Add initial prototype for the GN meta-buildsystem.

tools/gn/pattern.h

Index: tools/gn/pattern.h
diff --git a/tools/gn/pattern.h b/tools/gn/pattern.h
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+++ b/tools/gn/pattern.h
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+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef TOOLS_GN_PATTERN_H_
+#define TOOLS_GN_PATTERN_H_
+
+#include <string>
+#include <vector>
+
+#include "tools/gn/value.h"
+
+class Pattern {
+ public:
+  struct Subrange {
+    enum Type {
+      LITERAL,  // Matches exactly the contents of the string.
+      ANYTHING,  // * (zero or more chars).
+      PATH_BOUNDARY  // '/' or beginning of string.
+    };
+
+    Subrange(Type t, const std::string& l = std::string())
+        : type(t),
+          literal(l) {
+    }
+
+    // Returns the minimum number of chars that this subrange requires.
+    size_t MinSize() const {
+      switch (type) {
+        case LITERAL:
+          return literal.size();
+        case ANYTHING:
+          return 0;
+        case PATH_BOUNDARY:
+          return 0;  // Can match beginning or end of string, which is 0 len.
+        default:
+          return 0;
+      }
+    }
+
+    Type type;
+
+    // When type == LITERAL this is the text to match.
+    std::string literal;
+  };
+
+  Pattern(const std::string& s);
+  ~Pattern();
+
+  // Returns true if the current pattern matches the given string.
+  bool MatchesString(const std::string& s) const;
+
+ private:
+  // allow_implicit_path_boundary determines if a path boundary should accept
+  // matches at the beginning or end of the string.
+  bool RecursiveMatch(const std::string& s,
+                      size_t begin_char,
+                      size_t subrange_index,
+                      bool allow_implicit_path_boundary) const;
+
+  std::vector<Subrange> subranges_;
+
+  // Set to true when the subranges are "*foo" ("ANYTHING" followed by a
+  // literal). This covers most patterns so we optimize for this.
+  bool is_suffix_;
+};
+
+class PatternList {
+ public:
+  PatternList();
+  ~PatternList();
+
+  bool is_empty() const { return patterns_.empty(); }
+
+  // Initializes the pattern list from a give list of pattern strings. Sets
+  // |*err| on failure.
+  void SetFromValue(const Value& v, Err* err);
+
+  bool MatchesString(const std::string& s) const;
+  bool MatchesValue(const Value& v) const;
+
+ private:
+  std::vector<Pattern> patterns_;
+};
+
+#endif  // TOOLS_GN_PATTERN_H_