flag for printing positions of matchesHEADmain

(instead of just printing them, might be useful for scripts — also, I've
not come up with a better name than "nixq" yet, so it really ought to be
able to query things)

1 files changed, 45 insertions, 0 deletions

diff --git a/src/changes.rs b/src/changes.rs
index 5099364..986e9c4 100644
--- a/src/changes.rs
+++ b/src/changes.rs
@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 use rowan::NodeOrToken;
 use crate::pipeline::Change;
 
@@ -174,3 +176,46 @@ fn next_indentation(node: &rnix::SyntaxNode) -> Option<usize> {
         None
     }
 }
+
+/// give line & column of a position marker in the given string
+fn line_at_textpos(content: &str, pos: rowan::TextSize) -> Option<(usize, usize)> {
+    let pos: usize = pos.into();
+    content
+        .split("\n")
+        .scan(0usize, |acc,line| {
+            let start = *acc;
+            let end = line.len() + 1 + start;
+            *acc = end;
+            Some((start, end))
+        })
+        .enumerate()
+        .find(|(_, (_, end))| *end > pos)
+        .map(|(line, (start, _))| (line + 1, pos + 1 - start))
+}
+
+pub fn format_pos(path: &PathBuf, content: &str, pos1: rowan::TextSize) -> String {
+    let (line1, col1) = line_at_textpos(content, pos1).unwrap();
+    format!("{path:?}:{line1}:{col1}")
+}
+
+pub fn format_range(path: &PathBuf, content: &str, range: rowan::TextRange) -> String {
+    let (line1, col1) = line_at_textpos(content, range.start()).unwrap();
+    let (line2, col2) = line_at_textpos(content, range.end()).unwrap();
+    format!("{}:{line1}:{col1}-{line2}:{col2}", path.to_string_lossy())
+}
+
+pub fn format_range_json(path: &PathBuf, content: &str, range: rowan::TextRange) -> serde_json::Value {
+    let (line1, col1) = line_at_textpos(content, range.start()).unwrap();
+    let (line2, col2) = line_at_textpos(content, range.end()).unwrap();
+    serde_json::json!({
+        "file": path,
+        "start": {
+            "line": line1,
+            "column": col1
+        },
+        "end": {
+            "line": line2,
+            "column": col2
+        }
+    })
+}