1 files changed, 115 insertions, 0 deletions
diff --git a/src/mongo/db/pipeline/field_path.h b/src/mongo/db/pipeline/field_path.h
new file mode 100755
index 00000000000..c3b9aa2a22c
--- /dev/null
+++ b/src/mongo/db/pipeline/field_path.h
@@ -0,0 +1,115 @@
+/**
+ * Copyright (c) 2011 10gen Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "mongo/pch.h"
+
+namespace mongo {
+
+    class FieldPath {
+    public:
+
+        /**
+         * Constructor.
+         *
+         * @param fieldPath the dotted field path string or non empty pre-split vector.
+         * The constructed object will have getPathLength() > 0.
+         * Uassert if any component field names do not pass validation.
+         */
+        FieldPath(const string& fieldPath);
+        FieldPath(const vector<string>& fieldPath);
+
+        /**
+          Get the number of path elements in the field path.
+
+          @returns the number of path elements
+         */
+        size_t getPathLength() const;
+
+        /**
+          Get a particular path element from the path.
+
+          @param i the zero based index of the path element.
+          @returns the path element
+         */
+        string getFieldName(size_t i) const;
+
+        /**
+          Get the full path.
+
+          @param fieldPrefix whether or not to include the field prefix
+          @returns the complete field path
+         */
+        string getPath(bool fieldPrefix) const;
+
+        /**
+          Write the full path.
+
+          @param outStream where to write the path to
+          @param fieldPrefix whether or not to include the field prefix
+        */
+        void writePath(ostream &outStream, bool fieldPrefix) const;
+
+        /**
+           Get the prefix string.
+
+           @returns the prefix string
+         */
+        static const char *getPrefix();
+
+        static const char prefix[];
+
+        /**
+         * A FieldPath like this but missing the first element (useful for recursion).
+         * Precondition getPathLength() > 1.
+         */
+        FieldPath tail() const;
+
+    private:
+        /** Uassert if a field name does not pass validation. */
+        static void uassertValidFieldName(const string& fieldName);
+
+        /**
+         * Push a new field name to the back of the vector of names comprising the field path.
+         * Uassert if 'fieldName' does not pass validation.
+         */
+        void pushFieldName(const string& fieldName);
+
+        vector<string> vFieldName;
+    };
+}
+
+
+/* ======================= INLINED IMPLEMENTATIONS ========================== */
+
+namespace mongo {
+
+    inline size_t FieldPath::getPathLength() const {
+        return vFieldName.size();
+    }
+
+    inline string FieldPath::getFieldName(size_t i) const {
+        verify(i < getPathLength());
+        return vFieldName[i];
+    }
+
+    inline const char *FieldPath::getPrefix() {
+        return prefix;
+    }
+
+}
+