Go Parser

A high-performance Go expression parser that supports numeric calculations, string concatenation, function calls, conditional statements, function definitions, and registration.

Features

• ✨ Numeric Operations: Supports +, -, *, /, and () operators
• 🔤 String Concatenation: Using + operator
• 📝 Variable Substitution: Variables with $ prefix
• 🎯 Function Calls: Functions with @ prefix
• ⚡ Conditional Statements: Supports >, <, >=, <=, ==, !=, &&, ||, ! operators
• 🚀 High Performance: Excellent concurrent execution performance

Usage Guide

1. Basic Syntax

Numeric Calculations

Numeric expressions must be wrapped in parentheses:

(1+2)*3  # Result: 9

String Concatenation

Use + operator to concatenate strings, strings must be wrapped in double quotes:

"hello"+"world"  # Result: helloworld

Variables

Variables must start with $, underscores are allowed but other special characters are not:

$price+100  # price is a variable, value is passed during execution

Function Calls

Function calls must start with @:

@calculate($price, 100)  # Calling calculate function

Conditional Expressions

Supports complex conditional logic:

($price >= 100 && $price < 200) || @isVIP($userId)

2. Code Examples

Function Registration

// Function definition
type Function func(args ...any) any

// Register function
RegisterFunc(name string, f Function)

Expression Execution

// Simple calculation
expr, err := ParseExpression("($price+100)*0.8")
result := expr.Execute(map[string]any{"price": 200})

// Conditional evaluation
expr, err := ParseExpression(`$price > 100 && @isVIP($userId)`)
result := expr.Execute(map[string]any{
    "price": 150,
    "userId": "user123",
})

Performance Benchmarks

go test -bench=. -benchmem -tags -v
goos: darwin
goarch: arm64
pkg: github.com/go-parser/parser
cpu: Apple M1 Pro
BenchmarkHardCode-8                  	 6342241	       174.6 ns/op	     112 B/op	       3 allocs/op
BenchmarkHardCodeParallel-8          	17822409	        68.70 ns/op	     112 B/op	       3 allocs/op
BenchmarkGoParserExecute-8           	 6851533	       174.5 ns/op	     112 B/op	       4 allocs/op
BenchmarkGoParserExecuteParallel-8   	20086538	        63.08 ns/op	     112 B/op	       4 allocs/op
BenchmarkExprLangExecute-8           	 2112973	       558.4 ns/op	     368 B/op	      14 allocs/op
BenchmarkExprLangExecuteParallel-8   	 5690395	       234.4 ns/op	     368 B/op	      14 allocs/op
PASS
ok  	github.com/go-parser/parser	8.986s