1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use std::cmp::Ordering;
13 use syntax::ast::{self, Visibility, Attribute, MetaItem, MetaItem_};
14 use syntax::codemap::{CodeMap, Span, BytePos};
16 use comment::FindUncommented;
17 use rewrite::{Rewrite, RewriteContext};
21 // Computes the length of a string's last line, minus offset.
23 pub fn extra_offset(text: &str, offset: usize) -> usize {
24 match text.rfind('\n') {
25 // 1 for newline character
26 Some(idx) => text.len() - idx - 1 - offset,
32 pub fn span_after(original: Span, needle: &str, codemap: &CodeMap) -> BytePos {
33 let snippet = codemap.span_to_snippet(original).unwrap();
35 original.lo + BytePos(snippet.find_uncommented(needle).unwrap() as u32 + 1)
39 pub fn make_indent(width: usize) -> String {
40 let mut indent = String::with_capacity(width);
48 pub fn format_visibility(vis: Visibility) -> &'static str {
50 Visibility::Public => "pub ",
51 Visibility::Inherited => "",
56 pub fn format_mutability(mutability: ast::Mutability) -> &'static str {
58 ast::Mutability::MutMutable => "mut ",
59 ast::Mutability::MutImmutable => "",
63 // The width of the first line in s.
65 pub fn first_line_width(s: &str) -> usize {
72 // The width of the last line in s.
74 pub fn last_line_width(s: &str) -> usize {
76 Some(n) => s.len() - n - 1,
82 fn is_skip(meta_item: &MetaItem) -> bool {
83 match meta_item.node {
84 MetaItem_::MetaWord(ref s) => *s == SKIP_ANNOTATION,
90 pub fn contains_skip(attrs: &[Attribute]) -> bool {
91 attrs.iter().any(|a| is_skip(&a.node.value))
94 // Find the end of a TyParam
96 pub fn end_typaram(typaram: &ast::TyParam) -> BytePos {
101 ast::RegionTyParamBound(ref lt) => lt.span,
102 ast::TraitTyParamBound(ref prt, _) => prt.span,
105 .unwrap_or(typaram.span)
110 #[cfg(target_pointer_width="64")]
111 // Based on the trick layed out at
112 // http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
113 pub fn round_up_to_power_of_two(mut x: usize) -> usize {
114 x = x.wrapping_sub(1);
125 #[cfg(target_pointer_width="32")]
126 pub fn round_up_to_power_of_two(mut x: usize) -> usize {
127 x = x.wrapping_sub(1);
136 // Macro for deriving implementations of Decodable for enums
138 macro_rules! impl_enum_decodable {
139 ( $e:ident, $( $x:ident ),* ) => {
140 impl ::rustc_serialize::Decodable for $e {
141 fn decode<D: ::rustc_serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
142 let s = try!(d.read_str());
145 stringify!($x) => Ok($e::$x),
147 _ => Err(d.error("Bad variant")),
152 impl ::std::str::FromStr for $e {
153 type Err = &'static str;
155 fn from_str(s: &str) -> Result<Self, Self::Err> {
158 stringify!($x) => Ok($e::$x),
160 _ => Err("Bad variant"),
167 // Same as try!, but for Option
169 macro_rules! try_opt {
170 ($expr:expr) => (match $expr {
172 None => { return None; }
176 // Wraps string-like values in an Option. Returns Some when the string adheres
177 // to the Rewrite constraints defined for the Rewrite trait and else otherwise.
178 pub fn wrap_str<S: AsRef<str>>(s: S, max_width: usize, width: usize, offset: usize) -> Option<S> {
180 let snippet = s.as_ref();
182 if !snippet.contains('\n') && snippet.len() > width {
185 let mut lines = snippet.lines();
187 // The caller of this function has already placed `offset`
188 // characters on the first line.
189 let first_line_max_len = try_opt!(max_width.checked_sub(offset));
190 if lines.next().unwrap().len() > first_line_max_len {
194 // The other lines must fit within the maximum width.
195 if lines.find(|line| line.len() > max_width).is_some() {
199 // `width` is the maximum length of the last line, excluding
201 // A special check for the last line, since the caller may
202 // place trailing characters on this line.
203 if snippet.lines().rev().next().unwrap().len() > offset + width {
212 impl Rewrite for String {
213 fn rewrite(&self, context: &RewriteContext, width: usize, offset: usize) -> Option<String> {
214 wrap_str(self, context.config.max_width, width, offset).map(ToOwned::to_owned)
218 // Binary search in integer range. Returns the first Ok value returned by the
220 // The callback takes an integer and returns either an Ok, or an Err indicating
221 // whether the `guess' was too high (Ordering::Less), or too low.
222 // This function is guaranteed to try to the hi value first.
223 pub fn binary_search<C, T>(mut lo: usize, mut hi: usize, callback: C) -> Option<T>
224 where C: Fn(usize) -> Result<T, Ordering>
229 match callback(middle) {
230 Ok(val) => return Some(val),
231 Err(Ordering::Less) => {
238 middle = (hi + lo) / 2;
245 fn bin_search_test() {
249 j if j > 4 => Err(Ordering::Less),
250 j if j < 4 => Err(Ordering::Greater),
255 assert_eq!(Some(()), binary_search(1, 10, &closure));
256 assert_eq!(None, binary_search(1, 3, &closure));
257 assert_eq!(Some(()), binary_search(0, 44, &closure));
258 assert_eq!(Some(()), binary_search(4, 125, &closure));
259 assert_eq!(None, binary_search(6, 100, &closure));
263 fn power_rounding() {
264 assert_eq!(0, round_up_to_power_of_two(0));
265 assert_eq!(1, round_up_to_power_of_two(1));
266 assert_eq!(64, round_up_to_power_of_two(33));
267 assert_eq!(256, round_up_to_power_of_two(256));