1.1.0 - 1.2.0

CHANGELOG.md

@@ -1,3 +1,17 @@
-## 1.0.0
+# 1.2.0
+
+- Fix README
+- Moved integrating features to a separate package library `math_parser_integrate`
+
+
+# 1.1.0
+
+- Custom variables support.
+- `MathFunctionX`deprecated.
+- `MathVariable` introduced.
+- You need to pass an instance of `MathVariableValues` instead of a num to the `calc()` function now
+
+
+# 1.0.0
 
 - Initial version.

README.md

@@ -19,15 +19,16 @@ All the child classes names begin with the family they belong to.
 ## Evaluation
 
 You can evaluate a MathNode and its subnodes recursively by calling
-`MathNode.calc(num x)` and passing custom `x` variable value.
+`MathNode.calc(MathVariableValues values)` and passing custom
+variable values.
 
 Example: Calculate `x + 3`, where `x = 5`.
 
 ```dart
 MathOperatorAddition(
-    MathFunctionX(),
+    MathVariable('x'),
     const MathValue(3),
-).calc(5);
+).calc(MathVariableValues.x(5));
 ```
 
 ## Parsing String to MathNode
@@ -43,8 +44,15 @@ and return them as a machine-readable `MathNode` using
 ### Parse priority:
 
 1. Parentheses () []
-2. Variables: x, e, pi (π)
-3. Functions:
+2. Variables: e, pi (π) and custom ones. `x` is being interpreted as a var
+   by default, but you can override this behavior with the variableNames
+   parameter. You can rewrite e and pi by defining it in variableNames and
+   mentioning it during the calc call.
+   First character must be a letter, others - letters, digits, or
+   underscore. Letters may be latin or Greek, both lower or capital case.
+   You can't use built-in function names like sin, cos, etc. Variable names
+   are case-sensitive
+3. Functions (case-sensitive):
    - sin, cos, tan (tg), cot (ctg)
    - sqrt (√) (interpreted as power of 1/2), complex numbers not supported
    - ln (base=E), lg (base=2), log\[base\]\(x\)
@@ -65,19 +73,25 @@ MathNode fromString(
 
     /// Allows skipping the multiplication (*) operator
     bool isImplicitMultiplication = true,
+
+    /// Expressions which should be marked as variables
+    Set<String> variableNames = const {'x'},
   });
 ```
 
-Example for parsing a string and evaluating it with `x = 20`:
+Example for parsing a string and evaluating it with `x = 20`
+and `y = 5`:
 
 ```dart
 final expression = MathNodeExpression.fromString(
-    '(2x)^(e^3 + 4)',
+  '(2x)^(e^3 + 4) + y',
+).calc(
+  MathVariableValues({'x': 20, 'y': 5}),
 );
-print(expression.calc(20));
-
 ```
 
+More complicated work with variables is shown off in example.
+
 ## Other Features
 
 ### Numerical methods for Definite Integrals

example/math_parser_example.dart

@@ -1,13 +1,27 @@
 import 'package:math_parser/math_parser.dart';
+import 'package:math_parser/integrate.dart';
 
+/// Example function to calculate an expression from string
 void main() {
   // Parsing string to a MathNode
   final expression = MathNodeExpression.fromString(
-    '((2x)^(e^3 + 4) + cos(3)x) / log[x + 3^2e](2 + (3x)^2)^5 * (2 + x)(x^2 + 3) + arcctg(x)',
+    '((2x)^(e^3 + 4) + cos(3)x) / log[x_1*2 + 3^2e](2 + (3y)^2)^5 * (2 + y)(x^2 + 3) + arcctg(Θ)',
+    variableNames: {'x', 'y', 'Θ', 'x_1'},
   );
   // Display the parsed expression in human-readable form
   print(expression);
 
-  // Evaluate the expression with `x = 20` and display result
-  print(expression.calc(20));
+  // Evaluate the expression with `x = 20`, `y = 2`, `theta = 1/2`
+  // and display result
+  print(expression.calc(
+    MathVariableValues({'x': 20, 'y': 2, 'Θ': 0.5, 'x_1': 3}),
+  ));
+}
+
+/// Integrate library example
+void integrate() {
+  print(
+    MathNodeExpression.fromString('cos(x)')
+        .definiteIntegralBySimpson(10, 0, 3.14),
+  );
 }

lib/integrate.dart

@@ -0,0 +1,11 @@
+/// Numerical methods for integrating extension
+///
+/// Following methods available:
+/// - By rectangles (left, middle, right)
+/// - Simpson's method
+/// - By trapezoids
+///
+/// In order to use the functionality import the `integrate.dart` file
+library math_parser_integrate;
+
+export 'src/extensions/integrate.dart';

lib/math_parser.dart

@@ -11,7 +11,7 @@
 ///
 /// void main() {
 ///   final expression = MathNodeExpression.fromString(
-///     '((2x)^(e^3 + 4)',
+///     '(2x)^(e^3 + 4)',
 ///   );
 ///   print(expression.calc(20));
 /// }
@@ -20,7 +20,5 @@ library math_parser;
 
 export 'src/math_node.dart';
 export 'src/parse.dart';
+export 'src/math_errors.dart';
 export 'src/parse_errors.dart';
-
-// Extensions
-export 'src/extensions/integrate.dart';

lib/src/extensions/integrate.dart

@@ -122,6 +122,6 @@ Iterable<num> _stepsAtMiddle(int n, num lowerLimit, num upperLimit) sync* {
 Iterable<num> _calculateMathNodeAtPoints(
     MathNode expression, Iterable<num> points) sync* {
   for (final point in points) {
-    yield expression.calc(point);
+    yield expression.calc(MathVariableValues.x(point));
   }
 }

lib/src/math_errors.dart

@@ -0,0 +1,25 @@
+/// Math parsing error
+///
+/// Errors must extends this class
+abstract class MathException implements Exception {
+  /// Creates a new Math Exception
+  const MathException();
+}
+
+/// Undefined Variable Exception
+///
+/// Thrown when there's a variable referenced in calculations which wasn't passed
+/// to the [MathNode.calc] function
+class UndefinedVariableException extends MathException {
+  @override
+  String toString() {
+    return 'UndefinedVariableException: Variable "$name" was not defined in '
+        'the calc() function. Variable names are case-sensitive';
+  }
+
+  /// The missing variable
+  final String name;
+
+  /// Created a new Undefined Variable Exception
+  const UndefinedVariableException(this.name);
+}