src/patterns.rs

   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.
   4 //
   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.
  10
  11 use Indent;
  12 use rewrite::{Rewrite, RewriteContext};
  13 use utils::{wrap_str, format_mutability, span_after};
  14 use lists::{format_item_list, itemize_list};
  15 use expr::{rewrite_unary_prefix, rewrite_pair, rewrite_tuple};
  16 use types::rewrite_path;
  17
  18 use syntax::ast::{BindingMode, Pat, Pat_};
  19
  20 // FIXME(#18): implement pattern formatting.
  21 impl Rewrite for Pat {
  22     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
  23         match self.node {
  24             Pat_::PatBox(ref pat) => rewrite_unary_prefix(context, "box ", &**pat, width, offset),
  25             Pat_::PatIdent(binding_mode, ident, None) => {
  26                 let (prefix, mutability) = match binding_mode {
  27                     BindingMode::BindByRef(mutability) => ("ref ", mutability),
  28                     BindingMode::BindByValue(mutability) => ("", mutability),
  29                 };
  30                 let mut_infix = format_mutability(mutability);
  31                 let result = format!("{}{}{}", prefix, mut_infix, ident.node);
  32                 wrap_str(result, context.config.max_width, width, offset)
  33             }
  34             Pat_::PatWild => {
  35                 if 1 <= width {
  36                     Some("_".to_owned())
  37                 } else {
  38                     None
  39                 }
  40             }
  41             Pat_::PatQPath(ref q_self, ref path) => {
  42                 rewrite_path(context, true, Some(q_self), path, width, offset)
  43             }
  44             Pat_::PatRange(ref lhs, ref rhs) => {
  45                 rewrite_pair(&**lhs, &**rhs, "", "...", "", context, width, offset)
  46             }
  47             Pat_::PatRegion(ref pat, mutability) => {
  48                 let prefix = format!("&{}", format_mutability(mutability));
  49                 rewrite_unary_prefix(context, &prefix, &**pat, width, offset)
  50             }
  51             Pat_::PatTup(ref items) => rewrite_tuple(context, items, self.span, width, offset),
  52             Pat_::PatEnum(ref path, Some(ref pat_vec)) => {
  53                 let path_str = try_opt!(::types::rewrite_path(context,
  54                                                               true,
  55                                                               None,
  56                                                               path,
  57                                                               width,
  58                                                               offset));
  59
  60                 if pat_vec.is_empty() {
  61                     Some(path_str)
  62                 } else {
  63                     // 1 = (
  64                     let width = try_opt!(width.checked_sub(path_str.len() + 1));
  65                     let offset = offset + path_str.len() + 1;
  66                     let items = itemize_list(context.codemap,
  67                                              pat_vec.iter(),
  68                                              ")",
  69                                              |item| item.span.lo,
  70                                              |item| item.span.hi,
  71                                              |item| item.rewrite(context, width, offset),
  72                                              span_after(self.span, "(", context.codemap),
  73                                              self.span.hi);
  74                     Some(format!("{}({})",
  75                                  path_str,
  76                                  try_opt!(format_item_list(items, width, offset, context.config))))
  77                 }
  78             }
  79             Pat_::PatLit(ref expr) => expr.rewrite(context, width, offset),
  80             // FIXME(#8): format remaining pattern variants.
  81             Pat_::PatIdent(_, _, Some(..)) |
  82             Pat_::PatEnum(_, None) |
  83             Pat_::PatStruct(..) |
  84             Pat_::PatVec(..) |
  85             Pat_::PatMac(..) => {
  86                 wrap_str(context.snippet(self.span),
  87                          context.config.max_width,
  88                          width,
  89                          offset)
  90             }
  91         }
  92     }
  93 }