C库来解析大致的日期

Question

我正在为date.js 寻找一个简单的C对应物date.parse().

也就是说,将"一周前"或"昨天"理解为输入的东西.只有英语才行.

注意:库不应该根据GPL许可,因此date.cGNU的Git 或解析器date -d不会.顺便说一句,如果你想知道我为什么不坐下来编写代码,那么去看看提到的库的来源......

Answer 1

以下解决方案并不完全是您所要求的,但我希望尽管不是简单的C答案,但它将满足您的需求.重新发明轮子不是一种方法,所以让我们使用Mac中的date.js,使用Mozilla JavaScript引擎SpiderMonkey运行它.

这就是我做到的.我已经开始下载date.js并将其翻译成一个const char*名为的code定义date.js.h.

( \
  echo 'const char *code =' ; \
  curl https://datejs.googlecode.com/files/date.js | \
    sed -e 's/\\/\\\\/g; s/"/\\"/g; s/^/"/; s/\r\?$/\\n"/'; \
  echo ';' \
) > date.js.h

然后我拿了JSAPI的Hello,World!作为一个起点.

#include "jsapi.h"
#include "date.js.h"

static JSClass global_class = { "global", JSCLASS_GLOBAL_FLAGS,
  JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_StrictPropertyStub,
  JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, JS_FinalizeStub,
  JSCLASS_NO_OPTIONAL_MEMBERS };

void reportError(JSContext *cx, const char *message, JSErrorReport *report) {
  fprintf(stderr, "%s:%u:%s\n",
      report->filename ? report->filename : "<no filename>",
      (unsigned int) report->lineno, message);
}

int main(int argc, const char *argv[]) {
  JSRuntime *rt;
  JSContext *cx;
  JSObject *global;
  rt = JS_NewRuntime(8L * 1024L * 1024L);
  if (rt == NULL) return 1;
  cx = JS_NewContext(rt, 8192);
  if (cx == NULL) return 1;
  JS_SetOptions(cx, JSOPTION_VAROBJFIX | JSOPTION_JIT | JSOPTION_METHODJIT);
  JS_SetVersion(cx, JSVERSION_LATEST);
  JS_SetErrorReporter(cx, reportError);
  global = JS_NewCompartmentAndGlobalObject(cx, &global_class, NULL);
  if (global == NULL) return 1;
  if (!JS_InitStandardClasses(cx, global)) return 1;

  /* Here's where the interesting stuff is starting to take place.
   * Begin by evaluating sources of date.js */

  jsval out;
  if (!JS_EvaluateScript(cx, global, code, strlen(code), "code", 1, &out))
    return 1;

  /* Now create a call to Date.parse and evaluate it. The return value should
   * be a timestamp of a given date. If no errors occur convert the timestamp
   * to a double and print it. */

  const int buflen = 1024;
  char parse[buflen + 1];
  snprintf(parse, buflen, "Date.parse(\"%s\").getTime();", argv[1]);

  if (!JS_EvaluateScript(cx, global, parse, strlen(parse), "parse", 1, &out))
    return 1;

  double val;
  JS_ValueToNumber(cx, out, &val);
  printf("%i\n", (int) (val / 1000));

  /* Finally, clean everything up. */

  JS_DestroyContext(cx);
  JS_DestroyRuntime(rt);
  JS_ShutDown();
  return 0;
}

这是它在实践中的运作方式.

$ time ./parse "week ago"
1331938800
0.01user 0.00system 0:00.02elapsed 92%CPU (0avgtext+0avgdata 6168maxresident)k
0inputs+0outputs (0major+1651minor)pagefaults 0swaps
$ time ./parse yesterday
1332457200
0.01user 0.00system 0:00.02elapsed 84%CPU (0avgtext+0avgdata 6168maxresident)k
0inputs+0outputs (0major+1653minor)pagefaults 0swaps

正如您所看到的那样,它非常快,您可以通过重新使用最初创建的上下文来进行所有后续调用来显着提高其性能Date.parse.

说到许可问题,date.js可以根据MIT条款获得,SpiderMonkey可以在MPL 1.1,GPL 2.0或LGPL 2.1下获得.动态链接它可以满足非GPL要求.

TL; DR: git clone https://gist.github.com/2180739.git && cd 2180739 && make && ./parse yesterday