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query stripper is implemented with the template metaprogramming

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This commit is contained in:
Marko Budiselic 2016-02-04 02:45:12 +01:00
parent 3e5f2de6c2
commit 499469aec2
4 changed files with 63 additions and 7 deletions
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BIN
query_engine/engine
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6
query_engine/query_engine.hpp
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@ -21,6 +21,10 @@ using std::endl;
class QueryEngine
{
public:
QueryEngine()
{
}
QueryResult execute(const std::string& query)
{
auto stripped = stripper.strip(query);
@ -35,7 +39,7 @@ public:
private:
// TODO: use IoC or something similar
QueryStripper stripper;
QueryStripper<int, int, int> stripper{TK_INT, TK_FLOAT, TK_STR};
QueryTraverser traverser;
CodeGenerator generator;
CodeCompiler compiler;

23
query_engine/query_stripper.hpp
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@ -1,27 +1,30 @@
#pragma once
#include <string>
#include <regex>
#include <tuple>
#include <utility>
#include "cypher/tokenizer/cypher_lexer.hpp"
#include "cypher/cypher.h"
#include "cypher/tokenizer/cypher_lexer.hpp"
#include "utils/variadic/variadic.hpp"
template<typename ...Ts>
class QueryStripper
{
public:
// TODO: extract parameters
QueryStripper(Ts&&... strip_types)
: strip_types(std::make_tuple(std::forward<Ts>(strip_types)...)) {}
std::string strip(const std::string& query)
{
auto tokenizer = lexer.tokenize(query);
std::string stripped = "";
int counter = 0;
constexpr auto size = std::tuple_size<decltype(strip_types)>::value;
while (auto token = tokenizer.lookup())
{
// TODO: do this more generic via template metaprogramming
if (token.id == TK_STR || token.id == TK_INT ||
token.id == TK_FLOAT) {
if (_or(token.id, strip_types, std::make_index_sequence<size>{})) {
stripped += "@" + std::to_string(counter++);
} else {
stripped += token.value;
@ -31,5 +34,13 @@ public:
}
private:
std::tuple<Ts...> strip_types;
CypherLexer lexer;
template<typename Value, typename Tuple, std::size_t ...index>
bool _or(Value&& value, Tuple&& tuple, std::index_sequence<index...>)
{
return or_vargs(std::forward<Value>(value),
std::get<index>(std::forward<Tuple>(tuple))...);
}
};

41
utils/variadic/variadic.hpp Normal file
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@ -0,0 +1,41 @@
#pragma once
#include <iostream>
// variadic argument printer
template<class Head>
void _print_vargs(std::ostream& s, Head&& head)
{
s << std::forward<Head>(head);
}
template<class Head, class ...Tail>
void _print_vargs(std::ostream& s, Head&& head, Tail&& ...tail)
{
s << std::forward<Head>(head);
_print_vargs(s, std::forward<Tail>(tail)...);
}
template<class ...Args>
void print_vargs(Args&&... args)
{
_print_vargs(std::cout, std::forward<Args>(args)...);
}
// value equality with any of variadic argument
// example: value == varg[0] OR value == varg[1] OR ...
template<class Value, class Head>
bool _or_vargs(Value&& value, Head&& head)
{
return value == head;
}
template<class Value, class Head, class ...Tail>
bool _or_vargs(Value&& value, Head&& head, Tail&& ...tail)
{
return value == head || _or_vargs(std::forward<Value>(value), tail...);
}
template<class Value, class ...Array>
bool or_vargs(Value&& value, Array&&... array)
{
return _or_vargs(std::forward<Value>(value), std::forward<Array>(array)...);
}