Add comments and a missing CHECK_FOR_INTERRUPTS in ts_headline.

I just spent an annoying amount of time reverse-engineering the
100%-undocumented API between ts_headline and the text search
parser's prsheadline function.  Add some commentary about that
while it's fresh in mind.  Also remove some unused macros in
wparser_def.c.

While at it, I noticed that when commit 78e73e875 added a
CHECK_FOR_INTERRUPTS call in TS_execute_recurse, it missed
doing so in the parallel function TS_phrase_execute, which
surely needs one just as much.

Back-patch because of the missing CHECK_FOR_INTERRUPTS.
Might as well back-patch the rest of this too.

3 files changed, 16 insertions, 4 deletions

diff --git a/src/backend/tsearch/ts_parse.c b/src/backend/tsearch/ts_parse.c
index 27b2cca2dfb..a87b442046a 100644
--- a/src/backend/tsearch/ts_parse.c
+++ b/src/backend/tsearch/ts_parse.c
@@ -433,6 +433,8 @@ parsetext(Oid cfgId, ParsedText *prs, char *buf, int buflen)
 /*
  * Headline framework
  */
+
+/* Add a word to prs->words[] */
 static void
 hladdword(HeadlineParsedText *prs, char *buf, int buflen, int type)
 {
@@ -449,6 +451,14 @@ hladdword(HeadlineParsedText *prs, char *buf, int buflen, int type)
 	prs->curwords++;
 }
 
+/*
+ * Add pos and matching-query-item data to the just-added word.
+ * Here, buf/buflen represent a processed lexeme, not raw token text.
+ *
+ * If the query contains more than one matching item, we replicate
+ * the last-added word so that each item can be pointed to.  The
+ * duplicate entries are marked with repeated = 1.
+ */
 static void
 hlfinditem(HeadlineParsedText *prs, TSQuery query, int32 pos, char *buf, int buflen)
 {
@@ -589,6 +599,9 @@ hlparsetext(Oid cfgId, HeadlineParsedText *prs, TSQuery query, char *buf, int bu
 	FunctionCall1(&(prsobj->prsend), PointerGetDatum(prsdata));
 }
 
+/*
+ * Generate the headline, as a text object, from HeadlineParsedText.
+ */
 text *
 generateHeadline(HeadlineParsedText *prs)
 {
diff --git a/src/backend/tsearch/wparser_def.c b/src/backend/tsearch/wparser_def.c
index 826027844e7..2323a3b9086 100644
--- a/src/backend/tsearch/wparser_def.c
+++ b/src/backend/tsearch/wparser_def.c
@@ -1914,10 +1914,6 @@ prsd_end(PG_FUNCTION_ARGS)
  */
 
 /* token type classification macros */
-#define LEAVETOKEN(x)	( (x)==SPACE )
-#define COMPLEXTOKEN(x) ( (x)==URL_T || (x)==NUMHWORD || (x)==ASCIIHWORD || (x)==HWORD )
-#define ENDPUNCTOKEN(x) ( (x)==SPACE )
-
 #define TS_IDIGNORE(x)	( (x)==TAG_T || (x)==PROTOCOL || (x)==SPACE || (x)==XMLENTITY )
 #define HLIDREPLACE(x)	( (x)==TAG_T )
 #define HLIDSKIP(x)		( (x)==URL_T || (x)==NUMHWORD || (x)==ASCIIHWORD || (x)==HWORD )
diff --git a/src/backend/utils/adt/tsvector_op.c b/src/backend/utils/adt/tsvector_op.c
index addc3491518..2ccd3bdbb0e 100644
--- a/src/backend/utils/adt/tsvector_op.c
+++ b/src/backend/utils/adt/tsvector_op.c
@@ -1622,6 +1622,9 @@ TS_phrase_execute(QueryItem *curitem, void *arg, uint32 flags,
 	/* since this function recurses, it could be driven to stack overflow */
 	check_stack_depth();
 
+	/* ... and let's check for query cancel while we're at it */
+	CHECK_FOR_INTERRUPTS();
+
 	if (curitem->type == QI_VAL)
 		return chkcond(arg, (QueryOperand *) curitem, data);