infix_expression_parser

Description:

infix expression parser

A dart package to help you parse and evaluate infix mathematical expressions into their prefix and postfix notations.
Features #

Convert an infix expression into its prefix and postfix notations
Evaluate a mathematical expression
Support for basic mathematical operations

Usage #
You can use infix-expression-parser as a library or as a CLI tool. Below are some examples explaining how to use the package in each case.
As a library #
The package exposes two main classes:

InfixExpressionConverter: Use this class when you have an infix expression and want to convert it either to its postfix or infix notation.
ExpressionEvaluator: Use this class when you already have a postfix or prefix expression and want to evaluate it to a result. Use in combination with InfixExpressionConverter to also evaluate infix expressions easily. Note that in order to return a value, you need to provide a context in which you give each symbol in the expression a numeric value.

Example #1: Converting an infix expression
import 'package:infix_expression_parser/infix_expression_converter.dart';

void main() {
// Provide an infix expression
const infixExpression = '(a-b+c)*(d+e*f)';

// Create an instance of InfixExpressionConverter
final converter = InfixExpressionConverter(expression: infixExpression);

final postfixExpression = converter.toPostfixNotation();
final prefixExpression = converter.toPrefixNotation();

print(postfixExpression); // ab-c+def*+*
print(prefixExpression); // *+-abc+d*ef
}
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Example #2: Evaluating a postfix expression
import 'package:infix_expression_parser/expression_evaluator.dart';

void main() {
// Define a context map
const context = {'a': 2, 'b': 3, 'c': 4, 'd': 5};

// Provide a postfix expression
const postfixExpression = 'abc+*d/';

// Use the static method provided by the ExpressionEvaluator class and pass both the expression and the context
final value = ExpressionEvaluator.evaluatePostfix(expression: postfixExpression, context: context);

print(value); // 2.8
}
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Example #3: Evaluating a prefix expression
import 'package:infix_expression_parser/expression_evaluator.dart';

void main() {
// Define a context map
const context = {'a': 2, 'b': 3, 'c': 4, 'd': 5, 'e': 6};

// Provide a postfix expression
const prefixExpression = '*-a/bc-/ade';

// Use the static method provided by the ExpressionEvaluator class and pass both the expression and the context
final value = ExpressionEvaluator.evaluatePrefix(expression: prefixExpression, context: context);

print(value); // -7.0
}
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Example #4: Evaluating an infix expression
import 'package:infix_expression_parser/infix_expression_converter.dart';
import 'package:infix_expression_parser/expression_evaluator.dart';

void main() {
// Provide an infix expression
const infixExpression = 'a-b+c-d*e';

// Convert it to either its postfix or prefix notation
final converter = InfixExpressionConverter(expression: infixExpression);
final postfixExpression = converter.toPostfixNotation();

// Define a context map
const context = {'a': 2, 'b': 3, 'c': 4, 'd': 5, 'e': 6};

// Use the static method provided by the ExpressionEvaluator class and pass both the expression and the context
final value = ExpressionEvaluator.evaluatePostfix(expression: postfixExpression, context: context);

print(value); // -27.0
}
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As a CLI tool #
The package expose a infix-parser command explained below:
A CLI tool for evaluating expressions in prefix or postfix notations or converting infix expressions.

Usage: infix-parser <command> [arguments]

Global options:
-h, --help Print this usage information.

Available commands:
convert Converts an expression to its prefix or postfix notation

Run "infix-parser help <command>" for more information about a command.
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You can use the convert sub-command to parse infix expressions.
Example #1: Converting an infix expression to a prefix expression
pub run infix_expression_parser:main convert '(a-b/c)*(a/d-e)' --prefix
*-a/bc-/ade
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Example #2: Converting an infix expression to a postfix expression
pub run infix_expression_parser:main convert '(a-b/c)*(a/d-e)' --postfix
abc/-ad/e-*
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Future improvements #

A sub-command for evaluating expressions in the command line may come in future iterations of this package
Support for other mathematical operations, functions and symbols may come come in future iterations of this package