diff options
Diffstat (limited to 'third_party/rust/wast/src/error.rs')
| -rw-r--r-- | third_party/rust/wast/src/error.rs | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/third_party/rust/wast/src/error.rs b/third_party/rust/wast/src/error.rs new file mode 100644 index 0000000000..214e678338 --- /dev/null +++ b/third_party/rust/wast/src/error.rs @@ -0,0 +1,196 @@ +use crate::lexer::LexError; +use crate::token::Span; +use std::fmt; +use std::path::{Path, PathBuf}; +use unicode_width::UnicodeWidthStr; + +/// A convenience error type to tie together all the detailed errors produced by +/// this crate. +/// +/// This type can be created from a [`LexError`]. This also contains +/// storage for file/text information so a nice error can be rendered along the +/// same lines of rustc's own error messages (minus the color). +/// +/// This type is typically suitable for use in public APIs for consumers of this +/// crate. +#[derive(Debug)] +pub struct Error { + inner: Box<ErrorInner>, +} + +#[derive(Debug)] +struct ErrorInner { + text: Option<Text>, + file: Option<PathBuf>, + span: Span, + kind: ErrorKind, +} + +#[derive(Debug)] +struct Text { + line: usize, + col: usize, + snippet: String, +} + +#[derive(Debug)] +enum ErrorKind { + Lex(LexError), + Custom(String), +} + +impl Error { + pub(crate) fn lex(span: Span, content: &str, kind: LexError) -> Error { + let mut ret = Error { + inner: Box::new(ErrorInner { + text: None, + file: None, + span, + kind: ErrorKind::Lex(kind), + }), + }; + ret.set_text(content); + ret + } + + pub(crate) fn parse(span: Span, content: &str, message: String) -> Error { + let mut ret = Error { + inner: Box::new(ErrorInner { + text: None, + file: None, + span, + kind: ErrorKind::Custom(message), + }), + }; + ret.set_text(content); + ret + } + + /// Creates a new error with the given `message` which is targeted at the + /// given `span` + /// + /// Note that you'll want to ensure that `set_text` or `set_path` is called + /// on the resulting error to improve the rendering of the error message. + pub fn new(span: Span, message: String) -> Error { + Error { + inner: Box::new(ErrorInner { + text: None, + file: None, + span, + kind: ErrorKind::Custom(message), + }), + } + } + + /// Return the `Span` for this error. + pub fn span(&self) -> Span { + self.inner.span + } + + /// To provide a more useful error this function can be used to extract + /// relevant textual information about this error into the error itself. + /// + /// The `contents` here should be the full text of the original file being + /// parsed, and this will extract a sub-slice as necessary to render in the + /// `Display` implementation later on. + pub fn set_text(&mut self, contents: &str) { + if self.inner.text.is_some() { + return; + } + self.inner.text = Some(Text::new(contents, self.inner.span)); + } + + /// To provide a more useful error this function can be used to set + /// the file name that this error is associated with. + /// + /// The `path` here will be stored in this error and later rendered in the + /// `Display` implementation. + pub fn set_path(&mut self, path: &Path) { + if self.inner.file.is_some() { + return; + } + self.inner.file = Some(path.to_path_buf()); + } + + /// Returns the underlying `LexError`, if any, that describes this error. + pub fn lex_error(&self) -> Option<&LexError> { + match &self.inner.kind { + ErrorKind::Lex(e) => Some(e), + _ => None, + } + } + + /// Returns the underlying message, if any, that describes this error. + pub fn message(&self) -> String { + match &self.inner.kind { + ErrorKind::Lex(e) => e.to_string(), + ErrorKind::Custom(e) => e.clone(), + } + } +} + +impl fmt::Display for Error { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + let err = match &self.inner.kind { + ErrorKind::Lex(e) => e as &dyn fmt::Display, + ErrorKind::Custom(e) => e as &dyn fmt::Display, + }; + let text = match &self.inner.text { + Some(text) => text, + None => { + return write!(f, "{} at byte offset {}", err, self.inner.span.offset); + } + }; + let file = self + .inner + .file + .as_ref() + .and_then(|p| p.to_str()) + .unwrap_or("<anon>"); + write!( + f, + "\ +{err} + --> {file}:{line}:{col} + | + {line:4} | {text} + | {marker:>0$}", + text.col + 1, + file = file, + line = text.line + 1, + col = text.col + 1, + err = err, + text = text.snippet, + marker = "^", + ) + } +} + +impl std::error::Error for Error {} + +impl Text { + fn new(content: &str, span: Span) -> Text { + let (line, col) = span.linecol_in(content); + let contents = content.lines().nth(line).unwrap_or(""); + let mut snippet = String::new(); + for ch in contents.chars() { + match ch { + // Replace tabs with spaces to render consistently + '\t' => { + snippet.push_str(" "); + } + // these codepoints change how text is rendered so for clarity + // in error messages they're dropped. + '\u{202a}' | '\u{202b}' | '\u{202d}' | '\u{202e}' | '\u{2066}' | '\u{2067}' + | '\u{2068}' | '\u{206c}' | '\u{2069}' => {} + + c => snippet.push(c), + } + } + // Use the `unicode-width` crate to figure out how wide the snippet, up + // to our "column", actually is. That'll tell us how many spaces to + // place before the `^` character that points at the problem + let col = snippet.get(..col).map(|s| s.width()).unwrap_or(col); + Text { line, col, snippet } + } +} |