From acced66e8edfe427f264b38921bb4200168301e2 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 14 May 2022 01:50:55 +0100
Subject: [PATCH] Provide toml_quote_string

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/utils.rs | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/utils.rs b/src/utils.rs
index 33da9663..d2b640bb 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -332,7 +332,30 @@ impl<Y: Sync, E: Sync, F: Sync + FnOnce() -> Result<Y,E>>
 
 // todo: DerefMut
 
-//========== toml_merge ====================
+//========== toml ====================
+
+// We reimplement this because the toml crate doesn't expose it, and
+// looking at the github issues etc. for that crate isn't encuraging.
+pub fn toml_quote_string(s: &str) -> String {
+  let mut o = String::new();
+  for c in s.chars() {
+    match c {
+      '"' | '\\'=> { o.push('\\'); o.push(c); },
+      c if (c < ' ' && c != '\t') || c == '\x7f' => {
+        write!(o, r#"\u{:04x}"#, c as u32).unwrap();
+        continue;
+      }
+      c => o.push(c),
+    }
+  }
+  o
+}
+
+#[test]
+fn toml_quote_string_test(){
+  assert_eq!(toml_quote_string(r#"w \ "	ƒ."#),
+                                r#"w \\ \"	\u0007\u007fƒ."#);
+}
 
 pub fn toml_merge<'u,
                   S: 'u + AsRef<str>,
-- 
2.30.2