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                             // 2 = "()".len()
  80                             let width = try_opt!(width.checked_sub(path_str.len() + 2));
  81                             // 1 = "(".len()
  82                             let offset = offset + path_str.len() + 1;
  83                             let items = itemize_list(context.codemap,
  84                                                      pat_vec.iter(),
  85                                                      ")",
  86                                                      |item| item.span.lo,
  87                                                      |item| item.span.hi,
  88                                                      |item| item.rewrite(context, width, offset),
  89                                                      context.codemap.span_after(self.span, "("),
  90                                                      self.span.hi);
  91                             Some(format!("{}({})",
  92                                          path_str,
  93                                          try_opt!(format_item_list(items,
  94                                                                    width,
  95                                                                    offset,
  96                                                                    context.config))))
  97                         }
  98                     }
  99                     None => Some(format!("{}(..)", path_str)),
 100                 }
 101             }
 102             PatKind::Lit(ref expr) => expr.rewrite(context, width, offset),
 103             PatKind::Vec(ref prefix, ref slice_pat, ref suffix) => {
 104                 // Rewrite all the sub-patterns.
 105                 let prefix = prefix.iter().map(|p| p.rewrite(context, width, offset));
 106                 let slice_pat = slice_pat.as_ref().map(|p| {
 107                     Some(format!("{}..", try_opt!(p.rewrite(context, width, offset))))
 108                 });
 109                 let suffix = suffix.iter().map(|p| p.rewrite(context, width, offset));
 110
 111                 // Munge them together.
 112                 let pats: Option<Vec<String>> = prefix.chain(slice_pat.into_iter())
 113                                                       .chain(suffix)
 114                                                       .collect();
 115
 116                 // Check that all the rewrites succeeded, and if not return None.
 117                 let pats = try_opt!(pats);
 118
 119                 // Unwrap all the sub-strings and join them with commas.
 120                 let result = format!("[{}]", pats.join(", "));
 121                 wrap_str(result, context.config.max_width, width, offset)
 122             }
 123             PatKind::Struct(ref path, ref fields, elipses) => {
 124                 let path = try_opt!(rewrite_path(context, true, None, path, width, offset));
 125
 126                 let (elipses_str, terminator) = if elipses {
 127                     (", ..", "..")
 128                 } else {
 129                     ("", "}")
 130                 };
 131
 132                 // 5 = `{` plus space before and after plus `}` plus space before.
 133                 let budget = try_opt!(width.checked_sub(path.len() + 5 + elipses_str.len()));
 134                 // FIXME Using visual indenting, should use block or visual to match
 135                 // struct lit preference (however, in practice I think it is rare
 136                 // for struct patterns to be multi-line).
 137                 // 3 = `{` plus space before and after.
 138                 let offset = offset + path.len() + 3;
 139
 140                 let items = itemize_list(context.codemap,
 141                                          fields.iter(),
 142                                          terminator,
 143                                          |f| f.span.lo,
 144                                          |f| f.span.hi,
 145                                          |f| f.node.rewrite(context, budget, offset),
 146                                          context.codemap.span_after(self.span, "{"),
 147                                          self.span.hi);
 148                 let mut field_string = try_opt!(format_item_list(items,
 149                                                                  budget,
 150                                                                  offset,
 151                                                                  context.config));
 152                 if elipses {
 153                     if field_string.contains('\n') {
 154                         field_string.push_str(",\n");
 155                         field_string.push_str(&offset.to_string(context.config));
 156                         field_string.push_str("..");
 157                     } else {
 158                         if field_string.len() > 0 {
 159                             field_string.push_str(", ");
 160                         }
 161                         field_string.push_str("..");
 162                     }
 163                 }
 164
 165                 if field_string.is_empty() {
 166                     Some(format!("{} {{}}", path))
 167                 } else {
 168                     Some(format!("{} {{ {} }}", path, field_string))
 169                 }
 170             }
 171             // FIXME(#819) format pattern macros.
 172             PatKind::Mac(..) => {
 173                 wrap_str(context.snippet(self.span),
 174                          context.config.max_width,
 175                          width,
 176                          offset)
 177             }
 178         }
 179     }
 180 }
 181
 182 impl Rewrite for FieldPat {
 183     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 184         let pat = self.pat.rewrite(context, width, offset);
 185         if self.is_shorthand {
 186             pat
 187         } else {
 188             wrap_str(format!("{}: {}", self.ident.to_string(), try_opt!(pat)),
 189                      context.config.max_width,
 190                      width,
 191                      offset)
 192         }
 193     }
 194 }