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templater: turn logical && and || into short-circuiting operators

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Since the context (or self) property is no longer passed by argument, it's easy
to implement short-circuiting behavior.
This commit is contained in:
Yuya Nishihara 2024-03-21 13:14:53 +09:00
parent df7be43ab6
commit 96e0bc0bdd
2 changed files with 18 additions and 7 deletions
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21
cli/src/template_builder.rs
View file

@ -495,16 +495,16 @@ fn build_binary_operation<'a, L: TemplateLanguage<'a> + ?Sized>(
) -> TemplateParseResult<L::Property> { ) -> TemplateParseResult<L::Property> {
match op { match op {
BinaryOp::LogicalOr => { BinaryOp::LogicalOr => {
// No short-circuiting supported
let lhs = expect_boolean_expression(language, build_ctx, lhs_node)?; let lhs = expect_boolean_expression(language, build_ctx, lhs_node)?;
let rhs = expect_boolean_expression(language, build_ctx, rhs_node)?; let rhs = expect_boolean_expression(language, build_ctx, rhs_node)?;
Ok(L::wrap_boolean((lhs, rhs).map(|(l, r)| l | r))) let out = lhs.and_then(move |l| Ok(l || rhs.extract()?));
Ok(L::wrap_boolean(out))
} }
BinaryOp::LogicalAnd => { BinaryOp::LogicalAnd => {
// No short-circuiting supported
let lhs = expect_boolean_expression(language, build_ctx, lhs_node)?; let lhs = expect_boolean_expression(language, build_ctx, lhs_node)?;
let rhs = expect_boolean_expression(language, build_ctx, rhs_node)?; let rhs = expect_boolean_expression(language, build_ctx, rhs_node)?;
Ok(L::wrap_boolean((lhs, rhs).map(|(l, r)| l & r))) let out = lhs.and_then(move |l| Ok(l && rhs.extract()?));
Ok(L::wrap_boolean(out))
} }
} }
} }
@ -1199,6 +1199,10 @@ mod tests {
} }
} }
fn new_error_property<O>(message: &str) -> impl TemplateProperty<Output = O> + '_ {
Literal(()).and_then(|()| Err(TemplatePropertyError(message.into())))
}
fn new_signature(name: &str, email: &str) -> Signature { fn new_signature(name: &str, email: &str) -> Signature {
Signature { Signature {
name: name.to_owned(), name: name.to_owned(),
@ -1490,7 +1494,7 @@ mod tests {
#[test] #[test]
fn test_logical_operation() { fn test_logical_operation() {
let env = TestTemplateEnv::new(); let mut env = TestTemplateEnv::new();
insta::assert_snapshot!(env.render_ok(r#"!false"#), @"true"); insta::assert_snapshot!(env.render_ok(r#"!false"#), @"true");
insta::assert_snapshot!(env.render_ok(r#"false || !false"#), @"true"); insta::assert_snapshot!(env.render_ok(r#"false || !false"#), @"true");
@ -1498,6 +1502,13 @@ mod tests {
insta::assert_snapshot!(env.render_ok(r#" !"" "#), @"true"); insta::assert_snapshot!(env.render_ok(r#" !"" "#), @"true");
insta::assert_snapshot!(env.render_ok(r#" "" || "a".lines() "#), @"true"); insta::assert_snapshot!(env.render_ok(r#" "" || "a".lines() "#), @"true");
// Short-circuiting
env.add_keyword("bad_bool", || L::wrap_boolean(new_error_property("Bad")));
insta::assert_snapshot!(env.render_ok(r#"false && bad_bool"#), @"false");
insta::assert_snapshot!(env.render_ok(r#"true && bad_bool"#), @"<Error: Bad>");
insta::assert_snapshot!(env.render_ok(r#"false || bad_bool"#), @"<Error: Bad>");
insta::assert_snapshot!(env.render_ok(r#"true || bad_bool"#), @"true");
} }
#[test] #[test]

4
docs/templates.md
View file

@ -31,8 +31,8 @@ The following operators are supported.
* `x.f()`: Method call. * `x.f()`: Method call.
* `-x`: Negate integer value. * `-x`: Negate integer value.
* `!x`: Logical not. * `!x`: Logical not.
* `x && y`: Logical and. * `x && y`: Logical and, short-circuiting.
* `x || y`: Logical or. * `x || y`: Logical or, short-circuiting.
* `x ++ y`: Concatenate `x` and `y` templates. * `x ++ y`: Concatenate `x` and `y` templates.
## Global functions ## Global functions