Factor out a base class of ManifestParser

Create a Parser base class that holds parser functionality not specific
to the build manifest file format.  This will allow it to be re-used for
other parsers later.

1 files changed, 50 insertions, 0 deletions

diff --git a/src/parser.h b/src/parser.h
new file mode 100644
index 0000000..e2d2b97
--- /dev/null
+++ b/src/parser.h
@@ -0,0 +1,50 @@
+// Copyright 2018 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.
+
+#ifndef NINJA_PARSER_H_
+#define NINJA_PARSER_H_
+
+#include <string>
+
+using namespace std;
+
+#include "lexer.h"
+
+struct FileReader;
+struct State;
+
+/// Base class for parsers.
+struct Parser {
+  Parser(State* state, FileReader* file_reader)
+      : state_(state), file_reader_(file_reader) {}
+
+  /// Load and parse a file.
+  bool Load(const string& filename, string* err, Lexer* parent = NULL);
+
+protected:
+  /// If the next token is not \a expected, produce an error string
+  /// saying "expected foo, got bar".
+  bool ExpectToken(Lexer::Token expected, string* err);
+
+  State* state_;
+  FileReader* file_reader_;
+  Lexer lexer_;
+
+private:
+  /// Parse a file, given its contents as a string.
+  virtual bool Parse(const string& filename, const string& input,
+                     string* err) = 0;
+};
+
+#endif  // NINJA_PARSER_H_