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最近给增加了一个新特性，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：
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。。
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.cxmake.lua generated, scan ok!��checking for the architecture ... x86_64checking for the Xcode SDK version for macosx ... 10.12checking for the target minimal version ... 10.12checking for the c compiler (cc) ... xcrun -sdk macosx clangchecking for the c++ compiler (cxx) ... xcrun -sdk macosx clangchecking for the objc compiler (mm) ... xcrun -sdk macosx clangchecking for the objc++ compiler (mxx) ... xcrun -sdk macosx clang++checking for the swift compiler (sc) ... xcrun -sdk macosx swiftcchecking for the assember (as) ... xcrun -sdk macosx clangchecking for the linker (ld) ... xcrun -sdk macosx clang++checking for the static library archiver (ar) ... xcrun -sdk macosx archecking for the static library extractor (ex) ... xcrun -sdk macosx archecking for the shared library linker (sh) ... xcrun -sdk macosx clang++checking for the debugger (dd) ... xcrun -sdk macosx lldbchecking for the golang compiler (go) ... goconfigure{ 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.abuild 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 targettarget("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。。
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
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.mxmake.lua generated, scan ok!��checking for the architecture ... armv7checking for the Xcode SDK version for iphoneos ... 10.1checking for the target minimal version ... 10.1checking for the c compiler (cc) ... xcrun -sdk iphoneos clangchecking for the c++ compiler (cxx) ... xcrun -sdk iphoneos clangchecking for the objc compiler (mm) ... xcrun -sdk iphoneos clangchecking for the objc++ compiler (mxx) ... xcrun -sdk iphoneos clang++checking for the assember (as) ... gas-preprocessor.pl xcrun -sdk iphoneos clangchecking for the linker (ld) ... xcrun -sdk iphoneos clang++checking for the static library archiver (ar) ... xcrun -sdk iphoneos archecking for the static library extractor (ex) ... xcrun -sdk iphoneos archecking for the shared library linker (sh) ... xcrun -sdk iphoneos clang++checking for the swift compiler (sc) ... xcrun -sdk iphoneos swiftcconfigure{ 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.abuild ok!�� 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.ctarget(ansi2knr): binary [+]: ./ansi2knr.ctarget(cjpeg): binary [+]: ./cjpeg.ctarget(ckconfig): binary [+]: ./ckconfig.ctarget(djpeg): binary [+]: ./djpeg.ctarget(jpegtran): binary [+]: ./jpegtran.ctarget(rdjpgcom): binary [+]: ./rdjpgcom.ctarget(wrjpgcom): binary [+]: ./wrjpgcom.cxmake.lua generated, scan ok!��checking for the architecture ... x86_64checking for the Xcode SDK version for macosx ... 10.12checking for the target minimal version ... 10.12checking for the c compiler (cc) ... xcrun -sdk macosx clangchecking for the c++ compiler (cxx) ... xcrun -sdk macosx clangchecking for the objc compiler (mm) ... xcrun -sdk macosx clangchecking for the objc++ compiler (mxx) ... xcrun -sdk macosx clang++checking for the swift compiler (sc) ... xcrun -sdk macosx swiftcchecking for the assember (as) ... xcrun -sdk macosx clangchecking for the linker (ld) ... xcrun -sdk macosx clang++checking for the static library archiver (ar) ... xcrun -sdk macosx archecking for the static library extractor (ex) ... xcrun -sdk macosx archecking for the shared library linker (sh) ... xcrun -sdk macosx clang++checking for the debugger (dd) ... xcrun -sdk macosx lldbchecking for the golang compiler (go) ... goconfigure{ 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 cjpegbuild 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.ctarget(cjpeg): binary [+]: ./cjpeg.ctarget(ckconfig): binary [+]: ./ckconfig.ctarget(djpeg): binary [+]: ./djpeg.ctarget(jpegtran): binary [+]: ./jpegtran.ctarget(rdjpgcom): binary [+]: ./rdjpgcom.ctarget(wrjpgcom): binary [+]: ./wrjpgcom.c
当前xmake的这种自动分析检测还不是非常智能，对于：
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.cjmemmac.cjmemansi.c
其中两个是没法编译过的，需要删掉后才行。。
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