1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
//! The main parser interface.

#![allow(internal_features)]
#![allow(rustc::diagnostic_outside_of_impl)]
#![allow(rustc::untranslatable_diagnostic)]
#![feature(array_windows)]
#![feature(box_patterns)]
#![feature(debug_closure_helpers)]
#![feature(if_let_guard)]
#![feature(iter_intersperse)]
#![feature(let_chains)]

use rustc_ast as ast;
use rustc_ast::token;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::{AttrItem, Attribute, MetaItem};
use rustc_ast_pretty::pprust;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{Diag, FatalError, PResult};
use rustc_session::parse::ParseSess;
use rustc_span::{FileName, SourceFile, Span};

use std::path::Path;

pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");

#[macro_use]
pub mod parser;
use parser::{make_unclosed_delims_error, Parser};
pub mod lexer;
pub mod validate_attr;

mod errors;

rustc_fluent_macro::fluent_messages! { "../messages.ftl" }

// A bunch of utility functions of the form `parse_<thing>_from_<source>`
// where <thing> includes crate, expr, item, stmt, tts, and one that
// uses a HOF to parse anything, and <source> includes file and
// `source_str`.

/// A variant of 'panictry!' that works on a `Vec<Diag>` instead of a single `Diag`.
macro_rules! panictry_buffer {
    ($e:expr) => {{
        use std::result::Result::{Err, Ok};
        match $e {
            Ok(e) => e,
            Err(errs) => {
                for e in errs {
                    e.emit();
                }
                FatalError.raise()
            }
        }
    }};
}

pub fn parse_crate_from_file<'a>(input: &Path, psess: &'a ParseSess) -> PResult<'a, ast::Crate> {
    let mut parser = new_parser_from_file(psess, input, None);
    parser.parse_crate_mod()
}

pub fn parse_crate_attrs_from_file<'a>(
    input: &Path,
    psess: &'a ParseSess,
) -> PResult<'a, ast::AttrVec> {
    let mut parser = new_parser_from_file(psess, input, None);
    parser.parse_inner_attributes()
}

pub fn parse_crate_from_source_str(
    name: FileName,
    source: String,
    psess: &ParseSess,
) -> PResult<'_, ast::Crate> {
    new_parser_from_source_str(psess, name, source).parse_crate_mod()
}

pub fn parse_crate_attrs_from_source_str(
    name: FileName,
    source: String,
    psess: &ParseSess,
) -> PResult<'_, ast::AttrVec> {
    new_parser_from_source_str(psess, name, source).parse_inner_attributes()
}

pub fn parse_stream_from_source_str(
    name: FileName,
    source: String,
    psess: &ParseSess,
    override_span: Option<Span>,
) -> TokenStream {
    source_file_to_stream(psess, psess.source_map().new_source_file(name, source), override_span)
}

/// Creates a new parser from a source string.
pub fn new_parser_from_source_str(psess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
    panictry_buffer!(maybe_new_parser_from_source_str(psess, name, source))
}

/// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
/// token stream; these must be consumed via `emit`, `cancel`, etc., otherwise a panic will occur
/// when they are dropped.
pub fn maybe_new_parser_from_source_str(
    psess: &ParseSess,
    name: FileName,
    source: String,
) -> Result<Parser<'_>, Vec<Diag<'_>>> {
    maybe_source_file_to_parser(psess, psess.source_map().new_source_file(name, source))
}

/// Creates a new parser, aborting if the file doesn't exist. If a span is given, that is used on
/// an error as the source of the problem.
pub fn new_parser_from_file<'a>(psess: &'a ParseSess, path: &Path, sp: Option<Span>) -> Parser<'a> {
    let source_file = psess.source_map().load_file(path).unwrap_or_else(|e| {
        let msg = format!("couldn't read {}: {}", path.display(), e);
        let mut err = psess.dcx.struct_fatal(msg);
        if let Some(sp) = sp {
            err.span(sp);
        }
        err.emit();
    });

    panictry_buffer!(maybe_source_file_to_parser(psess, source_file))
}

/// Given a session and a `source_file`, return a parser. Returns any buffered errors from lexing
/// the initial token stream.
fn maybe_source_file_to_parser(
    psess: &ParseSess,
    source_file: Lrc<SourceFile>,
) -> Result<Parser<'_>, Vec<Diag<'_>>> {
    let end_pos = source_file.end_position();
    let stream = maybe_file_to_stream(psess, source_file, None)?;
    let mut parser = stream_to_parser(psess, stream, None);
    if parser.token == token::Eof {
        parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt(), None);
    }

    Ok(parser)
}

// Base abstractions

/// Given a `source_file`, produces a sequence of token trees.
pub fn source_file_to_stream(
    psess: &ParseSess,
    source_file: Lrc<SourceFile>,
    override_span: Option<Span>,
) -> TokenStream {
    panictry_buffer!(maybe_file_to_stream(psess, source_file, override_span))
}

/// Given a source file, produces a sequence of token trees. Returns any buffered errors from
/// parsing the token stream.
fn maybe_file_to_stream<'psess>(
    psess: &'psess ParseSess,
    source_file: Lrc<SourceFile>,
    override_span: Option<Span>,
) -> Result<TokenStream, Vec<Diag<'psess>>> {
    let src = source_file.src.as_ref().unwrap_or_else(|| {
        psess.dcx.bug(format!(
            "cannot lex `source_file` without source: {}",
            psess.source_map().filename_for_diagnostics(&source_file.name)
        ));
    });

    lexer::parse_token_trees(psess, src.as_str(), source_file.start_pos, override_span)
}

/// Given a stream and the `ParseSess`, produces a parser.
pub fn stream_to_parser<'a>(
    psess: &'a ParseSess,
    stream: TokenStream,
    subparser_name: Option<&'static str>,
) -> Parser<'a> {
    Parser::new(psess, stream, subparser_name)
}

/// Runs the given subparser `f` on the tokens of the given `attr`'s item.
pub fn parse_in<'a, T>(
    psess: &'a ParseSess,
    tts: TokenStream,
    name: &'static str,
    mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
) -> PResult<'a, T> {
    let mut parser = Parser::new(psess, tts, Some(name));
    let result = f(&mut parser)?;
    if parser.token != token::Eof {
        parser.unexpected()?;
    }
    Ok(result)
}

pub fn fake_token_stream_for_item(psess: &ParseSess, item: &ast::Item) -> TokenStream {
    let source = pprust::item_to_string(item);
    let filename = FileName::macro_expansion_source_code(&source);
    parse_stream_from_source_str(filename, source, psess, Some(item.span))
}

pub fn fake_token_stream_for_crate(psess: &ParseSess, krate: &ast::Crate) -> TokenStream {
    let source = pprust::crate_to_string_for_macros(krate);
    let filename = FileName::macro_expansion_source_code(&source);
    parse_stream_from_source_str(filename, source, psess, Some(krate.spans.inner_span))
}

pub fn parse_cfg_attr(
    attr: &Attribute,
    psess: &ParseSess,
) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
    match attr.get_normal_item().args {
        ast::AttrArgs::Delimited(ast::DelimArgs { dspan, delim, ref tokens })
            if !tokens.is_empty() =>
        {
            crate::validate_attr::check_cfg_attr_bad_delim(psess, dspan, delim);
            match parse_in(psess, tokens.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
                Ok(r) => return Some(r),
                Err(e) => {
                    e.with_help(format!("the valid syntax is `{CFG_ATTR_GRAMMAR_HELP}`"))
                        .with_note(CFG_ATTR_NOTE_REF)
                        .emit();
                }
            }
        }
        _ => error_malformed_cfg_attr_missing(attr.span, psess),
    }
    None
}

const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
    <https://doc.rust-lang.org/reference/conditional-compilation.html\
    #the-cfg_attr-attribute>";

fn error_malformed_cfg_attr_missing(span: Span, psess: &ParseSess) {
    psess.dcx.emit_err(errors::MalformedCfgAttr { span, sugg: CFG_ATTR_GRAMMAR_HELP });
}