full site update

node_modules/dfa/README.md

@@ -0,0 +1,83 @@
+# 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](https://en.wikipedia.org/wiki/Hangul) syllables. The symbols defined in the machine are Unicode character categories which could be mapped from code points.
+
+Machine definition:
+
+```coffeescript
+# define symbols
+X   = 0; # Other character
+L   = 1; # Leading consonant
+V   = 2; # Medial vowel
+T   = 3; # Trailing consonant
+LV  = 4; # Composed <LV> syllable
+LVT = 5; # Composed <LVT> syllable
+M   = 6; # Tone mark
+
+# define variables
+decomposed = L V T?;
+partial = LV T?;
+composed = LVT;
+
+# define main state machine pattern
+main = (decomposed | partial | composed) M?;
+```
+
+Visualized, the machine looks like this (double circles are accepting states):
+
+![dfa](https://cloud.githubusercontent.com/assets/19409/19143719/8fbc6a12-8b5a-11e6-868d-99621644d094.png)
+
+Compiling and using the machine:
+
+```javascript
+import compile from 'dfa/compile';
+import fs from 'fs';
+
+let stateMachine = compile(fs.readFileSync('hangul.machine', 'utf8'));
+
+// find matches
+for (let [startIndex, endIndex] of stateMachine.match([0, 1, 2, 3, 0, 4, 6]) {
+  console.log('match:', startIndex, endIndex);
+}
+```
+
+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