feat(narrated): updated narrated handler

Cargo.toml

@@ -15,6 +15,7 @@ exclude = ["images/", "tests/", "miette-derive/"]
 thiserror = "1.0.26"
 miette-derive = { path = "miette-derive", version = "=3.0.0-beta.0"}
 once_cell = "1.8.0"
+itertools = "0.10.1"
 
 owo-colors = { version = "2.0.0", optional = true }
 atty = { version = "0.2.14", optional = true }
@@ -23,7 +24,6 @@ term_size = { version = "0.3.2", optional = true }
 supports-hyperlinks = { version = "1.1.0", optional = true }
 supports-color = { version = "1.0.4", optional = true }
 supports-unicode = { version = "1.0.0", optional = true }
-itertools = { version = "0.10.1", optional = true }
 backtrace = { version = "0.3.61", optional = true }
 
 [dev-dependencies]
@@ -46,7 +46,6 @@ fancy = [
     "supports-hyperlinks",
     "supports-color",
     "supports-unicode",
-    "itertools",
     "backtrace"
 ]
 

src/handlers/narratable.rs

@@ -1,8 +1,10 @@
 use std::fmt;
 
+use itertools::Itertools;
+
 use crate::chain::Chain;
 use crate::protocol::{Diagnostic, Severity};
-use crate::{ReportHandler, SourceCode, SourceSpan, SpanContents};
+use crate::{LabeledSpan, MietteError, ReportHandler, SourceCode, SourceSpan, SpanContents};
 
 /**
 [ReportHandler] that renders plain text and avoids extraneous graphics.
@@ -11,6 +13,7 @@ non-graphical environments, such as non-TTY output.
 */
 #[derive(Debug, Clone)]
 pub struct NarratableReportHandler {
+    context_lines: usize,
     footer: Option<String>,
 }
 
@@ -18,7 +21,10 @@ impl NarratableReportHandler {
     /// Create a new [NarratableReportHandler]. There are no customization
     /// options.
     pub fn new() -> Self {
-        Self { footer: None }
+        Self {
+            footer: None,
+            context_lines: 1,
+        }
     }
 
     /// Set the footer to be displayed at the end of the report.
@@ -26,6 +32,12 @@ impl NarratableReportHandler {
         self.footer = Some(footer);
         self
     }
+
+    /// Sets the number of lines of context to show around each error.
+    pub fn with_context_lines(mut self, lines: usize) -> Self {
+        self.context_lines = lines;
+        self
+    }
 }
 
 impl Default for NarratableReportHandler {
@@ -46,13 +58,7 @@ impl NarratableReportHandler {
     ) -> fmt::Result {
         self.render_header(f, diagnostic)?;
         self.render_causes(f, diagnostic)?;
-
-        // if let Some(labels) = diagnostic.labels() {
-        //     for label in labels {
-        //         self.render_label(f, &label)?;
-        //     }
-        // }
-
+        self.render_snippets(f, diagnostic)?;
         self.render_footer(f, diagnostic)?;
         Ok(())
     }
@@ -91,22 +97,131 @@ impl NarratableReportHandler {
         Ok(())
     }
 
-    /*
+    fn render_snippets(
+        &self,
+        f: &mut impl fmt::Write,
+        diagnostic: &(dyn Diagnostic),
+    ) -> fmt::Result {
+        if let Some(source) = diagnostic.source_code() {
+            if let Some(labels) = diagnostic.labels() {
+                let mut labels = labels.collect::<Vec<_>>();
+                labels.sort_unstable_by_key(|l| l.inner().offset());
+                if !labels.is_empty() {
+                    let contents = labels
+                        .iter()
+                        .map(|label| {
+                            source.read_span(label.inner(), self.context_lines, self.context_lines)
+                        })
+                        .collect::<Result<Vec<Box<dyn SpanContents<'_>>>, MietteError>>()
+                        .map_err(|_| fmt::Error)?;
+                    let contexts = labels.iter().cloned().zip(contents.iter()).coalesce(
+                        |(left, left_conts), (right, right_conts)| {
+                            let left_end = left.offset() + left.len();
+                            let right_end = right.offset() + right.len();
+                            if left_conts.line() + left_conts.line_count() >= right_conts.line() {
+                                // The snippets will overlap, so we create one Big Chunky Boi
+                                let new_span = LabeledSpan::new(
+                                    left.label().map(String::from),
+                                    left.offset(),
+                                    if right_end >= left_end {
+                                        // Right end goes past left end
+                                        right_end - left.offset()
+                                    } else {
+                                        // right is contained inside left
+                                        left.len()
+                                    },
+                                );
+                                if source
+                                    .read_span(
+                                        new_span.inner(),
+                                        self.context_lines,
+                                        self.context_lines,
+                                    )
+                                    .is_ok()
+                                {
+                                    Ok((
+                                        new_span, // We'll throw this away later
+                                        left_conts,
+                                    ))
+                                } else {
+                                    Err(((left, left_conts), (right, right_conts)))
+                                }
+                            } else {
+                                Err(((left, left_conts), (right, right_conts)))
+                            }
+                        },
+                    );
+                    for (ctx, _) in contexts {
+                        self.render_context(f, source, &ctx, &labels[..])?;
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+
+    fn render_context<'a>(
+        &self,
+        f: &mut impl fmt::Write,
+        source: &'a dyn SourceCode,
+        context: &LabeledSpan,
+        labels: &[LabeledSpan],
+    ) -> fmt::Result {
+        let (contents, lines) = self.get_lines(source, context.inner())?;
+        write!(f, "Begin snippet")?;
+        if let Some(filename) = contents.name() {
+            write!(f, " for {}", filename,)?;
+        }
+        writeln!(
+            f,
+            " starting at line {}, column {}",
+            contents.line() + 1,
+            contents.column() + 1
+        )?;
+        writeln!(f)?;
+        for line in &lines {
+            writeln!(f, "snippet line {}: {}", line.line_number, line.text)?;
+            let relevant = labels.iter().filter(|l| line.span_starts(l.inner()));
+            for label in relevant {
+                let contents = source
+                    .read_span(label.inner(), self.context_lines, self.context_lines)
+                    .map_err(|_| fmt::Error)?;
+                if contents.line() + 1 == line.line_number {
+                    write!(
+                        f,
+                        "    label starting at line {}, column {}",
+                        contents.line() + 1,
+                        contents.column() + 1
+                    )?;
+                    if let Some(label) = label.label() {
+                        write!(f, ": {}", label)?;
+                    }
+                    writeln!(f)?;
+                }
+            }
+        }
+        Ok(())
+    }
+
     fn get_lines<'a>(
         &'a self,
-        source: &'a dyn Source,
-    ) -> Result<(Box<dyn SpanContents + 'a>, Vec<Line>), fmt::Error> {
-        let context_data = source.read_span(&snippet.context).map_err(|_| fmt::Error)?;
+        source: &'a dyn SourceCode,
+        context_span: &'a SourceSpan,
+    ) -> Result<(Box<dyn SpanContents<'a> + 'a>, Vec<Line>), fmt::Error> {
+        let context_data = source
+            .read_span(context_span, self.context_lines, self.context_lines)
+            .map_err(|_| fmt::Error)?;
         let context = std::str::from_utf8(context_data.data()).expect("Bad utf8 detected");
         let mut line = context_data.line();
         let mut column = context_data.column();
-        let mut offset = snippet.context.offset();
+        let mut offset = context_data.span().offset();
         let mut line_offset = offset;
         let mut iter = context.chars().peekable();
         let mut line_str = String::new();
         let mut lines = Vec::new();
         while let Some(char) = iter.next() {
             offset += char.len_utf8();
+            let mut at_end_of_file = false;
             match char {
                 '\r' => {
                     if iter.next_if_eq(&'\n').is_some() {
@@ -117,8 +232,10 @@ impl NarratableReportHandler {
                         line_str.push(char);
                         column += 1;
                     }
+                    at_end_of_file = iter.peek().is_none();
                 }
                 '\n' => {
+                    at_end_of_file = iter.peek().is_none();
                     line += 1;
                     column = 0;
                 }
@@ -127,7 +244,8 @@ impl NarratableReportHandler {
                     column += 1;
                 }
             }
-            if iter.peek().is_none() {
+
+            if iter.peek().is_none() && !at_end_of_file {
                 line += 1;
             }
 
@@ -143,7 +261,6 @@ impl NarratableReportHandler {
         }
         Ok((context_data, lines))
     }
-    */
 }
 
 impl ReportHandler for NarratableReportHandler {