parsec #

The multi-platform parsec plugin for Flutter to calculate math equations using C++ library on native platforms and WebAssembly on web.

Platform Support #

Android	iOS	Windows	Linux	MacOS	Web
✔️	❌️	✔️	✔️	❌️	✔️

Installation #

Add parsec as a dependency in your pubspec.yaml file:

dependencies:
  parsec: ^0.3.1  # Use latest version

Then run:

flutter pub get

Web Platform Setup (Additional Step) #

For web platform support, include the parsec-web wrapper JS in your app's web/index.html:

<script type="module" src="packages/parsec_web/parsec-web/js/equations_parser_wrapper.js"></script>

The wrapper dynamically imports the WASM glue from packages/parsec_web/parsec-web/wasm/equations_parser.js. If the WASM glue is missing during local development, run:

cd parsec_web
dart bin/generate.dart

Requirements #

Platform	Requirements
Android	Android SDK, NDK
Linux	GCC/Clang compiler
Windows	Visual Studio Build Tools
Web	Modern browser with WebAssembly support

Usage #

Example #

import 'package:parsec/parsec.dart';

void main() {
    final Parsec parsec = Parsec();
    dynamic result;

    try {
        result = await parsec.eval('5*5 + 5!');
    } catch (e) {
        result = e.toString();
    }
}

Here are examples of equations which are accepted by the parsec #

final Parsec parsec = Parsec();

# Simple Math equations
parsec.eval('(5 + 1) + (6 - 2)')  # result => 10
parsec.eval('4 + 4 * 3')          # result => 16
parsec.eval('10.5 / 5.25')        # result => 2
parsec.eval('abs(-5)')            # result => 5
parsec.eval('sqrt(16) + cbrt(8)') # result => 6
parsec.eval('log10(10)')          # result => 1
parsec.eval('round(4.4)')         # result => 4
parsec.eval('(3^3)^2')            # result => 729
parsec.eval('3^(3^(2))')          # result => 19683
parsec.eval('10!')                # result => 3628800
parsec.eval('string(10)')         # result => "10"

# Complex Math equations
parsec.eval('log10(10) + ln(e) + log(10)')       # result => 4.30259
parsec.eval('sin(1) + cos(0) + tan(0.15722)')    # result => 2.0
parsec.eval('max(1, 2) + min(3, 4) + sum(5, 6)') # result => 16
parsec.eval('avg(9, 9.8, 10)')                   # result => 9.6
parsec.eval('pow(2, 3)')                         # result => 8
parsec.eval('round_decimal(4.559, 2)')           # result => 4.56

# IF THEN ELSE equations
parsec.eval('4 > 2 ? "bigger" : "smaller"')    # result => "bigger"
parsec.eval('2 == 2 ? true : false')           # result => true
parsec.eval('2 != 2 ? true : false')           # result => false
parsec.eval('"this" == "this" ? "yes" : "no"') # result => "yes"
parsec.eval('"this" != "that" ? "yes" : "no"') # result => "yes"

# Logic equations
parsec.eval('true and false')    # result => false
parsec.eval('true or false')     # result => true
parsec.eval('(3==3) and (3!=3)') # result => false
parsec.eval('exp(1) == e')       # result => true

# String equations
parsec.eval('length("test string")')     # result => 11
parsec.eval('toupper("test string")')    # result => "TEST STRING"
parsec.eval('tolower("TEST STRING")')    # result => "test string"
parsec.eval('concat("Hello ", "World")') # result => "Hello World"
parsec.eval('link("Title", "http://foo.bar")') # result => "<a href="http://foo.bar">Title</a>"
parsec.eval('str2number("5")')           # result => 5
parsec.eval('left("Hello World", 5)')    # result => "Hello"
parsec.eval('right("Hello World", 5)')   # result => "World"
parsec.eval('number("5")')               # result => 5

# Date equations (return the difference in days)
parsec.eval("current_date()"))                        # result => "2018-10-03"
parsec.eval('daysdiff(current_date(), "2018-10-04")') # result => 1
parsec.eval('daysdiff("2018-01-01", "2018-12-31")')   # result => 364

# DateTime equations (return the difference in hours)
parsec.eval('hoursdiff("2018-01-01", "2018-01-02")')             # result => 24
parsec.eval('hoursdiff("2019-02-01T08:00", "2019-02-01T12:00")') # result => 4
parsec.eval('hoursdiff("2019-02-01T08:20", "2019-02-01T12:00")') # result => 3.67
parsec.eval('hoursdiff("2018-01-01", "2018-01-01")')             # result => 0

The following functions can be used #

Math trigonometric functions: sin, cos, tan, sinh, cosh, tanh, asin, acos, atan, asinh, acosh, atanh
Math logarithm functions: ln, log, log10
Math standard functions: abs, sqrt, cbrt, pow, exp, round, round_decimal
Number functions: string
Math constants: e, pi
Unlimited number of arguments: min, max, sum, avg
String functions: concat, length, toupper, tolower, left, right, str2number, number, link
Complex functions: real, imag, conj, arg, norm
Array functions: sizeof, eye, ones, zeros
Date functions: current_date, daysdiff, hoursdiff
Extra functions: default_value

Testing #

Running Automated Tests #

Main Package Tests

cd parsec
flutter test

Platform-Specific Tests

# Android implementation
cd parsec_android
flutter test

# Linux implementation  
cd parsec_linux
flutter test

# Windows implementation
cd parsec_windows
flutter test

Manual Testing #

Web Platform (WebAssembly)

cd parsec/example
flutter run -d chrome

Native Platforms

cd parsec/example

# Linux
flutter run -d linux

# Android (with device connected)
flutter run -d android

# Windows (on Windows machine)  
flutter run -d windows

Web Setup (First Time Only) #

If you're testing the web platform for the first time, ensure the WASM files are generated:

cd parsec_web
dart bin/generate.dart

This builds the necessary WebAssembly files in the parsec_web package so they can be served from packages/parsec_web/parsec-web/....

Web Dev Prerequisites (for contributors)

Building the WebAssembly bundle locally requires Emscripten:

# Ubuntu/Debian
sudo apt-get install emscripten

# Or install via emsdk
git clone https://github.com/emscripten-core/emsdk.git
cd emsdk && ./emsdk install latest && ./emsdk activate latest
source ./emsdk_env.sh

Platform-Specific Implementation #

Web: Uses WebAssembly through the parsec-web JavaScript library for optimal performance
- Utilizes evalRaw() function for direct C++ JSON output, ensuring platform consistency
- Bypasses JavaScript type conversion for cleaner data flow: C++ → JSON → Dart
Android/Linux/Windows: Uses Method Channels to communicate with native C++ implementations
iOS/macOS: Not yet supported

Technical Implementation Details #

Web Platform Architecture

The web implementation has been optimized for performance and consistency:

Flutter Dart Code
       ↓
parsec_web Platform Channel
       ↓
JavaScript evalRaw() Function
       ↓
WebAssembly (C++ equations-parser)
       ↓
Raw JSON Response

Key Features:

Direct JSON Flow: Uses evalRaw() to get raw C++ JSON output without JavaScript type conversion
Platform Consistency: All platforms now receive identical JSON format from C++
Simplified Architecture: Eliminated complex type normalization and conversion layers
Better Performance: Direct data path reduces processing overhead
KISS Principle: Much cleaner codebase with 150+ lines of complex code removed

Performance #

Platform	Implementation	Typical Performance	Network Required
Web	WebAssembly	~1-10ms	No (offline)
Android	Method Channels + C++	~5-20ms	No (offline)
Linux	Method Channels + C++	~5-20ms	No (offline)
Windows	Method Channels + C++	~5-20ms	No (offline)

Expected Behavior #

The same equation should produce identical results across all supported platforms:

final parsec = Parsec();
final result = await parsec.eval('2 + 3 * sin(pi/2)'); // Should return 5.0 on all platforms

Troubleshooting #

Web Platform Issues #

"parsec-web JavaScript library not found"

# Ensure your app's web/index.html includes the wrapper:
# <script type="module" src="packages/parsec_web/parsec-web/js/equations_parser_wrapper.js"></script>

# Generate WASM files to ensure they are present
cd parsec_web
dart bin/generate.dart

# Verify bundled assets
ls parsec_web/lib/parsec-web/{js,wasm}/

WebAssembly module fails to load

Ensure your browser supports WebAssembly (all modern browsers do)
Check browser console for detailed error messages
Try hard refresh (Ctrl+Shift+R) to clear cache

Native Platform Issues #

Build errors on Android

# Ensure NDK is installed
flutter doctor

# Clean and rebuild
flutter clean
flutter pub get
flutter build android

Build errors on Linux/Windows

# Ensure proper build tools are installed
flutter doctor

# Verify platform is enabled
flutter create --platforms=linux,windows .

Tests failing

# Generate WASM files first for web platform
cd parsec_web && dart bin/generate.dart

# Check individual components
flutter test parsec/
flutter test parsec_android/
flutter test parsec_linux/
flutter test parsec_windows/
flutter test --platform chrome parsec/  # Web-specific tests

Web Testing (WebAssembly Integration) #

The Web platform uses real WebAssembly compiled from the same C++ equations-parser library used by native platforms, ensuring true cross-platform consistency.

Running Web Tests #

# Run all Web integration tests
cd parsec
flutter test --platform chrome

# Run specific Web integration tests
flutter test --platform chrome test/parsec_web_integration_test.dart

# Run with coverage
flutter test --platform chrome --coverage

Web JavaScript Library Tests (optional)

# Run JS tests for the parsec-web wrapper/library
cd parsec_web/lib/parsec-web
npm test

Automated Testing #

GitHub Actions automatically runs comprehensive Web tests:

Multi-Flutter Versions: Tests against Flutter 3.19.0 and 3.24.0
Browser Testing: Chrome-based automated testing
Performance Benchmarks: WebAssembly efficiency validation
Cross-Platform Consistency: Identical results across all platforms

See WEB_TESTING.md for detailed testing documentation.

Contributing #

Fork the repository
Create your feature branch (git checkout -b feature/amazing-feature)
Make your changes
Generate WASM files for web: cd parsec_web && dart bin/generate.dart
Run tests: flutter test
Commit your changes (git commit -m 'Add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

License #

This project is licensed under the Apache-2.0 license - see the LICENSE file for details.

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