jeff/expressive
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Document operations on values

Browse Source 
Relates to #16
This commit is contained in:
Sebastian Schmidt 2019-03-20 17:30:37 +02:00
parent d3deef1f53
commit 1375134e9f
2 changed files with 54 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
README.md
View File

@ -33,6 +33,10 @@ Then you can use `evalexpr` to evaluate expressions like this:
use evalexpr::*;
assert_eq!(eval("1 + 2 + 3"), Ok(Value::from(6)));
// `eval` returns a variant of the `Value` enum,
// while `eval_[type]` returns the respective type directly.
// Both can be used interchangeably.
assert_eq!(eval_int("1 + 2 + 3"), Ok(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)));
@ -68,6 +72,10 @@ configuration.insert_function("avg", Function::new(Some(2) /* argument amount */
})));
assert_eq!(eval_with_configuration("five + 8 > f(twelve)", &configuration), Ok(Value::from(true)));
// `eval_with_configuration` returns a variant of the `Value` enum,
// while `eval_[type]_with_configuration` returns the respective type directly.
// Both can be used interchangeably.
assert_eq!(eval_boolean_with_configuration("five + 8 > f(twelve)", &configuration), Ok(true));
assert_eq!(eval_with_configuration("avg(2, 4) == 3", &configuration), Ok(Value::from(true)));
```
@ -86,6 +94,10 @@ assert_eq!(precompiled.eval_with_configuration(&configuration), Ok(Value::from(t
configuration.insert_variable("c", 8);
assert_eq!(precompiled.eval_with_configuration(&configuration), Ok(Value::from(false)));
// `Node::eval_with_configuration` returns a variant of the `Value` enum,
// while `Node::eval_[type]_with_configuration` returns the respective type directly.
// Both can be used interchangeably.
assert_eq!(precompiled.eval_boolean_with_configuration(&configuration), Ok(false));
```
## Features
@ -155,6 +167,27 @@ Values are denoted as displayed in the following table.
| `Value::Float` | `3.`, `.35`, `1.00`, `0.5`, `123.554` |
Integers are internally represented as `i64`, and floating point numbers are represented as `f64`.
Values can be constructed either directly or using the `From` trait.
Values can be decomposed using the `Value::as_[type]` methods.
The type of a value can be checked using the `Value::is_[type]` methods.
**Examples for constructing a value:**
| Code | Result |
|------|--------|
| `Value::from(4)` | `Value::Int(4)` |
| `Value::from(4.4)` | `Value::Float(4.4)` |
| `Value::from(true)` | `Value::Boolean(true)` |
| `Value::from(vec![Value::from(3)])` | `Value::Tuple(vec![Value::Int(3)])` |
**Examples for deconstructing a value:**
| Code | Result |
|------|--------|
| `Value::from(4).as_int()` | `Ok(4)` |
| `Value::from(4.4).as_float()` | `Ok(4.4)` |
| `Value::from(true).as_int()` | `Err(Error::ExpectedInt {actual: Value::Boolean(true)})` |
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.

21
src/lib.rs
View File

@ -154,6 +154,27 @@
//! | `Value::Float` | `3.`, `.35`, `1.00`, `0.5`, `123.554` |
//!
//! Integers are internally represented as `i64`, and floating point numbers are represented as `f64`.
//! Values can be constructed either directly or using the `From` trait.
//! Values can be decomposed using the `Value::as_[type]` methods.
//! The type of a value can be checked using the `Value::is_[type]` methods.
//!
//! **Examples for constructing a value:**
//!
//! | Code | Result |
//! |------|--------|
//! | `Value::from(4)` | `Value::Int(4)` |
//! | `Value::from(4.4)` | `Value::Float(4.4)` |
//! | `Value::from(true)` | `Value::Boolean(true)` |
//! | `Value::from(vec![Value::from(3)])` | `Value::Tuple(vec![Value::Int(3)])` |
//!
//! **Examples for deconstructing a value:**
//!
//! | Code | Result |
//! |------|--------|
//! | `Value::from(4).as_int()` | `Ok(4)` |
//! | `Value::from(4.4).as_float()` | `Ok(4.4)` |
//! | `Value::from(true).as_int()` | `Err(Error::ExpectedInt {actual: Value::Boolean(true)})` |
//!
//! 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.