diff options
Diffstat (limited to 'src/mongo/db/field_ref.h')
| -rw-r--r-- | src/mongo/db/field_ref.h | 307 |
1 files changed, 157 insertions, 150 deletions
diff --git a/src/mongo/db/field_ref.h b/src/mongo/db/field_ref.h index b22bfcb3da9..82116faf6fe 100644 --- a/src/mongo/db/field_ref.h +++ b/src/mongo/db/field_ref.h @@ -37,165 +37,172 @@ namespace mongo { +/** + * A FieldPath represents a path in a document, starting from the root. The path + * is made of "field parts" separated by dots. The class provides an efficient means to + * "split" the dotted fields in its parts, but no validation is done. + * + * Any field part may be replaced, after the "original" field reference was parsed. Any + * part can be accessed through a StringData object. + * + * The class is not thread safe. + */ +class FieldRef { + MONGO_DISALLOW_COPYING(FieldRef); + +public: + FieldRef(); + + explicit FieldRef(StringData path); + /** - * A FieldPath represents a path in a document, starting from the root. The path - * is made of "field parts" separated by dots. The class provides an efficient means to - * "split" the dotted fields in its parts, but no validation is done. - * - * Any field part may be replaced, after the "original" field reference was parsed. Any - * part can be accessed through a StringData object. - * - * The class is not thread safe. + * Field parts accessed through getPart() calls no longer would be valid, after the + * destructor ran. */ - class FieldRef { - MONGO_DISALLOW_COPYING(FieldRef); - public: - FieldRef(); - - explicit FieldRef(StringData path); - - /** - * Field parts accessed through getPart() calls no longer would be valid, after the - * destructor ran. - */ - ~FieldRef() {} - - /** - * Builds a field path out of each field part in 'dottedField'. - */ - void parse(StringData dottedField); - - /** - * Sets the 'i-th' field part to point to 'part'. Assumes i < size(). Behavior is - * undefined otherwise. - */ - void setPart(size_t i, StringData part); - - /** - * Returns the 'i-th' field part. Assumes i < size(). Behavior is undefined otherwise. - */ - StringData getPart(size_t i) const; - - /** - * Returns true when 'this' FieldRef is a prefix of 'other'. Equality is not considered - * a prefix. - */ - bool isPrefixOf( const FieldRef& other ) const; - - /** - * Returns the number of field parts in the prefix that 'this' and 'other' share. - */ - size_t commonPrefixSize( const FieldRef& other ) const; - - /** - * Returns a StringData of the full dotted field in its current state (i.e., some parts may - * have been replaced since the parse() call). - */ - StringData dottedField( size_t offsetFromStart = 0 ) const; - - /** - * Returns a StringData of parts of the dotted field from startPart to endPart in its - * current state (i.e., some parts may have been replaced since the parse() call). - */ - StringData dottedSubstring(size_t startPart, size_t endPart) const; - - /** - * Compares the full dotted path represented by this FieldRef to other - */ - bool equalsDottedField( StringData other ) const; - - /** - * Return 0 if 'this' is equal to 'other' lexicographically, -1 if is it less than or - * +1 if it is greater than. - */ - int compare( const FieldRef& other ) const; - - /** - * Resets the internal state. See note in parse() call. - */ - void clear(); - - // - // accessors - // - - /** - * Returns the number of parts in this FieldRef. - */ - size_t numParts() const { return _size; } - - bool empty() const { return numParts() == 0; } - - private: - // Dotted fields are most often not longer than four parts. We use a mixed structure - // here that will not require any extra memory allocation when that is the case. And - // handle larger dotted fields if it is. The idea is not to penalize the common case - // with allocations. - static const size_t kReserveAhead = 4; - - /** - * Parses 'path' into parts. - */ - void _parse(StringData path); - - /** Converts the field part index to the variable part equivalent */ - size_t getIndex(size_t i) const { return i-kReserveAhead; } - - /** - * Returns the new number of parts after appending 'part' to this field path. It - * assumes that 'part' is pointing to an internally allocated area. - */ - size_t appendPart(StringData part); - - /** - * Re-assemble _dotted from components, including any replacements in _replacements, - * and update the StringData components in _fixed and _variable to refer to the parts - * of the new _dotted. This is used to make the storage for the current value of this - * FieldRef contiguous so it can be returned as a StringData from the dottedField - * method above. - */ - void reserialize() const; - - // number of field parts stored - size_t _size; - - // first kResevedAhead field components - mutable StringData _fixed[kReserveAhead]; - - // remaining field components - mutable std::vector<StringData> _variable; - - // cached dotted name - mutable std::string _dotted; - - // back memory added with the setPart call pointed to by _fized and _variable - mutable std::vector<std::string> _replacements; - }; - - inline bool operator==(const FieldRef& lhs, const FieldRef& rhs) { - return lhs.compare(rhs) == 0; - } + ~FieldRef() {} - inline bool operator!=(const FieldRef& lhs, const FieldRef& rhs) { - return lhs.compare(rhs) != 0; - } + /** + * Builds a field path out of each field part in 'dottedField'. + */ + void parse(StringData dottedField); - inline bool operator<(const FieldRef& lhs, const FieldRef& rhs) { - return lhs.compare(rhs) < 0; - } + /** + * Sets the 'i-th' field part to point to 'part'. Assumes i < size(). Behavior is + * undefined otherwise. + */ + void setPart(size_t i, StringData part); + + /** + * Returns the 'i-th' field part. Assumes i < size(). Behavior is undefined otherwise. + */ + StringData getPart(size_t i) const; + + /** + * Returns true when 'this' FieldRef is a prefix of 'other'. Equality is not considered + * a prefix. + */ + bool isPrefixOf(const FieldRef& other) const; + + /** + * Returns the number of field parts in the prefix that 'this' and 'other' share. + */ + size_t commonPrefixSize(const FieldRef& other) const; + + /** + * Returns a StringData of the full dotted field in its current state (i.e., some parts may + * have been replaced since the parse() call). + */ + StringData dottedField(size_t offsetFromStart = 0) const; + + /** + * Returns a StringData of parts of the dotted field from startPart to endPart in its + * current state (i.e., some parts may have been replaced since the parse() call). + */ + StringData dottedSubstring(size_t startPart, size_t endPart) const; + + /** + * Compares the full dotted path represented by this FieldRef to other + */ + bool equalsDottedField(StringData other) const; + + /** + * Return 0 if 'this' is equal to 'other' lexicographically, -1 if is it less than or + * +1 if it is greater than. + */ + int compare(const FieldRef& other) const; + + /** + * Resets the internal state. See note in parse() call. + */ + void clear(); + + // + // accessors + // - inline bool operator<=(const FieldRef& lhs, const FieldRef& rhs) { - return lhs.compare(rhs) <= 0; + /** + * Returns the number of parts in this FieldRef. + */ + size_t numParts() const { + return _size; } - inline bool operator>(const FieldRef& lhs, const FieldRef& rhs) { - return lhs.compare(rhs) > 0; + bool empty() const { + return numParts() == 0; } - inline bool operator>=(const FieldRef& lhs, const FieldRef& rhs) { - return lhs.compare(rhs) >= 0; +private: + // Dotted fields are most often not longer than four parts. We use a mixed structure + // here that will not require any extra memory allocation when that is the case. And + // handle larger dotted fields if it is. The idea is not to penalize the common case + // with allocations. + static const size_t kReserveAhead = 4; + + /** + * Parses 'path' into parts. + */ + void _parse(StringData path); + + /** Converts the field part index to the variable part equivalent */ + size_t getIndex(size_t i) const { + return i - kReserveAhead; } - std::ostream& operator<<(std::ostream& stream, const FieldRef& value); + /** + * Returns the new number of parts after appending 'part' to this field path. It + * assumes that 'part' is pointing to an internally allocated area. + */ + size_t appendPart(StringData part); + + /** + * Re-assemble _dotted from components, including any replacements in _replacements, + * and update the StringData components in _fixed and _variable to refer to the parts + * of the new _dotted. This is used to make the storage for the current value of this + * FieldRef contiguous so it can be returned as a StringData from the dottedField + * method above. + */ + void reserialize() const; + + // number of field parts stored + size_t _size; + + // first kResevedAhead field components + mutable StringData _fixed[kReserveAhead]; + + // remaining field components + mutable std::vector<StringData> _variable; + + // cached dotted name + mutable std::string _dotted; + + // back memory added with the setPart call pointed to by _fized and _variable + mutable std::vector<std::string> _replacements; +}; + +inline bool operator==(const FieldRef& lhs, const FieldRef& rhs) { + return lhs.compare(rhs) == 0; +} + +inline bool operator!=(const FieldRef& lhs, const FieldRef& rhs) { + return lhs.compare(rhs) != 0; +} + +inline bool operator<(const FieldRef& lhs, const FieldRef& rhs) { + return lhs.compare(rhs) < 0; +} + +inline bool operator<=(const FieldRef& lhs, const FieldRef& rhs) { + return lhs.compare(rhs) <= 0; +} + +inline bool operator>(const FieldRef& lhs, const FieldRef& rhs) { + return lhs.compare(rhs) > 0; +} + +inline bool operator>=(const FieldRef& lhs, const FieldRef& rhs) { + return lhs.compare(rhs) >= 0; +} + +std::ostream& operator<<(std::ostream& stream, const FieldRef& value); -} // namespace mongo +} // namespace mongo |