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.

configure.py

@@ -504,6 +504,7 @@ for name in ['build',
              'line_printer',
              'manifest_parser',
              'metrics',
+             'parser',
              'state',
              'string_piece_util',
              'util',

src/manifest_parser.cc

@@ -18,41 +18,18 @@
 #include <stdlib.h>
 #include <vector>
 
-#include "disk_interface.h"
 #include "graph.h"
-#include "metrics.h"
 #include "state.h"
 #include "util.h"
 #include "version.h"
 
 ManifestParser::ManifestParser(State* state, FileReader* file_reader,
                                ManifestParserOptions options)
-    : state_(state), file_reader_(file_reader),
+    : Parser(state, file_reader),
       options_(options), quiet_(false) {
   env_ = &state->bindings_;
 }
 
-bool ManifestParser::Load(const string& filename, string* err, Lexer* parent) {
-  METRIC_RECORD(".ninja parse");
-  string contents;
-  string read_err;
-  if (file_reader_->ReadFile(filename, &contents, &read_err) != FileReader::Okay) {
-    *err = "loading '" + filename + "': " + read_err;
-    if (parent)
-      parent->Error(string(*err), err);
-    return false;
-  }
-
-  // The lexer needs a nul byte at the end of its input, to know when it's done.
-  // It takes a StringPiece, and StringPiece's string constructor uses
-  // string::data().  data()'s return value isn't guaranteed to be
-  // null-terminated (although in practice - libc++, libstdc++, msvc's stl --
-  // it is, and C++11 demands that too), so add an explicit nul byte.
-  contents.resize(contents.size() + 1);
-
-  return Parse(filename, contents, err);
-}
-
 bool ManifestParser::Parse(const string& filename, const string& input,
                            string* err) {
   lexer_.Start(filename, input);
@@ -434,14 +411,3 @@ bool ManifestParser::ParseFileInclude(bool new_scope, string* err) {
 
   return true;
 }
-
-bool ManifestParser::ExpectToken(Lexer::Token expected, string* err) {
-  Lexer::Token token = lexer_.ReadToken();
-  if (token != expected) {
-    string message = string("expected ") + Lexer::TokenName(expected);
-    message += string(", got ") + Lexer::TokenName(token);
-    message += Lexer::TokenErrorHint(expected);
-    return lexer_.Error(message, err);
-  }
-  return true;
-}

src/manifest_parser.h

@@ -15,16 +15,10 @@
 #ifndef NINJA_MANIFEST_PARSER_H_
 #define NINJA_MANIFEST_PARSER_H_
 
-#include <string>
-
-using namespace std;
-
-#include "lexer.h"
+#include "parser.h"
 
 struct BindingEnv;
 struct EvalString;
-struct FileReader;
-struct State;
 
 enum DupeEdgeAction {
   kDupeEdgeActionWarn,
@@ -45,13 +39,10 @@ struct ManifestParserOptions {
 };
 
 /// Parses .ninja files.
-struct ManifestParser {
+struct ManifestParser : public Parser {
   ManifestParser(State* state, FileReader* file_reader,
                  ManifestParserOptions options = ManifestParserOptions());
 
-  /// Load and parse a file.
-  bool Load(const string& filename, string* err, Lexer* parent = NULL);
-
   /// Parse a text string of input.  Used by tests.
   bool ParseTest(const string& input, string* err) {
     quiet_ = true;
@@ -72,14 +63,7 @@ private:
   /// Parse either a 'subninja' or 'include' line.
   bool ParseFileInclude(bool new_scope, string* err);
 
-  /// 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_;
   BindingEnv* env_;
-  FileReader* file_reader_;
-  Lexer lexer_;
   ManifestParserOptions options_;
   bool quiet_;
 };

src/parser.cc

@@ -0,0 +1,51 @@
+// 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.
+
+#include "parser.h"
+
+#include "disk_interface.h"
+#include "metrics.h"
+
+bool Parser::Load(const string& filename, string* err, Lexer* parent) {
+  METRIC_RECORD(".ninja parse");
+  string contents;
+  string read_err;
+  if (file_reader_->ReadFile(filename, &contents, &read_err) !=
+      FileReader::Okay) {
+    *err = "loading '" + filename + "': " + read_err;
+    if (parent)
+      parent->Error(string(*err), err);
+    return false;
+  }
+
+  // The lexer needs a nul byte at the end of its input, to know when it's done.
+  // It takes a StringPiece, and StringPiece's string constructor uses
+  // string::data().  data()'s return value isn't guaranteed to be
+  // null-terminated (although in practice - libc++, libstdc++, msvc's stl --
+  // it is, and C++11 demands that too), so add an explicit nul byte.
+  contents.resize(contents.size() + 1);
+
+  return Parse(filename, contents, err);
+}
+
+bool Parser::ExpectToken(Lexer::Token expected, string* err) {
+  Lexer::Token token = lexer_.ReadToken();
+  if (token != expected) {
+    string message = string("expected ") + Lexer::TokenName(expected);
+    message += string(", got ") + Lexer::TokenName(token);
+    message += Lexer::TokenErrorHint(expected);
+    return lexer_.Error(message, err);
+  }
+  return true;
+}

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_