New reranker extraction. supporting last line.

Author: Sixzero

src/rerankers/RankingExtractor.jl

@@ -1,9 +1,10 @@
 """
 Extract rankings from LLM response content, handling various output formats.
 Returns a vector of integers representing document IDs.
-Accepted first-line formats:
+Accepted formats:
 - "[1, 2, 3]"
 - "1,2,3" (optionally space-separated), extra text after the list is ignored.
+- Checks both first and last non-empty lines
 """
 function extract_ranking(content::AbstractString; verbose::Int=0)::Vector{Int}
     content = strip(content)
@@ -12,51 +13,58 @@ function extract_ranking(content::AbstractString; verbose::Int=0)::Vector{Int}
         return Int[]
     end
 
-    # Check if content is multiline (unexpected)
+    # Get all non-empty lines
     lines = split(content, '\n')
     non_empty_lines = filter(line -> !isempty(strip(line)), lines)
+    
+    if isempty(non_empty_lines)
+        verbose >= 1 && @info "extract_ranking: No non-empty lines found"
+        return Int[]
+    end
+
     if length(non_empty_lines) > 1 && verbose >= 2
-        @info "extract_ranking: Unexpected multiline content:\n$(content)"
+        @info "extract_ranking: Multiline content, checking first and last lines"
     end
 
-    # First non-empty line
-    first_line = ""
-    for line in lines
+    # Try both first and last non-empty lines
+    lines_to_try = length(non_empty_lines) == 1 ? [non_empty_lines[1]] : [non_empty_lines[end], non_empty_lines[1]]
+    
+    for line in lines_to_try
         line = strip(line)
-        if !isempty(line)
-            first_line = line
-            break
+        result = try_extract_from_line(line; verbose)
+        if !isempty(result)
+            return result
         end
     end
-    if isempty(first_line)
-        verbose >= 1 && @info "extract_ranking: No non-empty lines found"
-        return Int[]
-    end
 
+    # Fallback: unrecognizable format - always warn with full content
+    @warn "extract_ranking: Unrecognizable format, full content:\n$(content)"
+    return Int[]
+end
+
+function try_extract_from_line(line::AbstractString; verbose::Int=0)::Vector{Int}
     # Case 1: Bracket format [1,2,3] or [1]
-    if startswith(first_line, '[')
+    if startswith(line, '[')
         local inner        
-        if endswith(first_line, ']')
-            inner = first_line[2:end-1]
+        if endswith(line, ']')
+            inner = line[2:end-1]
         else
             # take until first closing bracket if present
-            ci = findfirst(==(']'), first_line)
-            inner = ci === nothing ? first_line[2:end] : first_line[2:ci-1]
-            verbose >= 1 && @info "extract_ranking: Bracket format without closing bracket: $(repr(first_line))"
+            ci = findfirst(==(']'), line)
+            inner = ci === nothing ? line[2:end] : line[2:ci-1]
+            verbose >= 1 && @info "extract_ranking: Bracket format without closing bracket: $(repr(line))"
         end
         result = parse_number_sequence(inner; verbose)
         return result
     end
 
     # Case 2: Starts with a number (comma/space separated); take number-prefix only
-    if !isempty(first_line) && isdigit(first_line[1])
-        number_prefix = take_number_prefix(first_line)
+    if !isempty(line) && isdigit(line[1])
+        number_prefix = take_number_prefix(line)
         result = parse_number_sequence(number_prefix; verbose)
         return result
     end
 
-    # Fallback: unrecognizable format - always warn with full content
-    @warn "extract_ranking: Unrecognizable format, full content:\n$(content)"
     return Int[]
 end