Kapitel 4
Kapitel 4
Kapitel 4
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FIRST(γ) für Strings<br />
Compiler<br />
<strong>Kapitel</strong> 4<br />
Syntaktische Analyse<br />
Autor:<br />
Aho et al.<br />
• FIRST(Xγ) = FIRST(X)<br />
if not nullable(X)<br />
• FIRST(Xγ) = FIRST(X) ∪ FIRST(γ)<br />
if nullable(X)<br />
• Beispiel: FIRST(XYZ) =<br />
– {a,c} ∪ FIRST(YZ) =<br />
– {a,c} ∪ {c} ∪ FIRST(Z) =<br />
– {a,c} ∪ {c} ∪ {a,c,d} = {a,c,d}<br />
Y: {c} <br />
X: {a,c} <br />
Z: {a,c,d} <br />
Z → d Y→ ε X → Y <br />
Z → XYZ Y→ c X → a
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