condition

Documentation

Overview

Package condition provides condition evaluation functionality for StreamSQL.

This package implements condition evaluation using the expr-lang library, supporting complex boolean expressions for filtering and conditional logic. It provides custom functions for SQL-like operations including LIKE pattern matching and NULL checking.

Core Features

• Boolean Expression Evaluation - Evaluate complex boolean conditions • LIKE Pattern Matching - SQL-style pattern matching with % and _ wildcards • NULL Checking - Support for IS NULL and IS NOT NULL operations • Custom Functions - Extended function library for SQL compatibility • Type Safety - Automatic type conversion and validation • Performance Optimized - Compiled expressions for fast evaluation

Condition Interface

Unified interface for condition evaluation:

type Condition interface {
	Evaluate(env interface{}) bool
}

Custom Functions

Built-in SQL-compatible functions:

// LIKE pattern matching
like_match(text, pattern) - SQL LIKE operation with % and _ wildcards

// NULL checking
is_null(value) - Check if value is NULL
is_not_null(value) - Check if value is not NULL

Usage Examples

Basic condition evaluation:

condition, err := NewExprCondition("age >= 18 AND status == 'active'")
if err != nil {
	log.Fatal(err)
}

data := map[string]interface{}{
	"age": 25,
	"status": "active",
}

result := condition.Evaluate(data) // returns true

LIKE pattern matching:

condition, err := NewExprCondition("like_match(name, 'John%')")
data := map[string]interface{}{"name": "John Smith"}
result := condition.Evaluate(data) // returns true

NULL checking:

condition, err := NewExprCondition("is_not_null(email)")
data := map[string]interface{}{"email": "user@example.com"}
result := condition.Evaluate(data) // returns true

Complex conditions:

condition, err := NewExprCondition(`
	age >= 18 AND
	like_match(email, '%@company.com') AND
	is_not_null(department)
`)

Pattern Matching

LIKE pattern matching supports:

% - Matches any sequence of characters (including empty)
_ - Matches exactly one character

Examples:

'John%' matches 'John', 'John Smith', 'Johnny'
'J_hn' matches 'John' but not 'Johan'
'%@gmail.com' matches any email ending with @gmail.com

Integration

Integrates with other StreamSQL components:

• Stream package - Data filtering and conditional processing • RSQL package - WHERE and HAVING clause evaluation • Types package - Data type handling and conversion • Expr package - Expression parsing and evaluation

Index

• type Condition
  • func NewExprCondition(expression string) (Condition, error)
• type ExprCondition
  • func (ec *ExprCondition) Evaluate(env interface{}) bool

Types

type Condition

type Condition interface {
	Evaluate(env interface{}) bool
}

func NewExprCondition

func NewExprCondition(expression string) (Condition, error)

type ExprCondition

type ExprCondition struct {
	// contains filtered or unexported fields
}

func (*ExprCondition) Evaluate

func (ec *ExprCondition) Evaluate(env interface{}) bool