]> git.lizzy.rs Git - rust.git/blobdiff - src/lists.rs
Merge pull request #2138 from topecongiro/comments-around-trait-bounds
[rust.git] / src / lists.rs
index 048f11a18561a4a9cdd87a0dc33d8fe42b64cab5..d560c88886ce19a2ceddc0ec42a0c3aab38240e1 100644 (file)
 
 use syntax::codemap::{BytePos, CodeMap};
 
-use {Indent, Shape};
 use comment::{find_comment_end, rewrite_comment, FindUncommented};
 use config::{Config, IndentStyle};
 use rewrite::RewriteContext;
-use utils::{first_line_width, last_line_width, mk_sp};
+use shape::{Indent, Shape};
+use utils::{first_line_width, last_line_width, mk_sp, starts_with_newline};
 
-#[derive(Eq, PartialEq, Debug, Copy, Clone)]
 /// Formatting tactic for lists. This will be cast down to a
-/// DefinitiveListTactic depending on the number and length of the items and
+/// `DefinitiveListTactic` depending on the number and length of the items and
 /// their comments.
+#[derive(Eq, PartialEq, Debug, Copy, Clone)]
 pub enum ListTactic {
     // One item per row.
     Vertical,
@@ -61,6 +61,7 @@ pub struct ListFormatting<'a> {
     pub tactic: DefinitiveListTactic,
     pub separator: &'a str,
     pub trailing_separator: SeparatorTactic,
+    pub separator_place: SeparatorPlace,
     pub shape: Shape,
     // Non-expressions, e.g. items, will have a new line at the end of the list.
     // Important for comment styles.
@@ -70,15 +71,39 @@ pub struct ListFormatting<'a> {
     pub config: &'a Config,
 }
 
+impl<'a> ListFormatting<'a> {
+    pub fn needs_trailing_separator(&self) -> bool {
+        match self.trailing_separator {
+            // We always put separator in front.
+            SeparatorTactic::Always => true,
+            SeparatorTactic::Vertical => self.tactic == DefinitiveListTactic::Vertical,
+            SeparatorTactic::Never => {
+                self.tactic == DefinitiveListTactic::Vertical && self.separator_place.is_front()
+            }
+        }
+    }
+}
+
 impl AsRef<ListItem> for ListItem {
     fn as_ref(&self) -> &ListItem {
         self
     }
 }
 
+#[derive(PartialEq, Eq)]
+pub enum ListItemCommentStyle {
+    // Try to keep the comment on the same line with the item.
+    SameLine,
+    // Put the comment on the previous or the next line of the item.
+    DifferentLine,
+    // No comment available.
+    None,
+}
+
 pub struct ListItem {
     // None for comments mean that they are not present.
     pub pre_comment: Option<String>,
+    pub pre_comment_style: ListItemCommentStyle,
     // Item should include attributes and doc comments. None indicates a failed
     // rewrite.
     pub item: Option<String>,
@@ -89,12 +114,22 @@ pub struct ListItem {
 
 impl ListItem {
     pub fn inner_as_ref(&self) -> &str {
-        self.item.as_ref().map_or("", |s| &*s)
+        self.item.as_ref().map_or("", |s| s)
+    }
+
+    pub fn is_different_group(&self) -> bool {
+        self.inner_as_ref().contains('\n') || self.pre_comment.is_some()
+            || self.post_comment
+                .as_ref()
+                .map_or(false, |s| s.contains('\n'))
     }
 
     pub fn is_multiline(&self) -> bool {
-        self.inner_as_ref().contains('\n') || self.pre_comment.is_some() ||
-            self.post_comment
+        self.inner_as_ref().contains('\n')
+            || self.pre_comment
+                .as_ref()
+                .map_or(false, |s| s.contains('\n'))
+            || self.post_comment
                 .as_ref()
                 .map_or(false, |s| s.contains('\n'))
     }
@@ -102,8 +137,8 @@ pub fn is_multiline(&self) -> bool {
     pub fn has_comment(&self) -> bool {
         self.pre_comment
             .as_ref()
-            .map_or(false, |comment| comment.starts_with("//")) ||
-            self.post_comment
+            .map_or(false, |comment| comment.starts_with("//"))
+            || self.post_comment
                 .as_ref()
                 .map_or(false, |comment| comment.starts_with("//"))
     }
@@ -111,6 +146,7 @@ pub fn has_comment(&self) -> bool {
     pub fn from_str<S: Into<String>>(s: S) -> ListItem {
         ListItem {
             pre_comment: None,
+            pre_comment_style: ListItemCommentStyle::None,
             item: Some(s.into()),
             post_comment: None,
             new_lines: false,
@@ -118,8 +154,8 @@ pub fn from_str<S: Into<String>>(s: S) -> ListItem {
     }
 }
 
-#[derive(Eq, PartialEq, Debug, Copy, Clone)]
 /// The definitive formatting tactic for lists.
+#[derive(Eq, PartialEq, Debug, Copy, Clone)]
 pub enum DefinitiveListTactic {
     Vertical,
     Horizontal,
@@ -136,7 +172,7 @@ pub fn ends_with_newline(&self, indent_style: IndentStyle) -> bool {
 }
 
 /// The type of separator for lists.
-#[derive(Eq, PartialEq, Debug)]
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
 pub enum Separator {
     Comma,
     VerticalBar,
@@ -153,6 +189,32 @@ pub fn len(&self) -> usize {
     }
 }
 
+/// Where to put separator.
+#[derive(Eq, PartialEq, Debug, Copy, Clone)]
+pub enum SeparatorPlace {
+    Front,
+    Back,
+}
+
+impl_enum_serialize_and_deserialize!(SeparatorPlace, Front, Back);
+
+impl SeparatorPlace {
+    pub fn is_front(&self) -> bool {
+        *self == SeparatorPlace::Front
+    }
+
+    pub fn is_back(&self) -> bool {
+        *self == SeparatorPlace::Back
+    }
+
+    pub fn from_tactic(default: SeparatorPlace, tactic: DefinitiveListTactic) -> SeparatorPlace {
+        match tactic {
+            DefinitiveListTactic::Vertical => default,
+            _ => SeparatorPlace::Back,
+        }
+    }
+}
+
 pub fn definitive_tactic<I, T>(
     items: I,
     tactic: ListTactic,
@@ -181,8 +243,8 @@ pub fn definitive_tactic<I, T>(
     let total_sep_len = sep.len() * sep_count.checked_sub(1).unwrap_or(0);
     let real_total = total_width + total_sep_len;
 
-    if real_total <= limit && !pre_line_comments &&
-        !items.into_iter().any(|item| item.as_ref().is_multiline())
+    if real_total <= limit && !pre_line_comments
+        && !items.into_iter().any(|item| item.as_ref().is_multiline())
     {
         DefinitiveListTactic::Horizontal
     } else {
@@ -202,17 +264,18 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
 
     // Now that we know how we will layout, we can decide for sure if there
     // will be a trailing separator.
-    let mut trailing_separator = needs_trailing_separator(formatting.trailing_separator, tactic);
-    let mut result = String::new();
+    let mut trailing_separator = formatting.needs_trailing_separator();
+    let mut result = String::with_capacity(128);
     let cloned_items = items.clone();
     let mut iter = items.into_iter().enumerate().peekable();
     let mut item_max_width: Option<usize> = None;
+    let mut sep_place = SeparatorPlace::from_tactic(formatting.separator_place, tactic);
 
     let mut line_len = 0;
     let indent_str = &formatting.shape.indent.to_string(formatting.config);
     while let Some((i, item)) = iter.next() {
         let item = item.as_ref();
-        let inner_item = try_opt!(item.item.as_ref());
+        let inner_item = item.item.as_ref()?;
         let first = i == 0;
         let last = iter.peek().is_none();
         let mut separate = !last || trailing_separator;
@@ -226,7 +289,7 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
             inner_item.as_ref()
         };
         let mut item_last_line_width = item_last_line.len() + item_sep_len;
-        if item_last_line.starts_with(indent_str) {
+        if item_last_line.starts_with(&**indent_str) {
             item_last_line_width -= indent_str.len();
         }
 
@@ -246,13 +309,16 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
                     result.push('\n');
                     result.push_str(indent_str);
                     line_len = 0;
-                    if tactic == DefinitiveListTactic::Mixed && formatting.ends_with_newline {
+                    if formatting.ends_with_newline {
                         if last {
                             separate = true;
                         } else {
                             trailing_separator = true;
                         }
                     }
+                    sep_place = formatting.separator_place;
+                } else {
+                    sep_place = SeparatorPlace::Back;
                 }
 
                 if line_len > 0 {
@@ -270,40 +336,55 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
             // Block style in non-vertical mode.
             let block_mode = tactic != DefinitiveListTactic::Vertical;
             // Width restriction is only relevant in vertical mode.
-            let comment = try_opt!(rewrite_comment(
-                comment,
-                block_mode,
-                formatting.shape,
-                formatting.config,
-            ));
+            let comment =
+                rewrite_comment(comment, block_mode, formatting.shape, formatting.config)?;
             result.push_str(&comment);
 
             if tactic == DefinitiveListTactic::Vertical {
-                result.push('\n');
-                result.push_str(indent_str);
+                // We cannot keep pre-comments on the same line if the comment if normalized.
+                let keep_comment = if formatting.config.normalize_comments()
+                    || item.pre_comment_style == ListItemCommentStyle::DifferentLine
+                {
+                    false
+                } else {
+                    // We will try to keep the comment on the same line with the item here.
+                    // 1 = ` `
+                    let total_width = total_item_width(item) + item_sep_len + 1;
+                    total_width <= formatting.shape.width
+                };
+                if keep_comment {
+                    result.push(' ');
+                } else {
+                    result.push('\n');
+                    result.push_str(indent_str);
+                }
             } else {
                 result.push(' ');
             }
             item_max_width = None;
         }
 
+        if separate && sep_place.is_front() && !first {
+            result.push_str(formatting.separator.trim());
+            result.push(' ');
+        }
         result.push_str(&inner_item[..]);
 
         // Post-comments
         if tactic != DefinitiveListTactic::Vertical && item.post_comment.is_some() {
             let comment = item.post_comment.as_ref().unwrap();
-            let formatted_comment = try_opt!(rewrite_comment(
+            let formatted_comment = rewrite_comment(
                 comment,
                 true,
                 Shape::legacy(formatting.shape.width, Indent::empty()),
                 formatting.config,
-            ));
+            )?;
 
             result.push(' ');
             result.push_str(&formatted_comment);
         }
 
-        if separate {
+        if separate && sep_place.is_back() {
             result.push_str(formatting.separator);
         }
 
@@ -320,7 +401,7 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
                         formatting.config.max_width(),
                     ));
                 }
-                let overhead = if let &mut Some(max_width) = item_max_width {
+                let overhead = if let Some(max_width) = *item_max_width {
                     max_width + 2
                 } else {
                     // 1 = space between item and comment.
@@ -331,30 +412,31 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
                 let comment_shape = Shape::legacy(width, offset);
 
                 // Use block-style only for the last item or multiline comments.
-                let block_style = !formatting.ends_with_newline && last ||
-                    comment.trim().contains('\n') ||
-                    comment.trim().len() > width;
+                let block_style = !formatting.ends_with_newline && last
+                    || comment.trim().contains('\n')
+                    || comment.trim().len() > width;
 
                 rewrite_comment(comment, block_style, comment_shape, formatting.config)
             };
 
-            let mut formatted_comment = try_opt!(rewrite_post_comment(&mut item_max_width));
+            let mut formatted_comment = rewrite_post_comment(&mut item_max_width)?;
 
-            if !formatted_comment.starts_with('\n') {
+            if !starts_with_newline(&formatted_comment) {
                 let mut comment_alignment =
                     post_comment_alignment(item_max_width, inner_item.len());
-                if first_line_width(&formatted_comment) + last_line_width(&result) +
-                    comment_alignment + 1 > formatting.config.max_width()
+                if first_line_width(&formatted_comment) + last_line_width(&result)
+                    comment_alignment + 1 > formatting.config.max_width()
                 {
                     item_max_width = None;
-                    formatted_comment = try_opt!(rewrite_post_comment(&mut item_max_width));
+                    formatted_comment = rewrite_post_comment(&mut item_max_width)?;
                     comment_alignment = post_comment_alignment(item_max_width, inner_item.len());
                 }
                 for _ in 0..(comment_alignment + 1) {
                     result.push(' ');
                 }
-                // An additional space for the missing trailing comma
-                if last && item_max_width.is_some() && !separate {
+                // An additional space for the missing trailing separator.
+                if last && item_max_width.is_some() && !separate && !formatting.separator.is_empty()
+                {
                     result.push(' ');
                 }
             }
@@ -366,8 +448,8 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
             item_max_width = None;
         }
 
-        if formatting.preserve_newline && !last && tactic == DefinitiveListTactic::Vertical &&
-            item.new_lines
+        if formatting.preserve_newline && !last && tactic == DefinitiveListTactic::Vertical
+            && item.new_lines
         {
             item_max_width = None;
             result.push('\n');
@@ -392,9 +474,9 @@ fn max_width_of_item_with_post_comment<I, T>(
     for item in items.clone().into_iter().skip(i) {
         let item = item.as_ref();
         let inner_item_width = item.inner_as_ref().len();
-        if !first &&
-            (item.is_multiline() || !item.post_comment.is_some() ||
-                inner_item_width + overhead > max_budget)
+        if !first
+            && (item.is_different_group() || !item.post_comment.is_some()
+                || inner_item_width + overhead > max_budget)
         {
             return max_width;
         }
@@ -427,6 +509,7 @@ pub struct ListItems<'a, I, F1, F2, F3>
     prev_span_end: BytePos,
     next_span_start: BytePos,
     terminator: &'a str,
+    leave_last: bool,
 }
 
 impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
@@ -448,12 +531,33 @@ fn next(&mut self) -> Option<Self::Item> {
                 .span_to_snippet(mk_sp(self.prev_span_end, (self.get_lo)(&item)))
                 .unwrap();
             let trimmed_pre_snippet = pre_snippet.trim();
-            let has_pre_comment =
-                trimmed_pre_snippet.contains("//") || trimmed_pre_snippet.contains("/*");
-            let pre_comment = if has_pre_comment {
-                Some(trimmed_pre_snippet.to_owned())
+            let has_single_line_comment = trimmed_pre_snippet.starts_with("//");
+            let has_block_comment = trimmed_pre_snippet.starts_with("/*");
+            let (pre_comment, pre_comment_style) = if has_single_line_comment {
+                (
+                    Some(trimmed_pre_snippet.to_owned()),
+                    ListItemCommentStyle::DifferentLine,
+                )
+            } else if has_block_comment {
+                let comment_end = pre_snippet.chars().rev().position(|c| c == '/').unwrap();
+                if pre_snippet
+                    .chars()
+                    .rev()
+                    .take(comment_end + 1)
+                    .any(|c| c == '\n')
+                {
+                    (
+                        Some(trimmed_pre_snippet.to_owned()),
+                        ListItemCommentStyle::DifferentLine,
+                    )
+                } else {
+                    (
+                        Some(trimmed_pre_snippet.to_owned()),
+                        ListItemCommentStyle::SameLine,
+                    )
+                }
             } else {
-                None
+                (None, ListItemCommentStyle::None)
             };
 
             // Post-comment
@@ -468,37 +572,42 @@ fn next(&mut self) -> Option<Self::Item> {
             let comment_end = match self.inner.peek() {
                 Some(..) => {
                     let mut block_open_index = post_snippet.find("/*");
-                    // check if it realy is a block comment (and not //*)
+                    // check if it really is a block comment (and not //*)
                     if let Some(i) = block_open_index {
                         if i > 0 && &post_snippet[i - 1..i] == "/" {
                             block_open_index = None;
                         }
                     }
                     let newline_index = post_snippet.find('\n');
-                    let separator_index = post_snippet.find_uncommented(",").unwrap();
-
-                    match (block_open_index, newline_index) {
-                        // Separator before comment, with the next item on same line.
-                        // Comment belongs to next item.
-                        (Some(i), None) if i > separator_index => separator_index + 1,
-                        // Block-style post-comment before the separator.
-                        (Some(i), None) => cmp::max(
-                            find_comment_end(&post_snippet[i..]).unwrap() + i,
-                            separator_index + 1,
-                        ),
-                        // Block-style post-comment. Either before or after the separator.
-                        (Some(i), Some(j)) if i < j => cmp::max(
-                            find_comment_end(&post_snippet[i..]).unwrap() + i,
-                            separator_index + 1,
-                        ),
-                        // Potential *single* line comment.
-                        (_, Some(j)) if j > separator_index => j + 1,
-                        _ => post_snippet.len(),
+                    if let Some(separator_index) = post_snippet.find_uncommented(",") {
+                        match (block_open_index, newline_index) {
+                            // Separator before comment, with the next item on same line.
+                            // Comment belongs to next item.
+                            (Some(i), None) if i > separator_index => separator_index + 1,
+                            // Block-style post-comment before the separator.
+                            (Some(i), None) => cmp::max(
+                                find_comment_end(&post_snippet[i..]).unwrap() + i,
+                                separator_index + 1,
+                            ),
+                            // Block-style post-comment. Either before or after the separator.
+                            (Some(i), Some(j)) if i < j => cmp::max(
+                                find_comment_end(&post_snippet[i..]).unwrap() + i,
+                                separator_index + 1,
+                            ),
+                            // Potential *single* line comment.
+                            (_, Some(j)) if j > separator_index => j + 1,
+                            _ => post_snippet.len(),
+                        }
+                    } else {
+                        // Match arms may not have trailing comma. In any case, for match arms,
+                        // we will assume that the post comment belongs to the next arm if they
+                        // do not end with trailing comma.
+                        1
                     }
                 }
                 None => post_snippet
                     .find_uncommented(self.terminator)
-                    .unwrap_or(post_snippet.len()),
+                    .unwrap_or_else(|| post_snippet.len()),
             };
 
             if !post_snippet.is_empty() && comment_end > 0 {
@@ -507,12 +616,14 @@ fn next(&mut self) -> Option<Self::Item> {
 
                 // Everything from the separator to the next item.
                 let test_snippet = &post_snippet[comment_end - 1..];
-                let first_newline = test_snippet.find('\n').unwrap_or(test_snippet.len());
+                let first_newline = test_snippet
+                    .find('\n')
+                    .unwrap_or_else(|| test_snippet.len());
                 // From the end of the first line of comments.
                 let test_snippet = &test_snippet[first_newline..];
                 let first = test_snippet
                     .find(|c: char| !c.is_whitespace())
-                    .unwrap_or(test_snippet.len());
+                    .unwrap_or_else(|| test_snippet.len());
                 // From the end of the first line of comments to the next non-whitespace char.
                 let test_snippet = &test_snippet[..first];
 
@@ -526,7 +637,7 @@ fn next(&mut self) -> Option<Self::Item> {
             self.prev_span_end = (self.get_hi)(&item) + BytePos(comment_end as u32);
             let post_snippet = post_snippet[..comment_end].trim();
 
-            let post_snippet_trimmed = if post_snippet.starts_with(',') {
+            let post_snippet_trimmed = if post_snippet.starts_with(|c| c == ',' || c == ':') {
                 post_snippet[1..].trim_matches(white_space)
             } else if post_snippet.ends_with(',') {
                 post_snippet[..(post_snippet.len() - 1)].trim_matches(white_space)
@@ -542,7 +653,12 @@ fn next(&mut self) -> Option<Self::Item> {
 
             ListItem {
                 pre_comment: pre_comment,
-                item: (self.get_item_string)(&item),
+                pre_comment_style: pre_comment_style,
+                item: if self.inner.peek().is_none() && self.leave_last {
+                    None
+                } else {
+                    (self.get_item_string)(&item)
+                },
                 post_comment: post_comment,
                 new_lines: new_lines,
             }
@@ -560,6 +676,7 @@ pub fn itemize_list<'a, T, I, F1, F2, F3>(
     get_item_string: F3,
     prev_span_end: BytePos,
     next_span_start: BytePos,
+    leave_last: bool,
 ) -> ListItems<'a, I, F1, F2, F3>
 where
     I: Iterator<Item = T>,
@@ -576,17 +693,7 @@ pub fn itemize_list<'a, T, I, F1, F2, F3>(
         prev_span_end: prev_span_end,
         next_span_start: next_span_start,
         terminator: terminator,
-    }
-}
-
-fn needs_trailing_separator(
-    separator_tactic: SeparatorTactic,
-    list_tactic: DefinitiveListTactic,
-) -> bool {
-    match separator_tactic {
-        SeparatorTactic::Always => true,
-        SeparatorTactic::Vertical => list_tactic == DefinitiveListTactic::Vertical,
-        SeparatorTactic::Never => false,
+        leave_last: leave_last,
     }
 }
 
@@ -602,10 +709,10 @@ fn calculate_width<I, T>(items: I) -> (usize, usize)
         .fold((0, 0), |acc, l| (acc.0 + 1, acc.1 + l))
 }
 
-fn total_item_width(item: &ListItem) -> usize {
-    comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..])) +
-        comment_len(item.post_comment.as_ref().map(|x| &(*x)[..])) +
-        item.item.as_ref().map_or(0, |str| str.len())
+pub fn total_item_width(item: &ListItem) -> usize {
+    comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..]))
+        + comment_len(item.post_comment.as_ref().map(|x| &(*x)[..]))
+        item.item.as_ref().map_or(0, |str| str.len())
 }
 
 fn comment_len(comment: Option<&str>) -> usize {
@@ -630,14 +737,15 @@ pub fn struct_lit_shape(
     prefix_width: usize,
     suffix_width: usize,
 ) -> Option<(Option<Shape>, Shape)> {
-    let v_shape = match context.config.struct_lit_style() {
-        IndentStyle::Visual => try_opt!(
-            try_opt!(shape.visual_indent(0).shrink_left(prefix_width)).sub_width(suffix_width)
-        ),
+    let v_shape = match context.config.struct_lit_indent() {
+        IndentStyle::Visual => shape
+            .visual_indent(0)
+            .shrink_left(prefix_width)?
+            .sub_width(suffix_width)?,
         IndentStyle::Block => {
             let shape = shape.block_indent(context.config.tab_spaces());
             Shape {
-                width: try_opt!(context.config.max_width().checked_sub(shape.indent.width())),
+                width: context.budget(shape.indent.width()),
                 ..shape
             }
         }
@@ -658,7 +766,7 @@ pub fn struct_lit_tactic(
     items: &[ListItem],
 ) -> DefinitiveListTactic {
     if let Some(h_shape) = h_shape {
-        let prelim_tactic = match (context.config.struct_lit_style(), items.len()) {
+        let prelim_tactic = match (context.config.struct_lit_indent(), items.len()) {
             (IndentStyle::Visual, 1) => ListTactic::HorizontalVertical,
             _ => context.config.struct_lit_multiline_style().to_list_tactic(),
         };
@@ -689,8 +797,8 @@ pub fn struct_lit_formatting<'a>(
     context: &'a RewriteContext,
     force_no_trailing_comma: bool,
 ) -> ListFormatting<'a> {
-    let ends_with_newline = context.config.struct_lit_style() != IndentStyle::Visual &&
-        tactic == DefinitiveListTactic::Vertical;
+    let ends_with_newline = context.config.struct_lit_indent() != IndentStyle::Visual
+        && tactic == DefinitiveListTactic::Vertical;
     ListFormatting {
         tactic: tactic,
         separator: ",",
@@ -699,6 +807,7 @@ pub fn struct_lit_formatting<'a>(
         } else {
             context.config.trailing_comma()
         },
+        separator_place: SeparatorPlace::Back,
         shape: shape,
         ends_with_newline: ends_with_newline,
         preserve_newline: true,