first commit

third_party/yaml-cpp/util/read.cpp

@@ -0,0 +1,103 @@
+#include "yaml-cpp/emitterstyle.h"
+#include "yaml-cpp/eventhandler.h"
+#include "yaml-cpp/yaml.h"  // IWYU pragma: keep
+
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+
+class NullEventHandler : public YAML::EventHandler {
+ public:
+  using Mark = YAML::Mark;
+  using anchor_t = YAML::anchor_t;
+
+  NullEventHandler() = default;
+
+  void OnDocumentStart(const Mark&) override {}
+  void OnDocumentEnd() override {}
+  void OnNull(const Mark&, anchor_t) override {}
+  void OnAlias(const Mark&, anchor_t) override {}
+  void OnScalar(const Mark&, const std::string&, anchor_t,
+                const std::string&) override {}
+  void OnSequenceStart(const Mark&, const std::string&, anchor_t,
+                       YAML::EmitterStyle::value style) override {}
+  void OnSequenceEnd() override {}
+  void OnMapStart(const Mark&, const std::string&, anchor_t,
+                  YAML::EmitterStyle::value style) override {}
+  void OnMapEnd() override {}
+};
+
+void run(std::istream& in) {
+  YAML::Parser parser(in);
+  NullEventHandler handler;
+  parser.HandleNextDocument(handler);
+}
+
+void usage() { std::cerr << "Usage: read [-n N] [-c, --cache] [filename]\n"; }
+
+std::string read_stream(std::istream& in) {
+  return std::string((std::istreambuf_iterator<char>(in)),
+                     std::istreambuf_iterator<char>());
+}
+
+int main(int argc, char** argv) {
+  int N = 1;
+  bool cache = false;
+  std::string filename;
+  for (int i = 1; i < argc; i++) {
+    std::string arg = argv[i];
+    if (arg == "-n") {
+      i++;
+      if (i >= argc) {
+        usage();
+        return -1;
+      }
+      N = std::atoi(argv[i]);
+      if (N <= 0) {
+        usage();
+        return -1;
+      }
+    } else if (arg == "-c" || arg == "--cache") {
+      cache = true;
+    } else {
+      filename = argv[i];
+      if (i + 1 != argc) {
+        usage();
+        return -1;
+      }
+    }
+  }
+
+  if (N > 1 && !cache && filename.empty()) {
+    usage();
+    return -1;
+  }
+
+  if (cache) {
+    std::string input;
+    if (!filename.empty()) {
+      std::ifstream in(filename);
+      input = read_stream(in);
+    } else {
+      input = read_stream(std::cin);
+    }
+    std::istringstream in(input);
+    for (int i = 0; i < N; i++) {
+      in.seekg(std::ios_base::beg);
+      run(in);
+    }
+  } else {
+    if (!filename.empty()) {
+      std::ifstream in(filename);
+      for (int i = 0; i < N; i++) {
+        in.seekg(std::ios_base::beg);
+        run(in);
+      }
+    } else {
+      for (int i = 0; i < N; i++) {
+        run(std::cin);
+      }
+    }
+  }
+  return 0;
+}