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https://github.com/YACReader/yacreader
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101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
#ifndef QUERY_PARSER_H
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#define QUERY_PARSER_H
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#include "query_lexer.h"
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#include <map>
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#include <QSqlQuery>
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#include <string>
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#include <vector>
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#include <list>
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/**
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* This class is used to generate an SQL query string from a search expression,
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* with a syntax very similar to that used by the Google search engine.
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*
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* The code herein is based upon the SearchQueryParser python class written by
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* Kovid Goyal as part of the Calibre eBook manager (https://calibre-ebook.com)
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*
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* Grammar:
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* prog ::= or_expression
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* or_expression ::= and_expression [ 'or' or_expression ]
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* and_expression ::= not_expression [ [ 'and' ] and_expression ]
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* not_expression ::= [ 'not' ] location_expression
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* location_expression ::= base_token | ( '(' or_expression ')' )
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* base_token ::= a sequence of letters and colons, perhaps quoted
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*
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* Usage Example:
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* QSqlQuery selectQuery(db);
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* std::string queryString("SELECT ... FROM ... WHERE ");
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*
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* QueryParser parser; // Create the parser object
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* TreeNode result = parser.parse(expr); // Parse the query expression
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*
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* result.buildSqlString(queryString); // Append the SQL query to a string
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*
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* selectQuery.prepare(queryString.c_str()); // Convert the string to a query
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* result.bindValues(selectQuery); // Populate the SQL query variables
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*
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* selectQuery.exec();
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*/
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class QueryParser
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{
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public:
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struct TreeNode {
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std::string t;
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std::vector<TreeNode> children;
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explicit TreeNode(std::string t, std::vector<TreeNode> children)
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: t(t), children(children)
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{
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}
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int buildSqlString(std::string &sqlString, int bindPosition = 0) const;
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int bindValues(QSqlQuery &selectQuery, int bindPosition = 0) const;
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};
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explicit QueryParser();
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TreeNode parse(const std::string &expr);
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private:
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static std::string toLower(const std::string &string);
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std::string token(bool advance = false);
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std::string lcaseToken(bool advance = false);
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Token::Type tokenType();
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bool isEof() const;
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void advance();
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QueryLexer lexer = QueryLexer("");
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Token currentToken = Token(Token::Type::undefined);
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template<typename T>
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static bool isIn(const T &e, const std::list<T> &v)
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{
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return std::find(v.begin(), v.end(), e) != v.end();
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}
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enum class FieldType { unknown,
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numeric,
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text,
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boolean,
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date,
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folder,
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booleanFolder,
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filename };
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static FieldType fieldType(const std::string &str);
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static std::string join(const QStringList &strings, const std::string &delim);
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static QStringList split(const std::string &string, char delim);
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TreeNode orExpression();
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TreeNode andExpression();
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TreeNode notExpression();
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TreeNode locationExpression();
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TreeNode baseToken();
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static const std::map<FieldType, std::vector<std::string>> fieldNames;
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};
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#endif // QUERY_PARSER_H
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