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Add quickstart guide and detailed explanation of features

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Sebastian Schmidt 2019-03-19 12:01:06 +02:00
parent a51680da08
commit 2b9d50909e
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2
LICENSE
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@ -1,6 +1,6 @@
MIT License MIT License
Copyright (c) 2016 fengcen Copyright (c) 2019 Sebastian Schmidt
Permission is hereby granted, free of charge, to any person obtaining a copy Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal of this software and associated documentation files (the "Software"), to deal

205
README.md
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@ -9,151 +9,138 @@ Evalexpr is a powerful arithmetic and boolean expression evaluator.
<!-- cargo-sync-readme start --> <!-- cargo-sync-readme start -->
## Features ## Quickstart
### Operators Add `evalexpr` as dependency to your `Cargo.toml`:
Supported binary operators:
| Operator | Precedence | Description | | Operator | Precedence | Description |
|----------|------------|-------------|---|----------|------------|-------------|
| + | 95 | Sum | | < | 80 | Lower than |
| - | 95 | Difference | | \> | 80 | Greater than |
| * | 100 | Product | | <= | 80 | Lower than or equal |
| / | 100 | Division | | \>= | 80 | Greater than or equal |
| % | 100 | Modulo | | == | 80 | Equal |
| && | 75 | Logical and | | != | 80 | Not equal |
| &#124;&#124; | 70 | Logical or | | | |
Supported unary operators:
| Operator | Precedence | Description |
|----------|------------|-------------|
| - | 110 | Negation |
| ! | 110 | Logical not |
### Values
Operators take values as arguments and produce values as results.
Values can be boolean, integer or floating point numbers.
Strings are supported as well, but there are no operations defined for them yet.
Integers are internally represented as `i64`, and floating point numbers are represented as `f64`.
Operators that take numbers as arguments can either take integers or floating point numbers.
If one of the arguments is a floating point number, all others are converted to floating point numbers as well, and the resulting value is a floating point number as well.
Otherwise, the result is an integer.
### Variables
Supported binary operators: `!` `!=` `""` `''` `()` `[]` `,` `>` `<` `>=` `<=` `==`
`+` unary/binary `-` `*` `/` `%` `&&` `||` `n..m`.
Supported unary operators: ``
Built-in functions: `min()` `max()` `len()` `is_empty()` `array()` `converge()`.
See the `builtin` module for a detailed description of each.
Where can eval be used?
-----------------------
* Template engine
* Scripting language
* ...
Usage
-----
Add dependency to Cargo.toml
```toml ```toml
[dependencies] [dependencies]
evalexpr = "0.4" evalexpr = "0.5"
``` ```
In your `main.rs` or `lib.rs`: Add the `extern crate` definition to your `main.rs` or `lib.rs`:
```rust ```rust
extern crate evalexpr as eval; extern crate evalexpr;
``` ```
Examples Then you can use `evalexpr` to evaluate expressions like this:
--------
You can do mathematical calculations with supported operators:
```rust ```rust
use eval::{eval, to_value}; use evalexpr::*;
assert_eq!(eval("1 + 2 + 3"), Ok(to_value(6))); assert_eq!(eval("1 + 2 + 3"), Ok(Value::from(6)));
assert_eq!(eval("2 * 2 + 3"), Ok(to_value(7))); assert_eq!(eval("1 - 2 * 3"), Ok(Value::from(-5)));
assert_eq!(eval("2 / 2 + 3"), Ok(to_value(4.0))); assert_eq!(eval("1.0 + 2 * 3"), Ok(Value::from(7.0)));
assert_eq!(eval("2 / 2 + 3 / 3"), Ok(to_value(2.0))); assert_eq!(eval("true && 4 > 2"), Ok(Value::from(true)));
``` ```
You can eval with context: And you can use variables and functions in expressions like this:
```rust ```rust
use eval::{Expr, to_value}; use evalexpr::*;
assert_eq!(Expr::new("foo == bar") let mut configuration = HashMapConfiguration::new();
.value("foo", true) configuration.insert_variable("five", 5);
.value("bar", true) configuration.insert_variable("twelve", 12);
.exec(), configuration.insert_function("f", Function::new(1 /* argument amount */, Box::new(|arguments| {
Ok(to_value(true))); if let Value::Int(int) = arguments[0] {
Ok(Value::Int(int / 2))
} else if let Value::Float(float) = arguments[0] {
Ok(Value::Float(float / 2.0))
} else {
Err(Error::expected_number(arguments[0].clone()))
}
})));
assert_eq!(eval_with_configuration("five + 8 > f(twelve)", &configuration), Ok(Value::from(true)));
``` ```
You can access data like javascript by using `.` and `[]`. `[]` supports expression. You can also precompile expressions like this:
```rust ```rust
use eval::{Expr, to_value}; use evalexpr::*;
use std::collections::HashMap;
let mut object = HashMap::new(); let precompiled = build_operator_tree("a * b - c > 5").unwrap();
object.insert("foos", vec!["Hello", "world", "!"]);
assert_eq!(Expr::new("object.foos[1-1] == 'Hello'") let mut configuration = HashMapConfiguration::new();
.value("object", object) configuration.insert_variable("a", 6);
.exec(), configuration.insert_variable("b", 2);
Ok(to_value(true))); configuration.insert_variable("c", 3);
assert_eq!(precompiled.eval(&configuration), Ok(Value::from(true)));
configuration.insert_variable("c", 8);
assert_eq!(precompiled.eval(&configuration), Ok(Value::from(false)));
``` ```
You can eval with function: ## Features
```rust ### Operators
use eval::{Expr, to_value};
assert_eq!(Expr::new("say_hello()") Supported binary operators:
.function("say_hello", |_| Ok(to_value("Hello world!")))
.exec(),
Ok(to_value("Hello world!")));
```
You can create an array with `array()`: | Operator | Precedence | Description | | Operator | Precedence | Description |
|----------|------------|-------------|---|----------|------------|-------------|
| + | 95 | Sum | | < | 80 | Lower than |
| - | 95 | Difference | | \> | 80 | Greater than |
| * | 100 | Product | | <= | 80 | Lower than or equal |
| / | 100 | Division | | \>= | 80 | Greater than or equal |
| % | 100 | Modulo | | == | 80 | Equal |
| && | 75 | Logical and | | != | 80 | Not equal |
| &#124;&#124; | 70 | Logical or | | | |
```rust Supported unary operators:
use eval::{eval, to_value};
assert_eq!(eval("array(1, 2, 3, 4, 5)"), Ok(to_value(vec![1, 2, 3, 4, 5]))); | Operator | Precedence | Description |
``` |----------|------------|-------------|
| - | 110 | Negation |
| ! | 110 | Logical not |
You can create an integer array with `n..m`: ### Values
```rust Operators take values as arguments and produce values as results.
use eval::{eval, to_value}; Values can be boolean, integer or floating point numbers.
Strings are supported as well, but there are no operations defined for them yet.
Values are denoted as displayed in the following table.
assert_eq!(eval("0..5"), Ok(to_value(vec![0, 1, 2, 3, 4]))); | Value type | Example |
``` |------------|---------|
| `Value::Boolean` | `true`, `false` |
| `Value::Int` | `3`, `-9`, `0`, `135412` |
| `Value::Float` | `3.`, `.35`, `1.00`, `0.5`, `123.554` |
License Integers are internally represented as `i64`, and floating point numbers are represented as `f64`.
------- Operators that take numbers as arguments can either take integers or floating point numbers.
If one of the arguments is a floating point number, all others are converted to floating point numbers as well, and the resulting value is a floating point number as well.
Otherwise, the result is an integer.
evalexpr is primarily distributed under the terms of the MIT license. ### Variables
See [LICENSE](LICENSE) for details.
This crate allows to compile parameterizable formulas by using variables.
A variable is a literal in the formula, that does not contain whitespace or can be parsed as value.
The user needs to provide bindings to the variables for evaluation.
This is done with the `Configuration` trait.
Two structs implementing this trait are predefined.
There is `EmptyConfiguration`, that returns `None` for each request, and `HashMapConfiguration`, that stores mappings from literals to variables in a hash map.
Variables do not have fixed types in the expression itself, but aer typed by the configuration.
The `Configuration` trait contains a function that takes a string literal and returns a `Value` enum.
The variant of this enum decides the type on evaluation.
### Functions
This crate also allows to define arbitrary functions to be used in parsed expressions.
A function is defined as a `Function` instance.
It contains two properties, the `argument_amount` and the `function`.
The `function` is a boxed `Fn(&[Value]) -> Result<Value, Error>`.
The `argument_amount` is verified on execution by the crate and does not need to be verified by the `function`.
It determines the length of the slice that is passed to `function`.
See the examples section above for examples on how to construct a function instance.
## License
This crate is primarily distributed under the terms of the MIT license.
See [LICENSE](LICENSE) for details.
<!-- cargo-sync-readme end --> <!-- cargo-sync-readme end -->

8
src/configuration/mod.rs
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@ -33,12 +33,12 @@ impl HashMapConfiguration {
} }
} }
pub fn insert_variable(&mut self, identifier: String, value: Value) { pub fn insert_variable<S: Into<String>, V: Into<Value>>(&mut self, identifier: S, value: V) {
self.variables.insert(identifier, value); self.variables.insert(identifier.into(), value.into());
} }
pub fn insert_function(&mut self, identifier: String, function: Function) { pub fn insert_function<S: Into<String>>(&mut self, identifier: S, function: Function) {
self.functions.insert(identifier, function); self.functions.insert(identifier.into(), function);
} }
} }

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src/lib.rs
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@ -1,4 +1,68 @@
//! //!
//! ## Quickstart
//!
//! Add `evalexpr` as dependency to your `Cargo.toml`:
//!
//! ```toml
//! [dependencies]
//! evalexpr = "0.5"
//! ```
//!
//! Add the `extern crate` definition to your `main.rs` or `lib.rs`:
//!
//! ```rust
//! extern crate evalexpr;
//! ```
//!
//! Then you can use `evalexpr` to evaluate expressions like this:
//!
//! ```rust
//! use evalexpr::*;
//!
//! assert_eq!(eval("1 + 2 + 3"), Ok(Value::from(6)));
//! assert_eq!(eval("1 - 2 * 3"), Ok(Value::from(-5)));
//! assert_eq!(eval("1.0 + 2 * 3"), Ok(Value::from(7.0)));
//! assert_eq!(eval("true && 4 > 2"), Ok(Value::from(true)));
//! ```
//!
//! And you can use variables and functions in expressions like this:
//!
//! ```rust
//! use evalexpr::*;
//!
//! let mut configuration = HashMapConfiguration::new();
//! configuration.insert_variable("five", 5);
//! configuration.insert_variable("twelve", 12);
//! configuration.insert_function("f", Function::new(1 /* argument amount */, Box::new(|arguments| {
//! if let Value::Int(int) = arguments[0] {
//! Ok(Value::Int(int / 2))
//! } else if let Value::Float(float) = arguments[0] {
//! Ok(Value::Float(float / 2.0))
//! } else {
//! Err(Error::expected_number(arguments[0].clone()))
//! }
//! })));
//!
//! assert_eq!(eval_with_configuration("five + 8 > f(twelve)", &configuration), Ok(Value::from(true)));
//! ```
//!
//! You can also precompile expressions like this:
//!
//! ```rust
//! use evalexpr::*;
//!
//! let precompiled = build_operator_tree("a * b - c > 5").unwrap();
//!
//! let mut configuration = HashMapConfiguration::new();
//! configuration.insert_variable("a", 6);
//! configuration.insert_variable("b", 2);
//! configuration.insert_variable("c", 3);
//! assert_eq!(precompiled.eval(&configuration), Ok(Value::from(true)));
//!
//! configuration.insert_variable("c", 8);
//! assert_eq!(precompiled.eval(&configuration), Ok(Value::from(false)));
//! ```
//!
//! ## Features //! ## Features
//! //!
//! ### Operators //! ### Operators
@ -27,6 +91,13 @@
//! Operators take values as arguments and produce values as results. //! Operators take values as arguments and produce values as results.
//! Values can be boolean, integer or floating point numbers. //! Values can be boolean, integer or floating point numbers.
//! Strings are supported as well, but there are no operations defined for them yet. //! Strings are supported as well, but there are no operations defined for them yet.
//! Values are denoted as displayed in the following table.
//!
//! | Value type | Example |
//! |------------|---------|
//! | `Value::Boolean` | `true`, `false` |
//! | `Value::Int` | `3`, `-9`, `0`, `135412` |
//! | `Value::Float` | `3.`, `.35`, `1.00`, `0.5`, `123.554` |
//! //!
//! Integers are internally represented as `i64`, and floating point numbers are represented as `f64`. //! Integers are internally represented as `i64`, and floating point numbers are represented as `f64`.
//! Operators that take numbers as arguments can either take integers or floating point numbers. //! Operators that take numbers as arguments can either take integers or floating point numbers.
@ -35,115 +106,31 @@
//! //!
//! ### Variables //! ### Variables
//! //!
//! This crate allows to compile parameterizable formulas by using variables.
//! A variable is a literal in the formula, that does not contain whitespace or can be parsed as value.
//! The user needs to provide bindings to the variables for evaluation.
//! This is done with the `Configuration` trait.
//! Two structs implementing this trait are predefined.
//! There is `EmptyConfiguration`, that returns `None` for each request, and `HashMapConfiguration`, that stores mappings from literals to variables in a hash map.
//! //!
//! Variables do not have fixed types in the expression itself, but aer typed by the configuration.
//! The `Configuration` trait contains a function that takes a string literal and returns a `Value` enum.
//! The variant of this enum decides the type on evaluation.
//! //!
//! ### Functions
//! //!
//! This crate also allows to define arbitrary functions to be used in parsed expressions.
//! A function is defined as a `Function` instance.
//! It contains two properties, the `argument_amount` and the `function`.
//! The `function` is a boxed `Fn(&[Value]) -> Result<Value, Error>`.
//! The `argument_amount` is verified on execution by the crate and does not need to be verified by the `function`.
//! It determines the length of the slice that is passed to `function`.
//! See the examples section above for examples on how to construct a function instance.
//! //!
//! //! ## License
//!Supported binary operators: `!` `!=` `""` `''` `()` `[]` `,` `>` `<` `>=` `<=` `==`
//!`+` unary/binary `-` `*` `/` `%` `&&` `||` `n..m`.
//! //!
//!Supported unary operators: `` //! This crate is primarily distributed under the terms of the MIT license.
//! //! See [LICENSE](LICENSE) for details.
//!Built-in functions: `min()` `max()` `len()` `is_empty()` `array()` `converge()`.
//!See the `builtin` module for a detailed description of each.
//!
//!Where can eval be used?
//!-----------------------
//!
//!* Template engine
//!* Scripting language
//!* ...
//!
//!Usage
//!-----
//!
//!Add dependency to Cargo.toml
//!
//!```toml
//![dependencies]
//!evalexpr = "0.4"
//!```
//!
//!In your `main.rs` or `lib.rs`:
//!
//!```rust
//!extern crate evalexpr as eval;
//!```
//!
//!Examples
//!--------
//!
//!You can do mathematical calculations with supported operators:
//!
//!```rust
//!use eval::{eval, to_value};
//!
//!assert_eq!(eval("1 + 2 + 3"), Ok(to_value(6)));
//!assert_eq!(eval("2 * 2 + 3"), Ok(to_value(7)));
//!assert_eq!(eval("2 / 2 + 3"), Ok(to_value(4.0)));
//!assert_eq!(eval("2 / 2 + 3 / 3"), Ok(to_value(2.0)));
//!```
//!
//!You can eval with context:
//!
//!```rust
//!use eval::{Expr, to_value};
//!
//!assert_eq!(Expr::new("foo == bar")
//! .value("foo", true)
//! .value("bar", true)
//! .exec(),
//! Ok(to_value(true)));
//!```
//!
//!You can access data like javascript by using `.` and `[]`. `[]` supports expression.
//!
//!```rust
//!use eval::{Expr, to_value};
//!use std::collections::HashMap;
//!
//!let mut object = HashMap::new();
//!object.insert("foos", vec!["Hello", "world", "!"]);
//!
//!assert_eq!(Expr::new("object.foos[1-1] == 'Hello'")
//! .value("object", object)
//! .exec(),
//! Ok(to_value(true)));
//!```
//!
//!You can eval with function:
//!
//!```rust
//!use eval::{Expr, to_value};
//!
//!assert_eq!(Expr::new("say_hello()")
//! .function("say_hello", |_| Ok(to_value("Hello world!")))
//! .exec(),
//! Ok(to_value("Hello world!")));
//!```
//!
//!You can create an array with `array()`:
//!
//!```rust
//!use eval::{eval, to_value};
//!
//!assert_eq!(eval("array(1, 2, 3, 4, 5)"), Ok(to_value(vec![1, 2, 3, 4, 5])));
//!```
//!
//!You can create an integer array with `n..m`:
//!
//!```rust
//!use eval::{eval, to_value};
//!
//!assert_eq!(eval("0..5"), Ok(to_value(vec![0, 1, 2, 3, 4])));
//!```
//!
//!License
//!-------
//!
//!evalexpr is primarily distributed under the terms of the MIT license.
//!See [LICENSE](LICENSE) for details.
//! //!
mod configuration; mod configuration;
@ -316,6 +303,8 @@ mod test {
Box::new(|arguments| { Box::new(|arguments| {
if let Value::Int(int) = arguments[0] { if let Value::Int(int) = arguments[0] {
Ok(Value::Int(int - 2)) Ok(Value::Int(int - 2))
} else if let Value::Float(float) = arguments[0] {
Ok(Value::Float(float - 2.0))
} else { } else {
Err(Error::expected_number(arguments[0].clone())) Err(Error::expected_number(arguments[0].clone()))
} }

36
src/value/mod.rs
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@ -41,3 +41,39 @@ impl Value {
} }
} }
} }
impl From<String> for Value {
fn from(string: String) -> Self {
Value::String(string)
}
}
impl From<&str> for Value {
fn from(string: &str) -> Self {
Value::String(string.to_string())
}
}
impl From<FloatType> for Value {
fn from(float: FloatType) -> Self {
Value::Float(float)
}
}
impl From<IntType> for Value {
fn from(int: IntType) -> Self {
Value::Int(int)
}
}
impl From<bool> for Value {
fn from(boolean: bool) -> Self {
Value::Boolean(boolean)
}
}
impl From<Value> for Result<Value, Error> {
fn from(value: Value) -> Self {
Ok(value)
}
}