Allow the flatbuffer compiler (flatc) to be built as a library.

Change-Id: I71baff427243f96be1596b01ff3405fdf39386d7

include/flatbuffers/flatc.h

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "flatbuffers/flatbuffers.h"
+#include "flatbuffers/idl.h"
+#include "flatbuffers/util.h"
+#include <functional>
+#include <limits>
+#include <string>
+
+#ifndef FLATC_H_
+#define FLATC_H_
+
+namespace flatbuffers {
+
+class FlatCompiler {
+ public:
+  // Output generator for the various programming languages and formats we
+  // support.
+  struct Generator {
+    typedef bool (*GenerateFn)(const flatbuffers::Parser &parser,
+                               const std::string &path,
+                               const std::string &file_name);
+    typedef std::string (*MakeRuleFn)(const flatbuffers::Parser &parser,
+                                      const std::string &path,
+                                      const std::string &file_name);
+
+    GenerateFn generate;
+    const char *generator_opt_short;
+    const char *generator_opt_long;
+    const char *lang_name;
+    GenerateFn generateGRPC;
+    flatbuffers::IDLOptions::Language lang;
+    const char *generator_help;
+    MakeRuleFn make_rule;
+  };
+
+  typedef void (*WarnFn)(const FlatCompiler *flatc,
+                         const std::string &warn,
+                         bool show_exe_name);
+
+  typedef void (*ErrorFn)(const FlatCompiler *flatc,
+                          const std::string &err,
+                          bool usage, bool show_exe_name);
+
+  // Parameters required to initialize the FlatCompiler.
+  struct InitParams {
+    InitParams()
+        : generators(nullptr),
+          num_generators(0),
+          warn_fn(nullptr),
+          error_fn(nullptr) {}
+
+    const Generator* generators;
+    size_t num_generators;
+    WarnFn warn_fn;
+    ErrorFn error_fn;
+  };
+
+  explicit FlatCompiler(const InitParams& params) : params_(params) {}
+
+  int Compile(int argc, const char** argv);
+
+  std::string GetUsageString(const char* program_name) const;
+
+ private:
+  void ParseFile(flatbuffers::Parser &parser,
+                 const std::string &filename,
+                 const std::string &contents,
+                 std::vector<const char *> &include_directories) const;
+
+  void Warn(const std::string &warn, bool show_exe_name = true) const;
+
+  void Error(const std::string &err, bool usage = true,
+             bool show_exe_name = true) const;
+
+  InitParams params_;
+};
+
+
+}  // namespace flatbuffers
+
+#endif  // FLATC_H_