openpilot v0.4.6 release

phonelibs/capnp-cpp/include/capnp/schema-parser.h

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+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef CAPNP_SCHEMA_PARSER_H_
+#define CAPNP_SCHEMA_PARSER_H_
+
+#if defined(__GNUC__) && !defined(CAPNP_HEADER_WARNINGS)
+#pragma GCC system_header
+#endif
+
+#include "schema-loader.h"
+#include <kj/string.h>
+
+namespace capnp {
+
+class ParsedSchema;
+class SchemaFile;
+
+class SchemaParser {
+  // Parses `.capnp` files to produce `Schema` objects.
+  //
+  // This class is thread-safe, hence all its methods are const.
+
+public:
+  SchemaParser();
+  ~SchemaParser() noexcept(false);
+
+  ParsedSchema parseDiskFile(kj::StringPtr displayName, kj::StringPtr diskPath,
+                             kj::ArrayPtr<const kj::StringPtr> importPath) const;
+  // Parse a file located on disk.  Throws an exception if the file dosen't exist.
+  //
+  // Parameters:
+  // * `displayName`:  The name that will appear in the file's schema node.  (If the file has
+  //   already been parsed, this will be ignored and the display name from the first time it was
+  //   parsed will be kept.)
+  // * `diskPath`:  The path to the file on disk.
+  // * `importPath`:  Directories to search when resolving absolute imports within this file
+  //   (imports that start with a `/`).  Must remain valid until the SchemaParser is destroyed.
+  //   (If the file has already been parsed, this will be ignored and the import path from the
+  //   first time it was parsed will be kept.)
+  //
+  // This method is a shortcut, equivalent to:
+  //     parser.parseFile(SchemaFile::newDiskFile(displayName, diskPath, importPath))`;
+  //
+  // This method throws an exception if any errors are encountered in the file or in anything the
+  // file depends on.  Note that merely importing another file does not count as a dependency on
+  // anything in the imported file -- only the imported types which are actually used are
+  // "dependencies".
+
+  ParsedSchema parseFile(kj::Own<SchemaFile>&& file) const;
+  // Advanced interface for parsing a file that may or may not be located in any global namespace.
+  // Most users will prefer `parseDiskFile()`.
+  //
+  // If the file has already been parsed (that is, a SchemaFile that compares equal to this one
+  // was parsed previously), the existing schema will be returned again.
+  //
+  // This method reports errors by calling SchemaFile::reportError() on the file where the error
+  // is located.  If that call does not throw an exception, `parseFile()` may in fact return
+  // normally.  In this case, the result is a best-effort attempt to compile the schema, but it
+  // may be invalid or corrupt, and using it for anything may cause exceptions to be thrown.
+
+  template <typename T>
+  inline void loadCompiledTypeAndDependencies() {
+    // See SchemaLoader::loadCompiledTypeAndDependencies().
+    getLoader().loadCompiledTypeAndDependencies<T>();
+  }
+
+private:
+  struct Impl;
+  class ModuleImpl;
+  kj::Own<Impl> impl;
+  mutable bool hadErrors = false;
+
+  ModuleImpl& getModuleImpl(kj::Own<SchemaFile>&& file) const;
+  SchemaLoader& getLoader();
+
+  friend class ParsedSchema;
+};
+
+class ParsedSchema: public Schema {
+  // ParsedSchema is an extension of Schema which also has the ability to look up nested nodes
+  // by name.  See `SchemaParser`.
+
+public:
+  inline ParsedSchema(): parser(nullptr) {}
+
+  kj::Maybe<ParsedSchema> findNested(kj::StringPtr name) const;
+  // Gets the nested node with the given name, or returns null if there is no such nested
+  // declaration.
+
+  ParsedSchema getNested(kj::StringPtr name) const;
+  // Gets the nested node with the given name, or throws an exception if there is no such nested
+  // declaration.
+
+private:
+  inline ParsedSchema(Schema inner, const SchemaParser& parser): Schema(inner), parser(&parser) {}
+
+  const SchemaParser* parser;
+  friend class SchemaParser;
+};
+
+// =======================================================================================
+// Advanced API
+
+class SchemaFile {
+  // Abstract interface representing a schema file.  You can implement this yourself in order to
+  // gain more control over how the compiler resolves imports and reads files.  For the
+  // common case of files on disk or other global filesystem-like namespaces, use
+  // `SchemaFile::newDiskFile()`.
+
+public:
+  class FileReader {
+  public:
+    virtual bool exists(kj::StringPtr path) const = 0;
+    virtual kj::Array<const char> read(kj::StringPtr path) const = 0;
+  };
+
+  class DiskFileReader final: public FileReader {
+    // Implementation of FileReader that uses the local disk.  Files are read using mmap() if
+    // possible.
+
+  public:
+    static const DiskFileReader instance;
+
+    bool exists(kj::StringPtr path) const override;
+    kj::Array<const char> read(kj::StringPtr path) const override;
+  };
+
+  static kj::Own<SchemaFile> newDiskFile(
+      kj::StringPtr displayName, kj::StringPtr diskPath,
+      kj::ArrayPtr<const kj::StringPtr> importPath,
+      const FileReader& fileReader = DiskFileReader::instance);
+  // Construct a SchemaFile representing a file on disk (or located in the filesystem-like
+  // namespace represented by `fileReader`).
+  //
+  // Parameters:
+  // * `displayName`:  The name that will appear in the file's schema node.
+  // * `diskPath`:  The path to the file on disk.
+  // * `importPath`:  Directories to search when resolving absolute imports within this file
+  //   (imports that start with a `/`).  The array content must remain valid as long as the
+  //   SchemaFile exists (which is at least as long as the SchemaParser that parses it exists).
+  // * `fileReader`:  Allows you to use a filesystem other than the actual local disk.  Although,
+  //   if you find yourself using this, it may make more sense for you to implement SchemaFile
+  //   yourself.
+  //
+  // The SchemaFile compares equal to any other SchemaFile that has exactly the same disk path,
+  // after canonicalization.
+  //
+  // The SchemaFile will throw an exception if any errors are reported.
+
+  // -----------------------------------------------------------------
+  // For more control, you can implement this interface.
+
+  virtual kj::StringPtr getDisplayName() const = 0;
+  // Get the file's name, as it should appear in the schema.
+
+  virtual kj::Array<const char> readContent() const = 0;
+  // Read the file's entire content and return it as a byte array.
+
+  virtual kj::Maybe<kj::Own<SchemaFile>> import(kj::StringPtr path) const = 0;
+  // Resolve an import, relative to this file.
+  //
+  // `path` is exactly what appears between quotes after the `import` keyword in the source code.
+  // It is entirely up to the `SchemaFile` to decide how to map this to another file.  Typically,
+  // a leading '/' means that the file is an "absolute" path and is searched for in some list of
+  // schema file repositories.  On the other hand, a path that doesn't start with '/' is relative
+  // to the importing file.
+
+  virtual bool operator==(const SchemaFile& other) const = 0;
+  virtual bool operator!=(const SchemaFile& other) const = 0;
+  virtual size_t hashCode() const = 0;
+  // Compare two SchemaFiles to see if they refer to the same underlying file.  This is an
+  // optimization used to avoid the need to re-parse a file to check its ID.
+
+  struct SourcePos {
+    uint byte;
+    uint line;
+    uint column;
+  };
+  virtual void reportError(SourcePos start, SourcePos end, kj::StringPtr message) const = 0;
+  // Report that the file contains an error at the given interval.
+
+private:
+  class DiskSchemaFile;
+};
+
+}  // namespace capnp
+
+#endif  // CAPNP_SCHEMA_PARSER_H_