acdc_parser/

warning.rs

//! Non-fatal parser diagnostics.
//!
//! Warnings are conditions the parser recovers from but that a caller (CLI,
//! LSP, editor) may want to surface to the user. They are carried on
//! [`ParseResult::warnings`](crate::ParseResult::warnings) and also emitted
//! through `tracing::warn!` as a belt-and-suspenders fallback for callers
//! that ignore the returned slice.

use std::{borrow::Cow, fmt};

use crate::SourceLocation;

/// A non-fatal condition detected during parsing.
///
/// Use [`Warning::source_location`] to map to a location for diagnostic
/// rendering, and [`Warning::advice`] for help text mirroring
/// [`Error::advice`](crate::Error::advice).
#[derive(Debug, PartialEq)]
#[non_exhaustive]
pub struct Warning {
    /// The specific non-fatal condition.
    pub kind: WarningKind,
    /// Where the condition was detected, when known. Absent for warnings
    /// raised outside any source context (e.g. preprocessor configuration).
    pub location: Option<SourceLocation>,
}

impl Warning {
    /// Construct a warning tied to a specific source location.
    #[must_use]
    pub(crate) fn new(kind: WarningKind, location: Option<SourceLocation>) -> Self {
        Self { kind, location }
    }

    /// Source location for this warning, when available.
    #[must_use]
    pub fn source_location(&self) -> Option<&SourceLocation> {
        self.location.as_ref()
    }

    /// Advice text mirroring [`Error::advice`](crate::Error::advice).
    /// Returns `None` when there is no canned guidance for this kind.
    #[must_use]
    pub fn advice(&self) -> Option<&'static str> {
        match &self.kind {
            WarningKind::SectionLevelOutOfSequence { .. } => Some(
                "Section levels must increment by at most one. Renumber the heading so it is one level deeper than its parent (the document title counts as level 0).",
            ),
            WarningKind::NestedSectionInIndex => Some(
                "Move the nested section outside the index or replace its heading with a non-section block.",
            ),
            WarningKind::NestedSectionInBibliography => Some(
                "Move the nested section outside the bibliography section or replace its heading with a non-section block.",
            ),
            WarningKind::UnterminatedTable { .. }
            | WarningKind::UnterminatedDelimitedBlock { .. } => Some(
                "The opening delimiter was found but no matching closing delimiter was seen before end of document. Add the closing delimiter on its own line, or remove the opening delimiter if not intended.",
            ),
            WarningKind::TableUnknownFormat { .. } => Some(
                "Use a supported table format (`csv`, `dsv`, or `tsv`) or remove the `format` attribute to use the table delimiter's default separator.",
            ),
            WarningKind::TableIncompleteRow => Some(
                "Complete the final table row or remove the trailing cells that do not fill the configured column count.",
            ),
            WarningKind::TableCellOverflow { .. } | WarningKind::TableColumnCount { .. } => Some(
                "Adjust the `cols` attribute or the row's cells/spans so each row occupies the configured number of columns.",
            ),
            WarningKind::NonStandardAuthorLine { .. } => Some(
                "Author lines use `firstname [middlename] [lastname] [<email>]`, with multiple authors separated by `;`. Keeping the whole line as a single author name.",
            ),
            WarningKind::UnresolvedReference { .. } => Some(
                "Define an anchor with this id (e.g. `[[id]]` or `[#id]` on a block or section), or fix the reference to point at an existing id.",
            ),
            WarningKind::DuplicateId { .. } => Some(
                "Assign a unique id to each target. Cross-references use the first definition.",
            ),
            WarningKind::ConflictingFootnote { .. } => Some(
                "Use footnote:id[] to reuse the first definition, or choose a different id for a new footnote.",
            ),
            WarningKind::LegacyFloatDiscreteHeading => Some(
                "Replace the `float` attribute with `discrete` (e.g. `[discrete]`). `float` here does not control layout; it is an older name for a discrete (free-floating) heading.",
            ),
            WarningKind::InvalidDocumentAttribute { .. } => {
                Some("Use a value in the attribute's documented domain")
            }
            WarningKind::ContentRecovery { .. } | WarningKind::Other(_) => None,
        }
    }
}

impl fmt::Display for Warning {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let Some(loc) = &self.location else {
            return write!(f, "{}", self.kind);
        };
        if let Some(name) = loc
            .file
            .as_ref()
            .and_then(|p| p.file_name())
            .and_then(|s| s.to_str())
        {
            write!(f, "{name}: {}: {}", loc, self.kind)
        } else {
            write!(f, "{}: {}", loc, self.kind)
        }
    }
}

/// Categorised non-fatal conditions.
///
/// `Other` is an escape hatch for ad-hoc messages the parser has not yet
/// been taught to categorise. New variants should be added as callers need
/// to assert on them programmatically (e.g. LSP mapping `kind` to LSP
/// diagnostic codes, or tests matching on specific conditions without
/// resorting to string comparison).
#[derive(Debug, Clone, PartialEq, thiserror::Error)]
#[non_exhaustive]
pub enum WarningKind {
    /// A section title skips a level relative to its parent — either the first
    /// section after the document title is deeper than level 1, or a nested
    /// section jumps more than one level below its parent. Matches asciidoctor's
    /// "section title out of sequence" check; the section is still rendered at
    /// its literal level.
    #[error("section title out of sequence: expected level {expected}, got level {got}")]
    SectionLevelOutOfSequence {
        /// The level the section was expected to be (one deeper than its
        /// parent; `1` for the first section under a document title).
        expected: u8,
        /// The observed section level (e.g. `2` for `===`).
        got: u8,
    },

    /// A bibliography section contains a direct child section. The child is
    /// retained in the document, matching Asciidoctor's recovery behavior.
    #[error("bibliography sections do not support nested sections")]
    NestedSectionInBibliography,

    /// An index contains a direct child section. The child remains in the AST;
    /// each converter applies its usual index-content policy.
    #[error("index sections do not support nested sections")]
    NestedSectionInIndex,

    /// A table's opening delimiter was matched but no corresponding
    /// closing delimiter was found before end of input. Matches
    /// asciidoctor's "unterminated table block" warning.
    ///
    /// `delimiter` is the literal opening token as it appeared in the
    /// source (e.g. `"|==="`, `"!====="`).
    #[error("unterminated table block (opened by `{delimiter}`)")]
    UnterminatedTable {
        /// The opening delimiter that was left unmatched.
        delimiter: String,
    },

    /// A delimited block's opening delimiter was matched but no corresponding
    /// closing delimiter was found before end of input. Matches asciidoctor's
    /// "unterminated <kind> block" warning; the block is still rendered,
    /// closed at end of input. Tables use the separate [`UnterminatedTable`]
    /// variant.
    ///
    /// `delimiter` is the literal opening token as it appeared in the source
    /// (e.g. `"===="`, `"----"`).
    ///
    /// [`UnterminatedTable`]: WarningKind::UnterminatedTable
    #[error("unterminated {kind} block (opened by `{delimiter}`)")]
    UnterminatedDelimitedBlock {
        /// The block kind: `"example"`, `"listing"`, `"literal"`,
        /// `"sidebar"`, `"quote"`, `"open"`, `"comment"`, or `"pass"`.
        kind: &'static str,
        /// The opening delimiter that was left unmatched.
        delimiter: String,
    },

    /// A table declared an unsupported `format` attribute, so the parser fell
    /// back to the table delimiter's default separator.
    #[error("unknown table format `{format}`, using default separator")]
    TableUnknownFormat {
        /// The unsupported format value.
        format: String,
    },

    /// A table ended with cells that could not fill a complete row, so those
    /// trailing cells were dropped.
    #[error("dropping cells from incomplete row detected end of table")]
    TableIncompleteRow,

    /// A table row contained a cell/span that exceeded the configured column
    /// count, so the row was dropped.
    #[error(
        "dropping cell because it exceeds specified number of columns: actual={actual}, expected={expected}"
    )]
    TableCellOverflow {
        /// The row's logical column count.
        actual: usize,
        /// The configured column count.
        expected: usize,
    },

    /// A table row's logical column count did not match the configured column
    /// count, so the row was dropped.
    #[error(
        "table row has incorrect column count: actual={actual}, expected={expected}, occupied_from_rowspans={occupied_from_rowspans}"
    )]
    TableColumnCount {
        /// The row's logical column count.
        actual: usize,
        /// The configured column count.
        expected: usize,
        /// Columns already occupied by active rowspans.
        occupied_from_rowspans: usize,
    },

    /// A document header author line did not match the structured
    /// `firstname [middlename] [lastname] [<email>]` form, so the whole line
    /// was kept as a single author's name. asciidoctor accepts this silently;
    /// acdc surfaces it so a malformed author line is easy to spot.
    #[error(
        "author line `{line}` is not in `firstname [middlename] [lastname] [<email>]` form; using the whole line as a single author name"
    )]
    NonStandardAuthorLine {
        /// The author line as parsed (after attribute substitution).
        line: String,
    },

    /// A cross-reference (`<<id>>` / `xref:id[]`) points at an id that is not
    /// defined anywhere in the document. Matches asciidoctor's "invalid
    /// reference" warning.
    #[error("invalid reference: {target}")]
    UnresolvedReference {
        /// The unresolved target id.
        target: String,
    },

    /// More than one source definition uses the same ID. References keep the first.
    #[error("id already in use: {id} (first defined at {})", first_definition(.first))]
    DuplicateId {
        /// The original, unencoded ID.
        id: String,
        /// The first definition, including its original file and position.
        first: Box<SourceLocation>,
    },

    /// A named footnote is repeated with different text. The first body is retained.
    #[error("footnote '{id}' has different text from its first definition at {}; keeping the first definition", first_definition(.first))]
    ConflictingFootnote {
        /// The repeated footnote ID.
        id: String,
        /// The first definition, including its original file and position.
        first: Box<SourceLocation>,
    },

    /// A discrete heading was marked with the legacy `float` attribute rather
    /// than `discrete`. `float` is only supported because an older version of
    /// `AsciiDoc` called discrete headings "floating titles"; the current spec
    /// prefers `discrete`.
    #[error("`float` is a legacy alias for a discrete heading; prefer `discrete`")]
    LegacyFloatDiscreteHeading,

    /// A document attribute value did not match its documented domain.
    /// The previous effective value remains active.
    #[error("invalid document attribute `{name}` value `{value}`: expected {expected}")]
    InvalidDocumentAttribute {
        /// Document attribute name.
        name: String,
        /// Value as supplied by the document.
        value: String,
        /// Short description of the registered value domain.
        expected: &'static str,
    },

    /// Requested source content or substitutions were omitted, replaced, or recovered.
    ///
    /// Rendering can continue, but consumers that require complete source content
    /// must handle this condition before using the recovered document.
    #[error("{message}")]
    ContentRecovery {
        /// The recovery and the source content it affected.
        message: Cow<'static, str>,
    },

    /// Ad-hoc message not yet categorised into a typed variant.
    #[error("{0}")]
    Other(Cow<'static, str>),
}

fn first_definition(location: &SourceLocation) -> String {
    let file = location
        .file
        .as_deref()
        .map_or_else(|| "<input>".into(), std::path::Path::to_string_lossy);
    format!(
        "{file}:{}:{}",
        location.location.start.line, location.location.start.column
    )
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::Position;

    #[test]
    fn display_without_location() {
        let w = Warning::new(WarningKind::Other("something happened".into()), None);
        assert_eq!(format!("{w}"), "something happened");
    }

    #[test]
    fn display_with_location_no_file() {
        let loc = SourceLocation {
            file: None,
            location: crate::Location::point(Position::new(5, 1)),
        };
        let w = Warning::new(
            WarningKind::SectionLevelOutOfSequence {
                expected: 2,
                got: 3,
            },
            Some(loc),
        );
        assert_eq!(
            format!("{w}"),
            "line: 5, column: 1: section title out of sequence: expected level 2, got level 3",
        );
    }

    #[test]
    fn display_with_location_and_file() {
        let loc = SourceLocation {
            file: Some(std::path::PathBuf::from("/docs/guide.adoc")),
            location: crate::Location::point(Position::new(5, 1)),
        };
        let w = Warning::new(
            WarningKind::SectionLevelOutOfSequence {
                expected: 2,
                got: 3,
            },
            Some(loc),
        );
        assert_eq!(
            format!("{w}"),
            "guide.adoc: line: 5, column: 1: section title out of sequence: expected level 2, got level 3",
        );
    }

    #[test]
    fn equality_holds_on_kind_and_location() {
        let a = Warning::new(WarningKind::Other("x".into()), None);
        let b = Warning::new(WarningKind::Other("x".into()), None);
        let c = Warning::new(WarningKind::Other("y".into()), None);
        assert_eq!(a, b);
        assert_ne!(a, c);
    }

    #[test]
    fn unterminated_table_display_renders_original_token() {
        let w = Warning::new(
            WarningKind::UnterminatedTable {
                delimiter: "|===".into(),
            },
            None,
        );
        assert_eq!(
            format!("{w}"),
            "unterminated table block (opened by `|===`)",
        );
    }

    #[test]
    fn unterminated_table_display_preserves_longer_tokens() {
        let w = Warning::new(
            WarningKind::UnterminatedTable {
                delimiter: "!=====".into(),
            },
            None,
        );
        assert_eq!(
            format!("{w}"),
            "unterminated table block (opened by `!=====`)",
        );
    }
}