99 lines
2.5 KiB
Text
99 lines
2.5 KiB
Text
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/*
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* string1.lex: Handling strings by using input()
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*/
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%{
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#include <ctype.h>
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#include <malloc.h>
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#define ALLOC_SIZE 32 /* for (re)allocating the buffer */
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#define isodigit(x) ((x) >= '0' && (x) <= '7')
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#define hextoint(x) (isdigit((x)) ? (x) - '0' : ((x) - 'A') + 10)
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void yyerror(char *message)
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{
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printf("\nError: %s\n",message);
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}
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%}
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%%
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\" {
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int inch,count,max_size;
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char *buffer;
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int temp;
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buffer = malloc(ALLOC_SIZE);
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max_size = ALLOC_SIZE;
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inch = input();
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count = 0;
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while(inch != EOF && inch != '"' && inch != '\n'){
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if(inch == '\\'){
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inch = input();
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switch(inch){
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case '\n': inch = input(); break;
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case 'b' : inch = '\b'; break;
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case 't' : inch = '\t'; break;
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case 'n' : inch = '\n'; break;
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case 'v' : inch = '\v'; break;
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case 'f' : inch = '\f'; break;
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case 'r' : inch = '\r'; break;
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case 'X' :
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case 'x' : inch = input();
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if(isxdigit(inch)){
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temp = hextoint(toupper(inch));
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inch = input();
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if(isxdigit(inch)){
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temp = (temp << 4) + hextoint(toupper(inch));
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} else {
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unput(inch);
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}
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inch = temp;
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} else {
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unput(inch);
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inch = 'x';
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}
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break;
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default:
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if(isodigit(inch)){
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temp = inch - '0';
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inch = input();
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if(isodigit(inch)){
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temp = (temp << 3) + (inch - '0');
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} else {
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unput(inch);
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goto done;
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}
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inch = input();
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if(isodigit(inch)){
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temp = (temp << 3) + (inch - '0');
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} else {
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unput(inch);
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}
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done:
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inch = temp;
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}
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}
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}
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buffer[count++] = inch;
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if(count >= max_size){
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buffer = realloc(buffer,max_size + ALLOC_SIZE);
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max_size += ALLOC_SIZE;
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}
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inch = input();
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}
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if(inch == EOF || inch == '\n'){
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yyerror("Unterminated string.");
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}
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buffer[count] = '\0';
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printf("String = \"%s\"\n",buffer);
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free(buffer);
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}
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.
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\n
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%%
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