ref: 79213052a219d8c7ab85629807d07f7365ef9bec
dir: /sys/src/cmd/grep/grep.y/
%{ #include "grep.h" %} %union { int val; char* str; Re2 re; } %type <re> expr prog %type <re> expr0 expr1 expr2 expr3 expr4 %token <str> LCLASS %token <val> LCHAR %token LLPAREN LRPAREN LALT LSTAR LPLUS LQUES %token LBEGIN LEND LDOT LBAD LNEWLINE %% prog: /* empty */ { yyerror("empty pattern"); } | expr newlines { $$.beg = ral(Tend); $$.end = $$.beg; $$ = re2cat(re2star(re2or(re2char(0x00, '\n'-1), re2char('\n'+1, 0xff))), $$); $$ = re2cat($1, $$); $$ = re2cat(re2star(re2char(0x00, 0xff)), $$); topre = $$; } expr: expr0 | expr newlines expr0 { $$ = re2or($1, $3); } expr0: expr1 | LSTAR { literal = 1; } expr1 { $$ = $3; } expr1: expr2 | expr1 LALT expr2 { $$ = re2or($1, $3); } expr2: expr3 | expr2 expr3 { $$ = re2cat($1, $2); } expr3: expr4 | expr3 LSTAR { $$ = re2star($1); } | expr3 LPLUS { $$.beg = ral(Talt); patchnext($1.end, $$.beg); $$.beg->alt = $1.beg; $$.end = $$.beg; $$.beg = $1.beg; } | expr3 LQUES { $$.beg = ral(Talt); $$.beg->alt = $1.beg; $$.end = $1.end; appendnext($$.end, $$.beg); } expr4: LCHAR { $$.beg = ral(Tclass); $$.beg->lo = $1; $$.beg->hi = $1; $$.end = $$.beg; } | LBEGIN { $$.beg = ral(Tbegin); $$.end = $$.beg; } | LEND { $$.beg = ral(Tend); $$.end = $$.beg; } | LDOT { $$ = re2class("^\n"); } | LCLASS { $$ = re2class($1); } | LLPAREN expr1 LRPAREN { $$ = $2; } newlines: LNEWLINE | newlines LNEWLINE %% void yyerror(char *e, ...) { va_list args; fprint(2, "grep: "); if(filename) fprint(2, "%s:%ld: ", filename, lineno); else if (pattern) fprint(2, "%s: ", pattern); va_start(args, e); vfprint(2, e, args); va_end(args); fprint(2, "\n"); exits("syntax"); } long yylex(void) { char *q, *eq; int c, s; if(peekc) { s = peekc; peekc = 0; return s; } c = getrec(); if(literal) { if(c != 0 && c != '\n') { yylval.val = c; return LCHAR; } literal = 0; } switch(c) { default: yylval.val = c; s = LCHAR; break; case '\\': c = getrec(); yylval.val = c; s = LCHAR; if(c == '\n') s = LNEWLINE; break; case '[': goto getclass; case '(': s = LLPAREN; break; case ')': s = LRPAREN; break; case '|': s = LALT; break; case '*': s = LSTAR; break; case '+': s = LPLUS; break; case '?': s = LQUES; break; case '^': s = LBEGIN; break; case '$': s = LEND; break; case '.': s = LDOT; break; case 0: peekc = -1; case '\n': s = LNEWLINE; break; } return s; getclass: q = u.string; eq = q + nelem(u.string) - 5; c = getrec(); if(c == '^') { q[0] = '^'; q[1] = '\n'; q[2] = '-'; q[3] = '\n'; q += 4; c = getrec(); } for(;;) { if(q >= eq) error("class too long"); if(c == ']' || c == 0) break; if(c == '\\') { *q++ = c; c = getrec(); if(c == 0) break; } *q++ = c; c = getrec(); } *q = 0; if(c == 0) return LBAD; yylval.str = u.string; return LCLASS; }