fix os.host and add is_host

2 files changed, 62 insertions, 11 deletions

diff --git a/docs/manual.md b/docs/manual.md
index 803eb0283..aed9bdfef 100644
--- a/docs/manual.md
+++ b/docs/manual.md
@@ -28,18 +28,19 @@ It's according to the following rules:
 
 Conditions are generally used to handle some special compilation platforms. 
 
-| 接口                      | 描述                                     | 支持版本 |
-| ------------------------- | ---------------------------------------- | -------- |
-| [is_os](#is_os)           | Is the current compilation system?       | >= 2.0.1 |
-| [is_arch](#is_arch)       | Is the current compilation architecture? | >= 2.0.1 |
-| [is_plat](#is_plat)       | Is the current compilation platform?     | >= 2.0.1 |
-| [is_mode](#is_mode)       | Is the current compilation mode?         | >= 2.0.1 |
-| [is_kind](#is_kind)       | Is the current target kind?              | >= 2.0.1 |
-| [is_option](#is_option)   | Is the given options enabled?            | >= 2.0.1 |
+| 接口                      | 描述                                      | 支持版本 |
+| ------------------------- | ----------------------------------------  | -------- |
+| [is_os](#is_os)           | Is the current compilation target system? | >= 2.0.1 |
+| [is_arch](#is_arch)       | Is the current compilation architecture?  | >= 2.0.1 |
+| [is_plat](#is_plat)       | Is the current compilation platform?      | >= 2.0.1 |
+| [is_host](#is_host)       | Is the current compilation host system?   | >= 2.1.4 |
+| [is_mode](#is_mode)       | Is the current compilation mode?          | >= 2.0.1 |
+| [is_kind](#is_kind)       | Is the current target kind?               | >= 2.0.1 |
+| [is_option](#is_option)   | Is the given options enabled?             | >= 2.0.1 |
 
 ##### is_os 
 
-###### Is the current compilation system
+###### Is the current compilation target system
 
 ```lua
 if is_os("ios") then
@@ -110,6 +111,30 @@ Support platforms:
 * iphoneos
 * watchos
 
+##### is_host
+
+###### Is the current compilation host system
+
+Some compilation platforms can be built on multiple different operating systems, for example: android ndk (on linux, macOS and windows).
+
+So, we can use this api to determine the current host operating system.
+
+```lua
+if is_host("windows") then
+    add_includes("C:\\includes")
+else
+    add_includes("/usr/includess")
+end
+```
+
+Support hosts:
+
+* windows
+* linux
+* macosx
+
+We can also get it from [$(host)](#var-host) or [os.host](#os-host).
+
 ##### is_mode
 
 ###### Is the current compilation mode
diff --git a/docs/zh/manual.md b/docs/zh/manual.md
index d7a4d9b7d..63c6f7f0d 100755
--- a/docs/zh/manual.md
+++ b/docs/zh/manual.md
@@ -30,16 +30,17 @@ search: zh
 
 | 接口                      | 描述                          | 支持版本 |
 | ------------------------- | ----------------------------- | -------- |
-| [is_os](#is_os)           | 判断当前构建的操作系统        | >= 2.0.1 |
+| [is_os](#is_os)           | 判断当前构建目标的操作系统    | >= 2.0.1 |
 | [is_arch](#is_arch)       | 判断当前编译架构              | >= 2.0.1 |
 | [is_plat](#is_plat)       | 判断当前编译平台              | >= 2.0.1 |
+| [is_host](#is_host)       | 判断当前主机环境操作系统      | >= 2.1.4 |
 | [is_mode](#is_mode)       | 判断当前编译模式              | >= 2.0.1 |
 | [is_kind](#is_kind)       | 判断当前编译类型              | >= 2.0.1 |
 | [is_option](#is_option)   | 判断选项是否启用              | >= 2.0.1 |
 
 ##### is_os 
 
-###### 判断当前构建的操作系统
+###### 判断当前构建目标的操作系统
 
 ```lua
 -- 如果当前操作系统是ios
@@ -115,6 +116,31 @@ end
 
 当然你也可以自己扩展添加自己的平台。。。
 
+##### is_host
+
+###### 判断当前主机环境的操作系统
+
+有些编译平台是可以在多个不同的操作系统进行构建的，例如：android的ndk就支持linux,macOS还有windows环境。
+
+这个时候就可以通过这个接口，区分当前是在哪个系统环境下进行的构建。
+
+```lua
+-- 如果当前主机环境是windows
+if is_host("windows") then
+    add_includes("C:\\includes")
+else
+    add_includes("/usr/includess")
+end
+```
+
+目前支持的主机环境有：
+
+* windows
+* linux
+* macosx
+
+你也可以通过[$(host)](#var-host)内置变量或者[os.host](#os-host)接口，来进行获取
+
 ##### is_mode
 
 ###### 判断当前编译模式