Flex/Bison - Mein regulärer Ausdruck stimmt nicht mit Vorkommen von zwei oder mehr X überein, Beispiel XXY-1 oder XXY-1

Question

Ich erstelle einen Parser für eine fiktive Programmiersprache mit flex und bison. Es wird gültige und ungültige Variablennamen geben.

XXXX XY-1 // valid 
XXXXX Z // valid 
XXX Y // valid 
XXX 5Aet // invalid 
XXXX XXAB-Y // invalid 

Die x am Anfang geben nur die Größe der Variablen an. Die Variable 5Aet ist ungültig, weil es mit einer Nummer beginnt. Ich habe es geschafft für diesen

[\_\-0-9][a-zA-Z][a-zA-Z0-9\-\_]* yylval.string = strdup(yytext);return TERM_INVALID_VARIABLE_NAME; 

die Variable einen regulären Ausdruck übereinstimmen XXAB-Y ist ungültig weil ein Variablenname nicht mit zwei oder mehr x Zeichen beginnen.

Ich habe versucht, einen regulären Ausdruck dafür zu entsprechen, aber ich war nicht erfolgreich. Ich habe verschiedene Kombinationen des Ausdrucks ausprobiert, aber keiner von ihnen hat funktioniert. Die Variable wird immer als gültig erkannt.

[X]{2,}[A-Z0-9\-]* yylval.string = strdup(yytext);return TERM_INVALID_VARIABLE_NAME; 

[X]{2,0}[\_\-0-9][a-zA-Z][a-zA-Z0-9\-\_]* yylval.string = strdup(yytext);return TERM_INVALID_VARIABLE_NAME; 

lexer.l Schnipsel

[\t ]+ // ignore whitespaces 

\n // Ignore new line 

[\"][^"]*[\"] yylval.string = strdup(yytext); return TERM_STR; 

";" return TERM_SEPARATOR; 

"." return TERM_FULLSTOP; 

[0-9]+ yylval.integer = atoi(yytext); return TERM_INT; 

XX[A-Z0-9-]* yylval.string = strdup(yytext);return TERM_INVALID_VARIABLE_NAME; 

[\_\-0-9]+[a-zA-Z][a-zA-Z0-9\-\_]* yylval.string = strdup(yytext);return TERM_INVALID_VARIABLE_NAME; 

[A-Z][A-Z0-9\-]* yylval.string = strdup(yytext); return TERM_VARIABLE_NAME; 

[X]+ yylval.integer = yyleng; return TERM_SIZE; 

. return TERM_INVALID_TOKEN; 

parser.y

program: 
    /* empty */ | 
    begin middle_declarations body grammar_s end { 
     printf("\nParsing complete\n"); 
     exit(0); 
    }; 

begin: 
    TERM_BEGINING TERM_FULLSTOP; 

body: 
    TERM_BODY TERM_FULLSTOP; 

end: 
    TERM_END TERM_FULLSTOP; 

middle_declarations: 
    /* empty */ | 
    //Left recursive to allow for many declearations 
    middle_declarations declaration TERM_FULLSTOP; 

declaration: 
    TERM_SIZE TERM_VARIABLE_NAME { 
     createVar($1, $2); 
    } 
    | 
    TERM_SIZE TERM_INVALID_VARIABLE_NAME { 
     printInvalidVarName($2); 
    }; 

grammar_s: 
    /* empty */ | 
    grammar_s grammar TERM_FULLSTOP; 

grammar: 
    add | move | print | input; 

add: 
    TERM_ADD TERM_INT TERM_TO TERM_VARIABLE_NAME { 
     addIntToVar($2, $4); 
    } 
    | 
    TERM_ADD TERM_VARIABLE_NAME TERM_TO TERM_VARIABLE_NAME { 
     addVarToVar($2, $4); 
    } 

    ; 

move: 
    TERM_MOVE TERM_VARIABLE_NAME TERM_TO TERM_VARIABLE_NAME { 
     moveVarToVar($2, $4); 
    } 
    | 
    TERM_MOVE TERM_INT TERM_TO TERM_VARIABLE_NAME { 
     moveIntToVar($2, $4); 
    } 

    ; 

print: 
    /* empty */ | 
    TERM_PRINT rest_of_print { 
     printf("\n"); 
    }; 

rest_of_print: 
    /* empty */ | 
    rest_of_print other_print; 

other_print: 

    TERM_VARIABLE_NAME { 
     printVarValue($1); 
    } 
    | 
    TERM_SEPARATOR { 
     // do nothing 
    } 
    | 
    TERM_STR { 
     printf("%s", $1); 
    } 

    ; 

input: 
    // Fullstop declares grammar 
    TERM_INPUT other_input; 

other_input: 

    /* empty */ | 
    // Input var1 
    TERM_VARIABLE_NAME { 
     inputValues($1); 
    } 
    | 
    // Can be input var1; var2;...varN 
    other_input TERM_SEPARATOR TERM_VARIABLE_NAME { 
     inputValues($2); 
    } 
    ; 

Debug Ausgangs Schnipsel:

Starting parse 
Entering state 0 
Reading a token: Next token is token TERM_BEGINING (1.1:) 
Shifting token TERM_BEGINING (1.1:) 
Entering state 1 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 4 
Reducing stack by rule 3 (line 123): 
    $1 = token TERM_BEGINING (1.1:) 
    $2 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm begin (1.1:) 
Stack now 0 
Entering state 3 
Reducing stack by rule 6 (line 131): 
-> $$ = nterm middle_declarations (1.1:) 
Stack now 0 3 
Entering state 6 
Reading a token: Next token is token TERM_SIZE (1.1:) 
Shifting token TERM_SIZE (1.1:) 
Entering state 8 
Reading a token: Next token is token TERM_VARIABLE_NAME (1.1:) 
Shifting token TERM_VARIABLE_NAME (1.1:) 
Entering state 13 
Reducing stack by rule 8 (line 137): 
    $1 = token TERM_SIZE (1.1:) 
    $2 = token TERM_VARIABLE_NAME (1.1:) 
-> $$ = nterm declaration (1.1:) 
Stack now 0 3 6 
Entering state 10 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 15 
Reducing stack by rule 7 (line 134): 
    $1 = nterm middle_declarations (1.1:) 
    $2 = nterm declaration (1.1:) 
    $3 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm middle_declarations (1.1:) 
Stack now 0 3 
Entering state 6 
Reading a token: Next token is token TERM_SIZE (1.1:) 
Shifting token TERM_SIZE (1.1:) 
Entering state 8 
Reading a token: Next token is token TERM_VARIABLE_NAME (1.1:) 
Shifting token TERM_VARIABLE_NAME (1.1:) 
Entering state 13 
Reducing stack by rule 8 (line 137): 
    $1 = token TERM_SIZE (1.1:) 
    $2 = token TERM_VARIABLE_NAME (1.1:) 
-> $$ = nterm declaration (1.1:) 
Stack now 0 3 6 
Entering state 10 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 15 
Reducing stack by rule 7 (line 134): 
    $1 = nterm middle_declarations (1.1:) 
    $2 = nterm declaration (1.1:) 
    $3 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm middle_declarations (1.1:) 
Stack now 0 3 
Entering state 6 
Reading a token: Next token is token TERM_SIZE (1.1:) 
Shifting token TERM_SIZE (1.1:) 
Entering state 8 
Reading a token: Next token is token TERM_VARIABLE_NAME (1.1:) 
Shifting token TERM_VARIABLE_NAME (1.1:) 
Entering state 13 
Reducing stack by rule 8 (line 137): 
    $1 = token TERM_SIZE (1.1:) 
    $2 = token TERM_VARIABLE_NAME (1.1:) 
-> $$ = nterm declaration (1.1:) 
Stack now 0 3 6 
Entering state 10 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 15 
Reducing stack by rule 7 (line 134): 
    $1 = nterm middle_declarations (1.1:) 
    $2 = nterm declaration (1.1:) 
    $3 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm middle_declarations (1.1:) 
Stack now 0 3 
Entering state 6 
Reading a token: Next token is token TERM_BODY (1.1:) 
Shifting token TERM_BODY (1.1:) 
Entering state 7 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 11 
Reducing stack by rule 4 (line 126): 
    $1 = token TERM_BODY (1.1:) 
    $2 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm body (1.1:) 
Stack now 0 3 6 
Entering state 9 
Reducing stack by rule 10 (line 145): 
-> $$ = nterm grammar_s (1.1:) 
Stack now 0 3 6 9 
Entering state 14 
Reading a token: Next token is token TERM_PRINT (1.1:) 
Shifting token TERM_PRINT (1.1:) 
Entering state 20 
Reducing stack by rule 22 (line 180): 
-> $$ = nterm rest_of_print (1.1:) 
Stack now 0 3 6 9 14 20 
Entering state 34 
Reading a token: Next token is token TERM_STR (1.1:) 
Shifting token TERM_STR (1.1:) 
Entering state 41 
Reducing stack by rule 26 (line 194): 
    $1 = token TERM_STR (1.1:) 
-> $$ = nterm other_print (1.1:) 
Stack now 0 3 6 9 14 20 34 
Entering state 44 
Reducing stack by rule 23 (line 182): 
    $1 = nterm rest_of_print (1.1:) 
    $2 = nterm other_print (1.1:) 
-> $$ = nterm rest_of_print (1.1:) 
Stack now 0 3 6 9 14 20 
Entering state 34 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Reducing stack by rule 21 (line 176): 
    $1 = token TERM_PRINT (1.1:) 
    $2 = nterm rest_of_print (1.1:) 
"hEllo" 
-> $$ = nterm print (1.1:) 
Stack now 0 3 6 9 14 
Entering state 25 
Reducing stack by rule 14 (line 150): 
    $1 = nterm print (1.1:) 
-> $$ = nterm grammar (1.1:) 
Stack now 0 3 6 9 14 
Entering state 22 
Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 35 
Reducing stack by rule 11 (line 147): 
    $1 = nterm grammar_s (1.1:) 
    $2 = nterm grammar (1.1:) 
    $3 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm grammar_s (1.1:) 
Stack now 0 3 6 9 
Entering state 14 
Reading a token: Next token is token TERM_END (1.1:) 
Shifting token TERM_END (1.1:) 
Entering state 16 
Reading a token: Next token is token TERM_FULLSTOP (1.1:) 
Shifting token TERM_FULLSTOP (1.1:) 
Entering state 27 
Reducing stack by rule 5 (line 129): 
    $1 = token TERM_END (1.1:) 
    $2 = token TERM_FULLSTOP (1.1:) 
-> $$ = nterm end (1.1:) 
Stack now 0 3 6 9 14 
Entering state 21 
Reducing stack by rule 2 (line 113): 
    $1 = nterm begin (1.1:) 
    $2 = nterm middle_declarations (1.1:) 
    $3 = nterm body (1.1:) 
    $4 = nterm grammar_s (1.1:) 
    $5 = nterm end (1.1:) 

Probe Input:

BeGiNInG. 

X XXAB-. 
XX XXX7. 
XX XXXY. 

BoDY. 

print "hEllo". 

EnD. 

Answer 1

sollte gut funktionieren, und es funktioniert gut für mich.

XX[A-Z0-9-]* yylval.string = strdup(yytext);return TERM_INVALID_VARIABLE_NAME; 

da alle weiteren X Zeichen die [A-Z0-9-] Zeichenklasse: Er kann jedoch vereinfacht werden. (Beachten Sie, dass es nicht notwendig ist \- innerhalb einer Zeichenklasse zu schreiben; - tun, vorausgesetzt, dass es entweder die erste oder die letzte, was in der Zeichenklasse.)

Das Muster (wie Sie) passt auch nur XX, aber das [X]+ Muster wird gewinnen, da es früher in der Flex-Eingabedatei kommt.

{2,0} ist kein gültiges Intervall Ausdruck, da 0 kleiner als 2. „2 oder mehr X“ angeben, schreiben X{2,} (oder [X]{2,}, wenn Sie es vorziehen. "X"{2,} funktioniert auch.) Das von einer Fehlermeldung sollte flex, mit dem Ergebnis, dass kein lexikalischer Scanner produziert wird. (Es könnte jedoch immer noch ein alter herumliegen, was zu Verwirrung führen könnte.)