-summariseFile :: HscEnv -> FilePath
- -> Maybe (StringBuffer,ClockTime)
- -> IO ModSummary
--- Used for Haskell source only, I think
--- We know the file name, and we know it exists,
--- but we don't necessarily know the module name (might differ)
-summariseFile hsc_env file maybe_buf
- = do let dflags = hsc_dflags hsc_env
+summariseFile
+ :: HscEnv
+ -> [ModSummary] -- old summaries
+ -> FilePath -- source file name
+ -> Maybe Phase -- start phase
+ -> Maybe (StringBuffer,ClockTime)
+ -> IO ModSummary
+
+summariseFile hsc_env old_summaries file mb_phase maybe_buf
+ -- we can use a cached summary if one is available and the
+ -- source file hasn't changed, But we have to look up the summary
+ -- by source file, rather than module name as we do in summarise.
+ | Just old_summary <- findSummaryBySourceFile old_summaries file
+ = do
+ let location = ms_location old_summary
+
+ -- return the cached summary if the source didn't change
+ src_timestamp <- case maybe_buf of
+ Just (_,t) -> return t
+ Nothing -> getModificationTime file
+ -- The file exists; we checked in getRootSummary above.
+ -- If it gets removed subsequently, then this
+ -- getModificationTime may fail, but that's the right
+ -- behaviour.
+
+ if ms_hs_date old_summary == src_timestamp
+ then do -- update the object-file timestamp
+ obj_timestamp <- getObjTimestamp location False
+ return old_summary{ ms_obj_date = obj_timestamp }
+ else
+ new_summary
+
+ | otherwise
+ = new_summary
+ where
+ new_summary = do
+ let dflags = hsc_dflags hsc_env