208 lines
7.0 KiB
Rust
208 lines
7.0 KiB
Rust
// Copyright 2015 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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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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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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// Format list-like macro invocations. These are invocations whose token trees
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// can be interpreted as expressions and separated by commas.
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// Note that these token trees do not actually have to be interpreted as
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// expressions by the compiler. An example of an invocation we would reformat is
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// foo!( x, y, z ). The token x may represent an identifier in the code, but we
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// interpreted as an expression.
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// Macro uses which are not-list like, such as bar!(key => val), will not be
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// reformated.
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// List-like invocations with parentheses will be formatted as function calls,
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// and those with brackets will be formatted as array literals.
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use syntax::ast;
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use syntax::codemap::{mk_sp, BytePos};
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use syntax::parse::token::Token;
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use syntax::parse::tts_to_parser;
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use syntax::symbol;
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use syntax::util::ThinVec;
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use Shape;
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use codemap::SpanUtils;
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use rewrite::{Rewrite, RewriteContext};
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use expr::{rewrite_call, rewrite_array};
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use comment::{FindUncommented, contains_comment};
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const FORCED_BRACKET_MACROS: &'static [&'static str] = &["vec!"];
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// FIXME: use the enum from libsyntax?
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#[derive(Clone, Copy, PartialEq, Eq)]
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enum MacroStyle {
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Parens,
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Brackets,
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Braces,
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum MacroPosition {
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Item,
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Statement,
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Expression,
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}
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impl MacroStyle {
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fn opener(&self) -> &'static str {
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match *self {
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MacroStyle::Parens => "(",
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MacroStyle::Brackets => "[",
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MacroStyle::Braces => "{",
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}
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}
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}
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pub fn rewrite_macro(mac: &ast::Mac,
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extra_ident: Option<ast::Ident>,
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context: &RewriteContext,
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shape: Shape,
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position: MacroPosition)
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-> Option<String> {
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if context.config.use_try_shorthand {
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if let Some(expr) = convert_try_mac(mac, context) {
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return expr.rewrite(context, shape);
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}
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}
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let original_style = macro_style(mac, context);
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let macro_name = match extra_ident {
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None => format!("{}!", mac.node.path),
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Some(ident) => {
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if ident == symbol::keywords::Invalid.ident() {
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format!("{}!", mac.node.path)
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} else {
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format!("{}! {}", mac.node.path, ident)
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}
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}
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};
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let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
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MacroStyle::Brackets
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} else {
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original_style
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};
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if mac.node.tts.is_empty() && !contains_comment(&context.snippet(mac.span)) {
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return match style {
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MacroStyle::Parens if position == MacroPosition::Item => {
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Some(format!("{}();", macro_name))
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}
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MacroStyle::Parens => Some(format!("{}()", macro_name)),
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MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
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MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
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};
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}
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let mut parser = tts_to_parser(context.parse_session, mac.node.tts.clone());
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let mut expr_vec = Vec::new();
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if MacroStyle::Braces != style {
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loop {
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let expr = match parser.parse_expr() {
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Ok(expr) => {
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// Recovered errors.
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if context.parse_session.span_diagnostic.has_errors() {
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return None;
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}
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expr
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}
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Err(mut e) => {
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e.cancel();
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return None;
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}
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};
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expr_vec.push(expr);
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match parser.token {
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Token::Eof => break,
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Token::Comma => (),
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_ => return None,
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}
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parser.bump();
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if parser.token == Token::Eof {
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// vec! is a special case of bracket macro which should be formated as an array.
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if macro_name == "vec!" {
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break;
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} else {
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return None;
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}
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}
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}
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}
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match style {
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MacroStyle::Parens => {
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// Format macro invocation as function call.
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rewrite_call(context, ¯o_name, &expr_vec, mac.span, shape).map(|rw| {
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match position {
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MacroPosition::Item => format!("{};", rw),
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_ => rw,
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}
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})
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}
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MacroStyle::Brackets => {
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// Format macro invocation as array literal.
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let extra_offset = macro_name.len();
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let shape = try_opt!(shape.shrink_left(extra_offset));
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let rewrite = try_opt!(rewrite_array(expr_vec.iter().map(|x| &**x),
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mk_sp(context.codemap
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.span_after(mac.span,
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original_style.opener()),
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mac.span.hi - BytePos(1)),
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context,
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shape));
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Some(format!("{}{}", macro_name, rewrite))
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}
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MacroStyle::Braces => {
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// Skip macro invocations with braces, for now.
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None
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}
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}
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}
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/// Tries to convert a macro use into a short hand try expression. Returns None
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/// when the macro is not an instance of try! (or parsing the inner expression
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/// failed).
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pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
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if &format!("{}", mac.node.path)[..] == "try" {
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let mut parser = tts_to_parser(context.parse_session, mac.node.tts.clone());
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Some(ast::Expr {
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id: ast::NodeId::new(0), // dummy value
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node: ast::ExprKind::Try(try_opt!(parser.parse_expr().ok())),
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span: mac.span, // incorrect span, but shouldn't matter too much
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attrs: ThinVec::new(),
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})
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} else {
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None
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}
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}
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fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
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let snippet = context.snippet(mac.span);
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let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
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let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
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let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
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if paren_pos < bracket_pos && paren_pos < brace_pos {
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MacroStyle::Parens
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} else if bracket_pos < brace_pos {
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MacroStyle::Brackets
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} else {
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MacroStyle::Braces
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}
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}
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