Make the compile function plain C and take a JSON grammar

src/compiler/compile.h

@@ -0,0 +1,16 @@
+#ifndef COMPILER_COMPILE_H_
+#define COMPILER_COMPILE_H_
+
+#include <string>
+#include <utility>
+#include "compiler/compile_error.h"
+
+namespace tree_sitter {
+
+struct Grammar;
+
+std::pair<std::string, CompileError> compile(const Grammar &, std::string);
+
+}  // namespace tree_sitter
+
+#endif  // COMPILER_COMPILE_H_