#653 - Update the loclist binary search to work with buffer numbers, to filter out items for other buffers

3 files changed, 38 insertions, 22 deletions

diff --git a/autoload/ale/balloon.vim b/autoload/ale/balloon.vim
index 3d179a0d..41fa95fa 100644
--- a/autoload/ale/balloon.vim
+++ b/autoload/ale/balloon.vim
@@ -3,7 +3,7 @@
 
 function! ale#balloon#MessageForPos(bufnr, lnum, col) abort
     let l:loclist = get(g:ale_buffer_info, a:bufnr, {'loclist': []}).loclist
-    let l:index = ale#util#BinarySearch(l:loclist, a:lnum, a:col)
+    let l:index = ale#util#BinarySearch(l:loclist, a:bufnr, a:lnum, a:col)
 
     return l:index >= 0 ? l:loclist[l:index].text : ''
 endfunction
diff --git a/autoload/ale/cursor.vim b/autoload/ale/cursor.vim
index 72351c5f..340432f7 100644
--- a/autoload/ale/cursor.vim
+++ b/autoload/ale/cursor.vim
@@ -62,10 +62,11 @@ function! ale#cursor#TruncatedEcho(message) abort
 endfunction
 
 function! s:FindItemAtCursor() abort
-    let l:info = get(g:ale_buffer_info, bufnr(''), {})
+    let l:buf = bufnr('')
+    let l:info = get(g:ale_buffer_info, l:buf, {})
     let l:loclist = get(l:info, 'loclist', [])
     let l:pos = getcurpos()
-    let l:index = ale#util#BinarySearch(l:loclist, l:pos[1], l:pos[2])
+    let l:index = ale#util#BinarySearch(l:loclist, l:buf, l:pos[1], l:pos[2])
     let l:loc = l:index >= 0 ? l:loclist[l:index] : {}
 
     return [l:info, l:loc]
diff --git a/autoload/ale/util.vim b/autoload/ale/util.vim
index adfcd476..98fe53e8 100644
--- a/autoload/ale/util.vim
+++ b/autoload/ale/util.vim
@@ -41,37 +41,52 @@ function! ale#util#LocItemCompare(left, right) abort
     return 0
 endfunction
 
-" This function will perform a binary search to find a message from the
-" loclist to echo when the cursor moves.
-function! ale#util#BinarySearch(loclist, line, column) abort
+" This function will perform a binary search and a small sequential search
+" on the list to find the last problem in the buffer and line which is
+" on or before the column. The index of the problem will be returned.
+"
+" -1 will be returned if nothing can be found.
+function! ale#util#BinarySearch(loclist, buffer, line, column) abort
     let l:min = 0
     let l:max = len(a:loclist) - 1
-    let l:last_column_match = -1
 
     while 1
         if l:max < l:min
-            return l:last_column_match
+            return -1
         endif
 
         let l:mid = (l:min + l:max) / 2
-        let l:obj = a:loclist[l:mid]
+        let l:item = a:loclist[l:mid]
 
-        " Binary search to get on the same line
-        if a:loclist[l:mid]['lnum'] < a:line
+        " Binary search for equal buffers, equal lines, then near columns.
+        if l:item.bufnr < a:buffer
+            let l:min = l:mid + 1
+        elseif l:item.bufnr > a:buffer
+            let l:max = l:mid - 1
+        elseif l:item.lnum < a:line
             let l:min = l:mid + 1
-        elseif a:loclist[l:mid]['lnum'] > a:line
+        elseif l:item.lnum > a:line
             let l:max = l:mid - 1
         else
-            let l:last_column_match = l:mid
-
-            " Binary search to get the same column, or near it
-            if a:loclist[l:mid]['col'] < a:column
-                let l:min = l:mid + 1
-            elseif a:loclist[l:mid]['col'] > a:column
-                let l:max = l:mid - 1
-            else
-                return l:mid
-            endif
+            " This part is a small sequential search.
+            let l:index = l:mid
+
+            " Search backwards to find the first problem on the line.
+            while l:index > 0
+            \&& a:loclist[l:index - 1].bufnr == a:buffer
+            \&& a:loclist[l:index - 1].lnum == a:line
+                let l:index -= 1
+            endwhile
+
+            " Find the last problem on or before this column.
+            while l:index < l:max
+            \&& a:loclist[l:index + 1].bufnr == a:buffer
+            \&& a:loclist[l:index + 1].lnum == a:line
+            \&& a:loclist[l:index + 1].col <= a:column
+                let l:index += 1
+            endwhile
+
+            return l:index
         endif
     endwhile
 endfunction