rust/src/patterns.rs

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use Indent;
use rewrite::{Rewrite, RewriteContext};
use utils::{wrap_str, format_mutability, span_after};
use lists::{format_item_list, itemize_list};
use expr::{rewrite_unary_prefix, rewrite_pair, rewrite_tuple};
use types::rewrite_path;
use syntax::ast::{BindingMode, Pat, Pat_, FieldPat};
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impl Rewrite for Pat {
fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
match self.node {
Pat_::PatBox(ref pat) => rewrite_unary_prefix(context, "box ", &**pat, width, offset),
Pat_::PatIdent(binding_mode, ident, ref sub_pat) => {
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let (prefix, mutability) = match binding_mode {
BindingMode::BindByRef(mutability) => ("ref ", mutability),
BindingMode::BindByValue(mutability) => ("", mutability),
};
let mut_infix = format_mutability(mutability);
let id_str = ident.node.to_string();
let sub_pat = match *sub_pat {
Some(ref p) => {
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// 3 - ` @ `.
let width = try_opt!(width.checked_sub(prefix.len() + mut_infix.len() +
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id_str.len() +
3));
format!(" @ {}", try_opt!(p.rewrite(context, width, offset)))
}
None => "".to_owned(),
};
let result = format!("{}{}{}{}", prefix, mut_infix, id_str, sub_pat);
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wrap_str(result, context.config.max_width, width, offset)
}
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Pat_::PatWild => {
if 1 <= width {
Some("_".to_owned())
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} else {
None
}
}
Pat_::PatQPath(ref q_self, ref path) => {
rewrite_path(context, true, Some(q_self), path, width, offset)
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}
Pat_::PatRange(ref lhs, ref rhs) => {
rewrite_pair(&**lhs, &**rhs, "", "...", "", context, width, offset)
}
Pat_::PatRegion(ref pat, mutability) => {
let prefix = format!("&{}", format_mutability(mutability));
rewrite_unary_prefix(context, &prefix, &**pat, width, offset)
}
Pat_::PatTup(ref items) => {
rewrite_tuple(context,
items.iter().map(|x| &**x),
self.span,
width,
offset)
}
Pat_::PatEnum(ref path, ref pat_vec) => {
let path_str = try_opt!(rewrite_path(context, true, None, path, width, offset));
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match *pat_vec {
Some(ref pat_vec) => {
if pat_vec.is_empty() {
Some(path_str)
} else {
// 1 = (
let width = try_opt!(width.checked_sub(path_str.len() + 1));
let offset = offset + path_str.len() + 1;
let items = itemize_list(context.codemap,
pat_vec.iter(),
")",
|item| item.span.lo,
|item| item.span.hi,
|item| item.rewrite(context, width, offset),
span_after(self.span, "(", context.codemap),
self.span.hi);
Some(format!("{}({})",
path_str,
try_opt!(format_item_list(items,
width,
offset,
context.config))))
}
}
None => Some(format!("{}(..)", path_str)),
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}
}
Pat_::PatLit(ref expr) => expr.rewrite(context, width, offset),
Pat_::PatVec(ref prefix, ref slice_pat, ref suffix) => {
// Rewrite all the sub-patterns.
let prefix = prefix.iter().map(|p| p.rewrite(context, width, offset));
let slice_pat = slice_pat.as_ref().map(|p| {
Some(format!("{}..", try_opt!(p.rewrite(context, width, offset))))
});
let suffix = suffix.iter().map(|p| p.rewrite(context, width, offset));
// Munge them together.
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let pats: Option<Vec<String>> = prefix.chain(slice_pat.into_iter())
.chain(suffix)
.collect();
// Check that all the rewrites succeeded, and if not return None.
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let pats = try_opt!(pats);
// Unwrap all the sub-strings and join them with commas.
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let result = format!("[{}]", pats.join(", "));
wrap_str(result, context.config.max_width, width, offset)
}
Pat_::PatStruct(ref path, ref fields, elipses) => {
let path = try_opt!(rewrite_path(context, true, None, path, width, offset));
let (elipses_str, terminator) = if elipses {
(", ..", "..")
} else {
("", "}")
};
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// 5 = `{` plus space before and after plus `}` plus space before.
let budget = try_opt!(width.checked_sub(path.len() + 5 + elipses_str.len()));
// FIXME Using visual indenting, should use block or visual to match
// struct lit preference (however, in practice I think it is rare
// for struct patterns to be multi-line).
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// 3 = `{` plus space before and after.
let offset = offset + path.len() + 3;
let items = itemize_list(context.codemap,
fields.iter(),
terminator,
|f| f.span.lo,
|f| f.span.hi,
|f| f.node.rewrite(context, budget, offset),
span_after(self.span, "{", context.codemap),
self.span.hi);
let mut field_string = try_opt!(format_item_list(items,
budget,
offset,
context.config));
if elipses {
if field_string.contains('\n') {
field_string.push_str(",\n");
field_string.push_str(&offset.to_string(context.config));
field_string.push_str("..");
} else {
if field_string.len() > 0 {
field_string.push_str(", ");
}
field_string.push_str("..");
}
}
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if field_string.is_empty() {
Some(format!("{} {{}}", path))
} else {
Some(format!("{} {{ {} }}", path, field_string))
}
}
// FIXME(#819) format pattern macros.
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Pat_::PatMac(..) => {
wrap_str(context.snippet(self.span),
context.config.max_width,
width,
offset)
}
}
}
}
impl Rewrite for FieldPat {
fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
let pat = self.pat.rewrite(context, width, offset);
if self.is_shorthand {
pat
} else {
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wrap_str(format!("{}: {}", self.ident.to_string(), try_opt!(pat)),
context.config.max_width,
width,
offset)
}
}
}