make highlight friendly to English (#2417)

### What problem does this PR solve?

#2415

### Type of change

- [x] Performance Improvement

rag/nlp/__init__.py

     eng = 0
     if not texts: return False
     for t in texts:
-        if re.match(r"[a-zA-Z]{2,}", t.strip()):
+        if re.match(r"[ `a-zA-Z.,':;/\"?<>!\(\)-]", t.strip()):
             eng += 1
     if eng / len(texts) > 0.8:
         return True

rag/nlp/search.py

 
 from rag.settings import es_logger
 from rag.utils import rmSpace
-from rag.nlp import rag_tokenizer, query
+from rag.nlp import rag_tokenizer, query, is_english
 import numpy as np
 
 
             ids=self.es.getDocIds(res),
             query_vector=q_vec,
             aggregation=aggs,
-            highlight=self.getHighlight(res),
+            highlight=self.getHighlight(res, keywords, "content_with_weight"),
             field=self.getFields(res, src),
             keywords=list(kwds)
         )
         bkts = res["aggregations"]["aggs_" + g]["buckets"]
         return [(b["key"], b["doc_count"]) for b in bkts]
 
-    def getHighlight(self, res):
-        def rmspace(line):
-            eng = set(list("qwertyuioplkjhgfdsazxcvbnm"))
-            r = []
-            for t in line.split(" "):
-                if not t:
-                    continue
-                if len(r) > 0 and len(
-                        t) > 0 and r[-1][-1] in eng and t[0] in eng:
-                    r.append(" ")
-                r.append(t)
-            r = "".join(r)
-            return r
-
+    def getHighlight(self, res, keywords, fieldnm):
         ans = {}
         for d in res["hits"]["hits"]:
             hlts = d.get("highlight")
             if not hlts:
                 continue
-            ans[d["_id"]] = "".join([a for a in list(hlts.items())[0][1]])
+            txt = "...".join([a for a in list(hlts.items())[0][1]])
+            if not is_english(txt.split(" ")):
+                ans[d["_id"]] = txt
+                continue
+
+            txt = d["_source"][fieldnm]
+            txt = re.sub(r"[\r\n]", " ", txt, flags=re.IGNORECASE|re.MULTILINE)
+            txts = []
+            for w in keywords:
+                txt = re.sub(r"(^|[ .?/'\"\(\)!,:;-])(%s)([ .?/'\"\(\)!,:;-])"%re.escape(w), r"\1<em>\2</em>\3", txt, flags=re.IGNORECASE|re.MULTILINE)
+
+            for t in re.split(r"[.?!;\n]", txt):
+                if not re.search(r"<em>[^<>]+</em>", t, flags=re.IGNORECASE|re.MULTILINE): continue
+                txts.append(t)
+            ans[d["_id"]] = "...".join(txts) if txts else "...".join([a for a in list(hlts.items())[0][1]])
+
         return ans
 
     def getFields(self, sres, flds):

rag/utils/__init__.py

 
 
 def rmSpace(txt):
-    txt = re.sub(r"([^a-z0-9.,]) +([^ ])", r"\1\2", txt, flags=re.IGNORECASE)
-    return re.sub(r"([^ ]) +([^a-z0-9.,])", r"\1\2", txt, flags=re.IGNORECASE)
+    txt = re.sub(r"([^a-z0-9.,\)>]) +([^ ])", r"\1\2", txt, flags=re.IGNORECASE)
+    return re.sub(r"([^ ]) +([^a-z0-9.,\(<])", r"\1\2", txt, flags=re.IGNORECASE)
 
 
 def findMaxDt(fnm):