From f6199df9f923ff4baee1beac4971e7afa1bf6cec Mon Sep 17 00:00:00 2001
From: gwenn <gtreguier@gmail.com>
Date: Tue, 18 Jun 2019 19:03:13 +0200
Subject: [PATCH] Add binding to `sqlite3_collation_needed`

---
 src/collation.rs | 81 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 74 insertions(+), 7 deletions(-)

diff --git a/src/collation.rs b/src/collation.rs
index 03e9837..43ea660 100644
--- a/src/collation.rs
+++ b/src/collation.rs
@@ -1,6 +1,6 @@
 //! Add, remove, or modify a collation
 use std::cmp::Ordering;
-use std::os::raw::{c_int, c_void};
+use std::os::raw::{c_char, c_int, c_void};
 use std::panic::{catch_unwind, UnwindSafe};
 use std::ptr;
 use std::slice;
@@ -8,8 +8,6 @@ use std::slice;
 use crate::ffi;
 use crate::{str_to_cstring, Connection, InnerConnection, Result};
 
-// TODO sqlite3_collation_needed https://sqlite.org/c3ref/collation_needed.html
-
 // FIXME copy/paste from function.rs
 unsafe extern "C" fn free_boxed_value<T>(p: *mut c_void) {
     drop(Box::from_raw(p as *mut T));
@@ -26,6 +24,14 @@ impl Connection {
             .create_collation(collation_name, x_compare)
     }
 
+    /// Collation needed callback
+    pub fn collation_needed(
+        &self,
+        x_coll_needed: fn(&Connection, &str) -> Result<()>,
+    ) -> Result<()> {
+        self.db.borrow_mut().collation_needed(x_coll_needed)
+    }
+
     /// Remove collation.
     pub fn remove_collation(&self, collation_name: &str) -> Result<()> {
         self.db.borrow_mut().remove_collation(collation_name)
@@ -37,7 +43,7 @@ impl InnerConnection {
     where
         C: Fn(&str, &str) -> Ordering + Send + UnwindSafe + 'static,
     {
-        unsafe extern "C" fn call_boxed_closure<F>(
+        unsafe extern "C" fn call_boxed_closure<C>(
             arg1: *mut c_void,
             arg2: c_int,
             arg3: *const c_void,
@@ -45,12 +51,12 @@ impl InnerConnection {
             arg5: *const c_void,
         ) -> c_int
         where
-            F: Fn(&str, &str) -> Ordering,
+            C: Fn(&str, &str) -> Ordering,
         {
             use std::str;
 
             let r = catch_unwind(|| {
-                let boxed_f: *mut F = arg1 as *mut F;
+                let boxed_f: *mut C = arg1 as *mut C;
                 assert!(!boxed_f.is_null(), "Internal error - null function pointer");
                 let s1 = {
                     let c_slice = slice::from_raw_parts(arg3 as *const u8, arg2 as usize);
@@ -92,6 +98,48 @@ impl InnerConnection {
         self.decode_result(r)
     }
 
+    fn collation_needed(
+        &mut self,
+        x_coll_needed: fn(&Connection, &str) -> Result<()>,
+    ) -> Result<()> {
+        use std::mem;
+        unsafe extern "C" fn collation_needed_callback(
+            arg1: *mut c_void,
+            arg2: *mut ffi::sqlite3,
+            e_text_rep: c_int,
+            arg3: *const c_char,
+        ) {
+            use std::ffi::CStr;
+            use std::str;
+
+            if e_text_rep != ffi::SQLITE_UTF8 {
+                // TODO: validate
+                return;
+            }
+
+            let callback: fn(&Connection, &str) -> Result<()> = mem::transmute(arg1);
+            if let Err(_) = catch_unwind(|| {
+                let conn = Connection::from_handle(arg2).unwrap();
+                let collation_name = {
+                    let c_slice = CStr::from_ptr(arg3).to_bytes();
+                    str::from_utf8_unchecked(c_slice)
+                };
+                callback(&conn, collation_name)
+            }) {
+                return; // FIXME How ?
+            }
+        }
+
+        let r = unsafe {
+            ffi::sqlite3_collation_needed(
+                self.db(),
+                mem::transmute(x_coll_needed),
+                Some(collation_needed_callback),
+            )
+        };
+        self.decode_result(r)
+    }
+
     fn remove_collation(&mut self, collation_name: &str) -> Result<()> {
         let c_name = str_to_cstring(collation_name)?;
         let r = unsafe {
@@ -110,7 +158,7 @@ impl InnerConnection {
 
 #[cfg(test)]
 mod test {
-    use crate::{Connection, NO_PARAMS};
+    use crate::{Connection, Result, NO_PARAMS};
     use fallible_streaming_iterator::FallibleStreamingIterator;
     use std::cmp::Ordering;
     use unicase::UniCase;
@@ -125,6 +173,10 @@ mod test {
 
         db.create_collation("unicase", unicase_compare).unwrap();
 
+        collate(db);
+    }
+
+    fn collate(db: Connection) {
         db.execute_batch(
             "CREATE TABLE foo (bar);
              INSERT INTO foo (bar) VALUES ('Maße');
@@ -137,4 +189,19 @@ mod test {
         let rows = stmt.query(NO_PARAMS).unwrap();
         assert_eq!(rows.count().unwrap(), 1);
     }
+
+    fn collation_needed(db: &Connection, collation_name: &str) -> Result<()> {
+        if "unicase" == collation_name {
+            db.create_collation(collation_name, unicase_compare)
+        } else {
+            Ok(())
+        }
+    }
+
+    #[test]
+    fn test_collation_needed() {
+        let db = Connection::open_in_memory().unwrap();
+        db.collation_needed(collation_needed).unwrap();
+        collate(db);
+    }
 }