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

Use the new context macro in the README examples

Browse Source
This commit is contained in:
Ophir LOJKINE 2019-04-17 17:24:07 +02:00
parent 0eaeb3f6ab
commit 3d1b0696cb
1 changed files with 27 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
README.md
View File

@ -64,28 +64,29 @@ And you can use **variables** and **functions** in expressions like this:
use evalexpr::*;
use evalexpr::error::expect_number;
let mut context = HashMapContext::new();
context.set_value("five".into(), 5.into()).unwrap(); // Do proper error handling here
context.set_value("twelve".into(), 12.into()).unwrap(); // Do proper error handling here
context.set_function("f".into(), Function::new(Some(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(EvalexprError::expected_number(arguments[0].clone()))
}
}))).unwrap(); // Do proper error handling here
context.set_function("avg".into(), Function::new(Some(2) /* argument amount */, Box::new(|arguments| {
expect_number(&arguments[0])?;
expect_number(&arguments[1])?;
let context = context_map! {
"five" => 5,
"twelve" => 12,
"f" => Function::new(Some(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(EvalexprError::expected_number(arguments[0].clone()))
}
})),
"avg" => Function::new(Some(2) /* argument amount */, Box::new(|arguments| {
expect_number(&arguments[0])?;
expect_number(&arguments[1])?;
if let (Value::Int(a), Value::Int(b)) = (&arguments[0], &arguments[1]) {
Ok(Value::Int((a + b) / 2))
} else {
Ok(Value::Float((arguments[0].as_number()? + arguments[1].as_number()?) / 2.0))
}
}))).unwrap(); // Do proper error handling here
if let (Value::Int(a), Value::Int(b)) = (&arguments[0], &arguments[1]) {
Ok(Value::Int((a + b) / 2))
} else {
Ok(Value::Float((arguments[0].as_number()? + arguments[1].as_number()?) / 2.0))
}
}))
}.unwrap();
assert_eq!(eval_with_context("five + 8 > f(twelve)", &context), Ok(Value::from(true)));
// `eval_with_context` returns a variant of the `Value` enum,
@ -102,10 +103,11 @@ use evalexpr::*;
let precompiled = build_operator_tree("a * b - c > 5").unwrap(); // Do proper error handling here
let mut context = HashMapContext::new();
context.set_value("a".into(), 6.into()).unwrap(); // Do proper error handling here
context.set_value("b".into(), 2.into()).unwrap(); // Do proper error handling here
context.set_value("c".into(), 3.into()).unwrap(); // Do proper error handling here
let mut context = context_map! {
"a" => 6,
"b" => 2,
"c" => 3
}.unwrap();
assert_eq!(precompiled.eval_with_context(&context), Ok(Value::from(true)));
context.set_value("c".into(), 8.into()).unwrap(); // Do proper error handling here