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scanner.c
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scanner.c
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/************************************************
* CS3240 Project
* LL(1) scanner
* Authors: James McCarty, Logan Blyth, Rob Rayborn
*
************************************************/
/* Libraries */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<malloc.h>
/* Defines */
#define TOKENBUF 10
#define UNDERSCORE 95
/* Structures */
/* Function Prototypes */
char* open_file(char*);
void match(char*);
void scan(char*);
int is_digit(char);
int is_letter(char);
int is_whitespace(char);
/* returns 0 if char is a digit */
int is_digit(char sym) {
if(sym >= 48 && sym <= 57)
return 0;
return 1;
}
/* returns 0 if a char is a letter */
int is_letter(char sym) {
if( (sym >= 65 && sym <= 90) || /* uppercase */
(sym >= 97 && sym <= 122) ) /* lowercase */
return 0;
return 1;
}
int is_control(char sym) {
if(sym == '+' ||
sym == ';' ||
sym == '*' ||
sym == '(' ||
sym == ')' ||
sym == '%' ||
sym == '-' ||
sym == ',' )
return 0;
return 1;
}
/* returns 0 if a char is a whitespace symbol */
int is_whitespace(char sym) {
if( (sym == '\n') ||
(sym == ' ') ||
(sym == '\t' ))
return 0;
return 1;
}
/* take a char* and compare it to list of known strings */
void match(char* var) {
/* check for known symbols */
if(!strcmp(var, "begin")) {
printf("BEGIN");
}
else if(!strcmp(var, "end")) {
printf("END");
}
else if(!strcmp(var, "print")) {
printf("PRINT");
}
else if(!strcmp(var, "read")) {
printf("READ");
}
else if(!strcmp(var, ";")) {
printf("SEMICOLON");
}
else if(!strcmp(var, ",")) {
printf("COMMA");
}
else if(!strcmp(var, ":=")) {
printf("ASSIGN");
}
else if(!strcmp(var, "(")) {
printf("LEFTPAR");
}
else if(!strcmp(var, ")")) {
printf("RIGHTPAR");
}
else if(!strcmp(var, "+")) {
printf("PLUS");
}
else if(!strcmp(var, "-")) {
printf("MINUS");
}
else if(!strcmp(var, "*")) {
printf("MULTIPLY" );
}
else if(!strcmp(var, "%")) {
printf("MODULO");
}
else { /* determine if we have ID || INTNUM */
if(var[0] == UNDERSCORE ) { /* valid start of ID */
printf("ID");
}
else if(var[0] == '0') { /* ILLEGAL */
printf("\nERROR, illegal symbol in token %s\n", var);
exit(1);
}
else if(!is_digit(var[0])) { /* valid start of INTNUM */
printf("INTNUM");
}
else if(!is_letter(var[0])) { /* valid start of ID */
printf("ID");
}
else {
printf("\nERROR, could not parse token %s\n", var);
exit(1);
}
}
}
/* scan a buffer and match all symbols */
void scan(char* buffer)
{
char token[TOKENBUF+1];
int idx = 0;
long int index = 0;
/* parse over the entire buffer */
while(buffer[index] != EOF) {
/* clear token buffer */
memset(token, 0, TOKENBUF+1);
/* reset token buffer index */
idx = 0;
/* ignore whitespace */
while(!is_whitespace(buffer[index]))
index++;
/* determine if we have NUM, ASSIGN, or ID */
if(buffer[index] == ':') { /* assignment */
token[idx++] = buffer[index++];
token[idx++] = buffer[index++];
}
else if(!is_control(buffer[index])) { /* control char */
token[idx] = buffer[index++];
}
else if(!is_digit(buffer[index])) { /* NUM */
while(!is_digit(buffer[index])) {
if(idx == TOKENBUF) {
printf("\nERROR:Token starting with %s is too long\n", token);
exit(1);
}
token[idx++] = buffer[index++];
}
}
else if(!is_letter(buffer[index]) || buffer[index] == '_') { /* ID */
while( !is_letter(buffer[index]) ||
!is_digit(buffer[index]) ||
buffer[index] == '_' ) {
if(idx == TOKENBUF) {
printf("\nERROR:Token starting with %s is too long\n", token);
exit(1);
}
token[idx++] = buffer[index++];
}
}
/* match what we collected in the buffer */
if(token[0] != '\0')
match(token);
fputc(' ', stdout);
}
}
/* open a file and return a char buffer containing the file */
char* open_file(char* filename) {
FILE* input;
char* file_buffer;
long int filelen, read;
input = fopen(filename, "r"); /* open user given file */
if(input == NULL) { /* could not find specified file */
printf("Could not open file %s\n", filename);
exit(1);
}
/* determine size of input file */
fseek(input, 0, SEEK_END);
filelen = ftell(input);
rewind(input);
/* malloc space for input file */
file_buffer = (char*) malloc( ( filelen + 1 ) * sizeof(char));
if(file_buffer == NULL) {
printf("malloc() failed.\n");
exit(1);
}
read = fread(file_buffer, sizeof(char), filelen, input);
if(read != filelen) {
printf("Error reading input file.\n");
exit(1);
}
/* finished with input file */
fclose(input);
/* set EOF */
file_buffer[filelen] = EOF;
/* return buffer pointer to the user */
/* don't forget to free it later ! */
return file_buffer;
}
int main(int argc, char **argv) {
char* file_buffer;
if(argc != 2) { /* check for correctly given input file */
printf("Usage: scanner <file>\n");
return 1;
}
/* open user file and save it to file buffer */
file_buffer = open_file(argv[1]);
/* scan the buffer, output goes to stdout */
scan(file_buffer);
/* free any malloced memory */
free(file_buffer);
/* clean up output */
putc('\n', stdout);
fflush(stdout);
return 0;
}