Add support for spaces_within_parens config (#1187)

* Add support for spaces_within_parens config

* Changes based on review comments

5 files changed, 64 insertions, 8 deletions

diff --git a/src/config.rs b/src/config.rs
index f93a6e115a5..ad14f81a819 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -416,6 +416,7 @@ create_config! {
     space_after_bound_colon: bool, true,
         "Leave a space after the colon in a trait or lifetime bound";
     spaces_around_ranges: bool, false, "Put spaces around the  .. and ... range operators";
+    spaces_within_parens: bool, false, "Put spaces within non-empty parentheses";
     use_try_shorthand: bool, false, "Replace uses of the try! macro by the ? shorthand";
     write_mode: WriteMode, WriteMode::Replace,
         "What Write Mode to use when none is supplied: Replace, Overwrite, Display, Diff, Coverage";
diff --git a/src/expr.rs b/src/expr.rs
index ce1eb5dc053..e1d74a3cc79 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1536,7 +1536,11 @@ fn rewrite_call_inner<R>(context: &RewriteContext,
         None => return Err(Ordering::Less),
     };
 
-    Ok(format!("{}({})", callee_str, list_str))
+    Ok(if context.config.spaces_within_parens && list_str.len() > 0 {
+        format!("{}( {} )", callee_str, list_str)
+    } else {
+        format!("{}({})", callee_str, list_str)
+    })
 }
 
 fn rewrite_paren(context: &RewriteContext,
@@ -1549,7 +1553,12 @@ fn rewrite_paren(context: &RewriteContext,
     // paren on the same line as the subexpr.
     let subexpr_str = subexpr.rewrite(context, try_opt!(width.checked_sub(2)), offset + 1);
     debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
-    subexpr_str.map(|s| format!("({})", s))
+
+    subexpr_str.map(|s| if context.config.spaces_within_parens && s.len() > 0 {
+        format!("( {} )", s)
+    } else {
+        format!("({})", s)
+    })
 }
 
 fn rewrite_struct_lit<'a>(context: &RewriteContext,
@@ -1749,7 +1758,11 @@ pub fn rewrite_tuple<'a, I>(context: &RewriteContext,
         return items.next()
             .unwrap()
             .rewrite(&aligned, budget, indent)
-            .map(|s| format!("({},)", s));
+            .map(|s| if context.config.spaces_within_parens {
+                format!("( {}, )", s)
+            } else {
+                format!("({},)", s)
+            });
     }
 
     let list_lo = context.codemap.span_after(span, "(");
@@ -1764,7 +1777,11 @@ pub fn rewrite_tuple<'a, I>(context: &RewriteContext,
                              span.hi - BytePos(1));
     let list_str = try_opt!(format_item_list(items, budget, indent, context.config));
 
-    Some(format!("({})", list_str))
+    if context.config.spaces_within_parens && list_str.len() > 0 {
+        Some(format!("( {} )", list_str))
+    } else {
+        Some(format!("({})", list_str))
+    }
 }
 
 fn rewrite_binary_op(context: &RewriteContext,
diff --git a/src/items.rs b/src/items.rs
index 7e18f0a2f4d..c3e58cba835 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -961,7 +961,17 @@ fn format_tuple_struct(context: &RewriteContext,
                              context.codemap.span_after(span, "("),
                              span.hi);
     let body = try_opt!(format_item_list(items, item_budget, item_indent, context.config));
+
+    if context.config.spaces_within_parens && body.len() > 0 {
+        result.push(' ');
+    }
+
     result.push_str(&body);
+
+    if context.config.spaces_within_parens && body.len() > 0 {
+        result.push(' ');
+    }
+
     result.push(')');
 
     if !where_clause_str.is_empty() && !where_clause_str.contains('\n') &&
@@ -1386,12 +1396,18 @@ fn rewrite_fn_base(context: &RewriteContext,
             result.push_str(&arg_indent.to_string(context.config));
             arg_indent = arg_indent + 1; // extra space for `(`
             result.push('(');
+            if context.config.spaces_within_parens && fd.inputs.len() > 0 {
+                result.push(' ')
+            }
         } else {
             result.push_str("(\n");
             result.push_str(&arg_indent.to_string(context.config));
         }
     } else {
         result.push('(');
+        if context.config.spaces_within_parens && fd.inputs.len() > 0 {
+            result.push(' ')
+        }
     }
 
     if multi_line_ret_str {
@@ -1432,6 +1448,9 @@ fn rewrite_fn_base(context: &RewriteContext,
         result.push(')');
     } else {
         result.push_str(&arg_str);
+        if context.config.spaces_within_parens && fd.inputs.len() > 0 {
+            result.push(' ')
+        }
         result.push(')');
     }
 
diff --git a/src/patterns.rs b/src/patterns.rs
index 1aaa28b853a..149844cd196 100644
--- a/src/patterns.rs
+++ b/src/patterns.rs
@@ -234,10 +234,20 @@ fn rewrite_tuple_pat(pats: &[ptr::P<ast::Pat>],
         let list = try_opt!(format_item_list(items, width, offset, context.config));
 
         match path_str {
-            Some(path_str) => Some(format!("{}({})", path_str, list)),
+            Some(path_str) => {
+                Some(if context.config.spaces_within_parens {
+                    format!("{}( {} )", path_str, list)
+                } else {
+                    format!("{}({})", path_str, list)
+                })
+            }
             None => {
                 let comma = if add_comma { "," } else { "" };
-                Some(format!("({}{})", list, comma))
+                Some(if context.config.spaces_within_parens {
+                    format!("( {}{} )", list, comma)
+                } else {
+                    format!("({}{})", list, comma)
+                })
             }
         }
     }
diff --git a/src/types.rs b/src/types.rs
index a718750db95..624f17f6be8 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -311,7 +311,11 @@ fn format_function_type<'a, I>(inputs: I,
         String::new()
     };
 
-    Some(format!("({}){}{}", list_str, infix, output))
+    Some(if context.config.spaces_within_parens {
+        format!("( {} ){}{}", list_str, infix, output)
+    } else {
+        format!("({}){}{}", list_str, infix, output)
+    })
 }
 
 impl Rewrite for ast::WherePredicate {
@@ -575,7 +579,12 @@ impl Rewrite for ast::Ty {
             // comments.
             ast::TyKind::Paren(ref ty) => {
                 let budget = try_opt!(width.checked_sub(2));
-                ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("({})", ty_str))
+                ty.rewrite(context, budget, offset + 1)
+                    .map(|ty_str| if context.config.spaces_within_parens {
+                        format!("( {} )", ty_str)
+                    } else {
+                        format!("({})", ty_str)
+                    })
             }
             ast::TyKind::Vec(ref ty) => {
                 let budget = try_opt!(width.checked_sub(2));