最近给xmake增加了一个新特性，对于一份工程源码，可以不用编写makefile，也不用编写各种make相关的工程描述文件（例如：xmake.lua，makefile.am, cmakelist.txt等）
xmake就可以直接编译他们，这是如何做到的呢，简单来说下实现原理：
首先扫描当前目录下，xmake所以支持的所有源代码文件
分析代码，检测哪些代码拥有main入口函数
所有没有main入口的代码编译成静态库
带有main入口的代码，编译成可执行程序，同时链接其他静态库程序
这种代码扫描和智能编译，非常简单，目前xmake还不支持多级目录扫描，只对单级目录的代码进行扫描编译。。
开源代码的移植和编译
虽然这种方式，并不是非常智能，限制也不少，但是对于想临时写些代码进行编译运行，或者临时想交叉编译一些简单的开源库代码
这种方式已经足够使用了，下面看下一个实际的例子：
我下载了一份zlib-1.2.10的源码，想要编译它，只需要进入zlib的源码目录执行：
$ cd zlib-1.2.10
$ xmake就行了，输出结果如下：
xmake.lua not found, scanning files ..
target(zlib-1.2): static
[+]: ./adler32.c
[+]: ./compress.c
[+]: ./crc32.c
[+]: ./deflate.c
[+]: ./gzclose.c
[+]: ./gzlib.c
[+]: ./gzread.c
[+]: ./gzwrite.c
[+]: ./infback.c
[+]: ./inffast.c
[+]: ./inflate.c
[+]: ./inftrees.c
[+]: ./trees.c
[+]: ./uncompr.c
[+]: ./zutil.c
xmake.lua generated, scan ok!?
checking for the architecture ... x86_64
checking for the Xcode SDK version for macosx ... 10.12
checking for the target minimal version ... 10.12
checking for the c compiler (cc) ... xcrun -sdk macosx clang
checking for the c++ compiler (cxx) ... xcrun -sdk macosx clang
checking for the objc compiler (mm) ... xcrun -sdk macosx clang
checking for the objc++ compiler (mxx) ... xcrun -sdk macosx clang++
checking for the swift compiler (sc) ... xcrun -sdk macosx swiftc
checking for the assember (as) ... xcrun -sdk macosx clang
checking for the linker (ld) ... xcrun -sdk macosx clang++
checking for the static library archiver (ar) ... xcrun -sdk macosx ar
checking for the static library extractor (ex) ... xcrun -sdk macosx ar
checking for the shared library linker (sh) ... xcrun -sdk macosx clang++
checking for the debugger (dd) ... xcrun -sdk macosx lldb
checking for the golang compiler (go) ... go
configure
{
ex = "xcrun -sdk macosx ar"
, sh = "xcrun -sdk macosx clang++"
, host = "macosx"
, ar = "xcrun -sdk macosx ar"
, buildir = "build"
, as = "xcrun -sdk macosx clang"
, plat = "macosx"
, xcode_dir = "/Applications/Xcode.app"
, arch = "x86_64"
, mxx = "xcrun -sdk macosx clang++"
, go = "go"
, target_minver = "10.12"
, ccache = "ccache"
, mode = "release"
, clean = true
, cxx = "xcrun -sdk macosx clang"
, cc = "xcrun -sdk macosx clang"
, dd = "xcrun -sdk macosx lldb"
, kind = "static"
, ld = "xcrun -sdk macosx clang++"
, xcode_sdkver = "10.12"
, sc = "xcrun -sdk macosx swiftc"
, mm = "xcrun -sdk macosx clang"
}
configure ok!
clean ok!
[00%]: ccache compiling.release ./adler32.c
[06%]: ccache compiling.release ./compress.c
[13%]: ccache compiling.release ./crc32.c
[20%]: ccache compiling.release ./deflate.c
[26%]: ccache compiling.release ./gzclose.c
[33%]: ccache compiling.release ./gzlib.c
[40%]: ccache compiling.release ./gzread.c
[46%]: ccache compiling.release ./gzwrite.c
[53%]: ccache compiling.release ./infback.c
[60%]: ccache compiling.release ./inffast.c
[66%]: ccache compiling.release ./inflate.c
[73%]: ccache compiling.release ./inftrees.c
[80%]: ccache compiling.release ./trees.c
[86%]: ccache compiling.release ./uncompr.c
[93%]: ccache compiling.release ./zutil.c
[100%]: archiving.release libzlib-1.2.a
build ok!?通过输出结果，可以看到，xmake会去检测扫描当前目录下的所有.c代码，发现没有main入口，应该是静态库程序，因此执行xmake后，就直接编译成静态库libzlib-1.2.a了
连xmake.lua都没有编写，其实xmake在扫描完成后，会去自动在当前目录下生成一份xmake.lua，下次编译就不需要重新扫描检测了。
自动生成的xmake.lua内容如下：
-- define target
target("zlib-1.2")
-- set kind
set_kind("static")
-- add files
add_files("./adler32.c")
add_files("./compress.c")
add_files("./crc32.c")
add_files("./deflate.c")
add_files("./gzclose.c")
add_files("./gzlib.c")
add_files("./gzread.c")
add_files("./gzwrite.c")
add_files("./infback.c")
add_files("./inffast.c")
add_files("./inflate.c")
add_files("./inftrees.c")
add_files("./trees.c")
add_files("./uncompr.c")
add_files("./zutil.c")也许你会说，像这种开源库，直接configure; make不就好了吗，他们自己也有提供makefile来直接编译的，的确是这样，我这里只是举个例子而已。。
当然，很多开源库在交叉编译的时候，通过自带的configure，处理起来还是很繁琐的，用xmake进行交叉编译会更方便些。。
即时地代码编写和编译运行
xmake的这个扫描代码编译特性，主要的目的：还是为了让我们在临时想写些测试代码的时候，不用考虑太多东西，直接上手敲代码，然后快速执行xmake run 来调试验证结果。。
例如：
我想写了个简单的main.c的测试程序，打印hello world!，如果要写makefile或者直接通过gcc命令来，就很繁琐了，你需要：
gcc ./main.c -o demo
./demo最快速的方式，也需要执行两行命令，而如果用xmake，只需要执行：
xmake run就行了，它会自动检测到代码后，自动生成对应的xmake.lua，自动编译，自动运行，然后输出：
hello world!如果你有十几个代码文件，用手敲gcc的方式，或者写makefile的方式，这个差距就更明显了，用xmake还是只需要一行命令：
xmake run多语言支持
这种代码检测和即时编译，是支持多语言的，不仅支持c/c++，还支持objc/swift，后期还会支持golang（正在开发中）
例如我下载了一份fmdb的ios开源框架代码：
.
├── FMDB.h
├── FMDatabase.h
├── FMDatabase.m
├── FMDatabaseAdditions.h
├── FMDatabaseAdditions.m
├── FMDatabasePool.h
├── FMDatabasePool.m
├── FMDatabaseQueue.h
├── FMDatabaseQueue.m
├── FMResultSet.h
└── FMResultSet.m想要把它编译成ios的静态库，但是又不想写xmake.lua，或者makefile，那么只需要使用xmake的这个新特性，直接执行：
$ xmake f -p iphoneos; xmake就行了，输出结果如下：
xmake.lua not found, scanning files ..
target(FMDB): static
[+]: ./FMDatabase.m
[+]: ./FMDatabaseAdditions.m
[+]: ./FMDatabasePool.m
[+]: ./FMDatabaseQueue.m
[+]: ./FMResultSet.m
xmake.lua generated, scan ok!?
checking for the architecture ... armv7
checking for the Xcode SDK version for iphoneos ... 10.1
checking for the target minimal version ... 10.1
checking for the c compiler (cc) ... xcrun -sdk iphoneos clang
checking for the c++ compiler (cxx) ... xcrun -sdk iphoneos clang
checking for the objc compiler (mm) ... xcrun -sdk iphoneos clang
checking for the objc++ compiler (mxx) ... xcrun -sdk iphoneos clang++
checking for the assember (as) ... gas-preprocessor.pl xcrun -sdk iphoneos clang
checking for the linker (ld) ... xcrun -sdk iphoneos clang++
checking for the static library archiver (ar) ... xcrun -sdk iphoneos ar
checking for the static library extractor (ex) ... xcrun -sdk iphoneos ar
checking for the shared library linker (sh) ... xcrun -sdk iphoneos clang++
checking for the swift compiler (sc) ... xcrun -sdk iphoneos swiftc
configure
{
ex = "xcrun -sdk iphoneos ar"
, ccache = "ccache"
, host = "macosx"
, ar = "xcrun -sdk iphoneos ar"
, buildir = "build"
, as = "/usr/local/share/xmake/tools/utils/gas-preprocessor.pl xcrun -sdk iphoneos clang"
, arch = "armv7"
, mxx = "xcrun -sdk iphoneos clang++"
, cxx = "xcrun -sdk iphoneos clang"
, target_minver = "10.1"
, xcode_dir = "/Applications/Xcode.app"
, clean = true
, sh = "xcrun -sdk iphoneos clang++"
, cc = "xcrun -sdk iphoneos clang"
, ld = "xcrun -sdk iphoneos clang++"
, mode = "release"
, kind = "static"
, plat = "iphoneos"
, xcode_sdkver = "10.1"
, sc = "xcrun -sdk iphoneos swiftc"
, mm = "xcrun -sdk iphoneos clang"
}
configure ok!
clean ok!
[00%]: ccache compiling.release ./FMDatabase.m
[20%]: ccache compiling.release ./FMDatabaseAdditions.m
[40%]: ccache compiling.release ./FMDatabasePool.m
[60%]: ccache compiling.release ./FMDatabaseQueue.m
[80%]: ccache compiling.release ./FMResultSet.m
[100%]: archiving.release libFMDB.a
build ok!?同时编译多个可执行文件
输出结果的开头部分，就是对代码的分析结果，虽然目前只支持单级目录结构的代码扫描，但是还是可以同时支持检测和编译多个可执行文件的
我们以libjpeg的开源库为例：
我们进入jpeg-6b目录后，执行：
$ xmake输出如下：
xmake.lua not found, scanning files ..
target(jpeg-6b): static
[+]: ./cdjpeg.c
[+]: ./example.c
[+]: ./jcapimin.c
[+]: ./jcapistd.c
[+]: ./jccoefct.c
[+]: ./jccolor.c
[+]: ./jcdctmgr.c
[+]: ./jchuff.c
[+]: ./jcinit.c
[+]: ./jcmainct.c
[+]: ./jcmarker.c
[+]: ./jcmaster.c
[+]: ./jcomapi.c
[+]: ./jcparam.c
[+]: ./jcphuff.c
[+]: ./jcprepct.c
[+]: ./jcsample.c
[+]: ./jctrans.c
[+]: ./jdapimin.c
[+]: ./jdapistd.c
[+]: ./jdatadst.c
[+]: ./jdatasrc.c
[+]: ./jdcoefct.c
[+]: ./jdcolor.c
[+]: ./jddctmgr.c
[+]: ./jdhuff.c
[+]: ./jdinput.c
[+]: ./jdmainct.c
[+]: ./jdmarker.c
[+]: ./jdmaster.c
[+]: ./jdmerge.c
[+]: ./jdphuff.c
[+]: ./jdpostct.c
[+]: ./jdsample.c
[+]: ./jdtrans.c
[+]: ./jerror.c
[+]: ./jfdctflt.c
[+]: ./jfdctfst.c
[+]: ./jfdctint.c
[+]: ./jidctflt.c
[+]: ./jidctfst.c
[+]: ./jidctint.c
[+]: ./jidctred.c
[+]: ./jmemansi.c
[+]: ./jmemmgr.c
[+]: ./jmemname.c
[+]: ./jmemnobs.c
[+]: ./jquant1.c
[+]: ./jquant2.c
[+]: ./jutils.c
[+]: ./rdbmp.c
[+]: ./rdcolmap.c
[+]: ./rdgif.c
[+]: ./rdppm.c
[+]: ./rdrle.c
[+]: ./rdswitch.c
[+]: ./rdtarga.c
[+]: ./transupp.c
[+]: ./wrbmp.c
[+]: ./wrgif.c
[+]: ./wrppm.c
[+]: ./wrrle.c
[+]: ./wrtarga.c
target(ansi2knr): binary
[+]: ./ansi2knr.c
target(cjpeg): binary
[+]: ./cjpeg.c
target(ckconfig): binary
[+]: ./ckconfig.c
target(djpeg): binary
[+]: ./djpeg.c
target(jpegtran): binary
[+]: ./jpegtran.c
target(rdjpgcom): binary
[+]: ./rdjpgcom.c
target(wrjpgcom): binary
[+]: ./wrjpgcom.c
xmake.lua generated, scan ok!?
checking for the architecture ... x86_64
checking for the Xcode SDK version for macosx ... 10.12
checking for the target minimal version ... 10.12
checking for the c compiler (cc) ... xcrun -sdk macosx clang
checking for the c++ compiler (cxx) ... xcrun -sdk macosx clang
checking for the objc compiler (mm) ... xcrun -sdk macosx clang
checking for the objc++ compiler (mxx) ... xcrun -sdk macosx clang++
checking for the swift compiler (sc) ... xcrun -sdk macosx swiftc
checking for the assember (as) ... xcrun -sdk macosx clang
checking for the linker (ld) ... xcrun -sdk macosx clang++
checking for the static library archiver (ar) ... xcrun -sdk macosx ar
checking for the static library extractor (ex) ... xcrun -sdk macosx ar
checking for the shared library linker (sh) ... xcrun -sdk macosx clang++
checking for the debugger (dd) ... xcrun -sdk macosx lldb
checking for the golang compiler (go) ... go
configure
{
ex = "xcrun -sdk macosx ar"
, sh = "xcrun -sdk macosx clang++"
, host = "macosx"
, ar = "xcrun -sdk macosx ar"
, buildir = "build"
, as = "xcrun -sdk macosx clang"
, plat = "macosx"
, xcode_dir = "/Applications/Xcode.app"
, arch = "x86_64"
, mxx = "xcrun -sdk macosx clang++"
, go = "go"
, target_minver = "10.12"
, ccache = "ccache"
, mode = "release"
, clean = true
, cxx = "xcrun -sdk macosx clang"
, cc = "xcrun -sdk macosx clang"
, dd = "xcrun -sdk macosx lldb"
, kind = "static"
, ld = "xcrun -sdk macosx clang++"
, xcode_sdkver = "10.12"
, sc = "xcrun -sdk macosx swiftc"
, mm = "xcrun -sdk macosx clang"
}
configure ok!
clean ok!
[00%]: ccache compiling.release ./cdjpeg.c
[00%]: ccache compiling.release ./example.c
[00%]: ccache compiling.release ./jcapimin.c
[00%]: ccache compiling.release ./jcapistd.c
[00%]: ccache compiling.release ./jccoefct.c
[00%]: ccache compiling.release ./jccolor.c
[01%]: ccache compiling.release ./jcdctmgr.c
[01%]: ccache compiling.release ./jchuff.c
[01%]: ccache compiling.release ./jcinit.c
[01%]: ccache compiling.release ./jcmainct.c
[01%]: ccache compiling.release ./jcmarker.c
[02%]: ccache compiling.release ./jcmaster.c
[02%]: ccache compiling.release ./jcomapi.c
[02%]: ccache compiling.release ./jcparam.c
[02%]: ccache compiling.release ./jcphuff.c
[02%]: ccache compiling.release ./jcprepct.c
[03%]: ccache compiling.release ./jcsample.c
[03%]: ccache compiling.release ./jctrans.c
[03%]: ccache compiling.release ./jdapimin.c
[03%]: ccache compiling.release ./jdapistd.c
[03%]: ccache compiling.release ./jdatadst.c
[04%]: ccache compiling.release ./jdatasrc.c
[04%]: ccache compiling.release ./jdcoefct.c
[04%]: ccache compiling.release ./jdcolor.c
[04%]: ccache compiling.release ./jddctmgr.c
[04%]: ccache compiling.release ./jdhuff.c
[05%]: ccache compiling.release ./jdinput.c
[05%]: ccache compiling.release ./jdmainct.c
[05%]: ccache compiling.release ./jdmarker.c
[05%]: ccache compiling.release ./jdmaster.c
[05%]: ccache compiling.release ./jdmerge.c
[06%]: ccache compiling.release ./jdphuff.c
[06%]: ccache compiling.release ./jdpostct.c
[06%]: ccache compiling.release ./jdsample.c
[06%]: ccache compiling.release ./jdtrans.c
[06%]: ccache compiling.release ./jerror.c
[07%]: ccache compiling.release ./jfdctflt.c
[07%]: ccache compiling.release ./jfdctfst.c
[07%]: ccache compiling.release ./jfdctint.c
[07%]: ccache compiling.release ./jidctflt.c
[07%]: ccache compiling.release ./jidctfst.c
[08%]: ccache compiling.release ./jidctint.c
[08%]: ccache compiling.release ./jidctred.c
[08%]: ccache compiling.release ./jmemansi.c
[08%]: ccache compiling.release ./jmemmgr.c
[08%]: ccache compiling.release ./jmemname.c
[09%]: ccache compiling.release ./jmemnobs.c
[09%]: ccache compiling.release ./jquant1.c
[09%]: ccache compiling.release ./jquant2.c
[09%]: ccache compiling.release ./jutils.c
[09%]: ccache compiling.release ./rdbmp.c
[10%]: ccache compiling.release ./rdcolmap.c
[10%]: ccache compiling.release ./rdgif.c
[10%]: ccache compiling.release ./rdppm.c
[10%]: ccache compiling.release ./rdrle.c
[10%]: ccache compiling.release ./rdswitch.c
[11%]: ccache compiling.release ./rdtarga.c
[11%]: ccache compiling.release ./transupp.c
[11%]: ccache compiling.release ./wrbmp.c
[11%]: ccache compiling.release ./wrgif.c
[11%]: ccache compiling.release ./wrppm.c
[12%]: ccache compiling.release ./wrrle.c
[12%]: ccache compiling.release ./wrtarga.c
[12%]: archiving.release libjpeg-6b.a
[12%]: ccache compiling.release ./wrjpgcom.c
[25%]: linking.release wrjpgcom
[25%]: ccache compiling.release ./ansi2knr.c
[37%]: linking.release ansi2knr
[37%]: ccache compiling.release ./jpegtran.c
[50%]: linking.release jpegtran
[50%]: ccache compiling.release ./djpeg.c
[62%]: linking.release djpeg
[62%]: ccache compiling.release ./ckconfig.c
[75%]: linking.release ckconfig
[75%]: ccache compiling.release ./rdjpgcom.c
[87%]: linking.release rdjpgcom
[87%]: ccache compiling.release ./cjpeg.c
[100%]: linking.release cjpeg
build ok!?可以看到，处理静态库，xmake还分析出了很多可执行的测试程序，剩下的代码统一编译成一个 libjpeg.a 的静态库，供哪些测试程序链接使用。。
target(ansi2knr): binary
[+]: ./ansi2knr.c
target(cjpeg): binary
[+]: ./cjpeg.c
target(ckconfig): binary
[+]: ./ckconfig.c
target(djpeg): binary
[+]: ./djpeg.c
target(jpegtran): binary
[+]: ./jpegtran.c
target(rdjpgcom): binary
[+]: ./rdjpgcom.c
target(wrjpgcom): binary
[+]: ./wrjpgcom.c遇到的一些问题和限制
当前xmake的这种自动分析检测还不是非常智能，对于：
需要特殊的编译选项
需要依赖其他目录的头文件搜索
需要分条件编译不同源文件
同目录需要生成多个静态库
需要多级目录支持的源码库
以上这些情况，xmake暂时还没发自动化的智能处理，其中限制1，2还是可以解决的，通过半手动的方式，例如：
$ xmake f --cxflags="" --ldflags="" --includedirs="" --linkdirs=""; xmake在自动检测编译的时候，手动配置这个源码工程需要的特殊编译选项，就可以直接通过编译了
而限制3，暂时只能通过删源代码来解决了，就像刚才编译jpeg的代码，其实它的目录下面同时存在了：
jmemdos.c
jmemmac.c
jmemansi.c其中两个是没法编译过的，需要删掉后才行。。
个人主页：TBOOX开源工程
原文出处：http://tboox.org/cn/2017/01/07/build-without-makefile/
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