https://github.com/eltony81/easy_expression_eval
Math expression evaluator
https://github.com/eltony81/easy_expression_eval
crystal crystal-lang evaluator expression infix-notation math
Last synced: 24 days ago
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Math expression evaluator
- Host: GitHub
- URL: https://github.com/eltony81/easy_expression_eval
- Owner: eltony81
- License: mit
- Created: 2022-11-28T07:37:27.000Z (over 3 years ago)
- Default Branch: master
- Last Pushed: 2026-05-29T07:06:22.000Z (26 days ago)
- Last Synced: 2026-05-29T09:08:43.787Z (26 days ago)
- Topics: crystal, crystal-lang, evaluator, expression, infix-notation, math
- Language: Crystal
- Homepage:
- Size: 105 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Easy Expression Eval (eeeval)
**eeeval** is a lightweight and efficient expression evaluator for Crystal. It supports mathematical calculations, user-defined variables, pre-compiled ASTs for performance, and conditional expressions.
---
## Installation
1. Add the dependency to your `shard.yml`:
```yaml
dependencies:
eeeval:
github: eltony81/easy_expression_eval
```
2. Run `shards install`
## Features
### Mathematical Evaluation
You can evaluate complex mathematical expressions with a single call:
```crystal
require "eeeval"
# Simple evaluation
result = EEEval::CalcFuncParser.evaluate("(14.2 + 14.2) * 4 / 2 * 10.5 ^ (2 / 0.5)")
puts result
```
#### Variables Support
Pass a hash of variables to the evaluator:
```crystal
vars = {"x" => 3.0, "y" => 1.5}
result = EEEval::CalcFuncParser.evaluate("x^2 + sin(y)", vars)
puts result
```
#### Pre-compilation (AST)
For performance-critical code (e.g., inside loops), compile the expression into an AST once and reuse it:
```crystal
ast = EEEval::CalcFuncParser.compile("sin(x) * phi")
(0..100).each do |i|
res = EEEval::CalcFuncParser.evaluate(ast, {"x" => i.to_f})
puts "f(#{i}) = #{res}"
end
```
### Conditional Expressions
The library includes a `CondParser` for boolean logic:
```crystal
# Numeric comparisons
EEEval::CondParser.evaluate("10 == 10") # => true
EEEval::CondParser.evaluate("5 != 3") # => true
# String comparisons
EEEval::CondParser.evaluate("'hello' == 'hello'") # => true
# Logical operators
EEEval::CondParser.evaluate("(1 == 1) && (2 != 3)") # => true
EEEval::CondParser.evaluate("1 == 0 || 1 == 1") # => true
```
### Built-in Support
- **Constants**: `pi`, `e`, `tau`, `sqrt2`, `phi`, `rad2deg`, `deg2rad`, `g`, `inf`, `nan`.
- **Functions**: `sin`, `cos`, `tan`, `asin`, `acos`, `atan`, `sinh`, `cosh`, `tanh`, `log`, `log2`, `log10`, `exp`, `exp2`, `sqrt`, `abs`, `floor`, `ceil`, `round`, `sgn`, `gamma`.
- **Operators**: `+`, `-`, `*`, `/`, `^` (power), `%` (modulo).
---
## CLI Usage
The library includes a CLI tool for quick evaluations and range calculations.
### Parameters:
- `-v, --var VAR`: Specify the variable name to use in the expression (e.g., `x`, `t`).
- `-s, --start VAL`: Set the starting value for the range evaluation.
- `-e, --end VAL`: Set the ending value for the range evaluation.
- `-d, --step VAL`: Set the increment step size (defaults to `1.0`).
### Examples:
**Single expression evaluation:**
```bash
crystal run src/cli.cr -- "sin(pi/2) + e"
```
**Range evaluation (vector calculation):**
This will evaluate the expression for `x` from `0` to `10` with a step of `0.5`, producing a vector of results.
```bash
crystal run src/cli.cr -- -v x -s 0 -e 10 -d 0.5 "x^2 + sin(x)"
```
---
## Contributing
1. Fork it ()
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create a new Pull Request
## Contributors
- [eltony81](https://github.com/eltony81) - creator and maintainer