Lexical analysis of strings for the Cool programming language

gistfile1.c

<INITIAL>{QUOTE} { BEGIN STRCONST; string_buf_ptr = string_buf; }
<STRCONST>{QUOTE} { BEGIN 0; 
                    cool_yylval.symbol = stringtable.add_string(string_buf);
                    reset_buffer();
                    return STR_CONST;
                  }
<STRCONST>[^\\\"\n\0]+ { add_to_buffer(yytext); }
<STRCONST>\\\n { if(!add_to_buffer("\n")) { BEGIN 0; return ERROR; } }
<STRCONST>\\n { if(!add_to_buffer("\n")) { BEGIN 0; return ERROR; } }
<STRCONST>\\\\ { if(!add_to_buffer("\\")) { BEGIN 0; return ERROR; } }
<STRCONST>\\t { if (!add_to_buffer("\t")) { BEGIN 0; return ERROR; } }
<STRCONST>\\b { if(!add_to_buffer("\b")) { BEGIN 0; return ERROR; } }
<STRCONST>\\f { if(!add_to_buffer("\f")) { BEGIN 0; return ERROR; } }
<STRCONST>\\0 { if(!add_to_buffer("\0")) { BEGIN 0; return ERROR; } }
<STRCONST>\\/[^ntbf\n] { if(!add_to_buffer(yytext)) { BEGIN 0; return ERROR; } } 
<STRCONST>\n { BEGIN 0; cool_yylval.error_msg = "Unterminated string constant."; return ERROR; }
<STRCONST><<EOF>> { BEGIN 0; cool_yylval.error_msg = "EOF in string constant."; return ERROR; }
<STRCONST>\0 { BEGIN 0; cool_yylval.error_msg = "String contains null character."; return ERROR; }