Expand the deriving(ToStr) implementation
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Alex Crichton
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dc4560dc26
commit
30d755957a
@ -1562,7 +1562,9 @@ Supported traits for `deriving` are:
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* `IterBytes`, to iterate over the bytes in a data type.
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* `Rand`, to create a random instance of a data type.
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* `ToStr`, to convert to a string. For a type with this instance,
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`obj.to_str()` has the same output as `fmt!("%?", obj)`.
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`obj.to_str()` has similar output as `fmt!("%?", obj)`, but it differs in that
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each constituent field of the type must also implement `ToStr` and will have
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`field.to_str()` invoked to build up the result.
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# Statements and expressions
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@ -10,6 +10,7 @@
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use core::prelude::*;
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use ast;
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use ast::{meta_item, item, expr};
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use codemap::span;
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use ext::base::ExtCtxt;
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@ -40,16 +41,68 @@ pub fn expand_deriving_to_str(cx: @ExtCtxt,
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trait_def.expand(cx, span, mitem, in_items)
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}
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fn to_str_substructure(cx: @ExtCtxt, span: span, substr: &Substructure) -> @expr {
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match substr.self_args {
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[self_obj] => {
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let self_addr = cx.expr_addr_of(span, self_obj);
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cx.expr_call_global(span,
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~[cx.ident_of("std"),
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cx.ident_of("sys"),
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cx.ident_of("log_str")],
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~[self_addr])
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// It used to be the case that this deriving implementation invoked
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// std::sys::log_str, but this isn't sufficient because it doesn't invoke the
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// to_str() method on each field. Hence we mirror the logic of the log_str()
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// method, but with tweaks to call to_str() on sub-fields.
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fn to_str_substructure(cx: @ExtCtxt, span: span,
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substr: &Substructure) -> @expr {
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let to_str = cx.ident_of("to_str");
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let doit = |start: &str, end: @str, name: ast::ident,
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fields: &[(Option<ast::ident>, @expr, ~[@expr])]| {
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if fields.len() == 0 {
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cx.expr_str_uniq(span, cx.str_of(name))
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} else {
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let buf = cx.ident_of("buf");
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let start = cx.str_of(name) + start;
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let init = cx.expr_str_uniq(span, start.to_managed());
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let mut stmts = ~[cx.stmt_let(span, true, buf, init)];
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let push_str = cx.ident_of("push_str");
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let push = |s: @expr| {
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let ebuf = cx.expr_ident(span, buf);
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let call = cx.expr_method_call(span, ebuf, push_str, ~[s]);
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stmts.push(cx.stmt_expr(call));
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};
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for fields.iter().enumerate().advance |(i, &(name, e, _))| {
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if i > 0 {
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push(cx.expr_str(span, @", "));
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}
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match name {
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None => {}
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Some(id) => {
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let name = cx.str_of(id) + ": ";
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push(cx.expr_str(span, name.to_managed()));
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}
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}
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push(cx.expr_method_call(span, e, to_str, ~[]));
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}
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push(cx.expr_str(span, end));
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cx.expr_blk(cx.blk(span, stmts, Some(cx.expr_ident(span, buf))))
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}
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_ => cx.span_bug(span, "Invalid number of arguments in `deriving(ToStr)`")
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}
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};
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return match *substr.fields {
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Struct(ref fields) => {
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if fields.len() == 0 || fields[0].n0_ref().is_none() {
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doit("(", @")", substr.type_ident, *fields)
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} else {
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doit("{", @"}", substr.type_ident, *fields)
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}
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}
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EnumMatching(_, variant, ref fields) => {
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match variant.node.kind {
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ast::tuple_variant_kind(*) =>
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doit("(", @")", variant.node.name, *fields),
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ast::struct_variant_kind(*) =>
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doit("{", @"}", variant.node.name, *fields),
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}
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}
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_ => cx.bug("expected Struct or EnumMatching in deriving(ToStr)")
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};
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}
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@ -1,5 +1,4 @@
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// xfail-fast #6330
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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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@ -9,39 +8,42 @@
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use std::rand;
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#[deriving(ToStr)]
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enum A {}
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#[deriving(ToStr)]
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enum B { B1, B2, B3 }
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#[deriving(ToStr)]
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enum C { C1(int), C2(B), C3(~str) }
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#[deriving(ToStr)]
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enum D { D1{ a: int } }
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#[deriving(ToStr)]
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struct E;
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#[deriving(ToStr)]
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struct F(int);
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#[deriving(ToStr)]
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struct G(int, int);
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#[deriving(ToStr)]
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struct H { a: int }
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#[deriving(ToStr)]
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struct I { a: int, b: int }
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#[deriving(ToStr)]
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struct J(Custom);
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#[deriving(Rand,ToStr)]
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struct A;
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#[deriving(Rand,ToStr)]
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struct B(int, int);
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#[deriving(Rand,ToStr)]
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struct C {
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x: f64,
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y: (u8, u8)
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}
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#[deriving(Rand,ToStr)]
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enum D {
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D0,
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D1(uint),
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D2 { x: (), y: () }
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struct Custom;
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impl ToStr for Custom {
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fn to_str(&self) -> ~str { ~"yay" }
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}
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fn main() {
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macro_rules! t(
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($ty:ty) => {{
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let x =rand::random::<$ty>();
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assert_eq!(x.to_str(), fmt!("%?", x));
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}}
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);
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for 20.times {
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t!(A);
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t!(B);
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t!(C);
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t!(D);
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}
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assert_eq!(B1.to_str(), ~"B1");
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assert_eq!(B2.to_str(), ~"B2");
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assert_eq!(C1(3).to_str(), ~"C1(3)");
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assert_eq!(C2(B2).to_str(), ~"C2(B2)");
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assert_eq!(D1{ a: 2 }.to_str(), ~"D1{a: 2}");
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assert_eq!(E.to_str(), ~"E");
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assert_eq!(F(3).to_str(), ~"F(3)");
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assert_eq!(G(3, 4).to_str(), ~"G(3, 4)");
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assert_eq!(G(3, 4).to_str(), ~"G(3, 4)");
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assert_eq!(I{ a: 2, b: 4 }.to_str(), ~"I{a: 2, b: 4}");
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assert_eq!(J(Custom).to_str(), ~"J(yay)");
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}
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