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118 lines
4.3 KiB
118 lines
4.3 KiB
#ifndef SASS_NODE_H
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#define SASS_NODE_H
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#include <deque>
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#include <memory>
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#include "ast.hpp"
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namespace Sass {
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class Context;
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/*
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There are a lot of stumbling blocks when trying to port the ruby extend code to C++. The biggest is the choice of
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data type. The ruby code will pretty seamlessly switch types between an Array<SimpleSequence or Op> (libsass'
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equivalent is the Complex_Selector) to a Sequence, which contains more metadata about the sequence than just the
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selector info. They also have the ability to have arbitrary nestings of arrays like [1, [2]], which is hard to
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implement using Array equivalents in C++ (like the deque or vector). They also have the ability to include nil
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in the arrays, like [1, nil, 3], which has potential semantic differences than an empty array [1, [], 3]. To be
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able to represent all of these as unique cases, we need to create a tree of variant objects. The tree nature allows
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the inconsistent nesting levels. The variant nature (while making some of the C++ code uglier) allows the code to
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more closely match the ruby code, which is a huge benefit when attempting to implement an complex algorithm like
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the Extend operator.
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Note that the current libsass data model also pairs the combinator with the Complex_Selector that follows it, but
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ruby sass has no such restriction, so we attempt to create a data structure that can handle them split apart.
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*/
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class Node;
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typedef std::deque<Node> NodeDeque;
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typedef std::shared_ptr<NodeDeque> NodeDequePtr;
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class Node {
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public:
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enum TYPE {
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SELECTOR,
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COMBINATOR,
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COLLECTION,
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NIL
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};
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TYPE type() const { return mType; }
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bool isCombinator() const { return mType == COMBINATOR; }
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bool isSelector() const { return mType == SELECTOR; }
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bool isCollection() const { return mType == COLLECTION; }
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bool isNil() const { return mType == NIL; }
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bool got_line_feed;
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Complex_Selector::Combinator combinator() const { return mCombinator; }
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Complex_Selector_Obj selector() { return mpSelector; }
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Complex_Selector_Obj selector() const { return mpSelector; }
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NodeDequePtr collection() { return mpCollection; }
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const NodeDequePtr collection() const { return mpCollection; }
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static Node createCombinator(const Complex_Selector::Combinator& combinator);
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// This method will klone the selector, stripping off the tail and combinator
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static Node createSelector(const Complex_Selector& pSelector);
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static Node createCollection();
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static Node createCollection(const NodeDeque& values);
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static Node createNil();
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static Node naiveTrim(Node& seqses);
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Node klone() const;
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bool operator==(const Node& rhs) const;
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inline bool operator!=(const Node& rhs) const { return !(*this == rhs); }
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/*
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COLLECTION FUNCTIONS
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Most types don't need any helper methods (nil and combinator due to their simplicity and
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selector due to the fact that we leverage the non-node selector code on the Complex_Selector
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whereever possible). The following methods are intended to be called on Node objects whose
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type is COLLECTION only.
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*/
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// rhs and this must be node collections. Shallow copy the nodes from rhs to the end of this.
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// This function DOES NOT remove the nodes from rhs.
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void plus(Node& rhs);
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// potentialChild must be a node collection of selectors/combinators. this must be a collection
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// of collections of nodes/combinators. This method checks if potentialChild is a child of this
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// Node.
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bool contains(const Node& potentialChild) const;
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private:
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// Private constructor; Use the static methods (like createCombinator and createSelector)
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// to instantiate this object. This is more expressive, and it allows us to break apart each
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// case into separate functions.
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Node(const TYPE& type, Complex_Selector::Combinator combinator, Complex_Selector_Ptr pSelector, NodeDequePtr& pCollection);
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TYPE mType;
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// TODO: can we union these to save on memory?
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Complex_Selector::Combinator mCombinator;
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Complex_Selector_Obj mpSelector;
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NodeDequePtr mpCollection;
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};
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#ifdef DEBUG
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std::ostream& operator<<(std::ostream& os, const Node& node);
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#endif
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Node complexSelectorToNode(Complex_Selector_Ptr pToConvert);
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Complex_Selector_Ptr nodeToComplexSelector(const Node& toConvert);
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}
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#endif
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