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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 21 |
1 files changed, 13 insertions, 8 deletions
@@ -11,18 +11,13 @@ A simple math expressions calculator * Exceptions on divide by zero, or treat as zero * Unary Minus (e.g. -3) * Pi ($pi) and Euler's number ($e) support to 11 decimal places +* Easily extendable ## Install via Composer: -Stable branch ``` composer require "nxp/math-executor" ``` -Dev branch (currently unsupported) -``` -composer require "nxp/math-executor" "dev-dev" -``` - ## Sample usage: ```php require "vendor/autoload.php"; @@ -132,7 +127,7 @@ $executor->setVars([ echo $executor->execute("$var1 + $var2"); ``` ## Division By Zero Support: -By default, the result of division by zero is zero and no error is generated. You have the option to thow a \NXP\Exception\DivisionByZeroException by calling setDivisionByZeroException. +By default, the result of division by zero is zero and no error is generated. You have the option to throw a `\NXP\Exception\DivisionByZeroException` by calling `setDivisionByZeroException`. ```php $executor->setDivisionByZeroException(); @@ -144,7 +139,7 @@ try { ``` ## Unary Minus Operator: -Negative numbers are supported via the unary minus operator, but need to have a space before the minus sign. `-1+ -3` is legal, while '`-1+-3` will produce an error due to the way the parser works. Positive numbers are not explicitly supported as unsigned numbers are assumed positive. +Negative numbers are supported via the unary minus operator, but need to have a space before the minus sign. `-1+ -3` is legal, while `-1+-3` will produce an error due to the way the parser works. Positive numbers are not explicitly supported as unsigned numbers are assumed positive. ## String Support: Expressions can contain double or single quoted strings that are evaluated the same way as PHP evalutes strings as numbers. You can also pass strings to functions. @@ -152,3 +147,13 @@ Expressions can contain double or single quoted strings that are evaluated the s ```php echo $executor->execute("1 + '2.5' * '.5' + myFunction('category')"); ``` + +## Extending MathExecutor +You can add operators, functions and variables with the public methods in MathExecutor, but if you need to do more serious modifications to base behaviours, the easiest way to extend MathExecutor is to redefine the following methods in your derived class: +* defaultOperators +* defaultFunctions +* defaultVars + +This will allow you to remove functions and operators if needed, or implement different types more simply. + +Also note that you can replace an existing default operator by adding a new operator with the same regular expression string. For example if you just need to redefine TokenPlus, you can just add a new operator with the same regex string, in this case '\\+'. |