ruff/crates/ruff_formatter/src/macros.rs
2023-09-02 10:05:47 +02:00

503 lines
17 KiB
Rust

/// Constructs the parameters for other formatting macros.
///
/// This macro functions by taking a list of objects implementing [`crate::Format`]. It will canonicalize the
/// arguments into a single type.
///
/// This macro produces a value of type [`crate::Arguments`]. This value can be passed to
/// the macros within [crate]. All other formatting macros ([`format!`](crate::format!),
/// [`write!`](crate::write!)) are proxied through this one. This macro avoids heap allocations.
///
/// You can use the [`Arguments`] value that `format_args!` returns in `Format` contexts
/// as seen below.
///
/// ```rust
/// use ruff_formatter::{SimpleFormatContext, format, format_args};
/// use ruff_formatter::prelude::*;
///
/// # fn main() -> FormatResult<()> {
/// let formatted = format!(SimpleFormatContext::default(), [
/// format_args!(token("Hello World"))
/// ])?;
///
/// assert_eq!("Hello World", formatted.print()?.as_code());
/// # Ok(())
/// # }
/// ```
///
/// [`Format`]: crate::Format
/// [`Arguments`]: crate::Arguments
#[macro_export]
macro_rules! format_args {
($($value:expr),+ $(,)?) => {
$crate::Arguments::new(&[
$(
$crate::Argument::new(&$value)
),+
])
}
}
/// Writes formatted data into a buffer.
///
/// This macro accepts a 'buffer' and a list of format arguments. Each argument will be formatted
/// and the result will be passed to the buffer. The writer may be any value with a `write_fmt` method;
/// generally this comes from an implementation of the [`crate::Buffer`] trait.
///
/// # Examples
///
/// ```rust
/// use ruff_formatter::prelude::*;
/// use ruff_formatter::{Buffer, FormatState, SimpleFormatContext, VecBuffer, write};
///
/// # fn main() -> FormatResult<()> {
/// let mut state = FormatState::new(SimpleFormatContext::default());
/// let mut buffer = VecBuffer::new(&mut state);
/// write!(&mut buffer, [token("Hello"), space()])?;
/// write!(&mut buffer, [token("World")])?;
///
/// assert_eq!(
/// buffer.into_vec(),
/// vec![
/// FormatElement::Token { text: "Hello" },
/// FormatElement::Space,
/// FormatElement::Token { text: "World" },
/// ]
/// );
/// # Ok(())
/// # }
/// ```
#[macro_export]
macro_rules! write {
($dst:expr, [$($arg:expr),+ $(,)?]) => {{
let result = $dst.write_fmt($crate::format_args!($($arg),+));
result
}}
}
/// Writes formatted data into the given buffer and prints all written elements for a quick and dirty debugging.
///
/// An example:
///
/// ```rust
/// use ruff_formatter::prelude::*;
/// use ruff_formatter::{FormatState, VecBuffer};
///
/// # fn main() -> FormatResult<()> {
/// let mut state = FormatState::new(SimpleFormatContext::default());
/// let mut buffer = VecBuffer::new(&mut state);
///
/// dbg_write!(buffer, [token("Hello")])?;
/// // ^-- prints: [src/main.rs:7][0] = StaticToken("Hello")
///
/// assert_eq!(buffer.into_vec(), vec![FormatElement::Token { text: "Hello" }]);
/// # Ok(())
/// # }
/// ```
///
/// Note that the macro is intended as debugging tool and therefore you should avoid having
/// uses of it in version control for long periods (other than in tests and similar). Format output
/// from production code is better done with `[write!]`
#[macro_export]
macro_rules! dbg_write {
($dst:expr, [$($arg:expr),+ $(,)?]) => {{
use $crate::BufferExtensions;
let mut count = 0;
let mut inspect = $dst.inspect(|element: &FormatElement| {
std::eprintln!(
"[{}:{}][{}] = {element:#?}",
std::file!(), std::line!(), count
);
count += 1;
});
let result = inspect.write_fmt($crate::format_args!($($arg),+));
result
}}
}
/// Creates the Format IR for a value.
///
/// The first argument `format!` receives is the [`crate::FormatContext`] that specify how elements must be formatted.
/// Additional parameters passed get formatted by using their [`crate::Format`] implementation.
///
///
/// ## Examples
///
/// ```
/// use ruff_formatter::prelude::*;
/// use ruff_formatter::format;
///
/// let formatted = format!(SimpleFormatContext::default(), [token("("), token("a"), token(")")]).unwrap();
///
/// assert_eq!(
/// formatted.into_document(),
/// Document::from(vec![
/// FormatElement::Token { text: "(" },
/// FormatElement::Token { text: "a" },
/// FormatElement::Token { text: ")" },
/// ])
/// );
/// ```
#[macro_export]
macro_rules! format {
($context:expr, [$($arg:expr),+ $(,)?]) => {{
($crate::format($context, $crate::format_args!($($arg),+)))
}}
}
/// Provides multiple different alternatives and the printer picks the first one that fits.
/// Use this as last resort because it requires that the printer must try all variants in the worst case.
/// The passed variants must be in the following order:
/// - First: The variant that takes up most space horizontally
/// - Last: The variant that takes up the least space horizontally by splitting the content over multiple lines.
///
/// ## Examples
///
/// ```
/// use ruff_formatter::{Formatted, LineWidth, format, format_args, SimpleFormatOptions};
/// use ruff_formatter::prelude::*;
///
/// # fn main() -> FormatResult<()> {
/// let formatted = format!(
/// SimpleFormatContext::default(),
/// [
/// token("aVeryLongIdentifier"),
/// best_fitting!(
/// // Everything fits on a single line
/// format_args!(
/// token("("),
/// group(&format_args![
/// token("["),
/// soft_block_indent(&format_args![
/// token("1,"),
/// soft_line_break_or_space(),
/// token("2,"),
/// soft_line_break_or_space(),
/// token("3"),
/// ]),
/// token("]")
/// ]),
/// token(")")
/// ),
///
/// // Breaks after `[`, but prints all elements on a single line
/// format_args!(
/// token("("),
/// token("["),
/// block_indent(&token("1, 2, 3")),
/// token("]"),
/// token(")"),
/// ),
///
/// // Breaks after `[` and prints each element on a single line
/// format_args!(
/// token("("),
/// block_indent(&format_args![
/// token("["),
/// block_indent(&format_args![
/// token("1,"),
/// hard_line_break(),
/// token("2,"),
/// hard_line_break(),
/// token("3"),
/// ]),
/// token("]"),
/// ]),
/// token(")")
/// )
/// )
/// ]
/// )?;
///
/// let document = formatted.into_document();
///
/// // Takes the first variant if everything fits on a single line
/// assert_eq!(
/// "aVeryLongIdentifier([1, 2, 3])",
/// Formatted::new(document.clone(), SimpleFormatContext::default())
/// .print()?
/// .as_code()
/// );
///
/// // It takes the second if the first variant doesn't fit on a single line. The second variant
/// // has some additional line breaks to make sure inner groups don't break
/// assert_eq!(
/// "aVeryLongIdentifier([\n\t1, 2, 3\n])",
/// Formatted::new(document.clone(), SimpleFormatContext::new(SimpleFormatOptions { line_width: 21.try_into().unwrap(), ..SimpleFormatOptions::default() }))
/// .print()?
/// .as_code()
/// );
///
/// // Prints the last option as last resort
/// assert_eq!(
/// "aVeryLongIdentifier(\n\t[\n\t\t1,\n\t\t2,\n\t\t3\n\t]\n)",
/// Formatted::new(document.clone(), SimpleFormatContext::new(SimpleFormatOptions { line_width: 20.try_into().unwrap(), ..SimpleFormatOptions::default() }))
/// .print()?
/// .as_code()
/// );
/// # Ok(())
/// # }
/// ```
///
/// ### Enclosing group with `should_expand: true`
///
/// ```
/// use ruff_formatter::{Formatted, LineWidth, format, format_args, SimpleFormatOptions};
/// use ruff_formatter::prelude::*;
///
/// # fn main() -> FormatResult<()> {
/// let formatted = format!(
/// SimpleFormatContext::default(),
/// [
/// best_fitting!(
/// // Prints the method call on the line but breaks the array.
/// format_args!(
/// token("expect(a).toMatch("),
/// group(&format_args![
/// token("["),
/// soft_block_indent(&format_args![
/// token("1,"),
/// soft_line_break_or_space(),
/// token("2,"),
/// soft_line_break_or_space(),
/// token("3"),
/// ]),
/// token("]")
/// ]).should_expand(true),
/// token(")")
/// ),
///
/// // Breaks after `(`
/// format_args!(
/// token("expect(a).toMatch("),
/// group(&soft_block_indent(
/// &group(&format_args![
/// token("["),
/// soft_block_indent(&format_args![
/// token("1,"),
/// soft_line_break_or_space(),
/// token("2,"),
/// soft_line_break_or_space(),
/// token("3"),
/// ]),
/// token("]")
/// ]).should_expand(true),
/// )).should_expand(true),
/// token(")")
/// ),
/// )
/// ]
/// )?;
///
/// let document = formatted.into_document();
///
/// assert_eq!(
/// "expect(a).toMatch([\n\t1,\n\t2,\n\t3\n])",
/// Formatted::new(document.clone(), SimpleFormatContext::default())
/// .print()?
/// .as_code()
/// );
///
/// # Ok(())
/// # }
/// ```
///
/// The first variant fits because all its content up to the first line break fit on the line without exceeding
/// the configured print width.
///
/// ## Complexity
/// Be mindful of using this IR element as it has a considerable performance penalty:
/// - There are multiple representation for the same content. This results in increased memory usage
/// and traversal time in the printer.
/// - The worst case complexity is that the printer tires each variant. This can result in quadratic
/// complexity if used in nested structures.
///
/// ## Behavior
/// This IR is similar to Prettier's `conditionalGroup`. The printer measures each variant, except the [`MostExpanded`], in [`Flat`] mode
/// to find the first variant that fits and prints this variant in [`Flat`] mode. If no variant fits, then
/// the printer falls back to printing the [`MostExpanded`] variant in [`Expanded`] mode.
///
/// The definition of *fits* differs to groups in that the printer only tests if it is possible to print
/// the content up to the first non-soft line break without exceeding the configured print width.
/// This definition differs from groups as that non-soft line breaks make group expand.
///
/// [`crate::BestFitting`] acts as a "break" boundary, meaning that it is considered to fit
///
///
/// [`Flat`]: crate::format_element::PrintMode::Flat
/// [`Expanded`]: crate::format_element::PrintMode::Expanded
/// [`MostExpanded`]: crate::format_element::BestFittingVariants::most_expanded
#[macro_export]
macro_rules! best_fitting {
($least_expanded:expr, $($tail:expr),+ $(,)?) => {{
#[allow(unsafe_code)]
unsafe {
$crate::BestFitting::from_arguments_unchecked($crate::format_args!($least_expanded, $($tail),+))
}
}}
}
#[cfg(test)]
mod tests {
use crate::prelude::*;
use crate::{write, FormatState, SimpleFormatOptions, VecBuffer};
struct TestFormat;
impl Format<()> for TestFormat {
fn fmt(&self, f: &mut Formatter<()>) -> FormatResult<()> {
write!(f, [token("test")])
}
}
#[test]
fn test_single_element() {
let mut state = FormatState::new(());
let mut buffer = VecBuffer::new(&mut state);
write![&mut buffer, [TestFormat]].unwrap();
assert_eq!(
buffer.into_vec(),
vec![FormatElement::Token { text: "test" }]
);
}
#[test]
fn test_multiple_elements() {
let mut state = FormatState::new(());
let mut buffer = VecBuffer::new(&mut state);
write![
&mut buffer,
[token("a"), space(), token("simple"), space(), TestFormat]
]
.unwrap();
assert_eq!(
buffer.into_vec(),
vec![
FormatElement::Token { text: "a" },
FormatElement::Space,
FormatElement::Token { text: "simple" },
FormatElement::Space,
FormatElement::Token { text: "test" }
]
);
}
#[test]
fn best_fitting_variants_print_as_lists() {
use crate::prelude::*;
use crate::{format, format_args, Formatted};
// The second variant below should be selected when printing at a width of 30
let formatted_best_fitting = format!(
SimpleFormatContext::default(),
[
token("aVeryLongIdentifier"),
soft_line_break_or_space(),
best_fitting![
format_args![token(
"Something that will not fit on a line with 30 character print width."
)],
format_args![group(&format_args![
token("Start"),
soft_line_break(),
group(&soft_block_indent(&format_args![
token("1,"),
soft_line_break_or_space(),
token("2,"),
soft_line_break_or_space(),
token("3"),
])),
soft_line_break_or_space(),
soft_block_indent(&format_args![
token("1,"),
soft_line_break_or_space(),
token("2,"),
soft_line_break_or_space(),
group(&format_args!(
token("A,"),
soft_line_break_or_space(),
token("B")
)),
soft_line_break_or_space(),
token("3")
]),
soft_line_break_or_space(),
token("End")
])
.should_expand(true)],
format_args!(token("Most"), hard_line_break(), token("Expanded"))
]
]
)
.unwrap();
// This matches the IR above except that the `best_fitting` was replaced with
// the contents of its second variant.
let formatted_normal_list = format!(
SimpleFormatContext::default(),
[
token("aVeryLongIdentifier"),
soft_line_break_or_space(),
format_args![
token("Start"),
soft_line_break(),
&group(&soft_block_indent(&format_args![
token("1,"),
soft_line_break_or_space(),
token("2,"),
soft_line_break_or_space(),
token("3"),
])),
soft_line_break_or_space(),
&soft_block_indent(&format_args![
token("1,"),
soft_line_break_or_space(),
token("2,"),
soft_line_break_or_space(),
group(&format_args!(
token("A,"),
soft_line_break_or_space(),
token("B")
)),
soft_line_break_or_space(),
token("3")
]),
soft_line_break_or_space(),
token("End")
],
]
)
.unwrap();
let best_fitting_code = Formatted::new(
formatted_best_fitting.into_document(),
SimpleFormatContext::new(SimpleFormatOptions {
line_width: 30.try_into().unwrap(),
..SimpleFormatOptions::default()
}),
)
.print()
.expect("Document to be valid")
.as_code()
.to_string();
let normal_list_code = Formatted::new(
formatted_normal_list.into_document(),
SimpleFormatContext::new(SimpleFormatOptions {
line_width: 30.try_into().unwrap(),
..SimpleFormatOptions::default()
}),
)
.print()
.expect("Document to be valid")
.as_code()
.to_string();
// The variant that "fits" will print its contents as if it were a normal list
// outside of a BestFitting element.
assert_eq!(best_fitting_code, normal_list_code);
}
}