Added the ability to toggle ANSI styling

Author: zesterer

Cargo.toml

@@ -21,6 +21,7 @@ auto-color = ["concolor", "concolor/auto"]
 yansi = "1.0"
 unicode-width = "0.2.0"
 concolor = { version = "0.1", optional = true }
+strip-ansi-escapes = "0.2.1"
 
 [dev-dependencies]
 insta = "1.31.0"

src/draw.rs

@@ -216,6 +216,37 @@ impl<T: fmt::Display> fmt::Display for Background<T> {
     }
 }
 
+#[allow(clippy::large_enum_variant)]
+pub(crate) enum WrappedWriter<W: Write> {
+    Strip(strip_ansi_escapes::Writer<W>),
+    Keep(W),
+}
+
+impl<W: Write> WrappedWriter<W> {
+    pub(crate) fn new(w: W, config: &Config) -> Self {
+        match config.ansi_mode {
+            AnsiMode::Off => Self::Strip(strip_ansi_escapes::Writer::new(w)),
+            AnsiMode::On => Self::Keep(w),
+        }
+    }
+}
+
+impl<W: Write> Write for WrappedWriter<W> {
+    fn flush(&mut self) -> io::Result<()> {
+        match self {
+            Self::Strip(w) => w.flush(),
+            Self::Keep(w) => w.flush(),
+        }
+    }
+
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        match self {
+            Self::Strip(w) => w.write(buf),
+            Self::Keep(w) => w.write(buf),
+        }
+    }
+}
+
 /// A type that can generate distinct 8-bit colors.
 pub struct ColorGenerator {
     state: [u16; 3],

src/lib.rs

@@ -446,6 +446,15 @@ pub enum IndexType {
     Char,
 }
 
+/// Whether rendering of ANSI styling, such as color and font weight, is enabled.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum AnsiMode {
+    /// ANSI styling is disabled, diagnostics will display without styling.
+    Off,
+    /// ANSI styling is disabled, diagnostics will have ANSI styling escape codes included.
+    On,
+}
+
 /// A type used to configure a report
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct Config {
@@ -460,6 +469,7 @@ pub struct Config {
     index_type: IndexType,
     minimise_crossings: bool,
     context_lines: usize,
+    ansi_mode: AnsiMode,
 }
 
 impl Config {
@@ -544,6 +554,13 @@ impl Config {
         self.context_lines = context_lines;
         self
     }
+    /// Should ANSI escape code styling be included in the diagnostic after writing?
+    ///
+    /// If unspecified, this defaults to `AnsiMode::On`.
+    pub const fn with_ansi_mode(mut self, ansi_mode: AnsiMode) -> Self {
+        self.ansi_mode = ansi_mode;
+        self
+    }
 
     fn error_color(&self) -> Option<Color> {
         Some(Color::Red).filter(|_| self.color)
@@ -597,6 +614,7 @@ impl Config {
             index_type: IndexType::Char,
             minimise_crossings: false,
             context_lines: 0,
+            ansi_mode: AnsiMode::On,
         }
     }
 }

src/write.rs

@@ -3,7 +3,7 @@ use std::ops::Range;
 
 use crate::{Config, IndexType, LabelDisplay};
 
-use super::draw::{self, StreamAwareFmt, StreamType};
+use super::draw::{self, StreamAwareFmt, StreamType, WrappedWriter};
 use super::{Cache, CharSet, LabelAttach, Report, ReportKind, Show, Span, Write};
 
 // A WARNING, FOR ALL YE WHO VENTURE IN HERE
@@ -185,9 +185,10 @@ impl<S: Span> Report<'_, S> {
     fn write_for_stream<C: Cache<S::SourceId>, W: Write>(
         &self,
         mut cache: C,
-        mut w: W,
+        w: W,
         s: StreamType,
     ) -> io::Result<()> {
+        let mut w = WrappedWriter::new(w, &self.config);
         let draw = match self.config.char_set {
             CharSet::Unicode => draw::Characters::unicode(),
             CharSet::Ascii => draw::Characters::ascii(),
@@ -338,7 +339,7 @@ impl<S: Span> Report<'_, S> {
                 multi_labels_with_message.sort_by_key(|m| -(Span::len(&m.char_span) as isize));
             }
 
-            let write_margin = |w: &mut W,
+            let write_margin = |w: &mut WrappedWriter<W>,
                                 idx: usize,
                                 is_line: bool,
                                 is_ellipsis: bool,