Difference between revisions of "PLC Laboratory 4"
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| + | == LL1 Grammars == | ||
| + | On the input, there is a context free grammar. For this grammar compute sets FIRST and FOLLOW and based on these sets decide if the grammar is LL1. | ||
| + | |||
| + | To simplify the solution, you can use your solution from the previous laboratory: [[PLC_Laboratory_3 | Laboratory 3]] | ||
| + | == Input specification == | ||
| + | |||
| + | The input contains a context free grammar definition. Non-terminals are upper-case letters, terminals are lower-case letters. It composes from several lines; each line ends with the semicolon, and it contains rules for one nonterminal. The line starts with this nonterminal, then there is a colon and it is followed by right hand sides of its rules separated by <code>'|'</code>. | ||
| + | |||
| + | There may be also notes in the input, they are written in compose brackets. They have no meaning for the grammar definition. | ||
| + | |||
| + | For more detail see the example. | ||
| + | |||
| + | == Output specification == | ||
| + | |||
| + | For the context free grammar from the input write either <code>"It it LL1 grammar"</code> or <code>"It is not LL1 grammar"</code>. | ||
| + | |||
| + | == Example == | ||
| + | * Input | ||
| + | <syntaxhighlight lang="haskell" > | ||
| + | {Input grammar} | ||
| + | A : b C | B d; | ||
| + | B : C C | b A; | ||
| + | C : c C | {e}; | ||
| + | </syntaxhighlight > | ||
| + | |||
| + | * Output | ||
| + | <syntaxhighlight lang="haskell" > | ||
| + | It is not LL1 grammar | ||
| + | </syntaxhighlight > | ||
Latest revision as of 08:16, 27 January 2022
LL1 Grammars
On the input, there is a context free grammar. For this grammar compute sets FIRST and FOLLOW and based on these sets decide if the grammar is LL1.
To simplify the solution, you can use your solution from the previous laboratory: Laboratory 3
Input specification
The input contains a context free grammar definition. Non-terminals are upper-case letters, terminals are lower-case letters. It composes from several lines; each line ends with the semicolon, and it contains rules for one nonterminal. The line starts with this nonterminal, then there is a colon and it is followed by right hand sides of its rules separated by '|'.
There may be also notes in the input, they are written in compose brackets. They have no meaning for the grammar definition.
For more detail see the example.
Output specification
For the context free grammar from the input write either "It it LL1 grammar" or "It is not LL1 grammar".
Example
- Input
{Input grammar}
A : b C | B d;
B : C C | b A;
C : c C | {e};
- Output
It is not LL1 grammar
