From 7196b017f501a68e4eba3353d789cc33139b6009 Mon Sep 17 00:00:00 2001
From: Stephen Chung <schungx@live.com>
Date: Sun, 27 Jun 2021 22:10:52 +0800
Subject: [PATCH] Add is_odd, is_even and is_zero.

---
 CHANGELOG.md               |  5 +++++
 src/packages/arithmetic.rs | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0be17a00..2c1f9ffe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,11 @@ The official version `1.0`.
 
 Almost the same version as `0.20.3` but with deprecated API removed.
 
+Enhancements
+------------
+
+* New methods `is_odd`, `is_even` for integers, and `is_zero` for all numbers.
+
 
 Version 0.20.3
 ==============
diff --git a/src/packages/arithmetic.rs b/src/packages/arithmetic.rs
index 27d639c1..074b19cf 100644
--- a/src/packages/arithmetic.rs
+++ b/src/packages/arithmetic.rs
@@ -121,6 +121,15 @@ macro_rules! gen_arithmetic_functions {
                 pub fn binary_xor(x: $arg_type, y: $arg_type) -> $arg_type {
                     x ^ y
                 }
+                pub fn is_zero(x: $arg_type) -> bool {
+                    x == 0
+                }
+                pub fn is_odd(x: $arg_type) -> bool {
+                    x % 2 != 0
+                }
+                pub fn is_even(x: $arg_type) -> bool {
+                    x % 2 == 0
+                }
             }
         })* }
     }
@@ -174,6 +183,7 @@ macro_rules! reg_functions {
 }
 
 def_package!(crate:ArithmeticPackage:"Basic arithmetic", lib, {
+    combine_with_exported_module!(lib, "int", int_functions);
     reg_functions!(lib += signed_basic; INT);
 
     #[cfg(not(feature = "only_i32"))]
@@ -201,6 +211,19 @@ def_package!(crate:ArithmeticPackage:"Basic arithmetic", lib, {
     combine_with_exported_module!(lib, "decimal", decimal_functions);
 });
 
+#[export_module]
+mod int_functions {
+    pub fn is_zero(x: INT) -> bool {
+        x == 0
+    }
+    pub fn is_odd(x: INT) -> bool {
+        x % 2 != 0
+    }
+    pub fn is_even(x: INT) -> bool {
+        x % 2 == 0
+    }
+}
+
 gen_arithmetic_functions!(arith_basic => INT);
 
 #[cfg(not(feature = "only_i32"))]
@@ -315,6 +338,9 @@ mod f32_functions {
             1
         }
     }
+    pub fn is_zero(x: f32) -> bool {
+        x == 0.0
+    }
     #[rhai_fn(name = "**", return_raw)]
     pub fn pow_f_i(x: f32, y: INT) -> Result<f32, Box<EvalAltResult>> {
         if cfg!(not(feature = "unchecked")) && y > (i32::MAX as INT) {
@@ -420,6 +446,9 @@ mod f64_functions {
             1
         }
     }
+    pub fn is_zero(x: f64) -> bool {
+        x == 0.0
+    }
 }
 
 #[cfg(feature = "decimal")]
@@ -511,4 +540,7 @@ pub mod decimal_functions {
             1
         }
     }
+    pub fn is_zero(x: Decimal) -> bool {
+        x.is_zero()
+    }
 }