Improve pretty printing of viewdefs.

Some line feeds are added to target lists and from lists to make
them more readable. By default they wrap at 80 columns if possible,
but the wrap column is also selectable - if 0 it wraps after every
item.

Andrew Dunstan, reviewed by Hitoshi Harada.

1 files changed, 135 insertions, 2 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 9ad54c5decb..64ba8ec8917 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -73,6 +73,8 @@
 #define PRETTYFLAG_PAREN		1
 #define PRETTYFLAG_INDENT		2
 
+#define PRETTY_WRAP_DEFAULT     79
+
 /* macro to test if pretty action needed */
 #define PRETTY_PAREN(context)	((context)->prettyFlags & PRETTYFLAG_PAREN)
 #define PRETTY_INDENT(context)	((context)->prettyFlags & PRETTYFLAG_INDENT)
@@ -136,6 +138,7 @@ static SPIPlanPtr plan_getrulebyoid = NULL;
 static const char *query_getrulebyoid = "SELECT * FROM pg_catalog.pg_rewrite WHERE oid = $1";
 static SPIPlanPtr plan_getviewrule = NULL;
 static const char *query_getviewrule = "SELECT * FROM pg_catalog.pg_rewrite WHERE ev_class = $1 AND rulename = $2";
+static int pretty_wrap = PRETTY_WRAP_DEFAULT;
 
 /* GUC parameters */
 bool		quote_all_identifiers = false;
@@ -381,6 +384,23 @@ pg_get_viewdef_ext(PG_FUNCTION_ARGS)
 }
 
 Datum
+pg_get_viewdef_wrap(PG_FUNCTION_ARGS)
+{
+	/* By OID */
+	Oid			viewoid = PG_GETARG_OID(0);
+	int		    wrap = PG_GETARG_INT32(1);
+	int			prettyFlags;
+	char       *result;
+
+	/* calling this implies we want pretty printing */
+	prettyFlags = PRETTYFLAG_PAREN | PRETTYFLAG_INDENT;
+	pretty_wrap = wrap;
+	result = pg_get_viewdef_worker(viewoid, prettyFlags);
+	pretty_wrap = PRETTY_WRAP_DEFAULT;
+	PG_RETURN_TEXT_P(string_to_text(result));
+}
+
+Datum
 pg_get_viewdef_name(PG_FUNCTION_ARGS)
 {
 	/* By qualified name */
@@ -3013,6 +3033,7 @@ get_target_list(List *targetList, deparse_context *context,
 	char	   *sep;
 	int			colno;
 	ListCell   *l;
+	bool        last_was_multiline = false;
 
 	sep = " ";
 	colno = 0;
@@ -3021,6 +3042,10 @@ get_target_list(List *targetList, deparse_context *context,
 		TargetEntry *tle = (TargetEntry *) lfirst(l);
 		char	   *colname;
 		char	   *attname;
+		StringInfoData targetbuf;
+		int         leading_nl_pos =  -1;
+		char       *trailing_nl;
+		int         pos;
 
 		if (tle->resjunk)
 			continue;			/* ignore junk entries */
@@ -3030,6 +3055,15 @@ get_target_list(List *targetList, deparse_context *context,
 		colno++;
 
 		/*
+		 * Put the new field spec into targetbuf so we can
+		 * decide after we've got it whether or not it needs
+		 * to go on a new line.
+		 */
+
+		initStringInfo(&targetbuf);
+		context->buf = &targetbuf;
+
+		/*
 		 * We special-case Var nodes rather than using get_rule_expr. This is
 		 * needed because get_rule_expr will display a whole-row Var as
 		 * "foo.*", which is the preferred notation in most contexts, but at
@@ -3063,8 +3097,66 @@ get_target_list(List *targetList, deparse_context *context,
 		if (colname)			/* resname could be NULL */
 		{
 			if (attname == NULL || strcmp(attname, colname) != 0)
-				appendStringInfo(buf, " AS %s", quote_identifier(colname));
+				appendStringInfo(&targetbuf, " AS %s", quote_identifier(colname));
+		}
+
+		/* Restore context buffer */
+
+		context->buf = buf;
+
+		/* Does the new field start with whitespace plus a new line? */
+
+		for (pos=0; pos < targetbuf.len; pos++)
+		{
+			if (targetbuf.data[pos] == '\n')
+			{
+				leading_nl_pos = pos;
+				break;
+			}
+			if (targetbuf.data[pos] > ' ')
+				break;
+		}
+
+		/* Locate the start of the current  line in the buffer */
+
+		trailing_nl = (strrchr(buf->data,'\n'));
+		if (trailing_nl == NULL)
+			trailing_nl = buf->data;
+		else 
+			trailing_nl++;
+
+		/*
+		 * If the field we're adding is the first in the list, or it already 
+		 * has a leading newline, or wrap mode is disabled (pretty_wrap < 0), 
+		 * don't add anything.
+		 * Otherwise, add a newline, plus some  indentation, if either the 
+		 * new field would cause an overflow or the last field used more than
+		 * one line.
+		 */
+
+		if (colno > 1 &&
+			leading_nl_pos == -1 && 
+			pretty_wrap >= 0 &&
+			((strlen(trailing_nl) + strlen(targetbuf.data) > pretty_wrap) ||
+			 last_was_multiline))
+		{
+			appendContextKeyword(context, "", -PRETTYINDENT_STD, 
+								 PRETTYINDENT_STD, PRETTYINDENT_VAR);
 		}
+
+		/* Add the new field */
+
+		appendStringInfoString(buf, targetbuf.data);
+
+
+		/* Keep track of this field's status for next iteration */
+
+		last_was_multiline = 
+			(strchr(targetbuf.data + leading_nl_pos + 1,'\n') != NULL);
+
+		/* cleanup */
+
+		pfree (targetbuf.data);
 	}
 }
 
@@ -6445,11 +6537,52 @@ get_from_clause(Query *query, const char *prefix, deparse_context *context)
 			appendContextKeyword(context, prefix,
 								 -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
 			first = false;
+
+			get_from_clause_item(jtnode, query, context);
 		}
 		else
+		{
+			StringInfoData targetbuf;
+			char          *trailing_nl;
+
 			appendStringInfoString(buf, ", ");
+			
+			initStringInfo(&targetbuf);
+			context->buf = &targetbuf;
+
+			get_from_clause_item(jtnode, query, context);
+
+			context->buf = buf;
+
+			/* Locate the start of the current  line in the buffer */
+
+			trailing_nl = (strrchr(buf->data,'\n'));
+			if (trailing_nl == NULL)
+				trailing_nl = buf->data;
+			else 
+				trailing_nl++;
+			
+			/*
+			 * Add a newline, plus some  indentation, if pretty_wrap is on and the 
+			 * new from-clause item would cause an overflow.
+			 */
+			
+			if (pretty_wrap >= 0 &&
+				(strlen(trailing_nl) + strlen(targetbuf.data) > pretty_wrap))
+			{
+				appendContextKeyword(context, "", -PRETTYINDENT_STD, 
+									 PRETTYINDENT_STD, PRETTYINDENT_VAR);
+			}
+
+			/* Add the new item */
+
+			appendStringInfoString(buf, targetbuf.data);
+			
+			/* cleanup */
+
+			pfree (targetbuf.data);
+		}
 
-		get_from_clause_item(jtnode, query, context);
 	}
 }