Implement source chains

A SourceSpan can now contain a child SourceSpan, ad infinitum, in order
to represent a chain of locations. The report_source_issue function
has been changed to print the entire chain, instead of just one
SourceSpan.

The report_source_issue function has also been changed to correctly
print SourceSpans that extend across multiple source lines.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/locators/source.rs b/src/locators/source.rs
index 6837133..7e5abd2 100644
--- a/src/locators/source.rs
+++ b/src/locators/source.rs
@@ -9,12 +9,19 @@ pub struct SourceSpan {
     pub in_merged: SourceLocation,
     /// The location of this span in the original source file.
     pub in_source: Option<SourceLocation>,
+    /// Drill down to a more accurate location.
+    pub child: Option<Box<SourceSpan>>,
 }
 
 impl SourceSpan {
     pub fn location(&self) -> &SourceLocation {
         self.in_source.as_ref().unwrap_or(&self.in_merged)
     }
+
+    /// Wrap this source span around a child source span.
+    pub fn wrap(mut self, source: SourceSpan) -> Self {
+        self.child = Some(Box::new(source)); self
+    }
 }