95 lines
3 KiB
Text
95 lines
3 KiB
Text
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/*
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* string2.lex: An example of using scanning strings
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* by using start states.
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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 isodigit(x) ((x) >= '0' && (x) <= '7')
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#define hextoint(x) (isdigit((x)) ? (x) - '0' : ((x) - 'A') + 10)
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char *buffer = NULL;
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int buffer_size = 0;
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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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%x STRING
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hex (x|X)[0-9a-fA-F]{1,2}
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oct [0-7]{1,3}
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%%
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\" {
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buffer = malloc(1);
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buffer_size = 1; strcpy(buffer,"");
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BEGIN(STRING);
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}
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<STRING>\n {
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yyerror("Unterminated string");
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free(buffer);
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BEGIN(INITIAL);
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}
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<STRING><<EOF>> {
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yyerror("EOF in string");
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free(buffer);
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BEGIN(INITIAL);
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}
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<STRING>[^\\\n"] {
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buffer = realloc(buffer,buffer_size+yyleng+1);
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buffer_size += yyleng;
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strcat(buffer,yytext);
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}
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<STRING>\\\n /* ignore this */
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<STRING>\\{hex} {
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int temp =0,loop = 0;
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for(loop=yyleng-2; loop>0; loop--){
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temp <<= 4;
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temp += hextoint(toupper(yytext[yyleng-loop]));
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}
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buffer = realloc(buffer,buffer_size+1);
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buffer[buffer_size-1] = temp;
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buffer[buffer_size] = '\0';
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buffer_size += 1;
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}
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<STRING>\\{oct} {
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int temp =0,loop = 0;
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for(loop=yyleng-1; loop>0; loop--){
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temp <<= 3;
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temp += (yytext[yyleng-loop] - '0');
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}
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buffer = realloc(buffer,buffer_size+1);
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buffer[buffer_size-1] = temp;
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buffer[buffer_size] = '\0';
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buffer_size += 1;
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}
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<STRING>\\[^\n] {
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buffer = realloc(buffer,buffer_size+1);
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switch(yytext[yyleng-1]){
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case 'b' : buffer[buffer_size-1] = '\b'; break;
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case 't' : buffer[buffer_size-1] = '\t'; break;
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case 'n' : buffer[buffer_size-1] = '\n'; break;
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case 'v' : buffer[buffer_size-1] = '\v'; break;
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case 'f' : buffer[buffer_size-1] = '\f'; break;
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case 'r' : buffer[buffer_size-1] = '\r'; break;
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default : buffer[buffer_size-1] = yytext[yyleng-1];
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}
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buffer[buffer_size] = '\0';
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buffer_size += 1;
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}
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<STRING>\" {
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printf("string = \"%s\"",buffer);
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free(buffer);
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BEGIN(INITIAL);
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}
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%%
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