mant_core/mandoc/

mod.rs

//! Lowers the owned libmandoc syntax tree into `ManT`'s stable document model.

mod blocks;
mod diagnostics;
pub(crate) mod inline;
mod layout;
mod navigation;

use std::path::Path;

use libmandoc_rs::{Document, IncludePolicy, MacroSet, Node, ParseOptions, ParseReport, Parser};
use mant_ast::{
    DocumentMeta, DocumentSchema, DocumentSource, Engine, MantDocument, Producer, SourceFormat,
    SourceSpan,
};

use self::inline::{parse_roff_text, plain_text};

pub use libmandoc_rs::ParseError;

/// Parse and normalize one located man or mdoc source file.
///
/// # Errors
///
/// Returns [`ParseError`] when the source cannot be opened or parsed.
pub fn parse_manual_source(path: &Path) -> Result<MantDocument, ParseError> {
    let report = Parser::new(ParseOptions {
        includes: IncludePolicy::SourceTree,
        ..ParseOptions::default()
    })
    .parse_file(path)?;
    Ok(lower_mandoc_document(path, &report))
}

/// Convert a completed low-level parse into the stable document contract.
#[must_use]
pub fn lower_mandoc_document(path: &Path, report: &ParseReport) -> MantDocument {
    let parsed: &Document = &report.document;
    let mut context = LoweringContext::new(parsed.metadata.name.as_deref());
    let mut diagnostics = diagnostics::lower_diagnostics(&report.diagnostics);
    let mut sections = blocks::lower_sections(&parsed.root, &mut context);
    let explicit_targets = navigation::explicit_targets(&parsed.root);
    let mut retained_targets = explicit_targets.clone();
    retained_targets.extend(crate::definitions::identify_definitions(
        &mut sections,
        &explicit_targets,
    ));
    navigation::resolve_navigation(&mut sections, &retained_targets, &mut diagnostics);
    MantDocument {
        schema: DocumentSchema::V3,
        producer: Producer {
            name: "mant".to_owned(),
            version: env!("CARGO_PKG_VERSION").to_owned(),
            engine: Some(Engine {
                name: "libmandoc".to_owned(),
                version: libmandoc_rs::LIBMANDOC_VERSION.to_owned(),
            }),
        },
        source: DocumentSource {
            format: match parsed.macro_set {
                MacroSet::Mdoc => SourceFormat::Mdoc,
                MacroSet::Man | MacroSet::None => SourceFormat::Man,
            },
            path: Some(path.to_string_lossy().into_owned()),
            renderer: None,
        },
        meta: DocumentMeta {
            title: normalize_metadata(parsed.metadata.title.as_deref()),
            section: normalize_metadata(parsed.metadata.section.as_deref()),
            date: normalize_metadata(parsed.metadata.date.as_deref()),
            volume: normalize_metadata(parsed.metadata.volume.as_deref()),
            os: normalize_metadata(parsed.metadata.os.as_deref()),
            arch: normalize_metadata(parsed.metadata.arch.as_deref()),
            names: normalize_metadata(parsed.metadata.name.as_deref())
                .into_iter()
                .collect(),
            alias_target: parsed.metadata.alias_target.clone(),
        },
        diagnostics,
        blocks: Vec::new(),
        sections,
    }
}

/// Metadata strings come from roff macro arguments rather than visible text
/// nodes, so libmandoc can legitimately retain zero-width escapes such as
/// `\&`. Normalize them through the same inline decoder used for document
/// content before exposing the renderer-neutral contract.
fn normalize_metadata(value: Option<&str>) -> Option<String> {
    value.map(|value| plain_text(&parse_roff_text(value)))
}

struct LoweringContext<'a> {
    default_name: Option<&'a str>,
    next_section_id: usize,
}

impl<'a> LoweringContext<'a> {
    const fn new(default_name: Option<&'a str>) -> Self {
        Self {
            default_name,
            next_section_id: 1,
        }
    }

    fn section_id(&mut self, title: &str) -> String {
        let sequence = self.next_section_id;
        self.next_section_id += 1;
        let slug: String = title
            .chars()
            .flat_map(char::to_lowercase)
            .map(|character| {
                if character.is_alphanumeric() {
                    character
                } else {
                    '-'
                }
            })
            .collect::<String>()
            .split('-')
            .filter(|part| !part.is_empty())
            .collect::<Vec<_>>()
            .join("-");
        if slug.is_empty() {
            format!("section-{sequence}")
        } else {
            format!("{slug}-{sequence}")
        }
    }
}

fn source_span(node: &Node) -> Option<SourceSpan> {
    (node.line > 0).then_some(SourceSpan {
        line: node.line,
        column: node.column.max(1),
        end_line: None,
        end_column: None,
    })
}

fn part_children(node: &Node, kind: libmandoc_rs::NodeKind) -> &[Node] {
    node.children
        .iter()
        .find(|child| child.kind == kind)
        .map_or(&[], |child| child.children.as_slice())
}

#[cfg(test)]
mod tests {
    use std::{fs, process};

    use mant_ast::{Block, DiagnosticLevel, Inline, SourceFormat};

    use super::parse_manual_source;

    fn temporary_source(label: &str, source: &str) -> std::path::PathBuf {
        let path = std::env::temp_dir().join(format!("mant-lower-{label}-{}.1", process::id()));
        fs::write(&path, source).expect("write temporary roff fixture");
        path
    }

    #[test]
    fn lowers_man_sections_fonts_definitions_and_literal_blocks() {
        let path = temporary_source(
            "man",
            ".TH MANT 1 \"July 2026\"\n\
             .SH NAME\n\
             mant \\- a viewer\n\
             .SH OPTIONS\n\
             .TP\n\
             \\fB\\-h\\fR\n\
             Show help.\n\
             .nf\n\
             mant --help\n\
             mant git\n\
             .fi\n",
        );

        let document = parse_manual_source(&path).expect("lower man source");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert_eq!(document.source.format, SourceFormat::Man);
        assert_eq!(
            document
                .sections
                .iter()
                .map(|section| section.title.as_str())
                .collect::<Vec<_>>(),
            vec!["NAME", "OPTIONS"]
        );
        assert!(
            document.sections[1]
                .blocks
                .iter()
                .any(|block| matches!(block, Block::DefinitionList { .. }))
        );
        assert!(document.sections[1].blocks.iter().any(|block| matches!(
            block,
            Block::DefinitionList { items, .. }
                if items.iter().any(|item| item.description.iter().any(
                    |description| matches!(description, Block::Preformatted { .. })
                ))
        )));
    }

    #[test]
    fn separates_definition_layout_arguments_from_visible_terms() {
        let path = temporary_source(
            "definition-head-roles",
            ".TH HEAD-ROLES 1\n\
             .SH EXAMPLES\n\
             .TP \\w'man\\ 'u\n\
             .BI man \\ ls\n\
             Display ls.\n\
             .TP 4\n\
             4\n\
             A numeric term remains visible.\n\
             .IP \"1\" 8n\n\
             An IP width remains layout-only.\n",
        );

        let document = parse_manual_source(&path).expect("lower definition head roles");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [Block::DefinitionList { items, .. }] = document.sections[0].blocks.as_slice() else {
            panic!("expected one definition list");
        };
        assert_eq!(
            items
                .iter()
                .flat_map(|item| item.terms.iter())
                .map(|term| inline_text(term))
                .collect::<Vec<_>>(),
            ["man ls", "4", "1"]
        );
        assert!(matches!(
            items[0].terms[0].as_slice(),
            [Inline::Strong { .. }, Inline::Emphasis { .. }]
        ));
        assert!(
            items
                .iter()
                .flat_map(|item| item.terms.iter())
                .all(|term| !inline_text(term).contains("96u"))
        );
    }

    #[test]
    fn preserves_man_synopsis_flow_and_alternating_fonts() {
        let path = temporary_source(
            "man-synopsis-flow",
            ".TH MAN 1\n\
             .SH SYNOPSIS\n\
             .B man\n\
             .RI [\\| \"man options\" \\|]\n\
             .RI [\\|[\\| section \\|]\n\
             .IR page \\ \\|.\\|.\\|.\\|]\\ \\.\\|.\\|.\\&\n\
             .br\n\
             .B man\n\
             .B \\-k\n\
             .RI [\\| \"apropos options\" \\|]\n\
             .I regexp\n\
             \\&.\\|.\\|.\\&\n\
             .br\n\
             .B man\n\
             .BR \\-w \\||\\| \\-W\n\
             .RI [\\| \"man options\" \\|]\n\
             .I page\n\
             \\&.\\|.\\|.\\&\n",
        );

        let document = parse_manual_source(&path).expect("lower man synopsis");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [Block::Paragraph { children, .. }] = document.sections[0].blocks.as_slice() else {
            panic!("expected one synopsis paragraph");
        };
        assert_eq!(
            inline_text(children),
            "man [man options] [[section] page ...] ...\n\
             man -k [apropos options] regexp ...\n\
             man -w|-W [man options] page ..."
        );
        assert_eq!(
            children
                .iter()
                .filter(|node| matches!(node, Inline::LineBreak))
                .count(),
            2
        );
        assert!(children.iter().any(
            |node| matches!(node, Inline::Emphasis { children } if inline_text(children) == "man options")
        ));
        assert!(children.iter().any(
            |node| matches!(node, Inline::Strong { children } if inline_text(children) == "-w")
        ));
        assert!(children.iter().any(
            |node| matches!(node, Inline::Strong { children } if inline_text(children) == "-W")
        ));
    }

    #[test]
    fn lets_explicit_fonts_override_an_alternating_macro_default() {
        let path = temporary_source(
            "alternating-font-reset",
            ".TH MAN 1\n\
             .SH OPTIONS\n\
             .TP\n\
             .BI \\-r\\  prompt \\fR,\\ \\fB\\-\\-prompt= prompt\n\
             Set the pager prompt.\n",
        );

        let document = parse_manual_source(&path).expect("lower alternating font reset");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [Block::DefinitionList { items, .. }] = document.sections[0].blocks.as_slice() else {
            panic!("expected one definition list");
        };
        let term = items[0]
            .terms
            .first()
            .expect("first definition term")
            .iter()
            .filter(|inline| !matches!(inline, Inline::Anchor { .. }))
            .collect::<Vec<_>>();

        assert_eq!(term.len(), 5);
        assert!(matches!(term[0], Inline::Strong { children } if inline_text(children) == "-r "));
        assert!(
            matches!(term[1], Inline::Emphasis { children } if inline_text(children) == "prompt")
        );
        assert!(matches!(term[2], Inline::Text { value } if value == ", "));
        assert!(
            matches!(term[3], Inline::Strong { children } if inline_text(children) == "--prompt=")
        );
        assert!(
            matches!(term[4], Inline::Emphasis { children } if inline_text(children) == "prompt")
        );
    }

    #[test]
    fn suppresses_pod_font_requests_around_verbatim_blocks() {
        let path = temporary_source(
            "pod-verbatim-fonts",
            ".de Vb\n\
             .ft CW\n\
             .nf\n\
             ..\n\
             .de Ve\n\
             .ft R\n\
             .fi\n\
             ..\n\
             .TH POD 1\n\
             .SH EXAMPLES\n\
             .Vb 2\n\
             \\&struct A { int a; };\n\
             \\&struct B : A {};\n\
             .Ve\n",
        );

        let document = parse_manual_source(&path).expect("lower Pod::Man verbatim source");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert_eq!(document.sections[0].blocks.len(), 1);
        let Block::Preformatted { children, .. } = &document.sections[0].blocks[0] else {
            panic!("expected one preformatted block");
        };
        assert_eq!(
            inline_text(children),
            "struct A { int a; };\nstruct B : A {};"
        );
    }

    #[test]
    fn lowers_indented_aliases_without_roff_layout_arguments() {
        let path = temporary_source(
            "indented-aliases",
            ".TH CONTROL 1\n\
             .SH OPTIONS\n\
             .PD 0\n\
             .IP \"\\fB-a\\fR\" 4\n\
             .IP \"\\fB--all\\fR\" 4\n\
             Show all entries.\n\
             .PD\n\
             .in 168u\n",
        );

        let document = parse_manual_source(&path).expect("lower indented aliases");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [Block::DefinitionList { items, .. }] = document.sections[0].blocks.as_slice() else {
            panic!("expected one definition list");
        };
        assert_eq!(items.len(), 1);
        assert_eq!(
            items[0]
                .terms
                .iter()
                .map(|term| inline_text(term))
                .collect::<Vec<_>>(),
            ["-a", "--all"]
        );
        assert_eq!(items[0].description.len(), 1);
        let Block::Paragraph { children, .. } = &items[0].description[0] else {
            panic!("expected alias description paragraph");
        };
        assert_eq!(inline_text(children), "Show all entries.");
    }

    #[test]
    fn preserves_man_paragraph_distance_between_indented_paragraphs() {
        let path = temporary_source(
            "paragraph-distance",
            ".TH SPACING 1\n\
             .SH OPTIONS\n\
             .IP \"\\fB-a\\fR\" 4\n\
             First.\n\
             .IP \"\\fB-b\\fR\" 4\n\
             Second.\n\
             .PD 0\n\
             .IP \"\\fB-c\\fR\" 4\n\
             Third.\n\
             .IP \"\\fB-d\\fR\" 4\n\
             Fourth.\n\
             .PD\n\
             .IP \"\\fB-e\\fR\" 4\n\
             Fifth.\n",
        );

        let document = parse_manual_source(&path).expect("lower paragraph distance");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [Block::DefinitionList { items, compact, .. }] = document.sections[0].blocks.as_slice()
        else {
            panic!("expected one definition list");
        };
        assert!(!compact);
        assert_eq!(items.len(), 5);
        assert_eq!(
            items
                .iter()
                .map(|item| item.spacing_before_lines)
                .collect::<Vec<_>>(),
            [Some(0), Some(1), Some(0), Some(0), Some(1)]
        );
    }

    #[test]
    fn preserves_man_paragraph_and_heading_distance_as_one_layout_model() {
        let path = temporary_source(
            "vertical-layout",
            ".TH SPACING 1\n\
             .SH FIRST\n\
             First paragraph.\n\
             .PP\n\
             Second paragraph.\n\
             .SS CHILD\n\
             Child body.\n\
             .PD 0\n\
             .SS COMPACT\n\
             Compact child.\n\
             .SH NEXT\n\
             Next body.\n\
             .PD\n\
             .SH FINAL\n\
             Final body.\n",
        );

        let document = parse_manual_source(&path).expect("lower vertical layout");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [first, next, final_section] = document.sections.as_slice() else {
            panic!("expected three top-level sections");
        };
        assert_eq!(first.spacing_before_lines, 0);
        let [Block::Paragraph { .. }, Block::Paragraph { layout, .. }] = first.blocks.as_slice()
        else {
            panic!("expected two semantic paragraphs");
        };
        assert_eq!(layout.spacing_before_lines, 1);

        let [child, compact] = first.children.as_slice() else {
            panic!("expected two subsections");
        };
        assert_eq!(child.spacing_before_lines, 1);
        assert_eq!(compact.spacing_before_lines, 0);
        assert_eq!(next.spacing_before_lines, 0);
        assert_eq!(final_section.spacing_before_lines, 1);
    }

    #[test]
    fn does_not_duplicate_explicit_space_before_a_transparent_indent() {
        let path = temporary_source(
            "explicit-space-before-indent",
            ".TH SPACING 1\n\
             .SH CONTENT\n\
             Before.\n\
             .sp\n\
             .RS 4\n\
             After.\n\
             .RE\n",
        );

        let document = parse_manual_source(&path).expect("lower explicit indented spacing");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [
            Block::Paragraph { .. },
            Block::VerticalSpace { lines: 1, .. },
            Block::Paragraph { layout, .. },
        ] = document.sections[0].blocks.as_slice()
        else {
            panic!("expected prose, one explicit gap, and indented prose");
        };
        assert_eq!(layout.indent_columns, 4);
        assert_eq!(
            layout.spacing_before_lines, 0,
            "the explicit gap must not be repeated as wrapper boundary spacing",
        );
    }

    #[test]
    fn preserves_mdoc_paragraph_and_heading_distance() {
        let path = temporary_source(
            "mdoc-vertical-layout",
            ".Dd July 19, 2026\n\
             .Dt SPACING 1\n\
             .Os\n\
             .Sh FIRST\n\
             First paragraph.\n\
             .Pp\n\
             Second paragraph.\n\
             .Ss CHILD\n\
             Child body.\n",
        );

        let document = parse_manual_source(&path).expect("lower mdoc vertical layout");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let [first] = document.sections.as_slice() else {
            panic!("expected one top-level section");
        };
        assert_eq!(first.spacing_before_lines, 1);
        assert!(matches!(
            first.blocks.get(1),
            Some(Block::VerticalSpace { lines: 1, .. })
        ));
        assert_eq!(first.children[0].spacing_before_lines, 1);
    }

    #[test]
    fn lowers_mdoc_semantic_inline_nodes_and_nested_sections() {
        let path = temporary_source(
            "mdoc",
            ".Dd July 19, 2026\n\
             .Dt MANT 1\n\
             .Os\n\
             .Sh DESCRIPTION\n\
             Use\n\
             .Nm mant\n\
             with\n\
             .Xr man 1\n\
             Read\n\
             .Lk https://example.test/docs \"the documentation\"\n\
             or contact\n\
             .Mt docs@example.test\n\
             .Ss Details\n\
             .Fl h\n",
        );

        let document = parse_manual_source(&path).expect("lower mdoc source");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert_eq!(document.source.format, SourceFormat::Mdoc);
        assert_eq!(document.sections[0].children[0].title, "Details");
        let Block::Paragraph { children, .. } = &document.sections[0].blocks[0] else {
            panic!("expected description paragraph");
        };
        assert!(
            children
                .iter()
                .any(|inline| matches!(inline, Inline::Strong { .. }))
        );
        assert!(
            children.iter().any(
                |inline| matches!(inline, Inline::ManualReference { name, .. } if name == "man")
            )
        );
        assert!(children.iter().any(
            |inline| matches!(inline, Inline::ExternalLink { uri, .. } if uri == "https://example.test/docs")
        ));
        assert!(children.iter().any(
            |inline| matches!(inline, Inline::EmailLink { address, .. } if address == "docs@example.test")
        ));
    }

    #[test]
    fn resolves_mdoc_section_references_and_explicit_targets() {
        let path = temporary_source(
            "mdoc-navigation",
            ".Dd July 19, 2026\n\
             .Dt NAVIGATION 1\n\
             .Os\n\
             .Sh DESCRIPTION\n\
             Continue with\n\
             .Sx DETAILS\n\
             .Tg explicit-option\n\
             .Fl x\n\
             .Sh DETAILS\n\
             Target content.\n",
        );

        let document = parse_manual_source(&path).expect("lower navigation mdoc source");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert_eq!(document.sections[0].id, "description-1");
        assert_eq!(document.sections[1].id, "details-2");
        let Block::Paragraph { children, .. } = &document.sections[0].blocks[0] else {
            panic!("expected navigation paragraph");
        };
        assert!(children.iter().any(|inline| matches!(
            inline,
            Inline::SectionReference { target, children }
                if target == "details-2" && inline_text(children) == "DETAILS"
        )));
        assert!(children.iter().any(|inline| matches!(
            inline,
            Inline::Anchor { id } if id == "explicit-option"
        )));
    }

    #[test]
    fn degrades_unresolved_mdoc_section_references_to_text() {
        let path = temporary_source(
            "mdoc-missing-section",
            ".Dd July 19, 2026\n.Dt NAVIGATION 1\n.Os\n.Sh DESCRIPTION\n.Sx MISSING\n",
        );

        let document = parse_manual_source(&path).expect("lower unresolved navigation source");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let Block::Paragraph { children, .. } = &document.sections[0].blocks[0] else {
            panic!("expected reference paragraph");
        };
        assert_eq!(inline_text(children), "MISSING");
        assert!(
            children
                .iter()
                .all(|inline| !matches!(inline, Inline::SectionReference { .. }))
        );
        assert!(document.diagnostics.iter().any(|diagnostic| {
            diagnostic.code.as_deref() == Some("unresolved-section-reference")
        }));
    }

    #[test]
    fn turns_captured_parser_findings_into_structured_diagnostics() {
        let path = temporary_source(
            "unsupported",
            ".Dd July 19, 2026\n.Dt BAD 1\n.Os\n.Sh NAME\n.Nm bad\n.ab\n",
        );

        let document = parse_manual_source(&path).expect("best-effort parse");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert!(
            document
                .diagnostics
                .iter()
                .any(|diagnostic| diagnostic.level == DiagnosticLevel::Unsupported)
        );
    }

    #[test]
    fn lowers_normalized_ordered_lists_and_literal_displays() {
        let path = temporary_source(
            "normalized",
            ".Dd July 19, 2026\n.Dt NORMALIZED 1\n.Os\n.Sh CONTENT\n\
             .Bl -enum -compact\n.It\nfirst\n.It\nsecond\n.El\n\
             .Bd -literal -offset 6n\nline one\nline two\n.Ed\n",
        );

        let document = parse_manual_source(&path).expect("lower normalized mdoc");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert!(matches!(
            document.sections[0].blocks[0],
            Block::List {
                kind: mant_ast::ListKind::Ordered,
                compact: true,
                ..
            }
        ));
        assert!(matches!(
            document.sections[0].blocks[1],
            Block::Preformatted { layout, .. } if layout.indent_columns == 6
        ));
    }

    #[test]
    fn mdoc_definition_layout_uses_the_normalized_list_width() {
        let path = temporary_source(
            "mdoc-definition-widths",
            ".Dd July 23, 2026\n.Dt WIDTHS 1\n.Os\n.Sh ITEMS\n\
             .Bl -tag -width 20n\n.It tenletters\nwide description\n.El\n\
             .Bl -tag -width 3n\n.It short\nnarrow description\n.El\n",
        );

        let document = parse_manual_source(&path).expect("lower mdoc definition widths");
        fs::remove_file(path).expect("remove temporary roff fixture");

        let lists = document.sections[0]
            .blocks
            .iter()
            .filter_map(|block| match block {
                Block::DefinitionList { items, .. } => Some(items),
                _ => None,
            })
            .collect::<Vec<_>>();
        assert_eq!(lists.len(), 2);
        assert!(lists[0][0].inline_term);
        assert!(!lists[1][0].inline_term);
    }

    #[test]
    fn lowers_the_pinned_large_mdoc_fixture_without_empty_sections() {
        let source = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
            .join("../libmandoc-rs/vendor/mandoc-1.14.6/mandoc.1");

        let document = parse_manual_source(&source).expect("lower vendored mandoc manual");

        assert!(document.sections.len() > 5);
        assert!(
            document
                .sections
                .iter()
                .any(|section| section.title == "DESCRIPTION")
        );
        assert!(
            document
                .sections
                .iter()
                .all(|section| !section.blocks.is_empty() || !section.children.is_empty())
        );
    }

    #[test]
    fn lowers_tbl_and_eqn_payloads_into_structured_blocks() {
        let path = temporary_source(
            "table-equation",
            ".TH PAYLOAD 1\n.SH TABLE\n.TS\ntab(|);\nl r.\nleft|right\n.TE\n\
             .SH EQUATION\n.EQ\nx sup 2\n.EN\n",
        );

        let document = parse_manual_source(&path).expect("lower table and equation");
        fs::remove_file(path).expect("remove temporary roff fixture");

        assert!(matches!(
            document.sections[0].blocks[0],
            Block::Table { ref rows, .. } if rows.len() == 1 && rows[0].cells.len() == 2
        ));
        assert!(matches!(
            document.sections[1].blocks[0],
            Block::Equation { ref value, .. } if value.contains('x')
        ));
    }

    fn inline_text(children: &[Inline]) -> String {
        children
            .iter()
            .map(|child| match child {
                Inline::Text { value } | Inline::Code { value } => value.clone(),
                Inline::Strong { children }
                | Inline::Emphasis { children }
                | Inline::ExternalLink { children, .. }
                | Inline::EmailLink { children, .. }
                | Inline::ManualReference { children, .. }
                | Inline::SectionReference { children, .. } => inline_text(children),
                Inline::Anchor { .. } => String::new(),
                Inline::LineBreak => "\n".to_owned(),
            })
            .collect()
    }
}