Merge pull request #3129 from otavio/issue-3104

[rust.git] / src / matches.rs

diff --git a/src/matches.rs b/src/matches.rs
index 231112edb1e1a0600870947349cdd5fbabe4cd9b..24f5548397228221133458dbf3919ea6ccedab69 100644 (file)
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -19,8 +19,8 @@
 use comment::{combine_strs_with_missing_comments, rewrite_comment};
 use config::{Config, ControlBraceStyle, IndentStyle};
 use expr::{
-    format_expr, is_empty_block, is_simple_block, is_unsafe_block, prefer_next_line,
-    rewrite_multiple_patterns, ExprType, RhsTactics, ToExpr,
+    format_expr, is_empty_block, is_simple_block, is_unsafe_block, prefer_next_line, rewrite_cond,
+    rewrite_multiple_patterns, ExprType, RhsTactics,
 };
 use lists::{itemize_list, write_list, ListFormatting};
 use rewrite::{Rewrite, RewriteContext};
@@ -231,7 +231,7 @@ fn rewrite_match_arm(
 ) -> Option<String> {
     let (missing_span, attrs_str) = if !arm.attrs.is_empty() {
         if contains_skip(&arm.attrs) {
-            let (_, body) = flatten_arm_body(context, &arm.body);
+            let (_, body) = flatten_arm_body(context, &arm.body, None);
             // `arm.span()` does not include trailing comma, add it manually.
             return Some(format!(
                 "{}{}",
@@ -247,52 +247,42 @@ fn rewrite_match_arm(
     } else {
         (mk_sp(arm.span().lo(), arm.span().lo()), String::new())
     };
-    let pats_str =
-        rewrite_match_pattern(context, &ptr_vec_to_ref_vec(&arm.pats), &arm.guard, shape)
-            .and_then(|pats_str| {
-                combine_strs_with_missing_comments(
-                    context,
-                    &attrs_str,
-                    &pats_str,
-                    missing_span,
-                    shape,
-                    false,
-                )
-            })?;
 
-    let arrow_span = mk_sp(arm.pats.last().unwrap().span.hi(), arm.body.span.lo());
-    rewrite_match_body(
-        context,
-        &arm.body,
-        &pats_str,
-        shape,
-        arm.guard.is_some(),
-        arrow_span,
-        is_last,
-    )
-}
-
-fn rewrite_match_pattern(
-    context: &RewriteContext,
-    pats: &[&ast::Pat],
-    guard: &Option<ptr::P<ast::Expr>>,
-    shape: Shape,
-) -> Option<String> {
     // Patterns
     // 5 = ` => {`
     let pat_shape = shape.sub_width(5)?;
-    let pats_str = rewrite_multiple_patterns(context, pats, pat_shape)?;
+    let pats_str = rewrite_multiple_patterns(context, &ptr_vec_to_ref_vec(&arm.pats), pat_shape)?;
 
     // Guard
+    let block_like_pat = trimmed_last_line_width(&pats_str) <= context.config.tab_spaces();
+    let new_line_guard = pats_str.contains('\n') && !block_like_pat;
     let guard_str = rewrite_guard(
         context,
-        guard,
+        &arm.guard,
         shape,
         trimmed_last_line_width(&pats_str),
-        pats_str.contains("\n"),
+        new_line_guard,
     )?;
 
-    Some(format!("{}{}", pats_str, guard_str))
+    let lhs_str = combine_strs_with_missing_comments(
+        context,
+        &attrs_str,
+        &format!("{}{}", pats_str, guard_str),
+        missing_span,
+        shape,
+        false,
+    )?;
+
+    let arrow_span = mk_sp(arm.pats.last().unwrap().span.hi(), arm.body.span.lo());
+    rewrite_match_body(
+        context,
+        &arm.body,
+        &lhs_str,
+        shape,
+        guard_str.contains('\n'),
+        arrow_span,
+        is_last,
+    )
 }
 
 fn block_can_be_flattened<'a>(
@@ -313,24 +303,33 @@ fn block_can_be_flattened<'a>(
 // (extend, body)
 // @extend: true if the arm body can be put next to `=>`
 // @body: flattened body, if the body is block with a single expression
-fn flatten_arm_body<'a>(context: &'a RewriteContext, body: &'a ast::Expr) -> (bool, &'a ast::Expr) {
+fn flatten_arm_body<'a>(
+    context: &'a RewriteContext,
+    body: &'a ast::Expr,
+    opt_shape: Option<Shape>,
+) -> (bool, &'a ast::Expr) {
+    let can_extend =
+        |expr| !context.config.force_multiline_blocks() && can_flatten_block_around_this(expr);
+
     if let Some(ref block) = block_can_be_flattened(context, body) {
         if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
             if let ast::ExprKind::Block(..) = expr.node {
-                flatten_arm_body(context, expr)
+                flatten_arm_body(context, expr, None)
             } else {
-                let can_extend_expr =
-                    !context.config.force_multiline_blocks() && can_flatten_block_around_this(expr);
-                (can_extend_expr, &*expr)
+                let cond_becomes_muti_line = opt_shape
+                    .and_then(|shape| rewrite_cond(context, expr, shape))
+                    .map_or(false, |cond| cond.contains('\n'));
+                if cond_becomes_muti_line {
+                    (false, &*body)
+                } else {
+                    (can_extend(expr), &*expr)
+                }
             }
         } else {
             (false, &*body)
         }
     } else {
-        (
-            !context.config.force_multiline_blocks() && body.can_be_overflowed(context, 1),
-            &*body,
-        )
+        (can_extend(body), &*body)
     }
 }
 
@@ -343,7 +342,11 @@ fn rewrite_match_body(
     arrow_span: Span,
     is_last: bool,
 ) -> Option<String> {
-    let (extend, body) = flatten_arm_body(context, body);
+    let (extend, body) = flatten_arm_body(
+        context,
+        body,
+        shape.offset_left(extra_offset(pats_str, shape) + 4),
+    );
     let (is_block, is_empty_block) = if let ast::ExprKind::Block(ref block, _) = body.node {
         (
             true,
@@ -484,10 +487,18 @@ fn rewrite_match_body(
     }
 }
 
+impl Rewrite for ast::Guard {
+    fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
+        match self {
+            ast::Guard::If(ref expr) => expr.rewrite(context, shape),
+        }
+    }
+}
+
 // The `if ...` guard on a match arm.
 fn rewrite_guard(
     context: &RewriteContext,
-    guard: &Option<ptr::P<ast::Expr>>,
+    guard: &Option<ast::Guard>,
     shape: Shape,
     // The amount of space used up on this line for the pattern in
     // the arm (excludes offset).