4.7 KiB
| layout |
|---|
| doc_page |
This expression language supports the following operators (listed in decreasing order of precedence).
| Operators | Description |
|---|---|
| !, - | Unary NOT and Minus |
| ^ | Binary power op |
| *, /, % | Binary multiplicative |
| +, - | Binary additive |
| <, <=, >, >=, ==, != | Binary Comparison |
| &&,|| | Binary Logical AND, OR |
Long, double and string data types are supported. If a number contains a dot, it is interpreted as a double, otherwise it is interpreted as a long. That means, always add a '.' to your number if you want it interpreted as a double value. String literal should be quoted by single quotation marks.
Expressions can contain variables. Variable names may contain letters, digits, '_' and '$'. Variable names must not begin with a digit. To escape other special characters, user can quote it with double quotation marks.
For logical operators, a number is true if and only if it is positive (0 or minus value means false). For string type, it's evaluation result of 'Boolean.valueOf(string)'.
Also, the following built-in functions are supported.
| name | description |
|---|---|
| cast | cast(expr,'LONG' or 'DOUBLE' or 'STRING') returns expr with specified type. exception can be thrown |
| if | if(predicate,then,else) returns 'then' if 'predicate' evaluates to a positive number, otherwise it returns 'else' |
| nvl | nvl(expr,expr-for-null) returns 'expr-for-null' if 'expr' is null (or empty string for string type) |
| timestamp | timestamp(expr[,format-string]) parses string expr into date then returns milli-seconds from java epoch. without 'format-string' it's regarded as ISO datetime format |
| unix_timestamp | same with 'timestamp' function but returns seconds instead |
And built-in math functions. See javadoc of java.lang.Math for detailed explanation for each function.
| name | description |
|---|---|
| abs | abs(x) would return the absolute value of x |
| acos | acos(x) would return the arc cosine of x |
| asin | asin(x) would return the arc sine of x |
| atan | atan(x) would return the arc tangent of x |
| atan2 | atan2(y, x) would return the angle theta from the conversion of rectangular coordinates (x, y) to polar * coordinates (r, theta) |
| cbrt | cbrt(x) would return the cube root of x |
| ceil | ceil(x) would return the smallest (closest to negative infinity) double value that is greater than or equal to x and is equal to a mathematical integer |
| copysign | copysign(x) would return the first floating-point argument with the sign of the second floating-point argument |
| cos | cos(x) would return the trigonometric cosine of x |
| cosh | cosh(x) would return the hyperbolic cosine of x |
| exp | exp(x) would return Euler's number raised to the power of x |
| expm1 | expm1(x) would return e^x-1 |
| floor | floor(x) would return the largest (closest to positive infinity) double value that is less than or equal to x and is equal to a mathematical integer |
| getExponent | getExponent(x) would return the unbiased exponent used in the representation of x |
| hypot | hypot(x, y) would return sqrt(x^2+y^2) without intermediate overflow or underflow |
| log | log(x) would return the natural logarithm of x |
| log10 | log10(x) would return the base 10 logarithm of x |
| log1p | log1p(x) would the natural logarithm of x + 1 |
| max | max(x, y) would return the greater of two values |
| min | min(x, y) would return the smaller of two values |
| nextafter | nextafter(x, y) would return the floating-point number adjacent to the x in the direction of the y |
| nextUp | nextUp(x) would return the floating-point value adjacent to x in the direction of positive infinity |
| pow | pow(x, y) would return the value of the x raised to the power of y |
| remainder | remainder(x, y) would return the remainder operation on two arguments as prescribed by the IEEE 754 standard |
| rint | rint(x) would return value that is closest in value to x and is equal to a mathematical integer |
| round | round(x) would return the closest long value to x, with ties rounding up |
| scalb | scalb(d, sf) would return d * 2^sf rounded as if performed by a single correctly rounded floating-point multiply to a member of the double value set |
| signum | signum(x) would return the signum function of the argument x |
| sin | sin(x) would return the trigonometric sine of an angle x |
| sinh | sinh(x) would return the hyperbolic sine of x |
| sqrt | sqrt(x) would return the correctly rounded positive square root of x |
| tan | tan(x) would return the trigonometric tangent of an angle x |
| tanh | tanh(x) would return the hyperbolic tangent of x |
| todegrees | todegrees(x) converts an angle measured in radians to an approximately equivalent angle measured in degrees |
| toradians | toradians(x) converts an angle measured in degrees to an approximately equivalent angle measured in radians |
| ulp | ulp(x) would return the size of an ulp of the argument x |