; /* Source EOF */
case '\n': line++; continue; /* Ignore new line, increment line count */
case '\r': line++; continue; /* CR, increment line count*/
case ' ': continue; /* Ignore white space */
case '\t': continue; /* Ignore tabs */
case ';': t.code = EOS_T; return t; /* End of statement */
case ',': t.code = COM_T; return t; /* Comma */
case '{': t.code = LBR_T; return t; /* Left brace */
case '}': t.code = RBR_T; return t; /* Right brace */
case '(': t.code = LPR_T; return t; /* Left parenthesis */
case ')': t.code = RPR_T; return t; /* Right parenthesis */
case '+': t.code = ART_OP_T; t.attribute.arr_op = PLUS; return t; /* Addition operator */
case '-': t.code = ART_OP_T; t.attribute.arr_op = MINUS; return t; /* Substraction operator */
case '*': t.code = ART_OP_T; t.attribute.arr_op = MULT; return t; /* Multiplication operator */
case '/': t.code = ART_OP_T; t.attribute.arr_op = DIV; return t; /* Devision operator */
case '>': t.code = REL_OP_T; t.attribute.rel_op = GT; return t; /* Greater-than relational operator */
case '<':
c = b_getc(sc_buf);
if (c == '>') {
t.code = REL_OP_T;
t.attribute.rel_op = NE; /* Negation operator */
return t;
}
else if (c == '<') {
t.code = SCC_OP_T; /* String concatenation operator */
}
else {
t.code = REL_OP_T;
t.attribute.rel_op = LT; /* Less-than operator */
}
return t;
case '.':
b_setmark(sc_buf, b_getcoffset(sc_buf)); /* Set mark before continuing (AND|OR case) */
c = b_getc(sc_buf);
if (c == 'A' && b_getc(sc_buf) == 'N' && b_getc(sc_buf) == 'D' && b_getc(sc_buf) == '.') {
t.code = LOG_OP_T;
t.attribute.log_op = AND;
return t;
}
else if (c == 'O' && b_getc(sc_buf) == 'R' && b_getc(sc_buf) == '.') {
t.code = LOG_OP_T;
t.attribute.log_op = OR;
return t;
}
t.code = ERR_T; /* "That character's not supposed to be here" case */
t.attribute.err_lex[0] = '.';
t.attribute.err_lex[1] = '\0';
b_retract_to_mark(sc_buf);
return t;
case '!':
c = b_getc(sc_buf);
if (c == '<') { /* It's a comment line */
/* Consume chars until line ends */
for (; c != '\0' && c != '\r' && c != '\n' && c != 255; c = b_getc(sc_buf));
line++;
continue;
}
else { /* Bad character, pump out an error token */
t.code = ERR_T;
b_retract(sc_buf);
b_retract(sc_buf);
t.attribute.err_lex[0] = c = b_getc(sc_buf);
t.attribute.err_lex[1] = c = b_getc(sc_buf);
t.attribute.err_lex[2] = '\0';
/* Consume the rest of the caracters to ignore the line*/
for (; c != '\0' && c != '\r' && c != '\n' && c != 255; c = b_getc(sc_buf));
return t;
}
case '=':
c = b_getc(sc_buf);
if (c == '=') { /* Relational equals-to operator */
t.code = REL_OP_T;
t.attribute.rel_op = EQ;
return t;
}
b_retract(sc_buf);
t.code = ASS_OP_T; /* Assignment operator */
return t;
case '\"': /* Don't quote me on this */
/* Track the beginning of string */
b_setmark(sc_buf, b_getcoffset(sc_buf));
lexstart = b_mark(sc_buf);
lexend = lexstart;
c = b_getc(sc_buf);
/* Step through the string literal and track progress *//*
c = b_getc(sc_buf);*/
for (; c != '\"' || c!= 255; c = b_getc(sc_buf), ++lexend) {
if (c == '\n' || c == '\r')
++line;
else if (c == '\0') { /* Illegal string, make it an error token */
b_retract_to_mark(sc_buf);
b_retract(sc_buf);
t.code = ERR_T;
for (i = 0; i < ERR_LEN; ++i)
t.attribute.err_lex[i] = b_getc(sc_buf);
/* If the erroneous string is too long,
* replace last three characterss with '...'' */
if ((lexend - lexstart) > ERR_LEN) {
t.attribute.err_lex[i - 1] = '.';
t.attribute.err_lex[i - 2] = '.';
t.attribute.err_lex[i - 3] = '.';
}
t.attribute.err_lex[i] = '\0';
scerrnum = 1;
return t;
}
} /* end for loop, string finished and considered valid */
lexend = b_getcoffset(sc_buf);
b_retract_to_mark(sc_buf);
/* Copy the matched string literal to str_LTBL */
for (; lexstart < lexend; ++lexstart, ++str_offset) {
b_addc(str_LTBL, b_getc(sc_buf));
}
b_addc(str_LTBL, '\0');
t.code = STR_T;
t.attribute.str_offset = str_offset;
return t;
default:
if (isalpha(c) || isalnum(c)) {
/*Set mark to beginning of lexeme*/
b_retract(sc_buf);
b_setmark(sc_buf, b_getcoffset(sc_buf));
lexstart = b_mark(sc_buf);
lexend = lexstart;
state = 0;
while (accept == NOAS) {
state = get_next_state(state, b_getc(sc_buf), &accept);
if (accept != NOAS) { break; }
/*c = b_getc(sc_buf);*/
}
/*
* Entering Accepting State
*/
if (as_table[state] == ASWR) { b_retract(sc_buf); }
/* Get end of lexeme */
lexend = b_getcoffset(sc_buf);
b_retract_to_mark(sc_buf);
lex_buf = b_create(1, 1, 'a');
/* Copy the scanned lexeme into lexical buffer */
for (; lexstart < lexend; ++lexstart) {
b_addc(lex_buf, b_getc(sc_buf));
}
b_addc(lex_buf, '\0');
if (aa_table[state] != NULL) {
t = aa_table[state](b_setmark(lex_buf, 0));
}
else {
scerrnum = 1;
t = aa_table[ES]("RUN TIME ERROR: ");
return t;
}
b_free(lex_buf);
}
/* Invalid character */
else {
t.code = ERR_T;
t.attribute.err_lex[0] = c;
t.attribute.err_lex[1] = '\0';
}
return t;
}
}//end while(1)
}
/* DO NOT MODIFY THE CODE OF THIS FUNCTION
YOU CAN REMOVE THE COMMENTS */
int get_next_state(int state, char c, int *accept)
{
int col;
int next;
col = char_class(c);
next = st_table[state][col];
#ifdef DEBUG
printf("Input symbol: %c Row: %d Column: %d Next: %d \n", c, state, col, next);
#endif
/*
The assert(int test) macro can be used to add run-time diagnostic to programs
and to "defend" from producing unexpected results.
assert() is a macro that expands to an if statement;
if test evaluates to false (zero) , assert aborts the program
(by calling abort()) and sends the following message on stderr:
Assertion failed: test, file filename, line linenum
The filename and linenum listed in the message are the source file name
and line number where the assert macro appears.
If you place the #define NDEBUG directive ("no debugging")
in the source code before the #include <assert.h> directive,
the effect is to comment out the assert statement.
*/
assert(next != IS);
/*
The other way to include diagnostics in a program is to use
conditional preprocessing as shown bellow. It allows the programmer
to send more details describing the run-time problem.
Once the program is tested thoroughly #define DEBUG is commented out
or #undef DEBUF is used - see the top of the file.
*/
#ifdef DEBUG
if (next == IS) {
printf("Scanner Error: Illegal state:\n");
printf("Input symbol: %c Row: %d Column: %d\n", c, state, col);
exit(1);
}
#endif
*accept = as_table[next];
return next;
}
int char_class(char c)
{
int val;
if (isalpha(c))
val = 0;
else if (c == '0')
val = 1;
else if (c > '0' && c < '8')
val = 2;
else if (c == '8' || c == '9')
val = 3;
else if (c == '.')
val = 4;
else if (c == '#')
val = 5;
else
val = 6;
return val;
}
/*
HERE YOU WRITE THE DEFINITIONS FOR YOUR ACCEPTING FUNCTIONS.
************************************************************
ACCEPTING FUNCTION FOR THE arithmentic variable identifier AND keywords (VID - AVID/KW)
REPLACE XX WITH THE CORRESPONDING ACCEPTING STATE NUMBER
*/
Token aa_func02(char lexeme[]) {
unsigned int i, kw_idx; /* Variable to contain keyword table index */
Token t;
char* temp_str;
#ifdef DEBUG
printf("Lexeme: '%s'\n", lexeme);
#endif
kw_idx = iskeyword(lexeme);
if (kw_idx != -1) { /* Keyword check */
t.code = KW_T;
t.attribute.kwt_idx = kw_idx;
return t;
}
/* Not a keyword? Must be AVID*/
t.code = AVID_T;
if ((temp_str = (char*)calloc(VID_LEN + 1, sizeof(char))) == NULL) {
return aa_table[ES]("RUN TIME ERROR: ");
}
for (i = 0; i < (VID_LEN) && i < strlen(lexeme); i++) {
temp_str[i] = lexeme[i];
}
strncpy(t.attribute.vid_lex, temp_str, VID_LEN);
t.attribute.vid_lex[strlen(temp_str)] = '\0';
free(temp_str);
switch (lexeme[0]) { /* Read first character of lexeme for implicit type (not used yet?)*/
case 'i':
case 'o':
case 'd':
case 'n':
/* Integer */
break;
default:
/* Floating point*/
break;
}
return t;
/*
WHEN CALLED THE FUNCTION MUST
1. CHECK IF THE LEXEME IS A KEYWORD.
IF YES, IT MUST RETURN A TOKEN WITH THE CORRESPONDING ATTRIBUTE
FOR THE KEYWORD. THE ATTRIBUTE CODE FOR THE KEYWORD
IS ITS INDEX IN THE KEYWORD LOOKUP TABLE (kw_table in table.h).
IF THE LEXEME IS NOT A KEYWORD, GO TO STEP 2.
2. SET a AVID TOKEN.
IF THE lexeme IS LONGER than VID_LEN (see token.h) CHARACTERS,
ONLY FIRST VID_LEN CHARACTERS ARE STORED
INTO THE VARIABLE ATTRIBUTE ARRAY vid_lex[](see token.h) .
ADD \0 AT THE END TO MAKE A C-type STRING.
*/
}
/*
ACCEPTING FUNCTION FOR THE string variable identifier (VID - SVID)
REPLACE XX WITH THE CORRESPONDING ACCEPTING STATE NUMBER
*/
Token aa_func03(char lexeme[]) {
Token t;
unsigned int i;
char* temp_str;
if ((temp_str = (char*)calloc(VID_LEN + 2, sizeof(char))) == NULL) {
return aa_table[ES]("RUN TIME ERROR: ");
}
for (i = 0; i < (VID_LEN) && i < strlen(lexeme); i++) {
temp_str[i] = lexeme[i];
}
temp_str[strlen(temp_str) - 1] = '#'; /* Add# to end of the SVID */
temp_str[strlen(temp_str)] = '\0';
strncpy(t.attribute.vid_lex, temp_str, VID_LEN);
t.attribute.vid_lex[strlen(temp_str)] = '\0';
free(temp_str);
t.code = SVID_T;
return t;
/*
WHEN CALLED THE FUNCTION MUST
1. SET a SVID TOKEN.
IF THE lexeme IS LONGER than VID_LEN characters,
ONLY FIRST VID_LEN-1 CHARACTERS ARE STORED
INTO THE VARIABLE ATTRIBUTE ARRAY vid_lex[],
AND THEN THE # CHARACTER IS APPENDED TO THE NAME.
ADD \0 AT THE END TO MAKE A C-type STRING.
*/
}
/*ACCEPTING FUNCTION FOR THE integer literal(IL)-decimal constant(DIL)*/
Token aa_func05(char lexeme[]) {
Token t;
long temp_num;
temp_num = atol(lexeme);
if (temp_num > SHRT_MAX || temp_num < 0) { /* Overflow error */
t = aa_table[ES](lexeme);
return t;
}
t.code = INL_T;
t.attribute.int_value = (int)temp_num;
return t;
/*
THE FUNCTION MUST CONVERT THE LEXEME REPRESENTING A DECIMAL CONSTANT
TO A DECIMAL INTEGER VALUE, WHICH IS THE ATTRIBUTE FOR THE TOKEN.
THE VALUE MUST BE IN THE SAME RANGE AS the value of 2-byte integer in C.
IN CASE OF ERROR (OUT OF RANGE) THE FUNCTION MUST RETURN ERROR TOKEN
THE ERROR TOKEN ATTRIBUTE IS lexeme. IF THE ERROR lexeme IS LONGER
than ERR_LEN characters, ONLY THE FIRST ERR_LEN-3 characters ARE
STORED IN err_lex. THEN THREE DOTS ... ARE ADDED TO THE END OF THE
err_lex C-type string. */
}
/*ACCEPTING FUNCTION FOR THE floating - point literal (FPL)*/
Token aa_func08(char lexeme[]) {
Token t;
double temp_dbl;
t.code = FPL_T;
if (strstr(lexeme, "0.0")) {
t.attribute.flt_value = 0.0f;
}
temp_dbl = atof(lexeme);
#ifdef DEBUG
printf("Lexeme: '%s' | FLT value: %f \n", lexeme, temp_dbl);
#endif
if ((temp_dbl > FLT_MAX) || (temp_dbl < 0)) { /* Overflow error */
t = aa_table[ES](lexeme);
return t;
}
t.attribute.flt_value = (float)temp_dbl;
return t;
/*
THE FUNCTION MUST CONVERT THE LEXEME TO A FLOATING POINT VALUE,
WHICH IS THE ATTRIBUTE FOR THE TOKEN.
THE VALUE MUST BE IN THE SAME RANGE AS the value of 4-byte float in C.
IN CASE OF ERROR (OUT OF RANGE) THE FUNCTION MUST RETURN ERROR TOKEN
THE ERROR TOKEN ATTRIBUTE IS lexeme. IF THE ERROR lexeme IS LONGER
than ERR_LEN characters, ONLY THE FIRST ERR_LEN-3 characters ARE
STORED IN err_lex. THEN THREE DOTS ... ARE ADDED TO THE END OF THE
err_lex C-type string. */
}
/*ACCEPTING FUNCTION FOR THE integer literal(IL) - octal constant (OIL)*/
Token aa_func10(char lexeme[]) {
Token t;
long new_olval;
if (strlen(lexeme) > INL_LEN + 1) {
t = aa_table[ES](lexeme);
}
t.code = INL_T;
new_olval = atool(lexeme);
if (new_olval < SHRT_MIN || new_olval > SHRT_MAX) {
t = aa_table[ES](lexeme);
return t;
}
t.code = INL_T;
t.attribute.int_value = (int)new_olval;
return t;
/*
THE FUNCTION MUST CONVERT THE LEXEME REPRESENTING AN OCTAL CONSTANT
TO A DECIMAL INTEGER VALUE WHICH IS THE ATTRIBUTE FOR THE TOKEN.
THE VALUE MUST BE IN THE SAME RANGE AS the value of 2-byte integer in C.
THIS FUNCTION IS SIMILAR TO THE FUNCTION ABOVE AND THEY CAN BE
COMBINED INTO ONE FUNCTION
THE MAIN DIFFERENCE IE THAT THIS FUNCTION CALLS
THE FUNCTION atool(char * lexeme) WHICH CONVERTS AN ASCII STRING
REPRESENTING AN OCTAL NUMBER TO INTEGER VALUE
IN CASE OF ERROR (OUT OF RANGE) THE FUNCTION MUST RETURN ERROR TOKEN
THE ERROR TOKEN ATTRIBUTE IS lexeme. IF THE ERROR lexeme IS LONGER
than ERR_LEN characters, ONLY THE FIRST ERR_LEN-3 characters ARE
STORED IN err_lex. THEN THREE DOTS ... ARE ADDED TO THE END OF THE
err_lex C-type string.
*/
}
/*ACCEPTING FUNCTION FOR THE ERROR TOKEN */
Token aa_func12(char lexeme[]) {
/*
Token t;
unsigned int i;
t.code = ERR_T;
for (i = 0; i < (ERR_LEN - 1) && i < strlen(lexeme); i++)
t.attribute.err_lex[i] = lexeme[i];
t.attribute.err_lex[i] = '\0';
return t;*/
return aa_table[ESWR](lexeme);
/*
THE FUNCTION SETS THE ERROR TOKEN. lexeme[] CONTAINS THE ERROR
THE ATTRIBUTE OF THE ERROR TOKEN IS THE lexeme ITSELF
AND IT MUST BE STORED in err_lex. IF THE ERROR lexeme IS LONGER
than ERR_LEN characters, ONLY THE FIRST ERR_LEN-3 characters ARE
STORED IN err_lex. THEN THREE DOTS ... ARE ADDED TO THE END OF THE
err_lex C-type string.
*/
}
Token aa_func13(char lexeme[]) {
Token t;
unsigned int i;
t.code = ERR_T;
for (i = 0; i < (ERR_LEN - 1) && i < strlen(lexeme); i++)
t.attribute.err_lex[i] = lexeme[i];
if (strlen(lexeme) > ERR_LEN) {
t.attribute.err_lex[i - 1] = '.';
t.attribute.err_lex[i - 2] = '.';
t.attribute.err_lex[i - 3] = '.';
}
t.attribute.err_lex[i] = '\0';
return t;
/*
THE FUNCTION SETS THE ERROR TOKEN. lexeme[] CONTAINS THE ERROR
THE ATTRIBUTE OF THE ERROR TOKEN IS THE lexeme ITSELF
AND IT MUST BE STORED in err_lex. IF THE ERROR lexeme IS LONGER
than ERR_LEN characters, ONLY THE FIRST ERR_LEN-3 characters ARE
STORED IN err_lex. THEN THREE DOTS ... ARE ADDED TO THE END OF THE
err_lex C-type string.
*/
}
/*CONVERSION FUNCTION*/
long atool(char * lexeme) {
int i, x = 1;
long result = 0;
for (i = strlen(lexeme); i > 0; i--, x *= 8) {
result += x*(lexeme[i - 1] - '0');
}
return result;
/*
THE FUNCTION CONVERTS AN ASCII STRING
REPRESENTING AN OCTAL INTEGER CONSTANT TO INTEGER VALUE
*/
}
/*HERE YOU WRITE YOUR ADDITIONAL FUNCTIONS (IF ANY).
FOR EXAMPLE*/
int iskeyword(char * kw_lexeme) {
int i;
if (kw_lexeme == NULL) return -1;
for (i = 0; i < KWT_SIZE; i++) {
if (strcmp(kw_table[i], kw_lexeme) == 0) { return i; }
}
return -1;
}
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