Lico San
84 lines
3.0 KiB
Markdown
84 lines
3.0 KiB
Markdown
# Formula1
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## Simple Mathematical formulas evaluator for PHP
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If you need to evaluate a formula with basic operators and variables, and
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* **No eval:** You dont want to use EVAL for obvious security reasons,
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* **No dependencies:** You don't want to rely on half the internet as dependencies, but prefer a single self-contained class,
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* **Old PHP OK:** You don't necessarily have the latest PHP version, or Composer,
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* **No spaghetti:** You want something readable that you could easily understand and customize,
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* **Arithmetic rules OK:** You need something that knows about operators priority, unary operators, and parenthesis,
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* **Rounding OK:** You want to specify a precision and rounding mode for the result,
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* **Recursive eval:** You want to be able to include sub-formulas inside your variables,
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* **Arrays OK:** You need to use indexed or key-value arrays as variable inside the formula,
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* **functions OK:** You need to use basic math functions inside the formula,
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* **Errors OK:** You need to have a human-friendly message telling why the formula is wrong when it is,
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...then you gonna like Formula1 ! ;-)
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**Simple usage no variables**
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```PHP
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$f1 = new Formula1('-45+(41*2)-(6/(3+1))');
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echo($f1->compute()); // 35.5
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```
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```PHP
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// With rounding (third and fourth params are precision and mode, like for the round function)
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$f1 = new Formula1('2/3', [], 3);
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echo($f1->compute()); // 0.667
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```
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**Simple usage with variables**
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```PHP
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$f1 = new Formula1('-45+(fourty_one*2)-(6/(three+1))' , ['fourty_one'=>41, 'three'=>3]);
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echo($f1->compute()); // 35.5
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```
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**Funky usage with variables that include formulas themselves (and recusrively)**
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```PHP
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$f1 = new Formula1('-45+(fourty_one*2)-(6/(three+1))' , ['fourty_one'=>'82/2', 'three'=>'12/four', 'four'=>4]);
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echo($f1->compute()); // 35.5
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```
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**Display parsing error if any**
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```PHP
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$f1 = new Formula1('-45+(fourty_one*2)-(6/(three+1)))' , ['fourty_one'=>'82/2', 'three'=>'12/four', 'four'=>4]);
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if($f1->parse_error=='') echo($f1->compute());
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else echo($f1->parse_error."<br>\n"); // Too many closing parenthesis !
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```
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**Using an indexed array**
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```PHP
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$f1 = new Formula1('toto*primes[6]',['toto'=>10,'primes'=>[2,3,5,7,11,13,17,19,23,29,31]]);
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echo($f1->compute()."<br>\n"); //170
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```
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**Using a key-value array**
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```PHP
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$f1 = new Formula1('toto*myar["zorglub_99"]',['toto'=>10,'myar'=>['aaa'=>2.5,'zorglub_99'=>5.5]]);
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echo($f1->compute()."<br>\n"); //55
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```
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**Using math functions**
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```PHP
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$f1 = new Formula1('2*5+sin(pi()/4)');
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echo($f1->compute()."<br>\n"); //7.071...
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```
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## TODO
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* Would be better to give parameters in the compute, to allow one parsing => many compute, with different values sets, but this needs a rewrite of the current parse-compute split.
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* The index of indexed arrays should be evaluated to allow formulas as indexes, but this needs a rewrite of the current parse-compute split.
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## Known bugs
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* Won't allow unary operator directly following a binary operator like "5*-x" or "5+-x".
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Your can workaround by using parenthesis like "5*(-x)" or "5+(-x)"
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