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::{CodeMapSpanUtils, wrap_str, format_mutability};
  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, PatKind, FieldPat};
  19
  20 impl Rewrite for Pat {
  21     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
  22         match self.node {
  23             PatKind::Box(ref pat) => rewrite_unary_prefix(context, "box ", &**pat, width, offset),
  24             PatKind::Ident(binding_mode, ident, ref sub_pat) => {
  25                 let (prefix, mutability) = match binding_mode {
  26                     BindingMode::ByRef(mutability) => ("ref ", mutability),
  27                     BindingMode::ByValue(mutability) => ("", mutability),
  28                 };
  29                 let mut_infix = format_mutability(mutability);
  30                 let id_str = ident.node.to_string();
  31
  32                 let sub_pat = match *sub_pat {
  33                     Some(ref p) => {
  34                         // 3 - ` @ `.
  35                         let width = try_opt!(width.checked_sub(prefix.len() + mut_infix.len() +
  36                                                                id_str.len() +
  37                                                                3));
  38                         format!(" @ {}", try_opt!(p.rewrite(context, width, offset)))
  39                     }
  40                     None => "".to_owned(),
  41                 };
  42
  43                 let result = format!("{}{}{}{}", prefix, mut_infix, id_str, sub_pat);
  44                 wrap_str(result, context.config.max_width, width, offset)
  45             }
  46             PatKind::Wild => {
  47                 if 1 <= width {
  48                     Some("_".to_owned())
  49                 } else {
  50                     None
  51                 }
  52             }
  53             PatKind::QPath(ref q_self, ref path) => {
  54                 rewrite_path(context, true, Some(q_self), path, width, offset)
  55             }
  56             PatKind::Range(ref lhs, ref rhs) => {
  57                 rewrite_pair(&**lhs, &**rhs, "", "...", "", context, width, offset)
  58             }
  59             PatKind::Ref(ref pat, mutability) => {
  60                 let prefix = format!("&{}", format_mutability(mutability));
  61                 rewrite_unary_prefix(context, &prefix, &**pat, width, offset)
  62             }
  63             PatKind::Tup(ref items) => {
  64                 rewrite_tuple(context,
  65                               items.iter().map(|x| &**x),
  66                               self.span,
  67                               width,
  68                               offset)
  69             }
  70             PatKind::Path(ref path) => rewrite_path(context, true, None, path, width, offset),
  71             PatKind::TupleStruct(ref path, ref pat_vec) => {
  72                 let path_str = try_opt!(rewrite_path(context, true, None, path, width, offset));
  73
  74                 match *pat_vec {
  75                     Some(ref pat_vec) => {
  76                         if pat_vec.is_empty() {
  77                             Some(path_str)
  78                         } else {
  79                             // 1 = (
  80                             let width = try_opt!(width.checked_sub(path_str.len() + 1));
  81                             let offset = offset + path_str.len() + 1;
  82                             let items = itemize_list(context.codemap,
  83                                                      pat_vec.iter(),
  84                                                      ")",
  85                                                      |item| item.span.lo,
  86                                                      |item| item.span.hi,
  87                                                      |item| item.rewrite(context, width, offset),
  88                                                      context.codemap.span_after(self.span, "("),
  89                                                      self.span.hi);
  90                             Some(format!("{}({})",
  91                                          path_str,
  92                                          try_opt!(format_item_list(items,
  93                                                                    width,
  94                                                                    offset,
  95                                                                    context.config))))
  96                         }
  97                     }
  98                     None => Some(format!("{}(..)", path_str)),
  99                 }
 100             }
 101             PatKind::Lit(ref expr) => expr.rewrite(context, width, offset),
 102             PatKind::Vec(ref prefix, ref slice_pat, ref suffix) => {
 103                 // Rewrite all the sub-patterns.
 104                 let prefix = prefix.iter().map(|p| p.rewrite(context, width, offset));
 105                 let slice_pat = slice_pat.as_ref().map(|p| {
 106                     Some(format!("{}..", try_opt!(p.rewrite(context, width, offset))))
 107                 });
 108                 let suffix = suffix.iter().map(|p| p.rewrite(context, width, offset));
 109
 110                 // Munge them together.
 111                 let pats: Option<Vec<String>> = prefix.chain(slice_pat.into_iter())
 112                                                       .chain(suffix)
 113                                                       .collect();
 114
 115                 // Check that all the rewrites succeeded, and if not return None.
 116                 let pats = try_opt!(pats);
 117
 118                 // Unwrap all the sub-strings and join them with commas.
 119                 let result = format!("[{}]", pats.join(", "));
 120                 wrap_str(result, context.config.max_width, width, offset)
 121             }
 122             PatKind::Struct(ref path, ref fields, elipses) => {
 123                 let path = try_opt!(rewrite_path(context, true, None, path, width, offset));
 124
 125                 let (elipses_str, terminator) = if elipses {
 126                     (", ..", "..")
 127                 } else {
 128                     ("", "}")
 129                 };
 130
 131                 // 5 = `{` plus space before and after plus `}` plus space before.
 132                 let budget = try_opt!(width.checked_sub(path.len() + 5 + elipses_str.len()));
 133                 // FIXME Using visual indenting, should use block or visual to match
 134                 // struct lit preference (however, in practice I think it is rare
 135                 // for struct patterns to be multi-line).
 136                 // 3 = `{` plus space before and after.
 137                 let offset = offset + path.len() + 3;
 138
 139                 let items = itemize_list(context.codemap,
 140                                          fields.iter(),
 141                                          terminator,
 142                                          |f| f.span.lo,
 143                                          |f| f.span.hi,
 144                                          |f| f.node.rewrite(context, budget, offset),
 145                                          context.codemap.span_after(self.span, "{"),
 146                                          self.span.hi);
 147                 let mut field_string = try_opt!(format_item_list(items,
 148                                                                  budget,
 149                                                                  offset,
 150                                                                  context.config));
 151                 if elipses {
 152                     if field_string.contains('\n') {
 153                         field_string.push_str(",\n");
 154                         field_string.push_str(&offset.to_string(context.config));
 155                         field_string.push_str("..");
 156                     } else {
 157                         if field_string.len() > 0 {
 158                             field_string.push_str(", ");
 159                         }
 160                         field_string.push_str("..");
 161                     }
 162                 }
 163
 164                 if field_string.is_empty() {
 165                     Some(format!("{} {{}}", path))
 166                 } else {
 167                     Some(format!("{} {{ {} }}", path, field_string))
 168                 }
 169             }
 170             // FIXME(#819) format pattern macros.
 171             PatKind::Mac(..) => {
 172                 wrap_str(context.snippet(self.span),
 173                          context.config.max_width,
 174                          width,
 175                          offset)
 176             }
 177         }
 178     }
 179 }
 180
 181 impl Rewrite for FieldPat {
 182     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 183         let pat = self.pat.rewrite(context, width, offset);
 184         if self.is_shorthand {
 185             pat
 186         } else {
 187             wrap_str(format!("{}: {}", self.ident.to_string(), try_opt!(pat)),
 188                      context.config.max_width,
 189                      width,
 190                      offset)
 191         }
 192     }
 193 }