Add role position comparison methods

src/structures/GuildMember.js

@@ -135,9 +135,7 @@ class GuildMember {
    * @readonly
    */
   get highestRole() {
-    return this.roles.reduce((prev, role) =>
+    return this.roles.reduce((prev, role) => !prev || role.comparePositionTo(prev) > 0 ? role : prev);
-      !prev || role.position > prev.position || (role.position === prev.position && role.id < prev.id) ? role : prev
-    );
   }
 
   /**
@@ -204,10 +202,7 @@ class GuildMember {
     if (this.user.id === this.client.user.id) return false;
     const clientMember = this.guild.member(this.client.user);
     if (!clientMember.hasPermission(Constants.PermissionFlags.KICK_MEMBERS)) return false;
-    const clientRole = clientMember.highestRole;
+    return clientMember.highestRole.comparePositionTo(this.highestRole) > 0;
-    const thisRole = this.highestRole;
-    return clientRole.position > thisRole.position ||
-      (clientRole.position === thisRole.position && clientRole.id < thisRole.id);
   }
 
   /**
@@ -220,10 +215,7 @@ class GuildMember {
     if (this.user.id === this.client.user.id) return false;
     const clientMember = this.guild.member(this.client.user);
     if (!clientMember.hasPermission(Constants.PermissionFlags.BAN_MEMBERS)) return false;
-    const clientRole = clientMember.highestRole;
+    return clientMember.highestRole.comparePositionTo(this.highestRole) > 0;
-    const thisRole = this.highestRole;
-    return clientRole.position > thisRole.position ||
-      (clientRole.position === thisRole.position && clientRole.id < thisRole.id);
   }
 
   /**

src/structures/Role.js

@@ -153,6 +153,16 @@ class Role {
     return permissions.map(p => this.hasPermission(p, explicit)).every(v => v);
   }
 
+  /**
+   * Compares this role's position to another role's.
+   * @param {Role} role Role to compare to this one
+   * @returns {number} Negative number if the this role's position is lower (other role's is higher),
+   * positive number if the this one is higher (other's is lower), 0 if equal
+   */
+  comparePositionTo(role) {
+    return this.constructor.comparePositions(this, role);
+  }
+
   /**
    * Edits the role
    * @param {RoleData} data The new data for the role
@@ -289,6 +299,18 @@ class Role {
   toString() {
     return `<@&${this.id}>`;
   }
+
+  /**
+   * Compares the positions of two roles.
+   * @param {Role} role1 First role to compare
+   * @param {Role} role2 Second role to compare
+   * @returns {number} Negative number if the first role's position is lower (second role's is higher),
+   * positive number if the first's is higher (second's is lower), 0 if equal
+   */
+  static comparePositions(role1, role2) {
+    if (role1.position === role2.position) return role1.id - role2.id;
+    return role1.position - role2.position;
+  }
 }
 
 module.exports = Role;