comparators.ts

//================================================================ 
/**
 * @packageDocumentation
 * @module std  
 */
//================================================================
import { IComparable } from "./IComparable";

import { get_uid } from "./uid";

/**
 * Test whether two arguments are equal.
 * 
 * @param x The first argument to compare.
 * @param y The second argument to compare.
 * @return Whether two arguments are equal or not.
 */
export function equal_to<T>(x: T, y: T): boolean
{
    // CONVERT TO PRIMITIVE TYPE
    x = x ? (x as any).valueOf() as T : x;
    y = y ? (y as any).valueOf() as T : y;

    // DO COMPARE
    if (x instanceof Object && (<any>x as IComparable<T>).equals instanceof Function)
        return (<any>x as IComparable<T>).equals(y);
    else
        return x === y;
}

/**
 * Test whether two arguments are not equal.
 * 
 * @param x The first argument to compare.
 * @param y The second argument to compare.
 * @return Returns `true`, if two arguments are not equal, otherwise `false`.
 */
export function not_equal_to<T>(x: T, y: T): boolean
{
    return !equal_to(x, y);
}

/**
 * Test whether *x* is less than *y*.
 * 
 * @param x The first argument to compare.
 * @param y The second argument to compare.
 * @return Whether *x* is less than *y*.
 */
export function less<T>(x: T, y: T): boolean
{
    // CONVERT TO PRIMITIVE TYPE
    x = (x as any).valueOf() as T;
    y = (y as any).valueOf() as T;

    // DO COMPARE
    if (x instanceof Object)
        if ((<any>x as IComparable<T>).less instanceof Function) // has less()
            return (<any>x as IComparable<T>).less(y);
        else
            return get_uid(<any>x) < get_uid(<any>y);
    else
        return x < y;
}

/**
 * Test whether *x* is less than or equal to *y*.
 * 
 * @param x The first argument to compare.
 * @param y The second argument to compare.
 * @return Whether *x* is less than or equal to *y*.
 */
export function less_equal<T>(x: T, y: T): boolean
{
    return less(x, y) || equal_to(x, y);
}

/**
 * Test whether *x* is greater than *y*.
 * 
 * @param x The first argument to compare.
 * @param y The second argument to compare.
 * @return Whether *x* is greater than *y*.
 */
export function greater<T>(x: T, y: T): boolean
{
    return !less_equal(x, y);
}

/**
 * Test whether *x* is greater than or equal to *y*.
 * 
 * @param x The first argument to compare.
 * @param y The second argument to compare.
 * @return Whether *x* is greater than or equal to *y*.
 */
export function greater_equal<T>(x: T, y: T): boolean
{
    return !less(x, y);
}