Include real line number on command parse error

src/builder.rs

@@ -2,7 +2,8 @@ use crate::{
  execute::{CodeExecuter, ExecutionHandle, ExecutionState, ProcessStatus},
  markdown::{
  elements::{
- Code, ListItem, ListItemType, MarkdownElement, ParagraphElement, StyledText, Table, TableRow, Text,
+ Code, ListItem, ListItemType, MarkdownElement, ParagraphElement, SourcePosition, StyledText, Table,
+ TableRow, Text,
  },
  text::{WeightedLine, WeightedText},
  },
@@ -20,7 +21,7 @@ use crate::{
 };
 use itertools::Itertools;
 use serde::Deserialize;
-use std::{borrow::Cow, cell::RefCell, iter, mem, path::PathBuf, rc::Rc, str::FromStr};
+use std::{borrow::Cow, cell::RefCell, fmt::Display, iter, mem, path::PathBuf, rc::Rc, str::FromStr};
 use unicode_width::UnicodeWidthStr;
 
 // TODO: move to a theme config.
@@ -116,7 +117,7 @@ impl<'a> PresentationBuilder<'a> {
  }
 
  fn process_element(&mut self, element: MarkdownElement) -> Result<(), BuildError> {
- let should_clear_last = !matches!(element, MarkdownElement::List(_) | MarkdownElement::Comment(_));
+ let should_clear_last = !matches!(element, MarkdownElement::List(_) | MarkdownElement::Comment { .. });
  match element {
  // This one is processed before everything else as it affects how the rest of the
  // elements is rendered.
@@ -128,7 +129,7 @@ impl<'a> PresentationBuilder<'a> {
  MarkdownElement::Code(code) => self.push_code(code),
  MarkdownElement::Table(table) => self.push_table(table),
  MarkdownElement::ThematicBreak => self.push_separator(),
- MarkdownElement::Comment(comment) => self.process_comment(comment)?,
+ MarkdownElement::Comment { comment, source_position } => self.process_comment(comment, source_position)?,
  MarkdownElement::BlockQuote(lines) => self.push_block_quote(lines),
  MarkdownElement::Image(path) => self.push_image(path)?,
  };
@@ -218,11 +219,14 @@ impl<'a> PresentationBuilder<'a> {
  self.terminate_slide();
  }
 
- fn process_comment(&mut self, comment: String) -> Result<(), BuildError> {
+ fn process_comment(&mut self, comment: String, source_position: SourcePosition) -> Result<(), BuildError> {
  if Self::should_ignore_comment(&comment) {
  return Ok(());
  }
- let comment = comment.parse::<CommentCommand>()?;
+ let comment = match comment.parse::<CommentCommand>() {
+ Ok(comment) => comment,
+ Err(error) => return Err(BuildError::CommandParse { line: source_position.line, error }),
+ };
  match comment {
  CommentCommand::Pause => self.process_pause(),
  CommentCommand::EndSlide => self.terminate_slide(),
@@ -712,8 +716,8 @@ pub enum BuildError {
  #[error("need to enter layout column explicitly using `column` command")]
  NotInsideColumn,
 
- #[error(transparent)]
- CommandParse(#[from] CommandParseError),
+ #[error("error parsing command at line {line}: {error}")]
+ CommandParse { line: usize, error: CommandParseError },
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize)]
@@ -740,9 +744,18 @@ impl FromStr for CommentCommand {
 }
 
 #[derive(thiserror::Error, Debug)]
-#[error("invalid command: {0}")]
 pub struct CommandParseError(#[from] serde_yaml::Error);
 
+impl Display for CommandParseError {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ let inner = self.0.to_string();
+ // Remove the trailing "at line X, ..." that comes from serde_yaml. This otherwise claims
+ // we're always in line 1 because the yaml is parsed in isolation out of the HTML comment.
+ let inner = inner.split(" at line").next().unwrap();
+ write!(f, "{inner}")
+ }
+}
+
 #[derive(Debug)]
 struct RunCodeOperationInner {
  handle: Option<ExecutionHandle>,
@@ -949,19 +962,19 @@ mod test {
  }
 
  fn build_pause() -> MarkdownElement {
- MarkdownElement::Comment("pause".into())
+ MarkdownElement::Comment { comment: "pause".into(), source_position: Default::default() }
  }
 
  fn build_end_slide() -> MarkdownElement {
- MarkdownElement::Comment("end_slide".into())
+ MarkdownElement::Comment { comment: "end_slide".into(), source_position: Default::default() }
  }
 
  fn build_column_layout(width: u8) -> MarkdownElement {
- MarkdownElement::Comment(format!("column_layout: [{width}]"))
+ MarkdownElement::Comment { comment: format!("column_layout: [{width}]"), source_position: Default::default() }
  }
 
  fn build_column(column: u8) -> MarkdownElement {
- MarkdownElement::Comment(format!("column: {column}"))
+ MarkdownElement::Comment { comment: format!("column: {column}"), source_position: Default::default() }
  }
 
  fn is_visible(operation: &RenderOperation) -> bool {
@@ -1016,7 +1029,7 @@ mod test {
  let elements = vec![
  MarkdownElement::FrontMatter("author: bob".to_string()),
  MarkdownElement::Heading { text: Text::from("hello"), level: 1 },
- MarkdownElement::Comment("end_slide".to_string()),
+ build_end_slide(),
  MarkdownElement::Heading { text: Text::from("bye"), level: 1 },
  ];
  let presentation = build_presentation(elements);
@@ -1035,7 +1048,7 @@ mod test {
  let elements = vec![
  MarkdownElement::FrontMatter("author: bob".to_string()),
  MarkdownElement::Heading { text: Text::from("hello"), level: 1 },
- MarkdownElement::Comment("end_slide".to_string()),
+ build_end_slide(),
  MarkdownElement::Heading { text: Text::from("bye"), level: 1 },
  ];
  let presentation = build_presentation(elements);
@@ -1094,26 +1107,28 @@ mod test {
 
  #[test]
  fn layout_without_init() {
- let elements = vec![MarkdownElement::Comment("column: 0".into())];
+ let elements = vec![build_column(0)];
  let result = try_build_presentation(elements);
  assert!(result.is_err());
  }
 
  #[test]
  fn already_in_column() {
  let elements = vec![
- MarkdownElement::Comment("column_layout: [1]".into()),
- MarkdownElement::Comment("column: 0".into()),
- MarkdownElement::Comment("column: 0".into()),
+ MarkdownElement::Comment { comment: "column_layout: [1]".into(), source_position: Default::default() },
+ MarkdownElement::Comment { comment: "column: 0".into(), source_position: Default::default() },
+ MarkdownElement::Comment { comment: "column: 0".into(), source_position: Default::default() },
  ];
  let result = try_build_presentation(elements);
  assert!(result.is_err());
  }
 
  #[test]
  fn column_index_overflow() {
- let elements =
- vec![MarkdownElement::Comment("column_layout: [1]".into()), MarkdownElement::Comment("column: 1".into())];
+ let elements = vec![
+ MarkdownElement::Comment { comment: "column_layout: [1]".into(), source_position: Default::default() },
+ MarkdownElement::Comment { comment: "column: 1".into(), source_position: Default::default() },
+ ];
  let result = try_build_presentation(elements);
  assert!(result.is_err());
  }
@@ -1123,14 +1138,18 @@ mod test {
  #[case::zero("column_layout: [0]")]
  #[case::one_is_zero("column_layout: [1, 0]")]
  fn invalid_layouts(#[case] definition: &str) {
- let elements = vec![MarkdownElement::Comment(definition.into())];
+ let elements =
+ vec![MarkdownElement::Comment { comment: definition.into(), source_position: Default::default() }];
  let result = try_build_presentation(elements);
  assert!(result.is_err());
  }
 
  #[test]
  fn operation_without_enter_column() {
- let elements = vec![MarkdownElement::Comment("column_layout: [1]".into()), MarkdownElement::ThematicBreak];
+ let elements = vec![
+ MarkdownElement::Comment { comment: "column_layout: [1]".into(), source_position: Default::default() },
+ MarkdownElement::ThematicBreak,
+ ];
  let result = try_build_presentation(elements);
  assert!(result.is_err());
  }
@@ -1209,7 +1228,7 @@ mod test {
  ListItem { depth: 1, contents: "one_one".into(), item_type: ListItemType::OrderedPeriod },
  ListItem { depth: 1, contents: "one_two".into(), item_type: ListItemType::OrderedPeriod },
  ]),
- MarkdownElement::Comment("pause".into()),
+ build_pause(),
  MarkdownElement::List(vec![ListItem {
  depth: 0,
  contents: "two".into(),

src/markdown/elements.rs

@@ -39,12 +39,17 @@ pub(crate) enum MarkdownElement {
  ThematicBreak,
 
  /// An HTML comment.
- Comment(String),
+ Comment { comment: String, source_position: SourcePosition },
 
  /// A quote.
  BlockQuote(Vec<String>),
 }
 
+#[derive(Clone, Debug, Default)]
+pub(crate) struct SourcePosition {
+ pub(crate) line: usize,
+}
+
 /// The components that make up a paragraph.
 ///
 /// This does not map one-to-one with the commonmark spec and only handles text (including its

src/markdown/parse.rs

@@ -1,3 +1,4 @@
+use super::elements::SourcePosition;
 use crate::{
  markdown::elements::{
  Code, CodeFlags, CodeLanguage, ListItem, ListItemType, MarkdownElement, ParagraphElement, StyledText, Table,
@@ -97,7 +98,10 @@ impl<'a> MarkdownParser<'a> {
  }
  let block = &block[start_tag.len()..];
  let block = &block[0..block.len() - end_tag.len()];
- Ok(MarkdownElement::Comment(block.into()))
+ Ok(MarkdownElement::Comment {
+ comment: block.into(),
+ source_position: SourcePosition { line: sourcepos.start.line },
+ })
  }
 
  fn parse_block_quote(node: &'a AstNode<'a>) -> ParseResult<MarkdownElement> {
@@ -705,8 +709,8 @@ echo hi mom
 <!-- foo -->
 ",
  );
- let MarkdownElement::Comment(text) = parsed else { panic!("not a comment: {parsed:?}") };
- assert_eq!(text, " foo ");
+ let MarkdownElement::Comment { comment, .. } = parsed else { panic!("not a comment: {parsed:?}") };
+ assert_eq!(comment, " foo ");
  }
 
  #[test]