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Realizácia zotavenia (1)

Realizácia zotavenia (1). Každú funkciu reprezentujúcu pravidlo EBNF je potrebné doplniť o parameter keys reprezentujúci množinu kľúčov (typu KeySet ) int Expr ( KeySet keys ) { ... } Volanie getsymbol () nahradiť : if (symbol == a ) { g etsymbol (); } else {

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Realizácia zotavenia (1)

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  1. Realizácia zotavenia (1) • Každú funkciu reprezentujúcu pravidlo EBNF je potrebné doplniť o parameter keys reprezentujúci množinu kľúčov (typu KeySet) intExpr(KeySetkeys){ ... } • Volanie getsymbol() nahradiť: if (symbol == a) { getsymbol(); } else { error(e, keys); }

  2. Realizácia zotavenia (2) • Pri volaní procedúr zodpovedajúcich neterminálnym symbolom doplniť argument s aktuálnou hodnotou množiny kľúčov. leftOp = Mul(allKeys); • Do každého bodu rozhodnutia (if+else, switch, while) umiestniť volanie check v tvare: check(e, keys);

  3. Zotavenie pri postupnosti neterminálov • A → S1 S2 S3 ... Si ... Sn A(KeySet keys) { S1 (H(S2) ⋃ H(S3)⋃ ... ⋃ H(Sn) ⋃ keys); S2 (H(S3) ⋃... ⋃ H(Sn) ⋃ keys); ... Si (H(Si+1)⋃ ... ⋃ H(Sn) ⋃ keys); ... Sn (keys); }

  4. Zotavenie pri vetvení • A → (S1 | S2 | ... | Sn) A(KeySet keys) { KeySetallkeys = H(S1) ⋃ ... ⋃ H(Sn) ⋃ keys; check(e,allkeys); switch (symbol) { caseH(S1): S1(keys); break; ... caseH(Sn): Sn(keys); break; default: error(e, keys); } }

  5. Zotavenie pri cykle • A → {S1 S2 ... Sn} A(keys) { loopkeys = H(S1) ⋃ ... ⋃ H(Sn); allkeys = loopkeys⋃ keys; check(e, allkeys); while (symbol ∈ loopkeys) S1(allkeys); S2(allkeys); ... Sn(allkeys); check(e, allkeys); } }

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