Installations
npm install dfa
Releases
Unable to fetch releases
Contributors
Developer
devongovett
Developer Guide
Module System
CommonJS
Min. Node Version
Typescript Support
No
Node Version
12.0.0
NPM Version
6.9.0
Statistics
61 Stars
16 Commits
10 Forks
7 Watching
1 Branches
2 Contributors
Updated on 02 Oct 2024
Languages
JavaScript (97.77%)
Makefile (2.23%)
Total Downloads
Cumulative downloads
Total Downloads
271,871,246
Last day
-4.6%
350,707
Compared to previous day
Last week
1.4%
1,961,727
Compared to previous week
Last month
5.4%
8,322,214
Compared to previous month
Last year
28.2%
89,010,747
Compared to previous year
Daily Downloads
Weekly Downloads
Monthly Downloads
Yearly Downloads
dfa
Compiles a regular expression like syntax to fast deterministic finite automata. Useful for pattern matching against non-string sequences.
Example
This example matches Hangul syllables. The symbols defined in the machine are Unicode character categories which could be mapped from code points.
Machine definition:
1# define symbols 2X = 0; # Other character 3L = 1; # Leading consonant 4V = 2; # Medial vowel 5T = 3; # Trailing consonant 6LV = 4; # Composed <LV> syllable 7LVT = 5; # Composed <LVT> syllable 8M = 6; # Tone mark 9 10# define variables 11decomposed = L V T?; 12partial = LV T?; 13composed = LVT; 14 15# define main state machine pattern 16main = (decomposed | partial | composed) M?;
Visualized, the machine looks like this (double circles are accepting states):
Compiling and using the machine:
1import compile from 'dfa/compile'; 2import fs from 'fs'; 3 4let stateMachine = compile(fs.readFileSync('hangul.machine', 'utf8')); 5 6// find matches 7for (let [startIndex, endIndex] of stateMachine.match([0, 1, 2, 3, 0, 4, 6]) { 8 console.log('match:', startIndex, endIndex); 9}
Output:
match: 1 3
match: 5 6
Syntax
A state machine file contains a list of assignment statements. Comments are also allowed
and are started with the #
character. Each statement is an assignment of a variable name
to a value or expression. Assigning a variable to a number produces a symbol, which is
added to the state machine's alphabet. Assigning a variable to an expression allows
for substitutions into later expressions. The special main
variable should always be
assigned to at the end of the file, and is the final expression that will be compiled.
A subset of common regular expression syntax is supported. A list of operators and their precedence is below. Operators with the same precedence are evaluated left to right.
Precedence | Syntax | Type | Meaning |
---|---|---|---|
1 | a | b | Alternation | Matches either a or b |
2 | a b | Concatenation | Matches a followed by b |
3 | a* | Repetition | Matches zero or more occurrences of a |
3 | a+ | Repetition | Matches one ore more occurrences of a |
3 | a? | Optional | Matches zero or one occurrence of a |
3 | a{n} | Repetition | Matches exactly n occurrences of a |
3 | a{n,} | Repetition | Matches n or more occurrences of a |
3 | a{,n} | Repetition | Matches up to n occurrences of a |
3 | a{n,m} | Repetition | Matches n to m occurrences of a |
4 | t:<expr> | Tag | Tags the following expression with tag t |
5 | (<expr>) | Grouping | Groups an expression |
License
MIT
No vulnerabilities found.
Reason
no binaries found in the repo
Reason
0 existing vulnerabilities detected
Reason
0 commit(s) and 0 issue activity found in the last 90 days -- score normalized to 0
Reason
Found 1/15 approved changesets -- score normalized to 0
Reason
no effort to earn an OpenSSF best practices badge detected
Reason
security policy file not detected
Details
- Warn: no security policy file detected
- Warn: no security file to analyze
- Warn: no security file to analyze
- Warn: no security file to analyze
Reason
project is not fuzzed
Details
- Warn: no fuzzer integrations found
Reason
license file not detected
Details
- Warn: project does not have a license file
Reason
branch protection not enabled on development/release branches
Details
- Warn: branch protection not enabled for branch 'master'
Reason
SAST tool is not run on all commits -- score normalized to 0
Details
- Warn: 0 commits out of 2 are checked with a SAST tool
Score
2.6
/10
Last Scanned on 2024-11-25
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