src/gromacs/utility/keyvaluetreetransform.h

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  35 /*! \libinternal \file
  36  * \brief
  37  * Declares utilities for transforming key-value trees.
  38  *
  39  * See \ref page_mdmodules for the main use case that these support.
  40  *
  41  * \author Teemu Murtola <teemu.murtola@gmail.com>
  42  * \inlibraryapi
  43  * \ingroup module_utility
  44  */
  45 #ifndef GMX_UTILITY_KEYVALUETREETRANSFORM_H
  46 #define GMX_UTILITY_KEYVALUETREETRANSFORM_H
  47
  48 #include <functional>
  49 #include <string>
  50 #include <typeindex>
  51 #include <vector>
  52
  53 #include "gromacs/utility/any.h"
  54 #include "gromacs/utility/classhelpers.h"
  55 #include "gromacs/utility/keyvaluetree.h"
  56
  57 namespace gmx
  58 {
  59
  60 class IKeyValueTreeErrorHandler;
  61 class KeyValueTreeObjectBuilder;
  62
  63 enum class StringCompareType;
  64
  65 class KeyValueTreeTransformResult;
  66 class KeyValueTreeTransformRuleBuilder;
  67 class KeyValueTreeTransformRulesScoped;
  68
  69 namespace internal
  70 {
  71 class KeyValueTreeTransformerImpl;
  72 }
  73
  74 /*! \libinternal \brief
  75  * Interface to declare rules for transforming key-value trees.
  76  *
  77  * This interface is used to add transformation rules for key-value trees.
  78  * A transformation is a set of rules that is used to map an input key-value
  79  * tree to an output key-value tree, with possible conversion steps performed
  80  * in the process.  Currently, each rule maps one item from the source tree to
  81  * one item in the target tree (it is possible to expand a single value into an
  82  * object with multiple properties).  See KeyValueTreeTransformRuleBuilder for
  83  * the kinds of rules currently supported.
  84  *
  85  * The main use currently is in converting flat-format mdp files to a
  86  * structured internal representation.
  87  *
  88  * \inlibraryapi
  89  * \ingroup module_utility
  90  */
  91 class IKeyValueTreeTransformRules
  92 {
  93 public:
  94     /*! \brief
  95      * Creates a new rule.
  96      *
  97      * Properties of the new rule must be specified using the returned
  98      * builder.
  99      */
 100     virtual KeyValueTreeTransformRuleBuilder addRule() = 0;
 101     /*! \brief
 102      * Creates a scoped set of rules, where all rules use a target sub-tree.
 103      *
 104      * \param[in] scope Prefix defining the scope in the target tree
 105      *
 106      * Any rules added to the returned scope will have `scope` prefixed to
 107      * their target paths, i.e., it is not possible to produce elements
 108      * outside the specified subtree.
 109      */
 110     virtual KeyValueTreeTransformRulesScoped scopedTransform(const KeyValueTreePath& scope) = 0;
 111
 112 protected:
 113     virtual ~IKeyValueTreeTransformRules();
 114 };
 115
 116 /*! \libinternal \brief
 117  * Helper object returned from IKeyValueTreeTransformRules::scopedTransform().
 118  *
 119  * \inlibraryapi
 120  * \ingroup module_utility
 121  */
 122 class KeyValueTreeTransformRulesScoped
 123 {
 124 public:
 125     //! Internal constructor for creating the scope.
 126     KeyValueTreeTransformRulesScoped(internal::KeyValueTreeTransformerImpl* impl,
 127                                      const KeyValueTreePath&                prefix);
 128     //! Supports returning the object from IKeyValueTreeTransformRules::scopedTransform().
 129     KeyValueTreeTransformRulesScoped(KeyValueTreeTransformRulesScoped&& other) noexcept;
 130     //! Supports returning the object from IKeyValueTreeTransformRules::scopedTransform().
 131     KeyValueTreeTransformRulesScoped& operator=(KeyValueTreeTransformRulesScoped&& other) noexcept;
 132     ~KeyValueTreeTransformRulesScoped();
 133
 134     //! Returns the interface for adding rules to this scope.
 135     IKeyValueTreeTransformRules* rules();
 136
 137 private:
 138     class Impl;
 139
 140     PrivateImplPointer<Impl> impl_;
 141 };
 142
 143 /*! \libinternal \brief
 144  * Provides methods to specify one transformation rule.
 145  *
 146  * \if internal
 147  * The builder is implemented as a set of nested objects, each of which is
 148  * provides methods for setting a particular property of the rule.  Setting a
 149  * property returns another object that has relevant methods for the context.
 150  * This provides some structure to the methods, and catches at least some types
 151  * of incorrect rules already at compile time.
 152  * Additionally, if you use an IDE with completion facilities, it can nicely
 153  * guide you through which values you need to specify.
 154  * All values are stored within the main builder object, and the rule is
 155  * created at the end of the statement.
 156  * \endif
 157  *
 158  * \inlibraryapi
 159  * \ingroup module_utility
 160  */
 161 class KeyValueTreeTransformRuleBuilder
 162 {
 163 public:
 164     /*! \internal \brief
 165      * Base class used for implementing parameter provider objects.
 166      */
 167     class Base
 168     {
 169     protected:
 170         //! Creates a parameter provider object within given builder.
 171         explicit Base(KeyValueTreeTransformRuleBuilder* builder) : builder_(builder) {}
 172
 173         //! The parent builder.
 174         KeyValueTreeTransformRuleBuilder* builder_;
 175     };
 176
 177     /*! \libinternal \brief
 178      * Properties that can be specified after from().to().
 179      *
 180      * \tparam FromType Type specified for from() to map from.
 181      * \tparam ToType Type specified for to() to map to.
 182      */
 183     template<typename FromType, typename ToType>
 184     class ToValue : public Base
 185     {
 186     public:
 187         //! Creates a parameter provider object within given builder.
 188         explicit ToValue(KeyValueTreeTransformRuleBuilder* builder) : Base(builder) {}
 189
 190         /*! \brief
 191          * Specifies the transformation function to convert the value
 192          * from FromType to ToType.
 193          */
 194         void transformWith(std::function<ToType(const FromType&)> transform)
 195         {
 196             builder_->addTransformToAny([transform](const Any& value) {
 197                 return Any::create<ToType>(transform(value.cast<FromType>()));
 198             });
 199         }
 200     };
 201
 202     /*! \libinternal \brief
 203      * Properties that can be specified after from().toObject().
 204      *
 205      * \tparam FromType Type specified for from() to map from.
 206      */
 207     template<typename FromType>
 208     class ToObject : public Base
 209     {
 210     public:
 211         //! Creates a parameter provider object within given builder.
 212         explicit ToObject(KeyValueTreeTransformRuleBuilder* builder) : Base(builder) {}
 213
 214         /*! \brief
 215          * Specifies the transformation function to build the output
 216          * object.
 217          *
 218          * The transform should build the output object with the
 219          * provided builder.
 220          */
 221         void transformWith(std::function<void(KeyValueTreeObjectBuilder*, const FromType&)> transform)
 222         {
 223             builder_->addTransformToObject([transform](KeyValueTreeObjectBuilder* builder, const Any& value) {
 224                 transform(builder, value.cast<FromType>());
 225             });
 226         }
 227     };
 228
 229     /*! \libinternal \brief
 230      * Properties that can be specified after from().
 231      *
 232      * \tparam FromType Type specified for from() to map from.
 233      */
 234     template<typename FromType>
 235     class AfterFrom : public Base
 236     {
 237     public:
 238         //! Creates a parameter provider object within given builder.
 239         explicit AfterFrom(KeyValueTreeTransformRuleBuilder* builder) : Base(builder) {}
 240
 241         /*! \brief
 242          * Specifies a rule that maps to a value at given path.
 243          *
 244          * \tparam ToType  Type to map to.
 245          * \param[in] path Path to map to.
 246          *
 247          * It is an error if multiple rules map to the same path, or to
 248          * a parent path of the target of an existing rule.
 249          * Note that it is possible to have a to() rule map to a child
 250          * of a toObject() rule, provided that the path is not created
 251          * by the object rule.
 252          */
 253         template<typename ToType>
 254         ToValue<FromType, ToType> to(const KeyValueTreePath& path)
 255         {
 256             builder_->setToPath(path);
 257             return ToValue<FromType, ToType>(builder_);
 258         }
 259
 260         /*! \brief
 261          * Specifies a rule that maps to an object (collection of named
 262          * values) at given path.
 263          *
 264          * \param[in] path Path to map to.
 265          *
 266          * It is an error if multiple rules map to the same path, or to
 267          * a parent path of the target of an existing rule.
 268          * However, it is allowed to have two toObject() rules map to
 269          * the same path, provided that the properties they produce are
 270          * distinct.
 271          */
 272         ToObject<FromType> toObject(const KeyValueTreePath& path)
 273         {
 274             builder_->setToPath(path);
 275             return ToObject<FromType>(builder_);
 276         }
 277     };
 278
 279     //! Internal constructor for creating a builder.
 280     KeyValueTreeTransformRuleBuilder(internal::KeyValueTreeTransformerImpl* impl,
 281                                      const KeyValueTreePath&                prefix);
 282     //! Supports returning the builder from IKeyValueTreeTransformRules::addRule().
 283     KeyValueTreeTransformRuleBuilder(KeyValueTreeTransformRuleBuilder&&) = default;
 284     //! Supports returning the builder from IKeyValueTreeTransformRules::addRule().
 285     KeyValueTreeTransformRuleBuilder& operator=(KeyValueTreeTransformRuleBuilder&&) = default;
 286     ~KeyValueTreeTransformRuleBuilder(); // NOLINT(bugprone-exception-escape)
 287
 288     /*! \brief
 289      * Specifies a rule that maps a value at given path.
 290      *
 291      * \tparam FromType Type of value expected at `path`.
 292      * \param[in] path Path to map in this rule.
 293      *
 294      * If the input tree has `path`, but it is not of type `FromType`,
 295      * the transform will produce an error.
 296      *
 297      * It is an error to use the same path in two from() rules.  Similarly,
 298      * it is an error to use a child path of a path used in a different
 299      * from() rule.
 300      */
 301     template<typename FromType>
 302     AfterFrom<FromType> from(const KeyValueTreePath& path)
 303     {
 304         setFromPath(path);
 305         setExpectedType(typeid(FromType));
 306         return AfterFrom<FromType>(this);
 307     }
 308     /*! \brief
 309      * Specifies how strings are matched when matching rules against a path.
 310      *
 311      * For properties of the object at `path`, `keyMatchType` is used for
 312      * string comparison.
 313      *
 314      * This rule must be specified first for a path, before any other
 315      * from() rule specifies the path or a subpath.
 316      * The rule only applies to immediate properties at the given path, not
 317      * recursively.
 318      * It is an error to specify the match type multiple times for a path.
 319      */
 320     void keyMatchType(const KeyValueTreePath& path, StringCompareType keyMatchType)
 321     {
 322         setFromPath(path);
 323         setKeyMatchType(keyMatchType);
 324     }
 325
 326 private:
 327     void setFromPath(const KeyValueTreePath& path);
 328     void setExpectedType(const std::type_index& type);
 329     void setToPath(const KeyValueTreePath& path);
 330     void setKeyMatchType(StringCompareType keyMatchType);
 331     void addTransformToAny(const std::function<Any(const Any&)>& transform);
 332     void addTransformToObject(const std::function<void(KeyValueTreeObjectBuilder*, const Any&)>& transform);
 333
 334     class Data;
 335
 336     internal::KeyValueTreeTransformerImpl* impl_;
 337     std::unique_ptr<Data>                  data_;
 338 };
 339
 340 class KeyValueTreeTransformer
 341 {
 342 public:
 343     KeyValueTreeTransformer();
 344     ~KeyValueTreeTransformer();
 345
 346     IKeyValueTreeTransformRules* rules();
 347
 348     std::vector<KeyValueTreePath> mappedPaths() const;
 349
 350     KeyValueTreeTransformResult transform(const KeyValueTreeObject&  tree,
 351                                           IKeyValueTreeErrorHandler* errorHandler) const;
 352
 353 private:
 354     PrivateImplPointer<internal::KeyValueTreeTransformerImpl> impl_;
 355 };
 356
 357 class IKeyValueTreeBackMapping
 358 {
 359 public:
 360     virtual ~IKeyValueTreeBackMapping();
 361
 362     virtual KeyValueTreePath originalPath(const KeyValueTreePath& path) const = 0;
 363 };
 364
 365 class KeyValueTreeTransformResult
 366 {
 367 public:
 368     KeyValueTreeObject              object() { return std::move(object_); }
 369     const IKeyValueTreeBackMapping& backMapping() const { return *mapping_; }
 370
 371 private:
 372     typedef std::unique_ptr<IKeyValueTreeBackMapping> MappingPointer;
 373
 374     KeyValueTreeTransformResult(KeyValueTreeObject&& object, MappingPointer&& mapping) :
 375         object_(std::move(object)),
 376         mapping_(std::move(mapping))
 377     {
 378     }
 379
 380     KeyValueTreeObject object_;
 381     MappingPointer     mapping_;
 382
 383     friend class internal::KeyValueTreeTransformerImpl;
 384 };
 385
 386 } // namespace gmx
 387
 388 #endif