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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
* Function list: scanner_init, malar_next_token, get_next_state, char_class,
aa_func02, aa_func03, aa_func05, aa_func08, aa_func10, aa_func12 aa_func13, atool, iskeyword
*/
/* 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"
#include "stable.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 */
extern STD sym_table; /* symbol table */
/* 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 */
/* Prepares the Scanner to read the source code buffer
* Author: Svillen Ranev
* Called functions: b_isempty, b_setmark, b_retract_to_mark, b_reset
* Parameters:
* - pBuffer sc_buf
* Return values:
* - 1 (failure), 0 (success)
*/
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 */
}
/* Reads the source code buffer and generates a token
* Author: Victor Fernandes
* Version: 0.0.1
* Called functions: aa_table[], b_getc, b_setmark, b_getcoffset, b_retract_to_mark,
b_retract, b_mark, b_eob, b_create, b_addc, b_free, isalpha, isalnum, get_next_state
* Parameters:
- pBuffer sc_buf
* Return values: Token
* Algorithm:
Read a character from the source buffer, one by one, and match string patterns to tokens.
If an illegal sequence is found while starting a pattern off of the first matching character,
it returns a token with an error code with the infringing character. If the scanner matches
a valid pattern it returns a Token with the appropriate code.
*/
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 */
/* Counter for loops in string error case */
int i;
/*String offset for the str_LTBL*/
static short str_offset = 0;
/* temporary buffer used to store an erroneous string literal*/
pBuffer err_lex_buf;
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 symbol from 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 */
return t;
}
else {
t.code = REL_OP_T;
t.attribute.rel_op = LT; /* Less-than operator */
b_retract(sc_buf);
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); /* Retract twice to re-read '!' */
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));
++line;
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 */
for (; c != '\"'; c = b_getc(sc_buf), ++lexend) {
if (c == '\n' || c == '\r')
++line;
if (c == '\0' || c == 255) { /* Illegal string, make it an error token */
b_retract_to_mark(sc_buf);
b_retract(sc_buf); /* Retract one more time to re-read '"' into err_lex */
t.code = ERR_T;
err_lex_buf = b_create(100, 10, 'a'); /* Start up temporary buffer */
c = b_getc(sc_buf);
for (i = 0; i < (lexend - lexstart); c = b_getc(sc_buf), ++i) {
/* Continue until the end of the lexeme where error was found */
if (i < (ERR_LEN) || c != 255 || c != '\0')
b_addc(err_lex_buf, c);
}
/* Pass the complete erroneous string to error state accepting function*/
t = aa_table[ES](b_setmark(err_lex_buf, 0));
b_free(err_lex_buf); /* Clean up the temporary buffer */
return t;
}
} /* end for loop, string finished and considered valid */
b_retract_to_mark(sc_buf);
/* Copy the matched string literal to str_LTBL */
t.attribute.str_offset = str_offset;
c = b_getc(sc_buf);
for (; lexstart < lexend; c = b_getc(sc_buf), ++lexstart, ++str_offset) {
b_addc(str_LTBL, c);
}
b_addc(str_LTBL, '\0'); ++str_offset; t.code = STR_T;
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; }
}
/*
* 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)*/
}
/* Looks up the transition table for the next state given the input character
Author: Victor Fernandes
Version: 0.0.1
Called functions: char_class, assert, printf, as_table
Parameters:
- int state: the starting point for the transition table lookup
- char c: the input character for table lookup
- int *accept: pointer to the accepting state of the scanner
Return values: int (the next state value of the scanner)
*/
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
assert(next != IS);
#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;
}
/* Matches the column value in the transition table to the given input character
Author: Victor Fernandes
Version: 0.0.1
Called functions: N/A
Parameters:
- char c: the input character to be matched in the transition table
Return values: int (the value representing the column in the transition table)
*/
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;
}
/* Generates a token for an arithmetic variable identifer or keyword
Author: Victor Fernandes
Version: 0.0.1
Called functions: iskeyword, calloc, aa_table[], strlen, strncpy, free
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
Token aa_func02(char lexeme[]) {
unsigned int i, kw_idx, offset; /* Variable to contain keyword table index */
Token t;
char v_type;
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: ");
}
strncpy(temp_str, lexeme, VID_LEN);
switch (lexeme[0]) { /* Read first character of lexeme for implicit type (not used yet?)*/
case 'i':
case 'o':
case 'd':
case 'n':
/* Integer */
v_type = 'I';
break;
default:
/* Floating point*/
v_type = 'F';
break;
}
if ((offset = st_install(sym_table, temp_str, v_type, line)) == -1){
printf("Error: Install failed - Symbol Table is full.\n");
st_store(sym_table);
free(temp_str);
exit(1);
}
t.attribute.vid_offset = offset;
free(temp_str);
return t;
}
/* Generates a token for an string variable identifer
Author: Victor Fernandes
Version: 0.0.1
Called functions: calloc, aa_table[], strlen, strncpy, free
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
Token aa_func03(char lexeme[]) {
Token t;
unsigned int i, offset;
char* temp_str;
if ((temp_str = (char*)calloc(VID_LEN + 2, sizeof(char))) == NULL) {
return aa_table[ES]("RUN TIME ERROR: ");
}
strncpy(temp_str, lexeme, VID_LEN);
temp_str[strlen(temp_str) - 1] = '#'; /* Add# to end of the SVID */
if ((offset = st_install(sym_table, temp_str, 'S', line)) == -1){
printf("Error: Install failed - Symbol Table is full.\n");
st_store(sym_table);
free(temp_str);
exit(1);
}
t.code = SVID_T;
t.attribute.vid_offset = offset;
free(temp_str);
return t;
}
/* Generates a token for a decimal integer literal constant (DIL)
Author: Victor Fernandes
Version: 0.0.1
Called functions: atol, aa_table[]
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
Token aa_func05(char lexeme[]) {
Token t;
long temp_num;
temp_num = atol(lexeme);
/* MOVE TO DEFINE */
if (temp_num > 32767 || 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;
}
/* Generates a token for a floating-point literal
Author: Victor Fernandes
Version: 0.0.1
Called functions: strtof, aa_table[]
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
Token aa_func08(char lexeme[]) {
Token t;
double temp_dbl = 0.0;
temp_dbl = atof(lexeme);
if ((temp_dbl > FLT_MAX) || ((temp_dbl != 0.0) && (temp_dbl < FLT_MIN))) { /* Overflow error */
return aa_table[ES](lexeme);
}
t.code = FPL_T;
t.attribute.flt_value = (float)temp_dbl;
return t;
}
/* Generates a token for an octal integer literal
Author: Victor Fernandes
Version: 0.0.1
Called functions: strlen, aa_table[], atool
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
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 < 0 || new_olval > 32767) {
t = aa_table[ES](lexeme);
return t;
}
t.code = INL_T;
t.attribute.int_value = (int)new_olval;
return t;
}
/* Generates a token for a general error token
Author: Victor Fernandes
Version: 0.0.1
Called functions: aa_table[]
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
Token aa_func12(char lexeme[]) {
/*
This function does the same as aa_func13, except that it is marked as
non-retracting in the accepting function state, but the token is generated
exactly the same way
*/
return aa_table[ESWR](lexeme);
}
/* Generates a token for a general error token
Author: Victor Fernandes
Version: 0.0.1
Called functions: strlen, aa_table[]
Parameters:
- char* lexeme: the string pattern matched by the FA
Return values: Token
*/
Token aa_func13(char lexeme[]) {
Token t;
unsigned int i;
t.code = ERR_T;
for (i = 0; i < (ERR_LEN) && 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;
}
/* Returns an octal representation of a string
Author: Victor Fernandes
Version: 0.0.1
Called functions: N/A
Parameters:
- char* lexeme: the string pattern to convert
Return values: long (integer representation of the octal string)
*/
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;
}
/* Looks up the string pattern on the keyword table
Author: Victor Fernandes
Version: 0.0.1
Called functions: N/A
Parameters:
- char* lexeme: the string pattern to look up in kw_table
Return values: int -1 (could not find a match),
int [1 - KW_SIZE] index location of the matching keyword
*/
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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