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Document operations on values

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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
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33
README.md
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@ -33,6 +33,10 @@ Then you can use `evalexpr` to evaluate expressions like this:
use evalexpr::*; use evalexpr::*;
assert_eq!(eval("1 + 2 + 3"), Ok(Value::from(6))); 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 - 2 * 3"), Ok(Value::from(-5)));
assert_eq!(eval("1.0 + 2 * 3"), Ok(Value::from(7.0))); assert_eq!(eval("1.0 + 2 * 3"), Ok(Value::from(7.0)));
assert_eq!(eval("true && 4 > 2"), Ok(Value::from(true))); 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))); 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))); 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); configuration.insert_variable("c", 8);
assert_eq!(precompiled.eval_with_configuration(&configuration), Ok(Value::from(false))); 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 ## Features
@ -155,6 +167,27 @@ Values are denoted as displayed in the following table.
| `Value::Float` | `3.`, `.35`, `1.00`, `0.5`, `123.554` | | `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`.
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. 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. 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. Otherwise, the result is an integer.

21
src/lib.rs
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@ -154,6 +154,27 @@
//! | `Value::Float` | `3.`, `.35`, `1.00`, `0.5`, `123.554` | //! | `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`.
//! 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. //! 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. //! 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. //! Otherwise, the result is an integer.