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LL1 Parsing a b $ S 1 A 4 B 3 2 - PowerPoint PPT Presentation

LL1 Parsing a b $ S 1 A 4 B 3 2 a b b b 1. S --> a B Input 2. B --> 3. B --> A S 4. A --> b B Parse Stack Compare Input and Stacktop 1 LL1 Parsing a b $ S 1 A


  1. LL1 Parsing a b $ S 1 A 4 B 3 2 a b b b 1. S --> a B Input 2. B --> “” 3. B --> A S 4. A --> b B Parse Stack Compare Input and Stacktop 1

  2. LL1 Parsing a b $ S 1 A 4 B 3 2 a b b b 1. S --> a B Input 2. B --> “” 3. B --> A S 4. A --> b B Parse Stack Get Predicted Production 2

  3. LL1 Parsing a b $ S 1 A 4 B 3 2 a b b b 1. S --> a B Input 2. B --> “” 3. B --> A S 4. A --> b B Parse Stack Replace Top with RHS 3

  4. LL1 Parsing a b $ S 1 A 4 B 3 2 a b b b 1. S --> a B Input 2. B --> “” a 3. B --> A B 4. A --> b B Parse Stack New Stack Contents 4

  5. LL1 Parsing a b $ S 1 A 4 B 3 2 a b b b 1. S --> a B Input 2. B --> “” a 3. B --> A B 4. A --> b B Parse Stack Discard Matching Tokens 5

  6. LL1 Parsing a b $ S 1 A 4 B 3 2 b b b 1. S --> a B Input 2. B --> “” 3. B --> A B 4. A --> b B Parse Stack Compare Input and Stacktop 6

  7. LL1 Parsing a b $ S 1 A 4 B 3 2 b b b 1. S --> a B Input 2. B --> “” 3. B --> A A 4. A --> b B Parse Stack Compare Input and Stacktop 7

  8. LL1 Parsing a b $ S 1 A 4 B 3 2 b b b 1. S --> a B Input 2. B --> “” b 3. B --> A B 4. A --> b B Parse Stack Discard Matching Tokens 8

  9. LL1 Parsing a b $ S 1 A 4 B 3 2 b b 1. S --> a B Input 2. B --> “” 3. B --> A B 4. A --> b B Parse Stack Compare Input and Stacktop 9

  10. LL1 Parsing a b $ S 1 A 4 B 3 2 b b 1. S --> a B Input 2. B --> “” 3. B --> A A 4. A --> b B Parse Stack Compare Input and Stacktop 10

  11. LL1 Parsing a b $ S 1 A 4 B 3 2 b b 1. S --> a B Input 2. B --> “” b 3. B --> A B 4. A --> b B Parse Stack Discard Matching Tokens 11

  12. LL1 Parsing a b $ S 1 A 4 B 3 2 b 1. S --> a B Input 2. B --> “” 3. B --> A B 4. A --> b B Parse Stack Compare Input and Stacktop 12

  13. LL1 Parsing a b $ S 1 A 4 B 3 2 b 1. S --> a B Input 2. B --> “” 3. B --> A A 4. A --> b B Parse Stack Compare Input and Stacktop 13

  14. LL1 Parsing a b $ S 1 A 4 B 3 2 b 1. S --> a B Input 2. B --> “” b 3. B --> A B 4. A --> b B Parse Stack Discard Matching Tokens 14

  15. LL1 Parsing a b $ S 1 A 4 B 3 2 1. S --> a B Input 2. B --> “” 3. B --> A B 4. A --> b B Parse Stack Compare Input and Stacktop 15

  16. LL1 Parsing a b $ S 1 A 4 B 3 2 1. S --> a B Input 2. B --> “” 3. B --> A 4. A --> b B Parse Stack DONE 16

  17. If Tokens don’t match you have an ERROR If Stacktop and Input have nothing predicted -- ERROR If you have a Semantic Action at Stacktop, EXECUTE IT 17

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