]> git.lizzy.rs Git - rust.git/blobdiff - src/types.rs
Simplify handling parens on generic bound trait
[rust.git] / src / types.rs
index 42dfd3596c8977cc630fdd5bd3614a630087b914..20828429cb1f99b401356541b408c389f7b5fdf4 100644 (file)
 
 use config::lists::*;
 use syntax::ast::{self, FunctionRetTy, Mutability};
-use syntax::codemap::{self, BytePos, Span};
+use syntax::source_map::{self, BytePos, Span};
 use syntax::symbol::keywords;
 
-use codemap::SpanUtils;
 use config::{IndentStyle, TypeDensity};
-use expr::{
-    rewrite_assign_rhs, rewrite_pair, rewrite_tuple, rewrite_unary_prefix, PairParts, ToExpr,
-};
+use expr::{rewrite_assign_rhs, rewrite_tuple, rewrite_unary_prefix};
 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
 use macros::{rewrite_macro, MacroPosition};
 use overflow;
+use pairs::{rewrite_pair, PairParts};
 use rewrite::{Rewrite, RewriteContext};
 use shape::Shape;
+use source_map::SpanUtils;
 use spanned::Spanned;
 use utils::{
-    colon_spaces, extra_offset, first_line_width, format_abi, format_mutability, last_line_width,
-    mk_sp, rewrite_ident,
+    colon_spaces, extra_offset, first_line_width, format_abi, format_mutability,
+    last_line_extendable, last_line_width, mk_sp, rewrite_ident,
 };
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -142,7 +141,7 @@ fn rewrite_path_segments<'a, I>(
 }
 
 #[derive(Debug)]
-enum SegmentParam<'a> {
+pub enum SegmentParam<'a> {
     LifeTime(&'a ast::Lifetime),
     Type(&'a ast::Ty),
     Binding(&'a ast::TypeBinding),
@@ -167,19 +166,6 @@ fn span(&self) -> Span {
     }
 }
 
-impl<'a> ToExpr for SegmentParam<'a> {
-    fn to_expr(&self) -> Option<&ast::Expr> {
-        None
-    }
-
-    fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
-        match *self {
-            SegmentParam::Type(ty) => ty.can_be_overflowed(context, len),
-            _ => false,
-        }
-    }
-}
-
 impl<'a> Rewrite for SegmentParam<'a> {
     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
         match *self {
@@ -253,7 +239,7 @@ fn rewrite_segment(
                 let generics_str = overflow::rewrite_with_angle_brackets(
                     context,
                     "",
-                    &param_list.iter().map(|e| &*e).collect::<Vec<_>>(),
+                    param_list.iter(),
                     shape,
                     mk_sp(*span_lo, span_hi),
                 )?;
@@ -268,7 +254,7 @@ fn rewrite_segment(
             ast::GenericArgs::Parenthesized(ref data) => {
                 let output = match data.output {
                     Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
-                    None => FunctionRetTy::Default(codemap::DUMMY_SP),
+                    None => FunctionRetTy::Default(source_map::DUMMY_SP),
                 };
                 result.push_str(&format_function_type(
                     data.inputs.iter().map(|x| &**x),
@@ -299,6 +285,8 @@ fn format_function_type<'a, I>(
     <I as Iterator>::Item: Deref,
     <I::Item as Deref>::Target: Rewrite + Spanned + 'a,
 {
+    debug!("format_function_type {:#?}", shape);
+
     // Code for handling variadics is somewhat duplicated for items, but they
     // are different enough to need some serious refactoring to share code.
     enum ArgumentKind<T>
@@ -361,23 +349,17 @@ enum ArgumentKind<T>
         Separator::Comma,
         budget,
     );
-
-    let fmt = ListFormatting {
-        tactic,
-        separator: ",",
-        trailing_separator: if !context.use_block_indent() || variadic {
-            SeparatorTactic::Never
-        } else {
-            context.config.trailing_comma()
-        },
-        separator_place: SeparatorPlace::Back,
-        shape: list_shape,
-        ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
-        preserve_newline: true,
-        nested: false,
-        config: context.config,
+    let trailing_separator = if !context.use_block_indent() || variadic {
+        SeparatorTactic::Never
+    } else {
+        context.config.trailing_comma()
     };
 
+    let fmt = ListFormatting::new(list_shape, context.config)
+        .tactic(tactic)
+        .trailing_separator(trailing_separator)
+        .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
+        .preserve_newline(true);
     let list_str = write_list(&item_vec, &fmt)?;
 
     let ty_shape = match context.config.indent_style() {
@@ -405,7 +387,7 @@ enum ArgumentKind<T>
             shape.block().indent.to_string_with_newline(context.config),
         )
     };
-    if last_line_width(&args) + first_line_width(&output) <= shape.width {
+    if output.is_empty() || last_line_width(&args) + first_line_width(&output) <= shape.width {
         Some(format!("{}{}", args, output))
     } else {
         Some(format!(
@@ -507,13 +489,15 @@ impl Rewrite for ast::GenericBound {
     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
         match *self {
             ast::GenericBound::Trait(ref poly_trait_ref, trait_bound_modifier) => {
-                match trait_bound_modifier {
+                let snippet = context.snippet(self.span());
+                let has_paren = snippet.starts_with("(") && snippet.ends_with(")");
+                let rewrite = match trait_bound_modifier {
                     ast::TraitBoundModifier::None => poly_trait_ref.rewrite(context, shape),
-                    ast::TraitBoundModifier::Maybe => {
-                        let rw = poly_trait_ref.rewrite(context, shape.offset_left(1)?)?;
-                        Some(format!("?{}", rw))
-                    }
-                }
+                    ast::TraitBoundModifier::Maybe => poly_trait_ref
+                        .rewrite(context, shape.offset_left(1)?)
+                        .map(|s| format!("?{}", s)),
+                };
+                rewrite.map(|s| if has_paren { format!("({})", s) } else { s })
             }
             ast::GenericBound::Outlives(ref lifetime) => lifetime.rewrite(context, shape),
         }
@@ -522,6 +506,10 @@ fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 
 impl Rewrite for ast::GenericBounds {
     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
+        if self.is_empty() {
+            return Some(String::new());
+        }
+
         join_bounds(context, shape, self, true)
     }
 }
@@ -549,7 +537,8 @@ fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
             };
             result.push_str(eq_str);
             let budget = shape.width.checked_sub(result.len())?;
-            let rewrite = def.rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
+            let rewrite =
+                def.rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
             result.push_str(&rewrite);
         }
 
@@ -651,12 +640,9 @@ fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
                 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
                     .map(|ty_str| format!("[{}]", ty_str))
             }
-            ast::TyKind::Tup(ref items) => rewrite_tuple(
-                context,
-                &::utils::ptr_vec_to_ref_vec(items),
-                self.span,
-                shape,
-            ),
+            ast::TyKind::Tup(ref items) => {
+                rewrite_tuple(context, items.iter(), self.span, shape, items.len() == 1)
+            }
             ast::TyKind::Path(ref q_self, ref path) => {
                 rewrite_path(context, PathContext::Type, q_self.as_ref(), path, shape)
             }
@@ -695,6 +681,8 @@ fn rewrite_bare_fn(
     context: &RewriteContext,
     shape: Shape,
 ) -> Option<String> {
+    debug!("rewrite_bare_fn {:#?}", shape);
+
     let mut result = String::with_capacity(128);
 
     if let Some(ref lifetime_str) = rewrite_lifetime_param(context, shape, &bare_fn.generic_params)
@@ -717,7 +705,11 @@ fn rewrite_bare_fn(
 
     result.push_str("fn");
 
-    let func_ty_shape = shape.offset_left(result.len())?;
+    let func_ty_shape = if context.use_block_indent() {
+        shape.offset_left(result.len())?
+    } else {
+        shape.visual_indent(result.len()).sub_width(result.len())?
+    };
 
     let rewrite = format_function_type(
         bare_fn.decl.inputs.iter(),
@@ -733,15 +725,30 @@ fn rewrite_bare_fn(
     Some(result)
 }
 
-fn join_bounds<T>(
+fn is_generic_bounds_in_order(generic_bounds: &[ast::GenericBound]) -> bool {
+    let is_trait = |b: &ast::GenericBound| match b {
+        ast::GenericBound::Outlives(..) => false,
+        ast::GenericBound::Trait(..) => true,
+    };
+    let is_lifetime = |b: &ast::GenericBound| !is_trait(b);
+    let last_trait_index = generic_bounds.iter().rposition(is_trait);
+    let first_lifetime_index = generic_bounds.iter().position(is_lifetime);
+    match (last_trait_index, first_lifetime_index) {
+        (Some(last_trait_index), Some(first_lifetime_index)) => {
+            last_trait_index < first_lifetime_index
+        }
+        _ => true,
+    }
+}
+
+fn join_bounds(
     context: &RewriteContext,
     shape: Shape,
-    items: &[T],
+    items: &[ast::GenericBound],
     need_indent: bool,
-) -> Option<String>
-where
-    T: Rewrite,
-{
+) -> Option<String> {
+    debug_assert!(!items.is_empty());
+
     // Try to join types in a single line
     let joiner = match context.config.type_punctuation_density() {
         TypeDensity::Compressed => "+",
@@ -752,7 +759,7 @@ fn join_bounds<T>(
         .map(|item| item.rewrite(context, shape))
         .collect::<Option<Vec<_>>>()?;
     let result = type_strs.join(joiner);
-    if items.len() == 1 || (!result.contains('\n') && result.len() <= shape.width) {
+    if items.len() <= 1 || (!result.contains('\n') && result.len() <= shape.width) {
         return Some(result);
     }
 
@@ -769,8 +776,26 @@ fn join_bounds<T>(
         (type_strs, shape.indent)
     };
 
-    let joiner = format!("{}+ ", offset.to_string_with_newline(context.config));
-    Some(type_strs.join(&joiner))
+    let is_bound_extendable = |s: &str, b: &ast::GenericBound| match b {
+        ast::GenericBound::Outlives(..) => true,
+        ast::GenericBound::Trait(..) => last_line_extendable(s),
+    };
+    let mut result = String::with_capacity(128);
+    result.push_str(&type_strs[0]);
+    let mut can_be_put_on_the_same_line = is_bound_extendable(&result, &items[0]);
+    let generic_bounds_in_order = is_generic_bounds_in_order(items);
+    for (bound, bound_str) in items[1..].iter().zip(type_strs[1..].iter()) {
+        if generic_bounds_in_order && can_be_put_on_the_same_line {
+            result.push_str(joiner);
+        } else {
+            result.push_str(&offset.to_string_with_newline(context.config));
+            result.push_str("+ ");
+        }
+        result.push_str(bound_str);
+        can_be_put_on_the_same_line = is_bound_extendable(bound_str, bound);
+    }
+
+    Some(result)
 }
 
 pub fn can_be_overflowed_type(context: &RewriteContext, ty: &ast::Ty, len: usize) -> bool {