[−][src]Crate nifty
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Description
The goal of this crate is not to be an efficient parsing library. Use a regex for that.
Rather, this crate aims to preserve the integrity of stepping through a DFA state diagram.
It allows you to build a DFA with states of a generic type S
that recognizes a language
whose symbols are of a generic type T
. You can traverse each transition symbol one by one, or you can
consume an iterator of symbols, which the DFA will either Accept
or Reject
.
DFAs are created using a DFABuilder, or by using the make_dfa!
macro.
Both methods ensure that the DFA has valid transitions for every symbol in its alphabet.
Documentation
Examples
Using the DFABuilder
Code
use nifty::make_dfa; let q0 = "q0"; let q1 = "q1"; let q2 = "q2"; let q3 = "q3"; let mut dfa = make_dfa! { states { q0, q1, q2, q3 } accept { q0, q1 } start { q0 } dead { q3 } transitions { 'a' => (q0, q1) 'b' => (q0, q3) 'a' => (q1, q1) 'b' => (q1, q2) 'a' => (q2, q1) 'b' => (q2, q2) } recognizes { "empty, or starts and ends with { a }" } }; dfa.evaluate("".chars()); // Accept dfa.evaluate("a".chars()); // Accept dfa.evaluate("b".chars()); // Reject dfa.evaluate("aa".chars()); // Accept dfa.evaluate("ab".chars()); // Reject dfa.evaluate("abb".chars()); // Reject dfa.evaluate("aba".chars()); // Accept dfa.evaluate("abba".chars()); // Accept dfa.evaluate("babba".chars()); // Reject
Tracing a Path
Code
use nifty::make_dfa; let q0 = "Seen { }"; let q1 = "Seen { b }"; let q2 = "Seen { ba }"; let q3 = "Seen { bab }"; let mut dfa = make_dfa! { states { q0, q1, q2, q3 } start { q0 } goal { q3 } transitions { 'a' => (q0, q0) 'a' => (q1, q2) 'a' => (q2, q0) 'b' => (q0, q1) 'b' => (q1, q1) 'b' => (q2, q3) } recognizes { "contains { bab }" } }; let path = "abaababa".chars() .map(|c| dfa.get_next(&c)) .collect::<Vec<_>>(); dbg!(&path);
Output
[src/main.rs:30] &path = [
"Seen { }",
"Seen { b }",
"Seen { ba }",
"Seen { }",
"Seen { b }",
"Seen { ba }",
"Seen { bab }",
"Seen { bab }",
]
Modules
dfa | |
make_dfa | Macro make_dfa! creates a DFA using the DFABuilder. |
Macros
make_dfa | Creates a DFA using the DFABuilder. |