extract string helper
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John
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/*
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* ebusd - daemon for communication with eBUS heating systems.
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* Copyright (C) 2022 John Baier <ebusd@ebusd.eu>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef LIB_EBUS_STRINGHELPER_H_
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#define LIB_EBUS_STRINGHELPER_H_
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#include <unistd.h>
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#include <cstdint>
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#include <map>
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#include <string>
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#include <sstream>
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#include <vector>
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#include "lib/ebus/message.h"
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namespace ebusd {
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/** @file lib/ebus/stringhelper.h
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* Helper classes for string replacement.
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*/
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using std::map;
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using std::ostringstream;
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using std::string;
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using std::vector;
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/**
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* Helper class for replacing a template string with real values.
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*/
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class StringReplacer {
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public:
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/**
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* Normalize the string to contain only alpha numeric characters plus underscore by replacing other characters with
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* an underscore.
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* @param str the string to normalize.
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*/
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static void normalize(string& str);
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/**
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* Get the template string.
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* @return the template string (might already be partially reduced).
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*/
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const string str() const;
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/**
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* Parse the template string.
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* @param templateStr the template string.
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* @param onlyKnown true to allow only known field names from @a knownFieldNames.
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* @param noKnownDuplicates true to now allow duplicates from @a knownFieldNames.
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* @param emptyIfMissing true when the complete result is supposed to be empty when at least one referenced variable
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* is empty or not defined.
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* @return true on success, false on malformed template string.
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*/
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bool parse(const string& templateStr, bool onlyKnown = false, bool noKnownDuplicates = false,
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bool emptyIfMissing = false);
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/**
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* Ensure the default parts are present (package prefix if empty, circuit and message name).
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* @param separator the separator between prefix, circuit, and message name (default slash).
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*/
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void ensureDefault(const string& separator = "/");
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/**
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* Return whether this replacer is completely empty.
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* @return true when empty.
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*/
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bool empty() const;
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/**
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* Return whether the specified field is used.
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* @param field the field name to check.
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* @return true when the specified field is used.
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*/
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bool has(const string& field) const;
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/**
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* Get the replaced template string.
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* @param values the named values for replacement.
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* @param untilFirstEmpty true to only return the prefix before the first empty field.
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* @param onlyAlphanum whether to only allow alpha numeric characters plus underscore.
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* @return the replaced template string.
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*/
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string get(const map<string, string>& values, bool untilFirstEmpty = true, bool onlyAlphanum = false) const;
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/**
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* Get the replaced template string.
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* @param circuit the circuit name for replacement.
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* @param name the message name for replacement.
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* @param fieldName the field name for replacement.
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* @return the replaced template string.
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*/
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string get(const string& circuit, const string& name, const string& fieldName = "") const;
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/**
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* Get the replaced template string.
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* @param message the Message from which to extract the values for replacement.
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* @param fieldName the field name for replacement.
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* @return the replaced template string.
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*/
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string get(const Message* message, const string& fieldName = "") const;
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/**
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* Check if the fields can be reduced to a constant value.
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* @param values the named values for replacement.
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* @return true if the result is final.
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*/
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bool isReducable(const map<string, string>& values) const;
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/**
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* Compress all subsequent constant values to a single constant value if possible.
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* @param values the named values for replacement.
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*/
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void compress(const map<string, string>& values);
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/**
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* Reduce the fields to a constant value if possible.
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* @param values the named values for replacement.
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* @param result the string to store the result in.
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* @param onlyAlphanum whether to only allow alpha numeric characters plus underscore.
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* @return true if the result is final.
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*/
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bool reduce(const map<string, string>& values, string& result, bool onlyAlphanum = false) const;
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/**
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* Check match-ability against a string.
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* @return true on success, false on bad match-ability.
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*/
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bool checkMatchability() const;
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/**
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* Match a string against the constant and variables parts.
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* @param str the string to match.
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* @param circuit pointer to the string receiving the circuit name if present.
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* @param name pointer to the string receiving the message name if present.
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* @param field pointer to the string receiving the field name if present.
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* @param separator the separator expected in the extra non-matched non-field parts (default slash).
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* @return the index of the last unmatched part, or the negative index minus one for extra non-matched non-field parts.
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*/
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ssize_t match(const string& str, string* circuit, string* name, string* field, const string& separator = "/") const;
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private:
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/**
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* the list of parts the template is composed of.
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* the string is either the plain string or the name of the field.
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* the number is negative for plain strings, the index to @a knownFieldNames for a known field, or the size of
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* @a knownFieldNames for an unknown field.
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*/
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vector<std::pair<string, int>> m_parts;
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/** true when the complete result is supposed to be empty when at least one referenced variable
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* is empty or not defined. */
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bool m_emptyIfMissing;
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/**
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* Create a named field or constant.
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* @param name the plain string or the name of the field.
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* @param isField true when it is a field.
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* @return the created pair.
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*/
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static std::pair<string, int> makeField(const string& name, bool isField);
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/**
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* Add a part to the list of parts.
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* @param stack the parsing stack.
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* @param inField 1 after '%', 2 after '%{', 0 otherwise.
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*/
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void addPart(ostringstream& stack, int inField);
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};
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/**
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* A set of constants and @a StringReplacer variables.
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*/
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class StringReplacers {
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public:
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/**
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* Get the value of the specified key from the constants only.
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* @param key the key for which to get the value.
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* @return the value string or empty.
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*/
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const string& operator[](const string& key) const;
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/**
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* Parse a continuation-normalized line.
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* @param line the line to parse.
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*/
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void parseLine(const string& line);
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/**
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* Parse a file with constants and variables.
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* @param filename the name (and path) of the file to parse.
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* @return true on success, false if the file is not readable.
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*/
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bool parseFile(const char* filename);
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/**
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* Check if the specified field is used by one of the replacers.
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* @param field the name of the field to check.
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* @return true if the specified field is used by one of the replacers.
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*/
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bool uses(const string& field) const;
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/**
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* Get the variable value of the specified key.
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* @param key the key for which to get the value.
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* @return the value @a StringReplacer.
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*/
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StringReplacer& get(const string& key);
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/**
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* Get the variable value of the specified key.
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* @param key the key for which to get the value.
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* @return the value @a StringReplacer.
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*/
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StringReplacer get(const string& key) const;
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/**
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* Get the variable or constant value of the specified key.
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* @param key the key for which to get the value.
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* @param untilFirstEmpty true to only return the prefix before the first empty field.
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* @param onlyAlphanum whether to only allow alpha numeric characters plus underscore.
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* @param fallbackKey optional fallback key to use when key value is undefined.
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* @return the value string or empty.
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*/
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string get(const string& key, bool untilFirstEmpty, bool onlyAlphanum = false, const string& fallbackKey = "") const;
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/**
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* Set the constant value of the specified key and additionally normalized with uppercase key only (if the key does
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* not contain an underscore).
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* @param key the key to store.
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* @param value the value string.
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* @param removeReplacer true to remove a replacer with the same name.
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* @return true when an upper case key was stored/updates as well.
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*/
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bool set(const string& key, const string& value, bool removeReplacer = true);
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/**
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* Set the constant value of the specified key.
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* @param key the key to store.
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* @param value the numeric value (converted to a string).
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*/
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void set(const string& key, int value);
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/**
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* Reduce as many variables to constants as possible.
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* @param compress true to compress non-reducable replacers if possible.
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*/
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void reduce(bool compress = false);
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private:
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/** constant values from the integration file. */
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map<string, string> m_constants;
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/** variable values from the integration file. */
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map<string, StringReplacer> m_replacers;
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};
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} // namespace ebusd
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#endif // LIB_EBUS_STRINGHELPER_H_
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