60 lines
1.7 KiB
C++
60 lines
1.7 KiB
C++
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#include "pointer.hpp"
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#include "tree.hpp"
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#include "../parse.hpp"
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#include <algorithm>
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#include <stdexcept>
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///////////////////////////////////////////////////////////////////////////////
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::json::tree::node&
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util::json::pointer::resolve (std::string const &path,
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::json::tree::node &root)
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{
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// we only handle fragment represenations currently, which start with a '#'
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auto cursor = path.begin ();
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if (cursor == path.end () || *cursor != '#')
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throw std::invalid_argument ("must be fragment representation");
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++cursor;
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auto obj = &root;
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// * step over each path segment
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// * index into the current node
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// * advance the node
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// * repeat until we reach the end of the query string
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for ( ; cursor != path.end (); ) {
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// step over the delimiting '/'
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if (*cursor != '/')
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break;
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++cursor;
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// find the start of the next segment (or the end of the string)
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// and extract the key.
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auto next = std::find (cursor, path.end (), '/');
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std::string const key { cursor, next };
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// try to index into the node and advance the node we're operating on
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switch (obj->type ()) {
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case ::json::tree::OBJECT:
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obj = &(*obj)[key];
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break;
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case ::json::tree::ARRAY:
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obj = &(*obj)[util::parse<size_t> (key)];
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break;
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case ::json::tree::STRING:
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case ::json::tree::NUMBER:
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case ::json::tree::BOOLEAN:
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case ::json::tree::NONE:
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throw std::invalid_argument ("indexing into wrong type");
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}
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// step to the beginning of the next component
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cursor = next;
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}
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return *obj;
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}
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