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/*
* This file is part of KiCad, a free EDA CAD application.
* Derived from libeval, a simple math expression evaluator.
*
* Copyright (C) 2017 Michael Geselbracht, mgeselbracht3@gmail.com
* Copyright The KiCad Developers, see AUTHORS.txt for contributors.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/*
An evaluator object is used to replace an input string that represents
a mathematical expression by its result.
Example: Consider the input "3+4". The result of this expression is "7".
The NumericEvaluator can be used like this:
NumericEvaluator eval;
eval.process("3+4");
printf("3+4", eval.result());
The same example with error checking. Please note that even a valid input string may result
in an empty output string or "NaN".
NumericEvaluator eval;
bool ret = eval.process("3+4");
assert(ret == eval.isValid()); // isValid() reflects return value of process().
if (eval.isValid()) printf("3+4=%s\n", eval.result());
Using variables
Expressions can refer to variables if they were defined by previous expressions.
A variable can be defined by an expression or by the setVar() method.
Expressions that define/set variables do not have a result.
eval.process("x=1; y=2"); // Result is NaN
eval.setVar("z", 3);
eval.process("x+y+z");
printf("x+y+z=%s\n", eval.result());
Input string storage
An evaluator object can store and retrieve the original input string using a pointer
as key. This can be used to restore the input string of a text entry field.
eval.process("25.4-0.7", &eval);
printf("%s = %s\n", eval.textInput(&eval), eval.result());
Unit conversion
The evaluator uses a default unit and constants can be specified with a unit.
As long as no units are used the default unit is not relevant.
Supported units are millimeters (mm), Mil (mil) and inch (")
eval.process("1\"");
printf("1\" = %s\n", eval.result());
eval.process("12.7 - 0.1\" - 50mil");
printf("12.7 - 0.1\" - 50mil = %s\n", eval.result());
*/
#ifndef NUMERIC_EVALUATOR_H_
#define NUMERIC_EVALUATOR_H_
#include <cstddef>
#include <map>
#include <string>
#include <eda_units.h>
// This namespace is used for the lemon parser
namespace numEval
{
struct TokenType
{
union
{
double dValue;
int iValue;
};
bool valid;
char text[32];
};
} // namespace numEval
class KICOMMON_API NUMERIC_EVALUATOR
{
enum class Unit { Invalid, UM, MM, CM, Inch, Mil, Degrees, SI };
public:
NUMERIC_EVALUATOR( EDA_UNITS aUnits );
~NUMERIC_EVALUATOR();
/* clear() should be invoked by the client if a new input string is to be processed. It
* will reset the parser. User defined variables are retained.
*/
void Clear();
void SetDefaultUnits( EDA_UNITS aUnits );
void LocaleChanged();
/* Used by the lemon parser */
void parseError(const char* s);
void parseOk();
void parseSetResult(double);
/* Check if previous invocation of process() was successful */
inline bool IsValid() const { return !m_parseError; }
/* Result of string processing. Undefined if !isValid() */
inline wxString Result() const { return wxString::FromUTF8( m_token.token ); }
/* Evaluate input string.
* Result can be retrieved by result().
* Returns true if input string could be evaluated, otherwise false.
*/
bool Process( const wxString& aString );
/* Retrieve the original text before evaluation. */
wxString OriginalText() const;
/* Add/set variable with value */
void SetVar( const wxString& aString, double aValue );
/* Get value of variable. Returns 0.0 if not defined. */
double GetVar( const wxString& aString );
/* Remove single variable */
void RemoveVar( const wxString& aString ) { m_varMap.erase( aString ); }
/* Remove all variables */
void ClearVar() { m_varMap.clear(); }
protected:
/* Token type used by the tokenizer */
struct Token
{
int token;
numEval::TokenType value;
};
/* Begin processing of a new input string */
void newString( const wxString& aString );
/* Tokenizer: Next token/value taken from input string. */
Token getToken();
/* Used by processing loop */
void parse( int token, numEval::TokenType value );
private:
void* m_parser; // the current lemon parser state machine
/* Token state for input string. */
struct TokenStat
{
TokenStat() :
input( nullptr ),
token( nullptr ),
inputLen( 0 ),
outputLen( 0 ),
pos( 0 )
{};
const char* input; // current input string ("var=4")
char* token; // output token ("var", type:VAR; "4", type:VALUE)
size_t inputLen; // strlen(input)
size_t outputLen; // At least 64, up to input length
size_t pos; // current index
} m_token;
char m_localeDecimalSeparator;
/* Parse progress. Set by parser actions. */
bool m_parseError;
bool m_parseFinished;
Unit m_defaultUnits; // Default unit for values
wxString m_originalText;
std::map<wxString, double> m_varMap;
};
#endif /* NUMERIC_EVALUATOR_H_ */
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