Add type definition

src/filtrex.d.ts

@@ -0,0 +1,60 @@
+/**
+ * A simple, safe, JavaScript expression engine, allowing end-users to enter arbitrary expressions without p0wning you.
+ * 
+ * @example
+ * // Input from user (e.g. search filter)
+ * let expression = 'transactions <= 5 and abs(profit) > 20.5';
+ *
+ * // Compile expression to executable function
+ * let myfilter = compileExpression(expression);
+ * 
+ * // Execute function
+ * myfilter({transactions: 3, profit:-40.5}); // returns 1
+ * myfilter({transactions: 3, profit:-14.5}); // returns 0
+ * 
+ * @param expression
+ * The expression to be parsed. Under the hood, the expression gets compiled to a clean and fast JavaScript function.
+ * There are only 2 types: numbers and strings. Numbers may be floating point or integers. Boolean logic is applied
+ * on the truthy value of values (e.g. any non-zero number is true, any non-empty string is true, otherwise false).
+ * Examples of numbers: `43`, `-1.234`; example of a string: `"hello"`; example of external data variable: `foo`, `a.b.c`,
+ * `'foo-bar'`.  
+ * You can use the following operators:
+ *  * `x + y` Add
+ *  * `x - y` Aubtract
+ *  * `x * y` Multiply
+ *  * `x / y` Divide
+ *  * `x % y` Modulo
+ *  * `x ^ y` Power
+ *  * `x == y` Equals
+ *  * `x < y` Less than
+ *  * `x <= y` Less than or equal to
+ *  * `x > y` Greater than
+ *  * `x >= y` Greater than or equal to
+ *  * `x in (a, b, c)` Equivalent to `(x == a or x == b or x == c)`
+ *  * `x not in (a, b, c)` Equivalent to `(x != a and x != b and x != c)`
+ *  * `x or y` Boolean or
+ *  * `x and y` Boolean and
+ *  * `not x` Boolean not
+ *  * `x ? y : z` If boolean x, value y, else z
+ *  * `( x )` Explicity operator precedence
+ *  * `abs(x)` Absolute value
+ *  * `ceil(x)` Round floating point up
+ *  * `floor(x)` Round floating point down
+ *  * `log(x)` Natural logarithm
+ *  * `max(a, b, c...)` Max value (variable length of args)
+ *  * `min(a, b, c...)` Min value (variable length of args)
+ *  * `random()` Random floating point from 0.0 to 1.0
+ *  * `round(x)` Round floating point
+ *  * `sqrt(x)` Square root
+ *  * `myFooBarFunction(x)` Custom function defined in `extraFunctions`
+ * 
+ * @param extraFunctions
+ * When integrating in to your application, you can add your own custom functions.
+ * These functions will be available in the expression in the same way as `sqrt(x)` and `round(x)`.
+ */
+export function compileExpression(
+    expression: string,
+    extraFunctions?: {
+        [T: string]: Function
+    }
+): (obj: {}) => any