src/google/protobuf/compiler/parser.h

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.
// http://code.google.com/p/protobuf/
//
// 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.

// Author: kenton@google.com (Kenton Varda)
//  Based on original Protocol Buffers design by
//  Sanjay Ghemawat, Jeff Dean, and others.
//
// Implements parsing of .proto files to FileDescriptorProtos.

#ifndef GOOGLE_PROTOBUF_COMPILER_PARSER_H__
#define GOOGLE_PROTOBUF_COMPILER_PARSER_H__

#include <map>
#include <string>
#include <utility>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/descriptor.h>
#include <google/protobuf/descriptor.pb.h>
#include <google/protobuf/repeated_field.h>
#include <google/protobuf/io/tokenizer.h>

namespace google {
namespace protobuf { class Message; }

namespace protobuf {
namespace compiler {

// Defined in this file.
class Parser;
class SourceLocationTable;

// Implements parsing of protocol definitions (such as .proto files).
//
// Note that most users will be more interested in the Importer class.
// Parser is a lower-level class which simply converts a single .proto file
// to a FileDescriptorProto.  It does not resolve import directives or perform
// many other kinds of validation needed to construct a complete
// FileDescriptor.
class LIBPROTOBUF_EXPORT Parser {
 public:
  Parser();
  ~Parser();

  // Parse the entire input and construct a FileDescriptorProto representing
  // it.  Returns true if no errors occurred, false otherwise.
  bool Parse(io::Tokenizer* input, FileDescriptorProto* file);

  // Optional fetaures:

  // Requests that locations of certain definitions be recorded to the given
  // SourceLocationTable while parsing.  This can be used to look up exact line
  // and column numbers for errors reported by DescriptorPool during validation.
  // Set to NULL (the default) to discard source location information.
  void RecordSourceLocationsTo(SourceLocationTable* location_table) {
    source_location_table_ = location_table;
  }

  // Requsets that errors be recorded to the given ErrorCollector while
  // parsing.  Set to NULL (the default) to discard error messages.
  void RecordErrorsTo(io::ErrorCollector* error_collector) {
    error_collector_ = error_collector;
  }

  // Returns the identifier used in the "syntax = " declaration, if one was
  // seen during the last call to Parse(), or the empty string otherwise.
  const string& GetSyntaxIndentifier() { return syntax_identifier_; }

  // If set true, input files will be required to begin with a syntax
  // identifier.  Otherwise, files may omit this.  If a syntax identifier
  // is provided, it must be 'syntax = "proto2";' and must appear at the
  // top of this file regardless of whether or not it was required.
  void SetRequireSyntaxIdentifier(bool value) {
    require_syntax_identifier_ = value;
  }

 private:
  // =================================================================
  // Error recovery helpers

  // Consume the rest of the current statement.  This consumes tokens
  // until it sees one of:
  //   ';'  Consumes the token and returns.
  //   '{'  Consumes the brace then calls SkipRestOfBlock().
  //   '}'  Returns without consuming.
  //   EOF  Returns (can't consume).
  // The Parser often calls SkipStatement() after encountering a syntax
  // error.  This allows it to go on parsing the following lines, allowing
  // it to report more than just one error in the file.
  void SkipStatement();

  // Consume the rest of the current block, including nested blocks,
  // ending after the closing '}' is encountered and consumed, or at EOF.
  void SkipRestOfBlock();

  // -----------------------------------------------------------------
  // Single-token consuming helpers
  //
  // These make parsing code more readable.

  // True if the current token is TYPE_END.
  inline bool AtEnd();

  // True if the next token matches the given text.
  inline bool LookingAt(const char* text);
  // True if the next token is of the given type.
  inline bool LookingAtType(io::Tokenizer::TokenType token_type);

  // If the next token exactly matches the text given, consume it and return
  // true.  Otherwise, return false without logging an error.
  bool TryConsume(const char* text);

  // These attempt to read some kind of token from the input.  If successful,
  // they return true.  Otherwise they return false and add the given error
  // to the error list.

  // Consume a token with the exact text given.
  bool Consume(const char* text, const char* error);
  // Same as above, but automatically generates the error "Expected \"text\".",
  // where "text" is the expected token text.
  bool Consume(const char* text);
  // Consume a token of type IDENTIFIER and store its text in "output".
  bool ConsumeIdentifier(string* output, const char* error);
  // Consume an integer and store its value in "output".
  bool ConsumeInteger(int* output, const char* error);
  // Consume a 64-bit integer and store its value in "output".  If the value
  // is greater than max_value, an error will be reported.
  bool ConsumeInteger64(uint64 max_value, uint64* output, const char* error);
  // Consume a number and store its value in "output".  This will accept
  // tokens of either INTEGER or FLOAT type.
  bool ConsumeNumber(double* output, const char* error);
  // Consume a string literal and store its (unescaped) value in "output".
  bool ConsumeString(string* output, const char* error);

  // -----------------------------------------------------------------
  // Error logging helpers

  // Invokes error_collector_->AddError(), if error_collector_ is not NULL.
  void AddError(int line, int column, const string& error);

  // Invokes error_collector_->AddError() with the line and column number
  // of the current token.
  void AddError(const string& error);

  // Record the given line and column and associate it with this descriptor
  // in the SourceLocationTable.
  void RecordLocation(const Message* descriptor,
                      DescriptorPool::ErrorCollector::ErrorLocation location,
                      int line, int column);

  // Record the current line and column and associate it with this descriptor
  // in the SourceLocationTable.
  void RecordLocation(const Message* descriptor,
                      DescriptorPool::ErrorCollector::ErrorLocation location);

  // =================================================================
  // Parsers for various language constructs

  // Parses the "syntax = \"proto2\";" line at the top of the file.  Returns
  // false if it failed to parse or if the syntax identifier was not
  // recognized.
  bool ParseSyntaxIdentifier();

  // These methods parse various individual bits of code.  They return
  // false if they completely fail to parse the construct.  In this case,
  // it is probably necessary to skip the rest of the statement to recover.
  // However, if these methods return true, it does NOT mean that there
  // were no errors; only that there were no *syntax* errors.  For instance,
  // if a service method is defined using proper syntax but uses a primitive
  // type as its input or output, ParseMethodField() still returns true
  // and only reports the error by calling AddError().  In practice, this
  // makes logic much simpler for the caller.

  // Parse a top-level message, enum, service, etc.
  bool ParseTopLevelStatement(FileDescriptorProto* file);

  // Parse various language high-level language construrcts.
  bool ParseMessageDefinition(DescriptorProto* message);
  bool ParseEnumDefinition(EnumDescriptorProto* enum_type);
  bool ParseServiceDefinition(ServiceDescriptorProto* service);
  bool ParsePackage(FileDescriptorProto* file);
  bool ParseImport(string* import_filename);
  bool ParseOption(Message* options);

  // These methods parse the contents of a message, enum, or service type and
  // add them to the given object.  They consume the entire block including
  // the beginning and ending brace.
  bool ParseMessageBlock(DescriptorProto* message);
  bool ParseEnumBlock(EnumDescriptorProto* enum_type);
  bool ParseServiceBlock(ServiceDescriptorProto* service);

  // Parse one statement within a message, enum, or service block, inclunding
  // final semicolon.
  bool ParseMessageStatement(DescriptorProto* message);
  bool ParseEnumStatement(EnumDescriptorProto* message);
  bool ParseServiceStatement(ServiceDescriptorProto* message);

  // Parse a field of a message.  If the field is a group, its type will be
  // added to "messages".
  bool ParseMessageField(FieldDescriptorProto* field,
                         RepeatedPtrField<DescriptorProto>* messages);

  // Parse an "extensions" declaration.
  bool ParseExtensions(DescriptorProto* message);

  // Parse an "extend" declaration.
  bool ParseExtend(RepeatedPtrField<FieldDescriptorProto>* extensions,
                   RepeatedPtrField<DescriptorProto>* messages);

  // Parse a single enum value within an enum block.
  bool ParseEnumConstant(EnumValueDescriptorProto* enum_value);

  // Parse a single method within a service definition.
  bool ParseServiceMethod(MethodDescriptorProto* method);

  // Parse "required", "optional", or "repeated" and fill in "label"
  // with the value.
  bool ParseLabel(FieldDescriptorProto::Label* label);

  // Parse a type name and fill in "type" (if it is a primitive) or
  // "type_name" (if it is not) with the type parsed.
  bool ParseType(FieldDescriptorProto::Type* type,
                 string* type_name);
  // Parse a user-defined type and fill in "type_name" with the name.
  // If a primitive type is named, it is treated as an error.
  bool ParseUserDefinedType(string* type_name);

  // Parses field options, i.e. the stuff in square brackets at the end
  // of a field definition.  Also parses default value.
  bool ParseFieldOptions(FieldDescriptorProto* field);

  // Parse the "default" option.  This needs special handling because its
  // type is the field's type.
  bool ParseDefaultAssignment(FieldDescriptorProto* field);

  // Parse a single option name/value pair, e.g. "ctype = CORD".  The name
  // identifies a field of the given Message, and the value of that field
  // is set to the parsed value.
  bool ParseOptionAssignment(Message* options);

  // =================================================================

  io::Tokenizer* input_;
  io::ErrorCollector* error_collector_;
  SourceLocationTable* source_location_table_;
  bool had_errors_;
  bool require_syntax_identifier_;
  string syntax_identifier_;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Parser);
};

// A table mapping (descriptor, ErrorLocation) pairs -- as reported by
// DescriptorPool when validating descriptors -- to line and column numbers
// within the original source code.
class LIBPROTOBUF_EXPORT SourceLocationTable {
 public:
  SourceLocationTable();
  ~SourceLocationTable();

  // Finds the precise location of the given error and fills in *line and
  // *column with the line and column numbers.  If not found, sets *line to
  // -1 and *column to 0 (since line = -1 is used to mean "error has no exact
  // location" in the ErrorCollector interface).  Returns true if found, false
  // otherwise.
  bool Find(const Message* descriptor,
            DescriptorPool::ErrorCollector::ErrorLocation location,
            int* line, int* column) const;

  // Adds a location to the table.
  void Add(const Message* descriptor,
           DescriptorPool::ErrorCollector::ErrorLocation location,
           int line, int column);

  // Clears the contents of the table.
  void Clear();

 private:
  typedef map<
    pair<const Message*, DescriptorPool::ErrorCollector::ErrorLocation>,
    pair<int, int> > LocationMap;
  LocationMap location_map_;
};

}  // namespace compiler
}  // namespace protobuf

}  // namespace google
#endif  // GOOGLE_PROTOBUF_COMPILER_PARSER_H__