144 lines
4.1 KiB
Rust
144 lines
4.1 KiB
Rust
use errors::{Applicability, DiagnosticBuilder};
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use syntax::ast::{self, *};
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use syntax::source_map::Spanned;
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use syntax::ext::base::*;
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use syntax::ext::build::AstBuilder;
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use syntax::parse::token;
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use syntax::parse::parser::Parser;
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use syntax::print::pprust;
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use syntax::ptr::P;
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use syntax::symbol::Symbol;
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use syntax::tokenstream::{TokenStream, TokenTree};
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use syntax_pos::{Span, DUMMY_SP};
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pub fn expand_assert<'cx>(
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cx: &'cx mut ExtCtxt<'_>,
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sp: Span,
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tts: &[TokenTree],
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) -> Box<dyn MacResult + 'cx> {
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let Assert { cond_expr, custom_message } = match parse_assert(cx, sp, tts) {
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Ok(assert) => assert,
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Err(mut err) => {
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err.emit();
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return DummyResult::expr(sp);
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}
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};
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let sp = sp.apply_mark(cx.current_expansion.mark);
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let panic_call = Mac_ {
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path: Path::from_ident(Ident::new(Symbol::intern("panic"), sp)),
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tts: custom_message.unwrap_or_else(|| {
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TokenStream::from(TokenTree::Token(
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DUMMY_SP,
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token::Literal(
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token::Lit::Str_(Name::intern(&format!(
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"assertion failed: {}",
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pprust::expr_to_string(&cond_expr).escape_debug()
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))),
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None,
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),
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))
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}).into(),
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delim: MacDelimiter::Parenthesis,
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};
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let if_expr = cx.expr_if(
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sp,
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cx.expr(sp, ExprKind::Unary(UnOp::Not, cond_expr)),
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cx.expr(
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sp,
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ExprKind::Mac(Spanned {
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span: sp,
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node: panic_call,
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}),
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),
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None,
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);
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MacEager::expr(if_expr)
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}
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struct Assert {
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cond_expr: P<ast::Expr>,
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custom_message: Option<TokenStream>,
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}
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fn parse_assert<'a>(
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cx: &mut ExtCtxt<'a>,
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sp: Span,
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tts: &[TokenTree]
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) -> Result<Assert, DiagnosticBuilder<'a>> {
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let mut parser = cx.new_parser_from_tts(tts);
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if parser.token == token::Eof {
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let mut err = cx.struct_span_err(sp, "macro requires a boolean expression as an argument");
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err.span_label(sp, "boolean expression required");
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return Err(err);
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}
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let cond_expr = parser.parse_expr()?;
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// Some crates use the `assert!` macro in the following form (note extra semicolon):
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//
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// assert!(
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// my_function();
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// );
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//
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// Warn about semicolon and suggest removing it. Eventually, this should be turned into an
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// error.
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if parser.token == token::Semi {
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let mut err = cx.struct_span_warn(sp, "macro requires an expression as an argument");
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err.span_suggestion(
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parser.span,
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"try removing semicolon",
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String::new(),
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Applicability::MaybeIncorrect
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);
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err.note("this is going to be an error in the future");
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err.emit();
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parser.bump();
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}
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// Some crates use the `assert!` macro in the following form (note missing comma before
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// message):
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//
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// assert!(true "error message");
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//
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// Parse this as an actual message, and suggest inserting a comma. Eventually, this should be
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// turned into an error.
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let custom_message = if let token::Literal(token::Lit::Str_(_), _) = parser.token {
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let mut err = cx.struct_span_warn(parser.span, "unexpected string literal");
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let comma_span = cx.source_map().next_point(parser.prev_span);
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err.span_suggestion_short(
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comma_span,
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"try adding a comma",
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", ".to_string(),
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Applicability::MaybeIncorrect
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);
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err.note("this is going to be an error in the future");
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err.emit();
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parse_custom_message(&mut parser)
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} else if parser.eat(&token::Comma) {
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parse_custom_message(&mut parser)
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} else {
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None
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};
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if parser.token != token::Eof {
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parser.expect_one_of(&[], &[])?;
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unreachable!();
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}
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Ok(Assert { cond_expr, custom_message })
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}
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fn parse_custom_message<'a>(parser: &mut Parser<'a>) -> Option<TokenStream> {
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let ts = parser.parse_tokens();
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if !ts.is_empty() {
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Some(ts)
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} else {
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None
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}
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}
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