Expose ScanError::info.

From https://github.com/chyh1990/yaml-rust/pull/190.

parser/src/scanner.rs

@@ -21,6 +21,7 @@ pub enum TScalarStyle {
     Foled,
 }
 
+/// A location in a yaml document.
 #[derive(Clone, Copy, PartialEq, Debug, Eq)]
 pub struct Marker {
     index: usize,
@@ -33,22 +34,26 @@ impl Marker {
         Marker { index, line, col }
     }
 
+    /// Return the index (in bytes) of the marker in the source.
     #[must_use]
     pub fn index(&self) -> usize {
         self.index
     }
 
+    /// Return the line of the marker in the source.
     #[must_use]
     pub fn line(&self) -> usize {
         self.line
     }
 
+    /// Return the column of the marker in the source.
     #[must_use]
     pub fn col(&self) -> usize {
         self.col
     }
 }
 
+/// An error that occured while scanning.
 #[derive(Clone, PartialEq, Debug, Eq)]
 pub struct ScanError {
     mark: Marker,
@@ -56,6 +61,7 @@ pub struct ScanError {
 }
 
 impl ScanError {
+    /// Create a new error from a location and an error string.
     #[must_use]
     pub fn new(loc: Marker, info: &str) -> ScanError {
         ScanError {
@@ -64,10 +70,17 @@ impl ScanError {
         }
     }
 
+    /// Return the marker pointing to the error in the source.
     #[must_use]
     pub fn marker(&self) -> &Marker {
         &self.mark
     }
+
+    /// Return the information string describing the error that happened.
+    #[must_use]
+    pub fn info(&self) -> &str {
+        self.info.as_ref()
+    }
 }
 
 impl Error for ScanError {

parser/tests/basic.rs

@@ -52,7 +52,15 @@ scalar
 key: [1, 2]]
 key1:a2
 ";
-    assert!(YamlLoader::load_from_str(s).is_err());
+    let Err(error) = YamlLoader::load_from_str(s) else { panic!() };
+    assert_eq!(
+        error.info(),
+        "mapping values are not allowed in this context"
+    );
+    assert_eq!(
+        error.to_string(),
+        "mapping values are not allowed in this context at line 4 column 4"
+    );
 }
 
 #[test]